AFO is proud to recognize outstanding student presentations at our annual meetings. To be considered for a student presentation award, see the criteria listed on the conference web site each year.
Click a year to expand for details on the award recipients:
Congratulations to the following students who received presentation awards at the 2020 NAOC virtual meeting:
Best Oral Presenation
Valentina Gomez-Bahamon, University of Illinois at Chicago, “Switches in Migratory Behavior and Speciation in Tyrant Flycatchers (Tyrannidae)”
Migratory bird species are often sister to year-round residents in the evolutionary tree of life. In theory, switches between migratory behavior and residency may result in the formation of new species because of correlated evolution among morphology, physiology and behavior. Comparative phylogenetic analyses in Tyrant Flycatchers suggest that migration has been lost more often than gained. These evolutionary transitions pass through an intermediate state in which lineages have both migratory and resident populations. Microevolutionary evidence supports this pattern showing that in Fork-tailed Flycatchers (Tyrannus savana), loss of migration has promoted shifts in breeding schedules, which coupled with geographic isolation of breeding populations has led to the evolution of premating isolation and correlated morphology. Migrant and resident birds differ in traits important for flight, such as wings and tails. In many Tyrant Flycatchers these traits are also used during displays. For instance, outer primary wing feathers differ in shape across Tyrannidae, and it has been suggested that they produce non-vocal acoustic signals. In Fork-tailed Flycatchers, outer primary wing feathers differ in the shape of a notch, which is significantly narrower in migratory birds. Behavioral studies using audio recordings and synchronized highspeed videos show that these feathers produce diverging non-vocal acoustic signals differing in pitch and amplitude. Moreover, flight simulations suggest that migratory feathers produce less turbulence when compared to those of year-round residents, suggesting that aerodynamic pressures may also affect shape evolution. Thus, loss of migration may indirectly influence conspecific communication by morphological evolution associated with flight efficiency, or vice versa.
Best Poster Presentation
Amy Strauss, University of Massachusetts Amherst, “Behavioral and Neural Responses to Far-Range Songs in a Territorial Songbird”
Acoustic signals are particularly useful for animals that communicate over distance or out of visual range of each other, as they enable long-distance interactions in real time. However, as sounds propagate over distance between signal senders and signal receivers, they are subject to distance- and habitat-dependent structural degradation. This physical phenomenon results in vocalizations that may acquire an acoustic transmission signature and provide receivers with information about singer location (’ranging hypothesis’). In territorial songbirds, the accuracy of locating singing conspecific rivals may have real fitness consequences, and the precision with which receivers can do so should depend on their perceptual discrimination abilities. In two parallel experiments, we tested acoustic distance assessment of conspecific song by song sparrows, an open habitat species. In field trials, we tested the behavioral responses of territorial males to playback of conspecific songs recorded locally at near to far ranges. In lab trials, we presented these same stimuli to anesthetized birds and measured neurophysiological activity in forebrain nuclei known to function in auditory discrimination. Results from field trials indicate that birds’ behavioral responses did not vary with degrees of stimulus degradation, suggesting that song sparrows do not rely solely on acoustic cues to determine signaler distance. Initial analyses from the electrophysiology experiments show no consistent firing differences in auditory processing nuclei in response to songs from near to far ranges, suggesting a potential perceptual limitation. We explore the potential role of habitat as a selective agent shaping neighbor localization strategies in territorial songbirds.
Congratulations to the following students who received presentation awards at the 2019 meeting:
Best Oral Presentation
Sean Mahoney, Northern Arizona University, “Assessing geographic variation in song structure and plumage coloration in the Willow Flycatcher (Empidonax traillii) species complex.”
Animals communicate their fitness as potential mates through various modalities including acoustic and visual signals. Divergence in these signals can be an important driver in speciation and can lead to reproductive isolation when characters between populations become too different for populations to recognize each other as the same species. Rigorously quantifying character divergence has recently gained more attention in ornithology, specifically with species of conservation concern such as the endangered Southwestern Willow Flycatcher (SWFL, Empidonax traillii extimus), a subspecies of the Willow Flycatcher (E. traillii). The subspecies designation was largely based on genetics, because the mtDNA C-haplotype is more frequent in SWFLs. However other aspects of the SWFL’s biology such as song and plumage coloration are incompletely known and have therefore been used to challenge its subspecific and endangered status. We assessed character divergence among willow flycatchers by 1) quantifying subspecific song structure differences, 2) tested for subspecific song recognition in male flycatchers using simulated territory intrusion playback experiments, and 3) assessed plumage differences among flycatcher subspecies by measuring spectral reflectance on museum specimens using spectrophotometry. We found 1) song differed among subspecies and SWFLs sang the most unique song, 2) individual birds responded more aggressively to songs that were structurally more similar to their own during playback experiments, and 3) subspecies exhibited plumage differences, with SWFLs occupying a unique tetrahedral colorspace relative to the other subspecies. Our results suggest SWFL song and plumage may be diverging and therefore deserve continued protection under the Endangered Species Act.
Best Poster Presentation
Patrick B. Newcombe, Sidwell Friends School, “Migratory flight on the Pacific Flyway: strategies and tendencies of wind drift compensation.”
Applications of remote sensing data to monitor bird migration usher a new understanding of magnitude and extent of movements across entire flyways. Millions of birds move through the western US, yet this region is understudied as a migratory corridor. Characterizing movements in the Pacific Flyway offers a unique opportunity to study complementary patterns to those recently highlighted in the Atlantic and Central Flyways. We use weather surveillance radar data from spring and fall (1995-2018) to examine migrants’ behaviors in relation to winds in the Pacific Flyway. Overall, spring migrants tended to drift on winds, but less so at northern latitudes and farther inland from the Pacific coastline. Relationships between winds and fall flight behaviors were less striking, with no latitudinal or coastal dependencies. Differences in the preferred direction of movement (PDM) and wind direction predicted drift patterns during spring and fall, with increased drift when wind direction and PDM differences were high. We also observed greater total flight activity through the Pacific Flyway during the spring as compared to the fall. Such complex relationships among birds’ flight strategies, winds, and seasonality highlight the variation within a migration system. Characterizations at these scales complement our understanding of strategies to clarify aerial animal movements.
Congratulations to the following students who received presentation awards at the 2018 meeting:
Best Undergraduate Presentation
Abigail Reid, Pawling High School, “Implications for using singed feathers in determining geographic origin with wildlife forensics approaches”
Despite the increasing popularity of renewable energy, utility-scale renewable energy facilities can adversely affect wildlife. Stable hydrogen isotope data (δ2H) can be used as a conservation forensics technique to infer the geographic origin of migratory animals and thus help assess the impact of such facilities on bird populations. At concentrating solar power plants, avian mortality often results from solar-flux effects, causing feather samples to be singed. Thus, it is essential to understand how heat and singeing may affect the δ2H values in feathers and subsequent geographic assignments. We heated feathers from two passerine species (Sturnella neglecta and Eremophila alpestris) in a muffle furnace in the lab at 200°C, 250°C, and 300°C for 60 seconds, and we also obtained field-singed and unsigned feathers from three different passerine species (Haemorhous mexicanus, Setophaga petechia, and Setophaga coronata) that were found dead at a concentrating solar-energy facility. The heating trials in the lab indicated significant changes in δ2H values and feather morphology at 300°C for both species. There was no consistent difference between the δ2H values of the field-singed and unsigned samples. Therefore, these preliminary results suggest that highly singed feathers should be avoided as the singeing process may alter δ2H values. However, exposure to moderate heat and singeing does not appear to dramatically alter δ2H values of feathers from passerines.
