Using radios and models to assess extinction risk in a Neotropical highland Cinclodes

 

What do the patterns of space use tell us about the risk of extinction of a species? This relationship is certainly strong. The number of individuals (population size) and the geographical range are among the main criteria for assessing the conservation status of a species by the IUCN (International Union for Conservation of Nature), and the knowledge about the habitats used is crucial for protecting the natural resources their need to survive.

Our research investigated population and spatial aspects of a largely unknown Neotropical passerine: Cipo Cinclodes (Cinclodes espinhacensis). It is a recently described Furnariidae from the mountains of Serra do Cipó, a locality at the long Espinhaço Range that rise in east Brazil. Most of the ~16 species of the South American ovenbird genus Cinclodes have restricted geographic ranges in the mountains or coastal rocky beaches, many living in extreme environments. A challenge to study the spatial ecology of Cipo Cinclodes was precisely to reach such extreme and isolated environments in the highlands of east Brazil and visit them enough to find populations and monitor individuals. To assist our research, we used two very useful tools in ecological studies: the radiotelemetry and the Species Distribution Modeling. Each of those operating in one of the two scales that our study was conducted: the individual distribution scale and species distribution scale, respectively.

Researchers setting up mist nets on rock outcrops to capture Cipo Cinclodes. Photo credit: Guilherme H. S. Freitas.

Radiotransmitters of only 1.7 g attached to birds were valuable to follow individuals of the Cipo Cinclodes along eight months. At this scale, we collected information on their population and spatial ecology distribution. We found that Cipo Cinclodes have relatively large home ranges (mean = 9.3 ha). The population density appears to be intermediate to those of other Cinclodes. Home range areas were occupied mostly by pairs, but some with unpaired males, which resulted in a male-skewed adult sex ratio. Cipo Cinclodes used all habitat types available in our study area, which is covered by the campos rupestres (rocky fields or rupestrian grasslands), a landscape mosaic where grasslands and rock outcrops predominate. However, habitat selection analyses revealed the importance of streams (margins and streambed) for foraging, and the rocky outcrops are fundamental for nesting. Complementary data collected in this population allow us to detect long-term fidelity in terms of home ranges, mates, and nest sites.

A Cipo Cinclodes captured with a radiotransmitter fitted. Photo credit: Lílian M. Costa.

The modeling was fundamental for our study at the species distribution scale to make the best use of the relatively small number of known and novel recorded locations to predict the Cipo Cinclodes geographical range. We used the area predicted by the species distribution model to estimate upper limits of IUCN parameters to assess the species’ conservation status. We estimated the sizes of the extent of occurrence (EOO) and the area of occupancy (AOO): the former is a continuous area encompassing all the occurrence points, while the latter is the sum of the smaller areas actually occupied by the species. Next, we estimated the global population size combining the AOO with the density data collected in the individual distribution scale. The three estimates, including their upper values, indicated that the species occur in a very small area, and probably has a small global population size, meeting the thresholds of the IUCN’s ‘Endangered’ category.

This study revealed important biological aspects of a Cinclodes species, a group of data-deficient birds in South American. Besides that, our study also contributed to bringing a new methodological approach in how to collect data on a rare Neotropical bird to better understand their biology and to access their conservation status.

A researcher tracking radiotransmitter signals. Photo credit: Guilherme H. S. Freitas.

A banded and radio-tagged Cipo Cinclodes. Photo credit: Guilherme H. S. Freitas.

Part of the study area in Serra do Cipó where we monitored a Cipo Cinclodes population. In this campos rupestres (rocky fields or rupestrian grasslands) landscape, rock outcrops and grasslands predominate, and riparian habitats were the most selected habitat by Cipo Cinclodes. Photo credit: Guilherme H. S. Freitas.

 

Linked paper: Freitas, G. H., Costa, L. M., Silva, P. H., Chaves, A. V., Ribeiro, L. C. and Rodrigues, M. 2019. Spatial ecology and conservation of the microendemic ovenbird Cipo Cinclodes (Cinclodes espinhacensis) from the Brazilian highlands. Journal of Field Ornithology. https://doi.org/10.1111/jofo.12296.

Related paper: Freitas, G. H., Chaves, A. V., Costa, L. M., Santos, F. R. and Rodrigues, M. 2012. A new species of Cinclodes from the Espinhaço Range, southeastern Brazil: insights into the biogeographical history of the South American highlands. Ibis, 154: 738-755. https://doi.org/10.1111/j.1474-919X.2012.01268.x.

 

Follow the authors on Twitter:

Lílian M. Costa: @LiliMaCosta
@espinhacensis

 

Guest post by:

Lílian M. Costa, Guilherme H. S. Freitas, and Marcos Rodrigues