A high metabolism
is not limited to hummingbirds or even birds
in general. As a rule, the smaller the mammal, the faster their metabolic rate
will be. Mammals are endothermic
, which means that they regulate their own body temperatures and keep warm using their own internal energy, which means that they use A LOT of energy when compared with cold-blooded
). And, in proportion to larger animals, small mammals lose heat more easily, so they need to consume a higher amount of energy in proportion to their body size. Of course, metabolism also depends on other factors, such as the level of activity and the amount of calories that must be devoted to structural requirements, but body size
has a comparatively large impact.
So it's really not surprising that hummingbirds have a high metabolism, is it?
And, now that I think of it, I find that when I go through bird phases where I consistently leap from tall buildings, waving my arms in an attempt to fly, I get hungry a lot quicker.