Best Graduate Presentation
William Fetzner, Texas Tech University, “The effect of whisper calls on settlement decisions in female Veeries (Catharus fuscescens)”
Emerging research has shown that many species of birds utilize low-amplitude vocalizations (LAVs) in a variety of social interactions, including male-male aggressive interactions. However, the function of these aggressive vocalizations in shaping the spatial dynamics of individuals within breeding populations remains unexplored. Since females may be attracted to settle near highly-aggressive males, LAVs may function to attract females to settle closer to males that use LAVs. Thus, to determine a putative role of LAVs in the context of territory establishment, I experimentally tested the function of LAVs in the settlement decisions of a migratory songbird (Veery; Catharus fuscescens) in a forest soundscape. Twenty sites were manipulated using playbacks of previously recorded male songs. Half of these sites had a 6-minute track that played back LAVs (i.e., whisper calls) after approximately every five songs while the other half broadcasted only the male song as the control treatment. Thirty nests were found during the 4-week experiment (20 near whisper call sites, 10 near control). Although nesting in proximity (within ~150m) to whisper call sites was marginally significant (P = 0.048), females nested at whisper call sites more often and earlier in the breeding season, and whisper call sites had higher numbers of breeding females in near proximity. These findings support the increasing number of studies that have shown LAVs to be aggressive signals in songbirds. However, this is the first study to experimentally show how a low-amplitude, aggressive signal can affect female settlement decisions.
Congratulations to the following students who received presentation awards at the 2017 meeting:
AFO undergraduate student oral presentation awards
Thays Vernoica Prestes, Universidade Federal do Paraná, Brasil, “Behavioral responses of urban birds to anthropogenic disturbance in green areas in Curtiba, Paraná, Brazil”
Proximity to humans can influence behaviors that are essential in a bird’s life, such as breeding, foraging and flight. In urban parks, which are important natural shelters to birds, human activity varies broadly in time such that attentiveness and escape behavior of birds may be intensified when density of humans increases. In this study, we tested this hypothesis in six green urban areas at Curitiba, S Brazil and using three common urban bird species as models, the Rufous Hornero (Furnarius rufus), the Southern Lapwing (Vanellus chilensis) and the Rufous-bellied Thrush (Turdus rufiventris). More specifically, we tested if foraging rate, alert distance (AD), flight initiation distance (FID) and flight distance (FD) are related to the number of humans within a bird’s home range area. Through linear mixed model, we found no influence of humans on birds foraging rate, whereas AD, FID and FD decreased with human density in the bird’s surroundings. We also found differences in birds escape strategy; “flying” strategy was associated with higher AD, FID and FD than “walking” strategy. Results also indicate that bird’s vigilance and flight responses were temporally affected by human presence and apparently reflect a strategy that ensures constant foraging rate irrespective of human density. Our study provides evidence of behavioral plasticity of the model species to the intensity of human use of their living area, which also highlights the importance of further efforts in creating refuges within these urban parks to minimize anthropic impacts on urban species.
Waleska E. dos Santos Barbosa, Instituto Nacional de Pesquisas da Amazonia, “Molecular systematic and biogeography of the Synallaxis rutilans species complex”
The Amazon has some of the highest levels of bird diversity of the world; however, phylogeographic studies show that this diversity is underestimated. The Synallaxis rutilans Temminck, 1823, species complex deserves attention for presenting a restricted distribution in the Amazon basin, and does not have a satisfying taxonomic resolution. The most recent taxonomic review for this species complex used morphological characters and recognized three taxons: rutilans, amazonica and omissa, and proposed the validation of S. omissa as a species, because of plumage differences and restrict geographic distribution to the Belém endemism area. For a better understanding of the evolution process in this complex we did phylogeographic and population analysis, sequencing two mitochondrial markers for 86 individuals, consisting of all taxons in this complex. The phylogenetic analysis recovered a well-supported topology by Bayesian inference with seven evolutionary lineages, whose distribution is delimited by the Amazon river’s main tributaries. The diversification of these lineages started at about 1.5 Ma at the Pleistocene. The population structure analysis recovered six populations. The populations of Belem and Xingu endemism area were grouped in the same population. The haplotype network showed that the lineages of the north Amazon river do not share haplotypes with the lineages of the south, the lineages of the opposite sides of the Negro River also do not share haplotypes. The historical demographic reconstruction of this complex showed that there was no population expansion or retraction over time. The molecular results corroborate the underestimated diversity of this group according to the current taxonomy.
Paulo Sergio Pereira de Amorim, Faculdade de Ciências da Educação e Saúde, UniCEUB, Brasil, “Experimental influence of a non-vocal signal on the vigilance of the Scaled Dove”
In social contexts, information exchange between individuals is an efficient mechanism to avoid predation and coordinate escape attempts. Different signs are recognized in avian communication, such as chemical, visual and acoustic. Considering acoustic signals, the role of non-vocal communication in antipredatory contexts have been overlooked and needs to be better exploited. The scaled dove (Columbina squammata) is a cryptic bird that gathers in flocks and produces a strong mechanical sound during takeoff flights. Previous study demonstrated that the emission of the non-vocal sound was related to the presence of a potential threat and that it influences the response of the other group members. In this context, we tried to experimentally evaluate the effect of the non-vocal signal on the vigilance of the C. squammata. The experimental manipulation was based on the emission of three different playbacks (treatments): (1) C. squammata takeoff flight sound (non-vocal signal), (2) vocalization of C. squammata and (3) vocalization of the sympatric species Troglodytes aedon musculus. After each treatment, the vigilance rate of the focal individual was recorded during five minutes. Results demonstrated that the non-vocal signal significantly enhanced the vigilance rate of the focal animal when compared to the other treatments. Considering the observed results, it is possible to infer that the non-vocal signal of C. squammata must have an important role on the communication, being used to transmit valuable information about predation risk.
AFO undergraduate student poster presentation awards
Bruno Riovitti, Universidad de Buenos Aires, Argentina, “Lower begging efficiency can constrain host use in the specialist Screaming Cowbird”
A generalist strategy of use of hosts by avian brood parasites requires that parasitic chicks be able to survive in a broad range of hosts. Coevolution with any particular host may constrain host use if increased specialization results in a lower efficiency of parasitic chicks to successfully exploit other host species. To test this idea we compared the begging efficiency of the specialist screaming cowbird (Molothrus rufoaxillaris) and the generalist shiny cowbird (M. bonariensis) in an alternative host, the chalk-browed mockingbird (Mimus saturninus). We manipulated mockingbird nests during breeding seasons 2010- 2011 y 2011-2012 to create two-chick broods as follows: one mockingbird and one screaming cowbird, one mockingbird and one shiny cowbird and two mockingbirds. Experimental broods were filmed on days 4 (n = 12, 17 and 24 for each treatment, respectively) and 8 (n = 6, 13 and 19) post-hatching to record the feeding frequency and begging intensity and duration of all chicks. Overall nest provisioning rates (feeding/h) did not differ among treatments at any age. The proportion of feedings received by cowbird and host chicks did not deviate from the random expectation of 0.5. However, screaming cowbird chicks had to strive harder to obtain food as they begged for significantly longer periods than shiny cowbird and mockingbird chicks. Furthermore, screaming cowbird-broods, but not shiny cowbird-broods, were more likely to be depredated than unparasitized ones. Our findings suggest that the lower begging efficiency of screaming cowbird chicks, which results in increased predation costs, can constrain colonization of new host species.
