Into Thin Air: Black Swift Movement Ecology Project 2020

Into Thin Air: Black Swift Movement Ecology Project 2020

Rob Sparks, Research Biologist with Bird Conservancy of the Rockies

The aerosphere is a body of air that envelops Earth, forming one of three major components of the biosphere. This is the last frontier in ecology where animal behavior, atmospheric science and ecology integrate to form the field of aeroecology with the aim to understand how organisms interact with and use this environment. Clouds form part of the aerosphere as do Black Swifts whistling through the air to forage on aerial plankton found here. They rely on the aerosphere for most of their existence, as do many other organisms. However little is known on how far and where Black Swifts forage during the breeding season or to what extent they are flying during the nonbreeding season.

Black Swift with Aerial Device

We can answer these questions by using small wing activity devices called accelerometers and GPS units attached to a birds’ leg or back. Accelerometers measure body acceleration in one, two or three axis and GPS units collect precise altitude and location information. These devices are expanding the frontiers of aeroecology and movement ecology opening up new perspectives on bird behavior and movement. The movement ecology paradigm revolves around the interaction between the birds’ internal state, movement, and external factors.

In order to attach these devices we must first capture the birds and then recapture them to download the data. At Zapata Falls we use a double stacked mist net reaching 21 feet high at the entrance of the canyon. We setup the nets before sunrise and wait for the swifts to leave the colony. In 2019 and 2020, we recovered seven of seven accelerometers, these devices hold the secret to the question of whether Black Swifts aerial roost during the wintering period. Aerial roosting is an incredible adaptation some swift species conduct where they are in flight for months on end during the wintering period. This year we found out the answer to this question and learned more about foraging flights. We have also recovered seven GPS units, which will add to our understanding of their foraging ecology.

Our results indicate that Black Swifts aerial roost during the non-breeding season, as do other swifts in Europe. We are able to graph wing activity and have observed that wing activity remains active during nighttime hours during the months of October to May and then subsides when on their breeding grounds where they roost at nest sites. We now have movement data during their full life cycle, which will fill missing information gaps needed for the conservation of this species. We hope to conduct one more recapture season next year to recover more GPS units, which will be important to increase sample size and strengthen our inference.

To learn more visit Bird Conservancy of the Rockies’ page on Black Swifts.