Conservation of the Puerto Rican Parrot

Through habitat destruction, overharvesting, and pollution among other causes, human activities have had a likely irreversible effect on natural habitats throughout the world. Countless species have been driven to extinction by our actions, likely many of them before they were ever discovered. Through conservation efforts and a shift toward environmentalism that was largely spawned when the problems were thrust into the public spotlight by Rachel Carson's Silent Spring, a great number may be saved. Perhaps the most well known success story is that of the bald eagle, which nearly became extinct as a result of the use of the pesticide DDT. Another hopeful success story has been in the making in Puerto Rico since the 1970s. The once abundant Puerto Rican Parrot hit a low of just over a dozen surviving birds in the middle of the last century. Today it's population is slowly rebounding thanks to a concerted effort by several organizations.

The Puerto Rican Parrot (Amazona vittata) is the only extant native species of parrot found in the United States or it's territories. The other parrot species native to the States, the Carolina Parakeet, became extinct in 1918, and the Puerto Rican Parrot is in danger of meeting the same fate. This species is endemic to the island of Puerto Rico, though it is closely related to other birds of the genus Amazona which reside throughout South America and are popular as pets. Once found in large numbers throughout the island, the Puerto Rican Parrot was added to the endangered species list on March 11, 1967 (Puerto Rican Parrot). The population hit its lowest point of 13 birds in 1975 (Puerto Rican Parrot Species Account, 1990). Currently 200 survive in captivity and in the wild.
The biggest reason for these birds becoming endangered is the human inhabitation of the island. For years the parrots were hunted for food by the first settlers on the island, though during this period the population remained stable, with an estimated population been between 100,000 and 1,000,000 individuals at the time when the first Europeans reached the island. At this point the species could be found in habitats throughout the island. From 1650 to 1850 the human population on Puerto Rico increased from 880 to 500,000, and it doubled to 1 million by 1900. At this point approximately 76% of the area of Puerto Rico had been deforested, with only 1% of the original old growth forest remaining (Myers). Currently the Parrots have a range of only 16 square kilometers, around 0.2% of their original range (Amazona vittata, 2006).

New predators that have been introduced since human inhabitation of the island also have contributed to the parrot's decline. Black rats and mongooses were likely accidental introductions to the island made by early settlers. Both of these predators are known to eat juveniles as well as compete with the parrots for nesting cavities in trees. Honeybees also have been introduced to the island by humans and are also in competition for these same tree cavities (Puerto Rican Parrot). Native species which prey on the parrot have also been a factor in its decline. Pearly-eyed thrashers and red-tailed hawks, both natural predators of the parrot, have shown population growth recently (Puerto Rican Parrot Species Account, 1990). Capture of wild birds for the pet trade has also had a negative impact on the Puerto Rican Parrot population.

In 1937 it was found in a survey by the US Forest Service that only approximately 2,000 of the birds remained and they were limited to only a small area in the Luquillo Mountains. Regular population surveys began in the 1950's and by the middle of the decade only 200 remained. The population was in a steady decline until conservation efforts began, at which point approximately 20 remained. Thanks to the Puerto Rican Parrot Recovery Program instituted in 1968 the population had climbed to 47 in 1989. A major setback occurred this year however, as Hurricane Hugo hit the island and devestated their remaining habitat. The hurricane left only approximately 23 Puerto Rican Parrots alive in the wild (Myers). Hugo had a much greater effect on the population than similar storms in the past would have had due to the extreme isolation of the population.

A comprehensive effort to save the bird from extinction known as the Puerto Rican Parrot Recovery Plan began in 1968. It is led by the US Fish and Wildlife Service (USFWS), with the US Forest Service (USFS), the Puerto Rican Department of Natural and Environmental Resources (PRDNER), and the World Wildlife Fund (WWF) assisting (Mowbray). The main component of this effort is a captive breeding program, currently utilizing two aviaries on opposite sides of the island. Currently 161 Puerto Rican Parrots reside in these aviaries. Since 2000 there have been 40 birds released to the wild as a result of this program (Stafford, 2007). The ultimate goal is to reach a sustainable wild population of 500 birds.

The conservation effort is receiving a large amount of support from both governmental and nongovernmental organizations. Beginning with a groundbreaking ceremony held February 18, 2005 a replacement for the main aviary of the captive breeding program was constructed in the El Yunque area of the Caribbean National Forest. The aviary had been housed in a military compound that had been out of use prior to its establishment in 1973. Congress contributed $1.7 million of the total $2.5 million cost of the new facility with the rest coming from various conservation groups such as Parrots International and the American Bird Conservatory (Puerto Rican Parrot Aviaries).