Florencia E. Curzel, Universidad de Buenos Aires, Argentina, “Wooded street use by birds in Buenos Aires city: the role of local characteristics and urban parks connectivity”
Every day, the urban environment expands on rural and natural areas. Therefore, knowing the environmental factors that determine bird diversity in urban areas is essential for the management and design of sustainable cities. In this study, we analyze how birds use wooded streets in the Buenos Aires city. We selected 26 wooded streets with different levels of tree cover, human disturbance (pedestrian and car traffic) and degree of connectivity with urban parks. We analyzed the relationship between bird richness, taxonomic and functional diversity and the environmental variables using Generalized Linear Models. We also modeled the standardized effect size of functional diversity to evaluate the environmental filtering variation on wooded streets. Bird richness, taxonomic and functional diversity were negatively related to human disturbance, whereas taxonomic diversity was positively related to urban parks connectivity and to tree height and its variation. The environmental filtering was greater on streets with a large amount of pedestrians, which were dominated by omnivorous birds that foraged gregariously on the ground. Results suggest that an urban design with streets connected with parks and having taller trees and a greater tree height variation would contribute to greater bird diversity. Moreover, the level of human disturbance caused by pedestrian traffic should be controlled to avoid a decrease of bird ecosystem functions.
Facundo Fermandez-Duque, Cornell University, “Plumage ornamentation as a potential driver of behavioral differences in a dichromatic passerine”
In sexually dimorphic species, energetically demanding traits can serve as an honest sexual signal, benefiting males with increased ornamentation. Although possibly a survival handicap, ornamentation may improve fitness by increasing reproductive opportunities. Conversely, conspicuous colorations may improve fitness if, by openly conveying that the individual is a difficult food source, they improve survival. It follows that exaggerated ornamentation may create selective pressures that affect the two phenotypes differently. Therefore, it can be predicted individuals of polymorphic species may show intra-species behavioral differences (predator avoidance, niche partitioning, grouping) to match their phenotypes. In this study we examined whether the ornamentation of male red-backed fairywrens (Malurus melanocephalus) was related to an increase in certain behaviors. We conducted focal observations (n=276) on bright (n=8) and cryptic males (n=55) during the nonbreeding season to compare basal behavioral differences. We found that bright plumage was related to increases in the time spent preening (12.1 ± 2.7 s), allo-preening (5.7 ± 1.6 s), courtship displays (8.1 ± 1.6 s), flying (2.5 ± 0.8 s), and sitting (11.1 ± 5.1 s). Of these five statistically significant results, three seem to be more biologically significant when extrapolated to a daily time allocation. Bright males spent 58, 53, and 39 minutes more than dull males per day preening, sitting, or displaying, respectively, but only 27 and 12 minutes/day moreallo-preening and flying. Preening and displaying have a direct connection to mate attraction, supporting the idea that exaggerated ornamentation positively alters sexual behaviors rather than vigilance or anti-predatory behavior.
AFO graduate student oral presentation awards
Young Ha Suh, Cornell University, “Potential mechanisms that influence first-breeding site selection and quality”
In cooperatively breeding species that delay dispersal, the proximate mechanism that drives variation in dispersal timing and subsequent selection is often unclear. We studied potential mechanisms that drive differences in first-time territory acquisition in the cooperative breeding, permanently territorial corvid, the Florida Scrub-Jay (Aphelocoma coerulescens, FSJ). A habitat specialist confined to fire-maintained, early successional oak scrub, FSJs experience increased fitness in high quality habitat in terms of recent fire history and amount of oak scrub available in the territory. We hypothesized that competition for the highest quality habitats helps explain the observed variation in timing of territory acquisition and in territory quality acquired by novice breeders. We examined three potential mechanisms – social dominance, duration of delay in dispersing, and mode of territory acquisition – that could affect territory acquisition. The hypotheses predicted that 1) more dominant and 2) older individuals disperse into higher quality habitat, and 3) certain acquisition modes are associated with habitat quality. We also predicted that males and females would differ. Using long-term data from Archbold Biological Station, FL, we looked at 439 individuals that became breeders between 1980 and 2015. We used linear mixed models to test for fixed and random effects. The results of the models showed that while dominance was not a significant predictor, the predictors sex, age at first breeding, and territory acquisition type were associated with differences in territory quality overall. This suggests that various mechanisms influence individual habitat selection, contributing to the variation observed.
Pedro Diniz, Universidade de Brasilia, “Duetting, extra-pair paternity and reproductive success in the Rufous Hornero”
Although intensively studied, we still have little consensus about the direct fitness consequences of vocal duetting. Some studies suggest that duetting functions in acoustic mate guarding to prevent cuckoldry, whereas other studies argue that duetting is a cooperative behavior to defend common territories. Thus, duetting parameters presumably could reflect territory quality and a pair’s reproductive success. We investigated extra-pair paternity and the relation among song traits, territory quality and reproductive success in the rufous hornero (Furnarius rufus), a Neotropical, socially monogamous bird. We found a lower than average rate of extra-pair paternity (3.33% of 120 offspring and 6.52% of 46 broods), and 100% apparent nest success. Female song (rate, output and latency to answer partner-initiated song) was positively correlated with territory size and quality, as reflected in amount and proportion of territory foraging patches. Duet duration, but not rate, was positively correlated with territory size. Our results suggest that female song and the pair duet are used in the defense of food resources within territories, or enable the acquisition of high quality and large territories. However, neither features of female song, male song, or duets, nor territory features correlated with reproductive success (number of social fledglings and post-fledging survival) in this species, suggesting that song or territory might affect fitness in other ways, such as in juvenile development or adult survival.
Laura Maria Schaedler, Universidade Federal do Paraná, Brazil, “Singing in unison: duets and choruses in Blue Manakins”
Acoustic signals are widespread in several animals and evolved as an important communication channel. Here, we studied sounds produced by blue manakins (Chiroxiphia caudata) and described its acoustic repertoire. We tested if our description based on visual inspection of spectrograms can be discriminated by five acoustic parameters of frequency (kHz) and time. We also described for the first time a synchronized vocal behavior in this species produced prior to the cooperative dance of males in lek areas. We classified and quantified the synchronization type and rate of this sound production. We recorded vocalizations and behavioral data at Mananciais da Serra Protected Area (Piraquara-PR), Brazil, and performed a linear discriminant analysis after extracting their acoustic parameters. We described ten vocalizations associated with eight behaviors and synchronized sounds, i.e. “duets” and “choruses”. Differently from other congeners, we found a large variation in this behavior. Synchronizations were antiphonal, overlapped or both and males also varied on the quantity of vocalizations emitted per bouts, ranging from two to 13 notes of three types in a sequence (3.3±1.84, n=141). Our study provided evidence that, within all Pipridae species, choruses are exclusive of blue manakins since two or more males can perform this behavior together. Although it is not clear how males choose their partners to perform together due to variation on the identity of males attending display courts, the high variation found in duets/choruses suggests that synchronization is an important factor in female attraction.
