To test Bergmann's hypothesis, a generalized linear model (GLM) was created in R Studio, using to examine bird size differences over the American continents.
The test whether a Trochilidae diversity gradient exists over the equator, we created a number of generalized linear models. Firstly, by sorting the species into blocks between each 5° latitude gradient.
To expand upon this analysis, we added to the 'vanilla' GLM an estimation of the land area that exists between each 5° latitudinal gradient, given one of the fundamental laws of ecology that species area tends to increase with land area \cite{Pigolotti_2009}.
Then using data from the Bird Life conservation project, we plotted the density of hummingbird species across the Americas, to better represent the diveristy gradients across the Americas.
Results