Payne, R. B. (1984). Sexual selection, lek and arena behavior, and
sexual size dimorphism in birds. Ornithological monographs, (33),
iii-52.
Barve, A., & Wagner, A. (2013). A latent capacity for evolutionary
innovation through exaptation in metabolic
systems. Nature , 500 (7461), 203.
Beltran, R. S., Burns, J. M., & Breed, G. A. (2018). Convergence of
biannual moulting strategies across birds and mammals. Proceedings
of the Royal Society B: Biological Sciences , 285 (1878),
20180318.
BirdLife International and Handbook of the Birds of the World. (2016).
Bird species distribution maps of the world. Version 6.0. Available at
http://datazone.birdlife.org/species/requestdis.
Bivand, R. & Lewin-Koh, N. (2016). maptools: Tools for Reading and
Handling Spatial Objects. R package version 0.8-39.
https://CRAN.R-project.org/package=maptools.