Biologists and technicians from the USFS have worked to create and maintain nesting sites throughout the parrot's habitat. In addition to creating these the USFS also works to control the populations of species that prey on the parrot or are in competition with them for the tree cavities used as nesting sites. This is done by providing rat bait near trees with nesting parrots to discourage predation of the eggs in the nest. Alternative nest boxes are provided for the pearly-eyed thrasher, which would otherwise lay eggs on top of parrot eggs in the same nest while the parent is away, causing the parrot to abandon it's eggs. Mongoose, which also prey on eggs or young chicks are trapped and removed from the nesting areas. The USFS also conducts a census of the population before and after the breeding season each year to determine the change, if any, in population. Other tasks the USFS performs as part of the program which don't directly affect the birds are constructing observation platforms to allow researchers to observe the wild population and maintaining service trails into the nesting area to facilitate management efforts (Mowbray).

The USFS and the USFWS together have designed and built artificial nest sites for the Puerto Rican Parrot. This was determined to be necessary due to the low number of trees which could serve as a nest location which remained in the parrot's habitat. In 2001 these artificial nests, created from PVC pipe and part of a tree trunk for a more natural look, were installed throughout the parrot's range. Since 2002 all wild breeding pairs have used these artificial nests, and 28 chicks have fledged as a result (Mowbray).

The USFWS conducts a great deal of biological research on the parrots and maintains the aviary located in the Caribbean National Forest. They are responsible for direct management of both the wild and captive flocks and provide veterinary service when it is needed. Scientists from the USFWS observe the parrots from blinds and equip young chicks with radio transmitters in order to monitor their movements, survival rate, and habitat use. In the aviary they maintain breeding pairs of adults are kept which lay eggs and fledge their own chicks. Juveniles which seem most fit for release to the wild are housed in a large flight cage which simulates a natural environment to train them to live in the wild (Mowbray).

The Puerto Rico Department of Natural and Environmental Resources maintains the second aviary that is part of the captive breeding program. This secondary aviary was established in response to concerns over the threat of a catastrophic event such as disease or another hurricane decimating the captive population located in a single area. The suitability of this aviary was tested using Hispanola parrots, which are closely related to the Puerto Rican Parrot, beginning in 1989. This initial test proved successful, and in 1993 a group of Puerto Rican Parrots was moved from the USFWS aviary to this secondary location. This aviary has been able to successfully fledge a number of chicks in the last 14 years (Mowbray). The oldest known Puerto Rican Parrot is housed here. A male named Rudy, he was born around 1968 (Puerto Rican Parrot Aviaries).

Until the end of 2006 all releases of captive chicks have been to the established wild population in the Caribbean National Forest. Approximately 41% of birds released so far have survived their first year in the wild. The most recent release, however, saw 60% (three out of five) released birds surviving their first year. The predatory red-tailed hawk has been found to be likely the largest threat to the released birds, with approximately half the deaths a result of predation. On November 19 2006, 22 Puerto Rican Parrots were released on the opposite side of the island from the currently established wild population. The goal is to establish a second breeding population, mainly to minimize the risk of the entire wild population being devastated by a hurricane as in 1989 with Hurricane Hugo.

Despite setbacks such as continued predation and nest site competition among the wild population, the population being halved by Hurricane Hugo, and low survival of captive born parrots released to the wild, the program has succeeded in dramatically increasing the population of Puerto Rican Parrots. From a low of only 13 birds in existence in 1975 the population has now risen to 44 in the wild and over 100 in the captive breeding program. With the opening of a newly constructed aviary these numbers should only continue to climb. Though it is a slow process, the Puerto Rican Parrot has for now been saved from extinction.

References

Amazona vittata. (2006). 2006 IUCN Red List of Endangered Species. Retrieved March 18, 2007 from http://www.iucnredlist.org/search/details.php/1069/allsv

Mowbray, A. (n.d.). The Puerto Rican Parrot - A story of an amazing rescue. Retreived March 22, 2007 from http://www.fs.fed.us/r8/caribbean/pr-parrot/puerto_rican_parrot-the_story_of_an_amazing_rescue.pdf

Myers, M. (n.d.) Puerto Rican Parrots. Retrieved March 18, 2007 from http://biology.usgs.gov/s+t/noframe/b016.htm

Puerto Rican Parrot. (n.d.) Retrieved March 18, 2007 from http://audubon2.org/webapp/watchlist/viewSpecies.jsp?id=168

Puerto Rican Parrot Aviaries. (n.d.) Retrieved April 21, 2007 from http://www.fws.gov/caribbean-ecoteam/PRP_aviaries.htm

Puerto Rican Parrot Species Account. (September 1990). Endangered and Threatened Species of the Southeastern United States. Retrieved March 18, 2007 from http://www.fws.gov/endangered/i/b/sab02.html

Stafford, M. (January 2007). The crown jewel of Puerto Rico. Retrieved March 22, 2007 from http://www.parrotsinternational.org/Species_Pages/Puerto_Rican_Amazon_pages/PR_Parrot_status_page.htm