AFO graduate student poster presentation awards
Cecília Licarião Luna, Universidade Federal do Ceará, “Body condition and abundance of endemic passerines of Fernando de Norohna, Brazil”
Habitat quality – resource availability and environmental conditions – affects body condition of birds, and when altered can lead to population decline and extinctions. Thus, we evaluated body condition and abundance of Noronha Elaenia (Elaenia ridleyana) and Noronha Vireo (Vireo gracilirostris) in anthropic and preserved areas in Fernando de Noronha, and sampled vegetation cover and food resource availability. We measured body condition (weight, fat, feather wear, ectoparasites, brood patch and cloacal protuberance) of 45 Noronha Elaenia and 52 Noronha Vireo, food resource availability (10 sample points of malaise trap and 20 of entomological umbrella) and vegetal cover (20 sample points). We observed that feathers were worn in the anthropic area for Noronha Elaenia (X2 = 15.2647; p = 0.009) and Noronha Vireo (X2 = 13.1024; p = 0.0042) and a greater number of Noronha Elaenia individuals with brood patches in the preserved area. The abundance of Noronha Elaenia and Noronha Vireo was greater in the preserved area (GLMM Chi2 = 9.9121, p = 0.001, GLMM Chi2 = 56.615, p <0.000, respectively), being associated with the vegetation cover. The anthropization process, with less food resource availability and vegetation cover in the anthropic area (t = -2.8959, df = 304.76, p-value = 0.004; F = 24.755, p = 0.001, respectively) may be leading to changes in body condition in Noronha Elaenia and Noronha Vireo. Our findings might assist with conservation and management actions, providing ecological information of endemic and threatened species exposed to habitat alteration.
Juan Manuel Rojas Ripari, Universidad de Buenos Aires, Argentina, “Response to nest predation risk in a cooperative breeder the Grayish Baywing”
Cooperative breeding is a reproductive system in which one or more adults (helpers) assist others in caring for young. Helpers typically participate in nest provisioning and defense, but individual contribution to parental care may vary broadly within and among cooperative groups. We studied group and individual responses to nest predation risk using a model presentation experiment in a banded-population of a facultative cooperative breeder, the Greyish Baywing (Agelaioides badius). We presented taxidermic mounts of a nest predator (Milvago chimango) and control species (Mimus saturninus, Paroaria coronarta and Colaptes melanochloros) to 13 Baywing nests at the nestling stage. Models were presented sequentially in random order for three minutes, with a 20-min resting interval between presentations. Presentations were filmed and observed from a hide to record the latency to first approach and individual behaviors towards each model. Baywings responded faster and more aggressively to predator than control models. Helper presence had no effect on the latency to approach predator models. Mobbing frequency was higher in the presence of helpers than for breeding pairs alone, but per capita rate of attacks was similar for breeding pairs and trios, suggesting an additive effect of helpers on nest defense. Breeding females mobbed predator models more frequently than males, but individual contribution to mobbing varied broadly both within and among groups. These results suggest that helpers did not improve predator detection but enhance defensive response. Further research on the genetic relationships within cooperative groups will help to explain individual contribution to nest defense.
Luiz Henrique Varzinczak, Universidade Federal do Paraná, Brazil, “Assessing nestedness for insular bird assemblages: contrasting island area and isolation for multiple dimensions of biodiversity”
The Theory of Island Biogeography has focused on the effects of island area and isolation as determinants of the taxonomic diversity found in these ecosystems. However, species are not independent from each other in their evolutionary and ecological relatedness. Thus, it is essential to use an approach that simultaneously considers the multiple dimensions of biodiversity to understand the patterns of diversity in insular assemblages. We tested the effects of island area and isolation from the mainland in taxonomic, phylogenetic and functional nestedness among nine insular bird assemblages in southern Brazil. We used a framework designed for dealing with nested structures of communities, in which species-poor sites are expected to be subsets of the richest ones. We compiled literature data on bird species composition for each island, and assessed the phylogenetic and functional nestedness through a phylogenetic tree and a dendrogram of species similarities, respectively. We found that, for these three components of biodiversity, island area is the main driver of nestedness among assemblages, indicating that smaller islands are not only inhabited by subsets of species, but they also present a subset of evolutionary lineages and functional diversities. Results on the influence of isolation on community structure were all non-significant. Island area is thought to be a proxy for habitat diversity, thus it is likely that a subset of diversity at smaller islands arises as consequence of their low diversity of habitats, which in turn should reflect a lower number of bird species and low phylogenetic and functional diversities.
Congratulations to the following students who received presentation awards at the 2016 NAOC:
AFO Best Oral Presenations
Santiago David, University of British Columbia, “Foraging niche structure and coexistence in a highly diverse community of Amazonian antbirds (Thamnophilidae: Aves)”
The high species richness of antbirds (Thamnophilidae) in Amazonian lowlands, where as many as 40 species may coexist at local scales, represents a major challenge to ecologists for explaining patterns of coexistence and niche evolution. I studied foraging ecology of a local community of antbirds in a 2-Km2 area in SE Peru to examine how co-occurring species differ in their use of foraging resources, and whether these differences result in niche partitioning at the community level. I also examine whether resource use similarity is related to phylogenetic similarity. Forty-four antbirds were detected in the plot in a four-year period, with 30 species categorized as a local assemblage of common resident breeders. Multivariate analysis of foraging parameters showed that segregation at two height layers in two forest type was more important than foraging substrates and maneuvers in explaining the differences in foraging behavior. However, a null model analysis revealed that at the community level, antbirds exhibited high foraging niche overlap, with average observed overlap significantly larger than expected by chance, indicating that antbirds prefer, rather than avoid, resources used by other species. No general relationship exists between phylogenetic similarity and niche overlap. Closely related species consistently exhibit high values of niche overlap, but some distantly related species also exhibit high niche similarity. Taken together, these results suggest that foraging niche similarity is the predominant pattern among co-occurring antbirds, and that positive interactions might explain the stable coexistence of species that use similar resource and habitats at a local scale.
Glenn Seeholzer, Louisiana State University, “Complex patterns of population divergence underly dramatic phenotypic cline in an Andean songbird”
Clinal phenotypic variation provides a window into the processes shaping population divergence. Phenotypic clines are commonly observed along environmental gradients where phenotypic and environmental variation are correlated. Such correlations provide some of the most-widespread evidence for natural selection’s role in population divergence, particularly when an underlying adaptive scenario links the correlated variables. Yet, correlated phenotypic and environmental variation alone is insufficient to claim selection because phenotypic clines can also be generated by neutral processes (e.g. isolation-by-distance). Genomic data can help distinguish between these alternatives by providing information on population connectivity and history. To investigate these issues we collected ~5,000 SNP’s from across the genome of the Linecheeked Spinetail (Cranioleuca antisiensis), a striking example of rapid divergence and morphological adaptation to elevation. C. antisiensis is distributed in the central Andes along an elevational gradient (950 – 4300 m) spanning dramatically different environments, along which its mass increases clinally more than twofold (12.5 to 30 g). We found a strong signal of isolation-by-distance along three distinct genetic clines that were correlated with mass even after controlling for geographic distance. This suggested that loci in our dataset were under selection, violating assumptions of neutrality. To identify these putatively adaptive loci we employed a Bayesian outlier detection algorithm and whole genome association analysis. When these adaptive loci were excluded, we found that the phenotypic variation was greater than expected given neutral genetic variation, indicating an adaptive origin of the phenotypic cline.
