The Weekly Chirp: Puzzling palates

Food: it keeps us alive and brings people together. As privileged college students, we enjoy a gastronomic cornucopia of daily options, and as a result it has allowed us to convert from generalist omnivores to picky specialists. A juicy piece of marinated steak fails to satisfy the progressive vegan diet, and a bean burger suffers rejection from the conservative football player unwilling to compromise his eternal desire for carnal protein. Paradoxically, our economic status and expansive range of opportunity have narrowed what we view as suitable sustenance.

Birds experience the same phenomenon, only in reverse. Many species of birds occupy specific feeding guilds in the ecosystems they inhabit, but often assume a generalist diet due to food availability. Take woodpeckers, for example. As their name suggests, woodpeckers have evolved a long, thick bill and fortified cranium over thousands of years to exploit the abundance of insects burrowed in dead trees. However, the casual birder will notice that woodpeckers do not spend all their time pecking wood. In fact, many woodpeckers consume seeds and fruit as well, especially where these items are abundant like in the tropics. The black-cheeked woodpecker of Central America is a prime example of this behavior. During my research in Belize, I observed a pair of black-cheeked woodpeckers devour the seeds and pulp of wild clementines for two hours, never once stopping to poke and prod at the bark of the tree.

Another tropical resident and cereal-box celebrity, the keel-billed toucan, often breaks the boundaries of its feeding guild as well. Traditionally considered a frugivore (fruit-eater), the keel-billed toucan is equipped with a massive bill which it uses to crush fruits of all sizes — but it doesn’t stop there. Most species of toucan see no issue in switching from a vegan diet to a carnivorous one, equally happy to gulp down the fresh, sweet pulp of a fig from a Ficus tree, swallow a lizard it found on the Ficus tree or devour the eggs of another bird that unfortunately decided to nest in the Ficus tree. Put simply, birds will eat that which is edible.

This simplicity can be frustrating — why would birds evolve to adopt a specific feeding guild and then ignore it? Remember, it’s all about availability. When food is scarce during a period of low productivity (i.e. a drought), birds utilize their niche-specific adaptations: woodpeckers eat bugs that no other bird can access, and toucans guzzle down fruit that cannot be consumed by smaller birds. The natural world cannot focus on preference because it is always focused on survival. In other words, a bird cannot afford to be choosy if it hopes to live. With this in mind, try to broaden your diet and eat what you take. If you don’t want to do it for you, do it for the birds.

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