“Factors affecting the life history, abundance, and distribution of the yellow-shouldered Amazon parrot of Bonaire”

 

On January 28th, 2010 CIEE welcomed its first guest lecturer of the New Year and new semester. Dr. Sam Williams of the University of Sheffield in England came to present on his doctoral work researching Bonaire’s endangered yellow-shouldered Amazon parrot. Dr. Williams’ involvement and interest in parrots began at a young age when he bred them in his backyard. At the age of 16 he was taken “under the wing” of Carl Jones with whom he studied the endangered echo parakeet on Mauritius Island. After completing his undergraduate degree from the University of Stirling in Scotland, Dr. Williams went to study the endangered Lear’s Macaw in Brazil.

- Dr. Sam Williams at CIEE -

In 2003 he made his first visit to Bonaire, working with the Fundashon Salvanos Lora on a registration campaign for captive birds on the island. Through public education and some enforcement all captive birds were registered and given rings. Additionally, responsible pet owners were commended through publicity in the local papers for good animal husbandry practices.

In addition to poaching for the animal trade, there are several threats which affect parrots throughout the Caribbean, including habitat destruction, competition and predation, and genetic erosion from bottlenecking and other factors. Caribbean-wide, there are 8 of 28 known species now listed as extinct and 11 listed as vulnerable. Of these, there are 11 Caribbean Amazon parrot species, of which 2 are extinct, 8 are vulnerable and 1 is near-threatened. To try and better understand the life history of parrots, Dr. Williams came back to Bonaire to study the endangered yellow-shouldered Amazon parrot (Amazona barbadensis) or as they are referred to locally, the “Lora.” Bonaire was chosen because of its small human population, availability of logistical and technical resources and the improved visibility of parrots in flight due to historical alteration of high canopy vegetation. Dr. Williams’ doctoral work focused on studying the life history of these parrots as well as determining their abundance and distribution throughout the island.

- Yellow Shouldered Amazon -

By direct and video surveillance, Dr. Williams and his colleagues were able to learn about the courtship, mating and rearing of the Lora. About 35 nests were regularly monitored, this small sample of reproductively active pairs only constitutes a small percentage of the total population of 650 individuals and may be a cause of some concern regarding genetic variation. Additionally, Dr. Williams found a lower than average survival rate of yellow-shouldered Amazon parrots from egg to fledgling than is found in most other birds. While ninety two eggs were laid over a three year monitoring period only fifty eight of these hatched with thirty three of those reaching the fledging stage. Of those which survived to an age at which they are less vulnerable to natural predation and competition, ten were assumedly captured for the illegal pet trade leaving only twenty three free in the wild. Reasons for the endangerment of this population include environmental conditions and inbreeding depression due to a small gene pool. Because parrots are known to mate for life, they tend to take longer to reproduce and do not reproduce as often as other bird species, if the survival rate of hatchlings remains low and those which become fledglings continue to be captured the population on Bonaire could become critically threatened.

- Yellow Shouldered Amazon -

Factors which affect the robustness, or ability of the population to withstand natural and introduced pressures, include the availability of food, the presence of competitors and predators, and the physical characteristics of nest sites. The abundance of parrots on this island is affected by habitat type. A heterogeneous habitat allows for selection of specific areas and the parrots were found to be more concentrated in locations characterized by higher altitudes and higher, more diverse vegetation. But the distribution of parrots on the island is affected by rainfall. During the summertime when there is drought, the parrots migrate to the urban areas where they can find food sources in irrigated gardens and kunukus. For some people, during this time of year the parrots can be perceived as pests since they compete with us for consumption and enjoyment of the fruits we grow. However, it is the degradation of the environment in the northern region of the island by goats and by reduction of plant species diversity which reduces the availability of food sources and drives the parrots into populated areas.

By better understanding how and why we find parrots in different locations on the island, perhaps we can discover new ways to improve the lives of all Bonaire’s inhabitants.

 

For more information on Lora click here.