AFO Outstanding Undergraduate Poster Presentation Award
Akshay Deverakonda, College of William & Mary, “Spatial Breeding Ecology of Wood Thrush Mating Pairs”
AFO Outstanding Graduate Student Poster Presentation Award
Stephanie Chin, College of William & Mary, “The Effect of Dietary Methylmercury on the Parental Care of a Model Avian Species”
AFO Outstanding Student Oral Presentation Awards
Jennifer McCabe, University of Maine-Orono, “Using an individual-based particle trajectory model to examine wind patterns as a major driver in the evolution and maintenance of North America’s migratory divides
Desiree Narango, University of Delaware, “Behavioral Responses to Non-Native Vegetation by Carolina Chickadees in Residential Landscapes”
Congratulations to the following students who received presentation awards at the 2014 meeting:
AFO Outstanding Student Oral Presentation Award
Sarah Goodwin, University of Massachusetts at Amherst, “Team of rivals: alliance formation in territorial songbirds is predicted by vocal signal structure”
AFO Outstanding Student Poster Award
Crissa Cooey, West Virginia University, “Age and Gender Population Demographics for Managed and Unmanaged Double-crested Cormorants in Lake Michigan”
AFO award for an outstanding poster presented by an undergraduate
John Szot, Villanova University, “Song recognition in Black-capped and Carolina chickadee hybrids: an experimental approach”
AFO Outstanding Poster Award (not from a university)
Kyle Davis, Big Walnut High School (working with Jed Burtt, Ohio Wesleyan University), “Changes in the Feather Microbiota in the Nest Lining of Tree Swallows (Tachycineta bicolor) During the Reproductive Cycle”
Congratulations to the following students who received presentation awards at the 2013 AFO meeting at Archbold Biological Station in Venus, Florida.
Best Oral Presentations
BLAKE JONES, University of Memphis, “Stress response correlates with learned antipredator behavior in free-living Florida Scrub-Jays (Aphelocoma coerulescens).”
The extent to which animals learn and retain information about predators, and the mechanisms that mediate these processes, remain largely unexplored. Corticosterone (CORT), the avian glucocorticoid, is released in response to stressful stimuli, including perception of a predator. Elevated CORT facilitates physiological and behavioral changes over the short-term that can enhance survival and, over the long-term, can a/ect memory function. 0us, CORT is a likely candidate to mediate learned antipredator behavior. Florida Scrub-Jays (FSJ) exhibit intraspeci.c variation of stress induced plasma CORT levels, which are repeatable within individuals. We used the FSJ as a model to test two hypotheses: 1) FSJs have the capacity to learn antipredator behavior and 2) CORT responsiveness is predictive of antipredator behavior. We developed a model to test for, and compare CORT responsiveness to, learned antipredator behavior in free-living FSJs. Compared to control birds, Individuals who were previously exposed to an arti.cial novel “predator” displayed longer flight initiation distances (FID) and alarm called more frequently in response to the novel “predator.” Also, CORT responsiveness was positively correlated with FID. These data indicate FSJs can learn to associate a novel “predator” stimulus as a threat after a single exposure, and that stress physiology is related to this cognitive process.
MARJORIE LIBERATI , Ohio State University (Co-author: Dr. Robert Gates), “Habitat selection and nesting ecology of Northern Bobwhite in Ohio.”
Local abundance of breeding Northern Bobwhites (Colinus virginianus) has increased with grasslands created through the Conservation Reserve Program but positive range-wide population growth has not occurred. Ohio’s bobwhite population experienced a 90% population decline after severe winters in 1976–1977 and 1977–1978 and populations continued at a 76% decline during 1984–2004. Radio-marked adult bobwhites were monitored during the breeding season (1 May –30 Sep, 2010–2011) on four private-lands study sites located in southwest Ohio. Eighty-six percent of nests (n = 52) were located in grassland habitats. Nest success was 27.9% and daily nest survival (96.9%) was not in2uenced by nesting habitat, nest initiation date, year, or study site. Row crop was the most abundant habitat type (41%) within breeding season home range areas, but was generally avoided. Early successional (ES) woody habitat (e.g., fencerows and ditches) was the most highly selected habitat type at all spatial scales. Grassland habitat was th e next most selected habitat type. Selection of forest and ES woody habitats diminished at study sites where these habitats had mature canopies and poorly developed understories. Future bobwhite management strategies should focus on providing more ES woody cover within landscapes because it can provide year-round bene.ts. Continuing to providing grassland habitat for bobwhites during the breeding season should not be abandoned due to its lower selection ranking because it provides important nesting habitat. Providing proximate ES woody cover near grasslands would enhance breeding habitat quality for bobwhites in Ohio and other areas of the Midwestern United States.
Best Poster Presentation
MOLLY GRACE, University of Central Florida (Co-author: Dr. Rindy Anderson), “Songbirds’ acoustically complex notes may facilitate communication in noisy urban areas.”
In an increasingly urban world, noise pollution creates communication challenges for wildlife. Loud, low-frequency traffic noise can mask songbird vocalizations, and populations of some urban songbird species have shifted the frequency of their vocalizations upward in response, which is energetically costly. However, acoustically complex notes have a quasi-harmonic frequency structure that may make them resistant to masking, suggesting that species that use them could be more successful in areas with high levels of traffic noise. Based on this idea, we hypothesized that complex notes are not produced at higher frequencies in response to traffic noise. We recorded Carolina Chickadees (Poecile carolinensis), whose calls feature complex ‘D’ notes, along a traffic noise gradient in Durham and Orange Counties, North Carolina, USA. There was no correlation between the frequency of ‘D’ notes and the level of noise in which they were recorded, implying that a frequency shift is not required for complex notes to be communicated in noise. Understanding how complex notes are affected by traffic noise will increase our ability to predict how the expansion of noisy areas may impact songbird community composition in the future.
Congratulations to the following students who received presentation awards at the 2012 NAOC meeting in Vancouver, B.C., Canada.
Best Oral Presentation
LEONARDO CALLE, M.S. Candidate, Florida Atlantic University (Advisor: Dr. Dale Gawlick), “Predicted changes in foraging habitat of the Little Blue Heron.”
Wading birds are restricted to feeding in shallow water because of their leg-length constraint, making them sensitive to small changes in water depth. In coastal systems, this sensitivity is pronounced because tidal fluctuations control both the spatial and temporal extent of available foraging habitat. Our objective was to determine the risk of the Little Blue Heron (Egretta caerulea) to sea level rise within the boundaries of the Great White Heron National Wildlife Refuge, in the Florida Keys, USA. Our approach to the problem was to develop a tide-driven simulation model to estimate foraging habitat availability (FHA). The FHA model incorporated fine-scale information on water depths used by the Little Blue Heron, predicted changes in habitat availability from the Sea Level Rise and Accretion Model, under 3 sea level rise scenarios. We validated the model’s ability to predict available foraging habitat using locations of foraging Little Blue Herons (N=509) observed during 14 surveys (Dec 2010–Jul 2011). Parameters to which the model was most sensitive were foraging water depth window, tide height, and the time of low tide, respectively. The model performed moderately well (78% correct classification using survey-specific FHA estimates) to very well (94% correct classification using mean annual FHA estimates) at predicting available foraging habitat. The majority (57%) of Little Blue Herons foraged at areas with tide-specific FHA values of >7 hectare-minutes. Under all three sea level rise scenarios daily foraging habitat declined, with the most severe declines occurring between 2050 and 2075. Our results may be liberal because we excluded mangrove islands as foraging habitat. We suspect that as mangrove habitats become inundated for longer periods of time they will become suitable foraging areas, if they are not already. The fine temporal scale of the FHA model (from a single-tide to ays, months) makes it potentially useful for addressing short- and longterm stressors to multiple wading bird species resulting from human disturbance or sea level rise. However, the sensitivity of the model to very small changes in tide height underscore the importance of having improved estimates of sea level rise at the local level.
