Referências:.
Wildbirds, beija-flores, borboletas, e Mais - www.birdfeedersonly.com/articles-how-do-birds-stay-warm
Colvin Run Habitat - https://crhabitat.blogspot.
com/2007/02/how-do-birds-stay -warm.html
Metabolismo aviária - https://people.eku.edu/ritchisong/birdmetabolism.html
Cornell Lab ou Ornitologia - https://www.birds.cornell.edu /netcommunity/page.aspx?pid=1670