Population and community dynamics of birds in “intact” Amazonia

Collaborators: Phil Stouffer, Cameron Rutt, Patty Rodrigues, Ryan Burner, et al.

In 2015 I started my PhD work in the lab of Phil Stouffer, who spent nearly 30 years leading the bird effort at the Biological Dynamics of Forest Fragments Project (BDFFP). As the name implies, the BDFFP was established to study the effects of forest disturbance on Amazonian biota. Over the nearly four decades of this effort, we gained a lot of understanding about what happens to birds when you cut rainforest into small pieces—see Phil’s overview here (spoiler: not good for birds). As my contribution to the BDFFP research, I focused my dissertation on the continuous primary forest at the BDFFP. More than 90% of the area is forested, most of that forest has never been cut, and bird data were collected there as controls for the fragment work.

Overall, research categorized under this “project” is a diverse set of efforts with several collaborators. Besides the bits that form my dissertation chapters, I touch on papers we wrote with Phil, Cameron, and Patty, along with a range of other coauthors. The overarching goal of this research is to understand the biological dynamics of “intact” Amazonia, taking advantage of the long-term data collected within primary forest. What we are beginning to notice is that direct disturbance such as deforestation is not the only threat to the vast Amazonian ecosystem—we see evidence of change even in what should be intact forest. Although the investigation is ongoing, these shifts are most likely tied to climate change.

What’s the story with birds in “intact” forest over the last 40 years?

After nearly five years in the works, we published capture trends of birds over time in continuous forest. We show that the numbers of birds (that are well-sampled with mist nets) have shifted to include (many) fewer terrestrial and near-ground insectivores. Curiously, these are the species that are most sensitive to landscape disturbance such as fragmentation—including possibly due to changes in microclimate as hotter and drier conditions seep in from cleared areas. Similar story was found some 2,000 km away in western Amazonia, at the Tiputini Biodiversity Station.

Why are ground-foraging birds disappearing from Amazonia?

To shed at least some light on this question, the main goal of my dissertation was to measure ambient conditions in the rainforest understory and track birds to see how they use this environment as these conditions fluctuate throughout the year. Nearly all my field time at the BDFFP was consumed by catching these now rare, enigmatic denizens of undisturbed Amazonia, deploying biologgers on them, and then trying to recapture the same birds a year later to collect the data. If this sounds easy, it wasn’t. Birds were sneaky, smart, and had large home ranges. In the end, however, we managed to get a reasonable sample size of about nine species. The results of this effort should be coming up in 2021.

The Black-faced Antthrush is one of our focal species. To catch it, we trawl the rainforest using the playback of its vocalizations—including the one above.

See coverage of this research by The Guardian, BBC, Mongabay, Daily Mail, AOS

Publications to date

• Philip C Stouffer, Vitek Jirinec, Cameron L. Rutt, Richard O. Bierregaard, Angélica Hernández‐Palma, Erik I. Johnson, Stephen R. Midway, Luke L. Powell, Jared D. Wolfe, and Thomas E. Lovejoy (2020). “Long-Term change in the avifauna of undisturbed Amazonian rainforest: Ground-foraging birds disappear and the baseline shifts.” Ecology Letters. https://doi.org/10.1111/ele.13628

• Cameron L. Rutt., Vitek Jirinec, Mario Cohn‐Haft, William F. Laurance, and Philip C Stouffer (2019). “Avian ecological succession in the Amazon: A long-term case study following experimental deforestation.” Ecology and Evolution. https://doi.org/10.1002/ece3.5822

• Cameron L. Rutt, Stephen R. Midway, Vitek Jirinec, Jared D. Wolfe, and Philip C. Stouffer (2019). “Examining the microclimate hypothesis in Amazonian birds: Indirect tests of the ‘visual constraints’ mechanism.” Oikos 128: 798–810. https://doi.org/10.1111/oik.05781

• Vitek Jirinec, Elisa C. Elizondo, Cameron L. Rutt, and Philip C. Stouffer (2018). “Space use, diurnal movement, and roosting of a Variegated Antpitta (Grallaria varia) in central Amazonia.” Ornitología Neotropical 29: 13–20.

• Cameron L. Rutt, Vitek Jirinec, Erik I. Johnson, Mario Cohn-Haft, Claudeir F. Vargas, and Philip C Stouffer (2017). “Twenty years later: An update to the birds of the Biological Dynamics of Forest Fragments Project, Amazonas, Brazil.” Revista Brasileira de Ornitologia - Brazilian Journal of Ornithology 25: 277-296–296.

Videos and photos