Best Poster Presentation
KATHARINE BATDORF, M.S. Candidate, The Ohio State University (Advisors: Paul Rodewald & Stephen Matthews), “Are all birds moving poleward? Understanding distributional shifts in Ohio’s breeding birds.”
Research on the effects of environmental changes on avian distributions is essential in predicting, managing, and conserving bird populations. Several recent studies have reported poleward shifts in bird distributions which are likely associated with a warming climate. However, only a few such studies have used fine-scaled regional data such as that generated by Breeding Bird Atlas projects, only one of which is from North America (New York State). The American Midwest presents different species assemblages and landscapes relative to these previous studies. Our study provides an opportunity to test whether poleward trends in avian distributions observed in other regions transcend these ecological differences. We used detailed grid-based data collected during two Ohio Breeding Bird Atlas projects (1982–1987, 2006–2011) to quantify changes in latitudinal extent, center of occurrence, and occupancy in 94 species within Ohio over ~25 years. Individual species demonstrated dramatic latitudinal changes in their distributions, with the centers of occurrence of 53% of species examined shifting north or south by more than 10km. Despite these results, our analyses did not show a significant poleward shift in distributions across species, although, on average, northern extent and center of occurrence of southerly species did shift north by 4.6km and 8.6km, respectively (p>0.10). Additionally, we found evidence of southward shifts in northerly species, with southern extents and center of occurrence shifting on average 19.6km and 6.5km south, respectively (p<0.05). Although northerly and southerly species did not differ significantly in occupancy changes, we found that for southerly species, the change in occupancy was positively associated with the proximity of a species’ distributional range boundary to our study area (p<0.05). This suggests that species along the northern periphery of their range gained more blocks than species for which Ohio is more central in their distribution. Poleward shifts in avian distributions may be more difficult to detect in our study because additional factors such as land cover change may affect distributions more strongly on this finer scale or within Ohio‘s largely human-utilized landscape. Our future analyses will attempt to partition variance in both climate and land cover change to elucidate environmental determinants of the changes we observed in Ohio‘s breeding bird distributions.
A copy of Kate’s poster can be viewed HERE.
Congratulations to the following students who received presentation awards at the 2011 AFO/COS/WOS meeting in Kearney, Nebraska.
Best Oral Presentation
CARA JOOS , Ph.D. Candidate, Division of Biological Sciences, University of Missouri, Columbia, MO (Advisor: Dr. John Faaborg), “Settlement order and productivity of Bell’s Vireo (Vireo bellii bellii).”
Assessing habitat quality is important in population studies because habitat quality influences the fitness of its occupants. We need a better understanding of the factors that influence fitness in order to make informed habitat management decisions. The ideal despotic distribution model hypothesizes that individuals select high quality territories first. This selection pattern should result in increased fitness of earlier arriving individuals, therefore territory settlement order will predict fitness of occupants. Cara and her co-authors estimated fitness as “productivity,” measured as total number of chicks fledged per territory and then tested if territory settlement date, the date the first egg was laid, whether males were philopatric or not, or Brown-headed Cowbird (Molothrus ater) abundance predicted productivity in a population of individually marked Bell’s Vireos (Vireo bellii bellii) in central Missouri. Prior to the arrival of vireos on their breeding grounds, Cara systematically searched territories for newly arriving males and noted the band combinations of returning occupants and color-banding as many new territory owners as possible. Next, she located and monitored nests to record the date that first eggs were laid and the number of chicks fledged. She also conducted point counts to estimate cowbird abundance. Cara found that both early arrival and nest initiation to be important predictors of productivity. Productivity declined with settlement date and first egg date but settlement date may be the more important of the two. For example, if two territories have the same first egg date, the one that was settled earlier will have higher productivity. Cara’s findings support the ideal despotic distribution model in which settlement order predicts fitness. Thus, if territory quality is a function of habitat features Cara’s results will allow us to better define high quality Bell’s Vireo habitat and allow land managers to make informed management decisions.
Best Poster Presentation
J. RYAN SHIPLEY, Oklahoma Biological Survey, University of Oklahoma, Norman, OK (Advisor: Dr. Jeff Kelly), “Why is there a gap in the breeding range of the Painted Bunting?”
Explaining the factors that influence a bird species’ breeding range is an enduring problem in ornithology. Ryan’s research focused on trying to explain the breeding range of the Painted Bunting (Passerina ciris) a small Neotropical migrant songbird that occurs in two disjunct breeding populations in the United States. The larger population occurs primarily in the states of Texas, Oklahoma, and Arkansas whereas a smaller population exists along the Atlantic coast in North Carolina, South Carolina, and Georgia. Although landscapes vary greatly between these two regions, no obvious climatological or geographic features exclude Painted Buntings from occupying the gap between them. To investigate explanations for the disjunction of these breeding populations, Ryan and his co-authors at the Oklahoma Biological Survey used species distribution modeling to determine if the bioclimatic envelope derived from breeding location data would occupy the region where the species is currently absent. In addition, they used winter presence data to delineate regions with suitable conditions on the breeding ground during spring arrival and examined historical origins of this gap in the breeding range by modeling current distribution variables onto two Last Glacial Maximum (ca. 21,000 years ago) paleoclimate models. The results suggest that (a) a bioclimatic explanation does not explain the gap between the current breeding distributions and (b) the species exhibits niche tracking within these breeding regions. In addition, the paleoclimate distribution reconstructions suggest that the species’ migratory distance was historically shorter than it is at present, and that two, or possibly three populations may have previously existed in western Mexico, the Yucatan Peninsula, and southern Florida. These different glacial refugia may help explain the differences in molting schedules and migratory behavior seen in the two present breeding populations.
Congratulations to the following students who received presentation awards at the 2010 AFO meeting in Ogden, Utah.
Best Oral Presentations (2 awards)
JASON M. TOWNSEND, Ph.D. Candidate, State University of New York College of Environmental Science and Forestry (Advisor: Dr. James Gibbs), “Catharus thrushes as bioindicators of mercury hotpots: from the Catskills to the Caribbean.”
