Bird Feeding Diversity

As could be expected, birds vary widely in the diversity of their diets. Blue Jays, for example, eat myriad kinds of seeds, grains, nuts, berries, and fruit, favoring acorns, corn, and sunflower seeds. They also eat a wide variety of insects, including caterpillars, grasshoppers, beetles, and snails, and they even capture mice, small birds, frogs, salamanders, and occasionally eggs stolen from other bird's nests. This broad diet classifies the blue Jay as a " diet generalist." "Diet Specialists," on the other hand, consume a much shorter list of food items. The Belted Kingfisher, for example, depends almost on entirely on one kind of food --- small fish it captures by plunging into shallow water. To ensure a year-round supply of fish, it must migrate southward in winter to find water that remains unfrozen. The Blue Jay is not as limited in its food sources and therefore can remain as a permanent resident over many parts of its winter range.

The diet of some birds, mainly tropical species, are even more specialized than that of the kingfisher. Hawaii's bright red Iiwi, a nectar-feeding honeycreeper, feeds mainly on flowers of a single species of tree, the ohia, a dominant tree in Hawaii's native forests.