Census in the Caribbean

The zoo scientists are quick to clarify that their December trip to Puerto Rico wasn’t a tropical holiday.

The Puerto Rican parrot nearly became extinct in the 1970s, but a conservation program—aided by Lincoln Park Zoo scientists—is seeing the species into recovery.

Preserving the Puerto Rican Parrot

The zoo scientists are quick to clarify that their December trip to Puerto Rico wasn’t a tropical holiday. “We didn’t even see the sun for the first half of the trip,” says Joanne Earnhardt, Ph.D., director of the Alexander Center for Applied Population Biology. Between long hours spent indoors compiling population data and driving rain that washed out a wild release of the very species that had drawn them to the island, their trip to the tropics might as well have been a wintry weekend back in Chicago, with rain gear standing in for winter coats.

Of course, the Puerto Rican parrot doesn’t make its nest in Lincoln Park. This critically endangered species is what prompted Earnhardt, Senior Population Biologist Sarah Long and Research Assistant Carrie Schloss to make their winter voyage. The only U.S. parrot, and one of the first species protected under the Endangered Species Act, the Puerto Rican parrot saw its numbers decline in parallel with the island’s development. Habitat loss was the primary culprit, although hunting, hurricanes, predation by hawks, boas and introduced rats, and parasitism from warble flies impacted the population as well.

Whereas the bird’s population once numbered in the tens of thousands, a 1930 survey identified 2,000 individuals on the island, and by 1975 the wild population had fallen to 13 parrots. In response to this decline, the U.S. Fish and Wildlife Service and Puerto Rico Department of Natural and Environmental Resources established a captive population in 1973 at the newly constructed Luquillo Aviary. This population produced its first chick in 1979 and has grown over time—expanding to a second aviary, Rio Abajo, in 1993—to more than 200 individuals in captivity.

So far, so good, from a conservation standpoint. The captive population has grown, and the wild population increased as well, thanks to the placement of captive-born chicks in wild nests and beginning in 2000, the release of adult birds to the wild. Today 50–60 wild birds can be found in the El Yunque National Forest and Rio Abajo Forest Reserve.

This success has raised its own issues, however. As wildlife managers have discovered, it’s much easier to manage population data for 13 parrots than several hundred. Aviary researchers had a wealth of records stretching back for more than a decade—births and deaths, family trees and releases to the wild—but while the information was detailed, it wasn’t organized in one place.

“Each aviary had its own method for data collection,” explains Schloss. “Different people recorded different information into different files, and there wasn’t a way to share all of the data at once.” Most of the records were based on housing, chronicling the flow of parrots in and out of, say, Cage 20. From a husbandry standpoint, this was ideal, but it made it difficult to follow a bird throughout its lifespan. While the parrot researchers had several hunches about the birds in their care—they thought females might be breeding at younger ages and clutch sizes might be increasing over time—they didn’t have any hard data to back them up.

Organizing data for small populations is a zoo specialty.

Zoo scientists applied their population-management expertise toward digitizing and analyzing the recovery effort's detailed paper records.

That’s where Lincoln Park Zoo came in. Organizing data for small populations is a zoo specialty. The Alexander Center for Applied Population biology has even produced a special software program—PopLink—that zoos across the country use to organize their animal info. It made sense to take a similar approach with the island’s parrot population. As Earnhardt explains, “It’s much easier to see population trends when all of your data is in one place.”

Of course, organizing several decades worth of data doesn’t happen overnight. The parrot researchers started the process by e-mailing all of their electronic records to Lincoln Park Zoo, where Schloss and intern Alex Rekkas worked to enter it into a central database. Each parrot logged into the system inspired further questions: was it still alive? Who were its parents? Had it been released to the wild? Answers came in further communiqués from the island, although the scientists also exercised their sleuthing skills, finding a population record produced by researchers at the University of Minnesota in 1994, a 1986 book on Luquillo’s parrots and a 2003 scientific paper analyzing the history of Puerto Rican parrot nests in the region.

Armed with this information, Earnhardt, Long and Schloss traveled to Puerto Rico to finalize the data collection in person. They were immediately impressed by the scale of the parrot conservation effort. The Luquillo Aviary had constructed a new facility in October 2007, one featuring a nutrition center, a quarantine area and even a secure hurricane room where parrots could ride out tropical storms.


The birds had a variety of open-air housing options, including isolated single units for territorial birds and concentrated “condos” for more social squawkers. A flight cage the size of a gymnasium served as a training ground for birds being prepared for release. Inside, parrots were able to seek out natural foods and build up their flight muscles for the wild. The zoo scientists were even recruited for a little personal training: “The parrots’ natural instinct is to fly away from people, so aviary personnel encouraged us to walk up for a closer look—it gave the birds a little exercise,” says Long.

The boundary between the aviary and the wild is a fluid one. In the wild, the parrots’ favored tree hollows remain in short supply, so aviary workers construct artificial nests to encourage breeding. Overhangs are installed above nests to protect against flooding and snakes; built-in doors enable researchers to monitor the health of the chicks inside. Released parrots have even been known to return to the aviary at dawn and dusk to chatter with old exhibitmates.

The zoo scientists came away with a healthy respect for the work being done on the island. They also came away with enough data to create a centralized population database with information on the lifespans and relationships of 612 Puerto Rican parrots, past and present. This information will assist conservation efforts by identifying population trends. In the future, it may even help to recommend the best birds for breeding or release to the wild.

Data collection is ongoing—a necessity for any living population—and the researchers in Puerto Rico are serving as collaborators in the process. Training sessions were conducted on the island to teach the scientists there how to maintain the centralized database. They enter changes in real-time, the zoo offers a periodic review and the Puerto Rican parrot population continues on its path to recovery.

“We’re always looking for situations where our skills can be of use, and the Puerto Rican parrot program pairs talented collaborators with an interesting balance between captive management and wild release,” says Vice President of Conservation and Science Dominic Travis, D.V.M. “It’s a perfect place for us to be.”

Even if it’s raining.


By James Seidler • Published September 13, 2010 • Originally published in Spring 2008 Lincoln Park Zoo Magazine