Jason’s research documented mercury bioaccumulation in a densely forested watershed of the Catskill Mountains, NY. Mercury is a potent neurotoxin that accumulates in the environment as a result of global atmospheric pollution. While many studies have documented mercury accumulation in aquatic ecosystems, little is known about mercury cycling in strictly terrestrial ecosystems. Jason’s study showed that mercury accumulation in the soil and leaf litter increased with elevation in this watershed. Thrushes of the genus Catharus, which are arrayed along this elevational gradient, also showed increased blood mercury content with increasing elevation. High elevation Bicknell’s Thrushes (C. bicknelli) and Swainson’s Thrushes (C. ustulatus) showed significantly greater blood mercury levels than did lower elevation congeners, Hermit Thrush (C. guttatus) and Veery (C. fuscescens). This finding could have particularly important health and conservation implications for Bicknell’s Thrush, which is generally restricted to forests above 1000 m in the northeastern United States. Furthermore, blood mercury levels in all species declined with season, indicating that early-season thrushes either carry mercury from their winter grounds or consume a diet higher in mercury during the early part of the breeding season (May–June 15). An additional analysis of mercury in Bicknell’s Thrushes wintering on Hispaniola showed the highest blood mercury levels of any birds in this study and also wide, site-specific variance, potentially reflecting local pollution patterns.
LINDA LAIT, M.S. Candidate, University of Lethbridge (Advisor: Dr. Theresa Burg), “The population structure and postglacial expansion of the Boreal Chickadee (Poecile hudsonicus).”
Explaining the geographic distribution of birds is an enduring pursuit in ornithology. Linda’s research examines the geographic distribution of Boreal Chickadees across northern North America. During the last glacial period, much of North America was covered by large ice sheets. Throughout this time, both fauna and flora survived in ice-free regions known as refugia. Two large refugia were known to have existed in North America—one south of the ice sheets, and one in Beringia (western Alaska). A number of smaller, disputed refugia may have also been present on both the east and west coasts of Canada. Many studies have looked at how mountain ranges and large bodies of water can act as barriers to gene flow. Obstacles such as these may have impacted the recolonization following the melting of the ice sheets, and may still play a role in limiting dispersal. The Boreal Chickadee (Poecile hudsonicus) is a small songbird that resides in the boreal forests of Canada and the northern United States. Linda used mitochondrial DNA from both field and museum samples covering all of the chickadee’s range to study the postglacial expansion of this species, and how physical barriers may affect the population structure. The mitochondrial DNA showed a general east/west split in the populations; the British Columbia/ Alberta/Alaska populations forming a ‘western haplogroup’ while the Newfoundland/Nova Scotia/ New Brunswick/Quebec populations form an ‘eastern haplogroup’. The Rocky Mountains do not appear to have acted as a barrier to dispersal in this species. Interestingly, both Alaska and Newfoundland were found to be distinct from all other populations. Microsatellite data supports Newfoundland as a distinct population, with little variation seen within the mainland populations.
Best Poster Presentation
CHRISTOPHER J. W. MCCLURE, Ph.D. Candidate, Auburn University (Advisor: Dr. Geoffery E. Hill), “Interpreting Breeding Bird Survey data in the face of climate change.”
Most bird monitoring programs rest on an assumption that bird species are not becoming harder (or easier) to detect as years go by. One can imagine that if a species is growing progressively quieter each time a survey is conducted, fewer individuals will be detected with each survey. This trend in fewer individuals being detected could then be misinterpreted as a population decline. Such a systematic change in bird detectability – the probability of detecting a bird, given that it is present – seemed unlikely until recently. Studies have shown that many bird species are breeding and migrating earlier, presumably due to climate change. Because bird song rate is tied to breeding stage, a progressively earlier breeding date could potentially shift the timing of peak song rate, thus causing birds to be progressively harder (or easier) to detect during survey dates each year. To address this issue, Chris and his co-authors first had to determine how bird detectability changes within a single breeding season. They used audio recordings within their study site in Tuskegee National Forest, AL to examine seasonal changes in the detectabilities of 31 species during the breeding season of 2008. Next, they calculated the effect of a one-week shift in breeding activity by shifting the timing of peak detectability one week later and determining the effect of that shift on the detectability of each species during the month of June and then tested whether changes in detectability were correlated with population trends reported using Breeding Bird Survey data within the state of Alabama. Chris’s results indicated that migrant species show greater variation in detectability than year-round residents within a breeding season. Therefore a shift in breeding date should cause migrant detectability to decline more sharply during fixed survey dates than resident detectability. However, their assumed annual changes in detectability were not correlated with the population trends reported by Breeding Bird Survey data within the state of Alabama. Chris and his co-authors concluded that the Breeding Bird Survey is a useful index of bird populations.
Best Undergraduate Poster Presentation
LUIS E. VARGAS, Universidad de Costa Rica (Advisor: Dr. Gerardo Ávalos), “Forest structure and territory size relationship in the neotropical understory insectivore White-breasted Wood-wren”
Ornithologists have long been interested in the factors that affect territory size in birds. The Neotropical terrestrial insectivore Henicorhina leucosticta (Troglodytidae) maintains long-term territories through vocalizations and forages among leaf litter trapped in the understory vegetation and ground litter. As part of a Research Experience for Undergraduates project, Luis, a 2008 graduate of the Universidad de Costa Rica, studied the relationship between forest structure and H. leucosticta territory size in La Selva Biological Station, Costa Rica, during the non-breeding season in 2009. Forest structure was measured by assessing canopy openness and leaf area index (LAI) using hemispherical photography. Territory size was estimated with playbacks using local conspecific vocalizations. Luis and his co-authors found that territory size decreased as median LAI within a territory increased. Since LAI indicates the foliage area over the respective area of ground, territories with higher LAI are more likely to have greater leaf fall and leaf litter accumulation over the understory plants. The leaves trapped over the understory plants, the ‘areal leaf litter’, provide an important reservoir of arthropods available to understory insectivorous birds. Moreover, H. leucosticta frequently searches for nest materials within the areal leaf litter. Therefore, the long-term capacity of a given territory to supply enough arthropod prey and nest material is of great importance and likely to affect territory size, with larger territories found where there is relatively lower LAI, and consequently lower supply of food and nest materials. Within the context of the ‘structural cues hypothesis’, which proposes that birds adjust territory size using habitat structure as a predictor of prey abundance within a given site, Luis suggests that greater LAI in tropical rainforests can be used to infer higher arthropod abundance or more potential prey microhabitats for H. leucosticta, as well as other insectivorous birds with similar foraging behavior. Luis is currently in the process of applying to graduate school where he intends to study animal communication.
Congratulations to the following students who received presentation awards from AFO at the joint meeting of the AFO and the Wilson Ornithological Society in Pittsburgh, Pennsylvania.
Best Oral Presentations (3 awards)
ALEJANDRO RICO-GUEVERA, Ph.D. Candidate, University of Connecticut (Advisor: Dr. Margaret Rubega), “Evolutionary insights about the bill structure of nectivores”
Alejandro’s research is focused on the evolutionary ecology of nectar-feeding birds. He is especially interested in both the morphological and ecological adaptations of nectivores and integrates the morphological study of museum specimens with performance experiments to test the functional significance of various traits. The research project he presented at the AFO meeting was aimed at examining the link between feeding mechanisms and social systems of nectivores. Studying arthropod foraging in hummingbirds with Gary Stiles, he decided to closely study hummingbird bills and found a puzzling set of hidden bill traits and hypothesized how those traits could be involved in feeding performance and social organization. Encouraged by his advisor, Margaret Rubega, Alejandro expanded his survey to all specialized nectivorous birds and found evolutionary convergences not previously reported. Features that improved feeding efficiency included structures finely tuned by physical laws in the nectar extraction process (e.g., forward projecting serrations, flexible tomia, and internal projections). Other traits, related to social systems, are sexually dimorphic backward serrations, bill tip daggers and hooks that Alejandro hypothesized were used as weapons by males during fights for resources. In short, nectivory in birds seems to favor the evolution of novel traits by coupling bill and tongue morphology to affect high nectar extraction efficiency, while dominance interactions over resources seems to favor the evolution of weapons in males.
