I'm excited to report that our first paper using citizen scientist-collected behavioral observations has been published in Behavioral Ecology (Miller et al. 2017). Well over a thousand FeederWatchers participated in the project, collecting data on aggressive interactions at feeders around North America. We assembled these interactions into a large directed network, and calculated some metrics of dominance. Ultimately, we settled on a modified version of the Bradley-Terry model (Bradley and Terry 1952) to calculate a species' dominance--other approaches yielded results that didn't make any biological sense.
In and of itself, this was a neat product--a continental dominance hierarchy of feeder birds! But what determined species' positions in the hierarchy? We found that, unsurprisingly, body mass explained a lot of the variance in species' positions. However, certain lineages (e.g., families) of birds tended to be more or less dominant than expected based on their body mass. Presumably, the members of these lineages share certain traits that make them more or less aggressive. Take woodpeckers for instance: long, heavy bills they wield against unwielding substrates every day. Or warblers: little, feather-clad bundles of anger. Ok, maybe that's not really a trait, but you get the point. We also looked for the existence of rock-paper-scissors relationships in the data. These sorts of relationships are interesting, as they are thought to promote local species coexistence (Levine et al. 2017); no species is able to gain a competitive advantage over all others. We found few such instances of these relationships, but those that we did find tended to involve invasive species. This seems like something worth following up in the future! Stay tuned for an upcoming blog about the paper on the FeederWatch page. Soon thereafter, keep your eyes peeled for a glossy article in the Living Bird, complete with original illustrations by Jillian Ditner! (http://jillianditnerstudios.com/). Literature cited: Bradley, R.A & M.E. Terry. 1952. Rank analysis of incomplete block designs: I. The method of paired comparisons. Biometrika. 39:324–345. Levine, J.M., J. Bascompte, P.B. Adler & S. Allesina. 2017. Beyond pairwise mechanisms of species coexistence in complex communities. Nature. 546:56-64. doi:10.1038/nature22898 Miller, E.T., D.N. Bonter, C. Eldermire, B.G. Freeman, E.I. Greig, L.J. Harmon, C. Lisle & W.M. Hochachka. 2017. Fighting over food unites the birds of North America in a continental dominance hierarchy. Behavioral Ecology. Online Early. doi:10.1093/beheco/arx108
0 Comments
Your comment will be posted after it is approved.
Leave a Reply. |
AuthorNSF post-doctoral researcher studying species interactions Archives
April 2019
Categories |