PUBLICATION: The Beach Times, Costa Rica, print edition
As far as birds go, the robin might make a good dinner date.
With her coquettish eyes and soft, auburn plumage, one imagines she would be pleasant company. The same could be said about the graceful swan, the peaceful dove, or the resonant nightingale—a creature whose seductive song has long inspired poetry.
Costa Rica’s magpie jay, however, is not one to bring home for supper.
The frumpy fowl, known in Spanish as the urraca, is loud, shrill, and temperamental. But restaurant owners and visitors to the coast will know them for the habit they have of swooping into restaurants during meals to steal food from diners.
In addition to social inaptitude, the bird—found between Guanacaste and southwestern Mexico—is often clumsy with words. Males, for example, are known to approach passersby and launch into prolonged tirades of seemingly senseless shrieks, eeks, twitters, and clucks.
Females, on the other hand, when preparing to nest, let out loud, repetitive screeches audible half a kilometer away.
Yet although the sounds appear as hapless racket, scientists believe there is more to the calls.
Cornell University graduate student Jesse Ellis has just wrapped up fieldwork for a thesis loosely titled “The Vocal Repertoire of the white-throated magpie jay.”
“I’m one of those sorts of geeks who have been interested in birds since I was very small,” he says. “I was interested in this whole issue of why any animal has the number of communication signals it has.
“One hypothesis is that it is related to social structure. The white-throated magpie jays were good candidates because they are social.”
Ellis has spent extensive time with the birds in Costa Rica and says he believes there are patterns in their vocalizations. The standing theory behind the female nesting sounds, for example, is they are calling for food because so much energy is needed to lay eggs.
“Producing eggs is a pretty high metabolic cost,” he says.
The graduate student says there are more than 50 distinct calls the birds make, which can be put into 11 groups based on context, including distress, pair bonding, group defense, alert, and alarm.
Some of the differences are subtle, he says, but distinct. The alert call, for instance, is often used when a raptor or other predator is flying high in the sky, but not an immediate threat. In contrast, the alarm call conveys a sense of urgency.
“The alarm call makes everyone dive into the bushes and hide,” Ellis says.
Distress calls are generally a signal for help from an individual bird. It has been heard when tracking bands are placed on the animals, as well as during physical fights between females.
Ellis uses two key methods for his studies. In the first, which he calls experimental playback, he tracks an individual bird, using a microphone to record its calls and taking notes of everything it does.
He compares the recording to others to look for patterns in behavior and, once a theory is determined, returns to the field. There he plays the sounds back for the birds to gauge their response.
In the second method, Ellis (pictured) attempts to recreate situations in question in order to record the birds’ vocal reactions. Methods have included using stuffed owls to create high-threat situations.
Ellis says there is difference between bird songs and calls, although it is a hazy one that scientists often dispute.
“Singing is usually defined as a very complex vocalization that’s given usually to defend the territory or call mates,” he says. “We have a definition of a call but there are a lot of things that fall in between.”
“It turns out most of the stuff your average Costa Rican (hears) is their standard mobbing call,” he says. “It’s not super high-pitched, but it’s quite loud and quite harsh.”
The creatures—Calocitta formosa by their scientific name—stretch about 68 centimeters (27 inches) from beak to tail and have a 48-centimeter (19-inch) wingspan. From February to July they build nests of thick sticks up to 30 meters (100 feet) in the treetops, and are known at times as nest-robbers.
Bird expert Richard Garrigues of Costa Rica’s Gone Birding describes the birds as “omnivorous and opportunistic,” and says they eat a varied diet of large insects, caterpillars, beetles, lizards, fruits, and corn.
“They certainly have an attitude that’s common of blue jays,” Mr Garrigues says. “They’re inquiring, inquisitive.”
The birds often scavenge around restaurants and eat human food, an adaptive quality Mr Garrigues says is also found in crows.
He says this opportunism is part of what has saved the creatures, which are listed as endangered but at “lower risk” on the World Conservation Union’s (IUCN) website, from becoming critically-threatened.
“Typically what we do is remove what was habitat for them and turn it in to something that isn’t, whether cattle land or hotel development,” the bird expert says. “They’re taking advantage of what otherwise would not be a good situation for them.”
Ellis says his vocalization work is based on research conducted by other graduate students that determined the birds’ social systems. He hopes to defend his thesis in a few months.
In the meantime, tourists and restaurant owners are making changes to adjust to the presence of the fearless creatures.
“We don’t have a buffet anymore,” laughs Sarah Pfeiffer, of Hotel Sugar Beach. “The birds were our biggest customers.”
This article was originally published in The Beach Times newspaper. Guanacaste, Costa Rica.