JASON HILL, Ph.D. candidate, Pennsylvania State University (Advisor: Dr. Duane Diefenbach), “Post-fledging movement, behavior, and habitat use of adult Saltmarsh Sharp-tailed Sparrows”
The behavior of birds during the post-fledging period is largely mysterious. Jason studied the postfledging movement and habitat use of adult female Saltmarsh Sharptailed Sparrows (Ammodramus caudacutus) in Connecticut. This globally red-listed species occurs only in salt marshes along the Atlantic coast of the U.S., and is highly unusual in a number of regards. Both males and females are non-territorial and males provide absolutely no parental care—females do it all. Salt marshes are highly productive ecosystems, which allow females to raise 3-5 young per brood. Tidal flooding often accounts for greater than 50% of nest loss for this ground-nesting species. To study the behavior and habitat use of females, Jason radio-tracked female sparrows during the post-fledging period when they were providing care to fledglings that cannot fly for the first week or so. He also sampled vegetation where he daily flushed females and also in random locations within each female’s home range. Females, on average, used ~ 0.5 ha of space during this time. They used areas of the marsh quite unlike what they use for nesting habitat. Nests are generally placed in areas of relatively high ground towards the center of the marsh. Jason thinks that this strategy may minimize nest losses from flooding and nest predation by mammals such as raccoons and house cats patrolling the edge of the marsh. During the post-fledging period, however, females moved towards the edge of the marsh and were strongly associated with artificial ditches and natural channels. At low tide these water features generally empty out exposing mud that is likely to be a highly productive foraging area. In addition, these water features often have very tall vegetation (e.g., Spartina alterniflora) growing in them that may provide cover for the fledglings. Moving towards the edge of the marsh may also reduce drowning risks for fledglings before they are able to fly. These findings demonstrate the importance of using a broader view when describing and protecting a species’ “breeding” habitat. Female Saltmarsh Sharp-tailed Sparrows use a very different habitat during the nesting and post-fledging periods. Management and conservation strategies should recognize this broader view of “breeding” habitat to ensure the long-term survival of this species.
SARAH KINGSTON, Ph.D. candidate, University of Maryland and National Museum of Natural History (Advisor: Dr. William Fagan), “Genome–wide levels of introgression and divergence across Mexican Towhee hybrid zones”
Sarah is interested in the evolutionary importance of introgression of genes across species boundaries and the interaction of hybridization with available habitat. To study this problem, Sarah’s research focuses on hybrid zones between two towhee species, the Spotted Towhee (Pipilo maculatus) and Collared Towhee (Pipilo ocai), in montane habitat in Mexico. These two species hybridize in two main areas: the Teziutlán and Transvolcanic gradients. The towhee system is a unique and interesting one to address questions about the evolutionary importance of introgression. A unique characteristic of the towhees in Mexico is an intersection of the two different hybrid areas and an area just south of the peak of hybridization, where each parental species exists in sympatry, but shows little evidence of interbreeding. This special area of sympatry offers an opportunity to contrast the habitats associated with hybridization and lack of hybridization. Much of the morphological variation across the hybrid gradients has been quantified, but a broad genome survey has not been completed. Sarah used a genomic approach to assess the prevalence of introgression in these towhee hybrid zones. Multi-locus analyses revealed not only a genetic differentiation between parental types, but also the divergence of populations within the areas of hybridization. Sarah also found evidence of bi-directional introgression across the species boundary which indicates that this boundary is porous to a portion of the genome. Finally, Sarah’s research with towhees suggests that the exchange of genes between species may be an important factor along the evolutionary trajectory of species.
Best Poster Presentation
KRISTEN M. LEAR, Undergraduate, Ohio Wesleyan University (Advisor: Dr. Jed Burtt), “Netting Methods Influence Age Distribution in Samples of Cliff Swallows.”
The way in which an organism is captured may affect the subset of the population sampled. When sampling birds such as Cliff Swallows (Petrochelidon pyrrhonota), mist netting is often the preferred method of capture. Because the birds must fly into the net, the sample population could be biased for traits associated with such flights. Kristen and her collaborators set out to determine whether their netting method influenced the subset of the population they captured. They set up mist nets at the opening of the culverts within which Cliff Swallows establish large nesting colonies. To determine if netting methods influenced the identity of birds captured they either allowed Cliff Swallows to voluntarily fly into nets as they exited the culverts or actively flushed them into nets. Flushing involved walking through a colony and driving the birds into the net. Flushing may eliminate the potentially skewed results given by voluntary capture. Data collected from 3 sites, using a summed sample size of 3,062 birds, found that flushed birds tended to be older than birds that made voluntary flights into the nets. Kristen’s results show that the method of netting can give a skewed perspective of a population’s age structure and that researchers who use mist nets should keep this in mind when asking questions about population dynamics.
Competition was stiff for the student presentation awards at the joint meeting of the AFO and the Wilson Ornithological Society in Mobile, Alabama in April 2008. Congratulations to the following students who stood out and received presentation awards from AFO.
Best Oral Presentations (3 awards)
MEGAN FITZPATRICK, Undergraduate, Albion College (Advisors: Douglas W. White and E. Dale Kennedy), “The Effects of Thermal Environment on Incubation Behavior in House Wrens (Troglodytes aedon)”
MIKAELA G. HOWIE, M.S. degree candidate, William and Mary College (Advisor: Dr. Dan Cristol), “The infiltration of aquatic mercury into a terrestrial ecosystem”
RYAN BURDGE, M.S. degree candidate, William and Mary College (Advisor: Dr. Dan Cristol), “Eastern Bluebirds on golf courses: nestling pesticide exposure and diet”
Best Poster Presentation:
ERIK JOHNSON, Ph.D. candidate, Louisiana State University (Advisor: Dr. Phil Stouffer), “Ectoparasites affect bird condition in neotropical forest fragments”;
2007: Outstanding student presentation awards were presented for the first time ever at the 2007 annual meeting of the AFO at the University of Maine in Orono. Students received a two-year memberships in the AFO. In addition, Wiley-Blackwell Publishing Co., W.H. Freeman Publishing Co., Sinauer Publishing Co., Oxford University Press and Princeton University Press all donated prizes (books) for students. The AFO is most grateful to these companies. Student presentation awards will now be a regular and prominent feature of annual AFO meetings.
Best Oral Presentations
SUSAN B. SMITH, University of Rhode Island, “Influence of diet and food availability on fuel use and storage in songbirds during autumn migration in Rhode Island”
ANDREA TOWNSEND, Cornell University, “A test of the genetic benefits hypothesis for extra-pair paternity in the American Crow”
Best Oral Presentations – Honorable Mention:
BRENT HORTON, University of Maine, “Corticosterone as a factor in parental behavior in male White-throated Sparrows”
JASON TOWNSEND, SUNY-ESF, Syracuse, “Bicknell’s Thrush overwinter ecology in the Dominican Republic”
Best Poster Presentation:
JULIA MACKENZIE, Anglia Ruskin University in Cambridge, UK, “Impact of non-native flora on breeding success of Blue and Great Tits”