Bringing Birds Back: The Alexander Center’s Computer Modeling Helps Conserve Puerto Rican Parrots

March 30, 2023

When you come to Lincoln Park Zoo’s Regenstein Small Mammal-Reptile House, you’ll encounter many unique scaled, water-based, furred (or not furred, in the case of the naked mole rats) creatures, from Egyptian fruit bats to prehensile-tailed porcupines and Jamaican iguanas. Every animal here is special, of course, but the building’s only feathered residents—two Puerto Rican parrots—have a particularly compelling conservation story that continues to move forward, thanks to a recent viability analysis conducted by zoo researchers.

Photo courtesy of Tanya Martinez.

The Story of the Puerto Rican Parrot

Back in the 1970s, the once-abundant and beautiful Puerto Rican parrots almost became extinct as a result of habitat loss, pest control measures, and hunting both for food and the pet trade. At that time, there were only 13 individuals left in the wild.

Measures were quickly taken by organizations, such as the U.S. Fish and Wildlife Service and the Puerto Rico Department of Natural and Environmental Resources, to save them through captive breeding and reintroductions.

In the mid-2000s, Lincoln Park Zoo joined this effort by lending population management expertise to already-ongoing efforts. In 2016, the zoo even became home to the first Puerto Rican parrots to leave the island since 1972, a gift from Puerto Rico as an effort to share the birds’ incredible story.

However, the birds remain vulnerable to unpredictable environmental fluctuations. The extinction vortex, which describes how declining populations experience multiple forces driving their sizes down toward extinction, makes these birds more vulnerable to such forces that drive their population numbers down.

Although this work has led to some important steps towards recovery, with two wild populations re-established and a third just getting started, there is still much work to do. But species recovery isn’t easy. Catastrophic events like the 2017 hurricanes Irma and Maria, which devastated the island and caused one of the wild populations to go extinct, can upend progress in an instant. The slow work of recovery requires natural history knowledge, collaboration, cooperation, and training, along with accurate data management, careful matchmaking, and precise modeling.

Computer Models for Saving Species

When this type of science is done in conjunction with on-the-ground work by conservation organizations in Puerto Rico, the parrot population benefits. It isn’t easy saving species, because of all the variables involved—but computer models can help us understand how close these populations are to extinction.

Zoo scientists in the Alexander Center for Applied Population Biology, in collaboration with partners in the field, have created a population viability analysis (PVA), a computer model which can help understand the chances of this species’ disappearance from the wild or recovery. Such risk-management studies predict births, deaths and movement in and out of the aviaries into the wild populations, and look at management strategies to increase diversity and population growth over the next 100 years.

A PVA allows scientists to run scenarios comparing different types of management to assess which offers the best chance of helping populations thrive. A PVA can also indicate what kinds of recovery goals should be targeted and timelines for that recovery.

The Alexander Center’s PVA Results Will Help Partners Strategize for the Future

Alexander Center scientists have just sent the final PVA report to government partners to be integrated into their management plans. The PVA results suggest challenges for one of the wild subpopulations, where reproduction is too low and mortality too high to overcome predicted declines without larger conservation changes.

Other wild subpopulations have more promising futures; the largest wild population has only a slight chance of long-term decline, and small improvements in its reproduction could quickly translate into long-term stability or growth. The two aviary populations, both based in Puerto Rico, should remain robust sources for releases of birds into the wild.

And with better data over the upcoming years on what is happening in the newer wild subpopulations, this model will help the zoo’s Puerto Rican partners better target their future conservation strategy for the species.

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