Trans-Saharan migratory bird species encounter large scale seasonal atmospheric convergence zones, where opposing monsoon and continental air masses meet. These macro-scale atmospheric conditions determine local weather, influence migratory and foraging behaviour and seasonal bird survival rates. Here we investigate the flight behaviour of Pallid swifts (Apus pallidus), a small aerial insectivore, in relation to non-breeding season atmospheric conditions using state-of-the-art GPS logged data. Our analysis suggests that pallid swift prey on insects by catching them where they are most densely concentrated within the atmosphere. Residence of birds in West Africa well past the vegetation minimum suggests that the state of the vegetation and associated local insect populations are not necessarily limiting. Migration events within, to and from, the non-breeding season foraging locations might therefore not only be guided by a decline in vegetation as common metric for prey availability, but also by shifting wind directions and their concentrating effects. Supporting materials This repository includes all data to reproduce the statistics in the described study, above. Certain omissions were made due to the data volumes involved. The latter mostly pertain to the visualization of the processes involved using transects through the atmosphere. Data structure Key data is saved in compressed R serial files (.rds) in the data folder. The position_data.rds file contains bird positions, headings and ancillary data to support most of the analysis in the study. Additional rds files are included which cover spatial analysis in support of the analysis (in the analysis folder). Code execution It is best to execute code in the numeric sequence as provided in the filename. Although it should not matter for the statistical analysis. Licensing For the data include be mindful of the Open Database License (ODbL) which is a copyleft license. Reuse is permitted on the condition that any database (including aggregated working data for analysis) in which our database is used remains open as well. The authors will enforce this policy. All other material such as figures and draft manuscripts are distributed under a CC-BY-SA-4.0 license. Referencing When referencing the data cite both the data repository as: Kearsley, L. et al. 2022. Data from: The aeroecology of atmospheric convergence zones: the case of pallid swifts. Zenodo Repository, https://doi.org/10.5281/zenodo.6320888) and the original paper (Kearsley et al. 2022, doi.org/10.1111/oik.08594).
The aeroecology of atmospheric convergence zones: the case of Pallid swifts
Dataset published at Zenodo repository.