Why Northern Animals Grow Larger.

If you are a hunter, and you want to hunt large animals in North America - Go North.

It is a pretty common observation that as you move away from the equator, the body mass of animals tends to (on average) get larger. Historically, this change has been explained as a difference in the need to retain body heat. Larger animals are better able to regulate their own temperature. This line of thought refers back to "Bergmann's rule".
Wikipedia read this way:

In zoology, Bergmann's rule is an ecogeographic rule that correlates latitude with body mass in animals.^[1] Broadly it asserts that within a species the body mass increases with latitude and colder climate, or that within closely related species that differ only in relation to size that one would expect the larger species to be found at the higher latitude.

But there may be another explanation.

Science Daily reports that experiments show it may be as simple as nutrition.

ScienceDaily (Jan. 29, 2010) — New research suggests that animals living at high latitudes grow better than their counterparts closer to the equator because higher-latitude vegetation is more nutritious. The study, published in the February issue of The American Naturalist, presents a novel explanation for Bergmann's Rule, the observation that animals tend to be bigger at higher latitudes.

The big question for me is does this translate to carnivores. Do those animals grow larger as well? I think about the larger northern wolves, the polar bears, the lynx as compared to the bobcat.

The larger gyrfalcon.

I think it must translate.

Read the rest of the article here.