The 2016 breeding season has turned out to be a very productive one for the Cayman Turtle Farm aviary flock.
“With about 10 breeding pairs of white-crowned pigeons, some of which have raised two to three clutches for the season, we have a bumper crop of juvenile captive-bred white crowned pigeons for wild release this year,” said Geddes Hislop, the Turtle Farm’s terrestrial exhibits and education programmes curator.
The first group, aged around four months, old hatched in early April and is on track to be released this week.
White-crowned pigeons, known locally as bald pates after their distinctive white head markings, are a naturally shy woodland-dwelling species. Like the Cayman parrot, they are fast losing the mature woodland and mangrove forests they depend on for food, shelter and breeding habitat.
Once hunted widely as a game bird, Cayman’s white-crowned pigeon population is considered “near threatened” and is now a protected species under the new National Conservation Law. The Turtle Farm’s aviary provides a protected space for the birds to breed and mature, and it is proving a successful venture.
“There are already 16 juvenile white-crowned pigeons which have been transferred to the Aviary breeding/release cage, undergoing preparations for wild release,” explained Mr. Hislop, noting a key step is having the birds transition to a wild diet, consisting mostly of ripe seagrape, silver thatch, red birch, and parrot berry fruit. The birds are attracted to the colorful berries by instinct.
“We collect the wild food and hang it up in the cage and reduce commercial food, and once they start choosing the wild food, we know they are ready to be released into the wild,” Mr. Hislop said.
“Over time we have noticed that color is key in having the birds choose the wild food over the seeds and pellets they have been eating in the aviary,” he continued.
He noted the birds’ instinctive attraction to colorful fruit comes from what scientists refer to as the “lizard brain” or the brain stem, the oldest part of the brain, responsible for primitive survival instincts. Birds introduced to wild foods while young will develop a natural preference for it.
“After they spend time in the transition cage, the instinct kicks in and the seeds and pellets start being eaten less and less,” said Mr. Hislop. “We check the droppings for the seeds from the fruits, which is important too for another reason, as the birds play a key role in spreading the seeds through their droppings.”
Mr. Hislop added that the transition cage is situated away from the main area of the Turtle Farm, where the birds have little contact with humans.
“That way they lose their habituation to people, so when they go out in the wild they will actually fly away from people.”
Once the current group of “teenage” birds have completed their transition to wild feed and been released, there are at least another dozen juveniles to be taken out of the aviary for a second release later this summer.
The birds are released into the wild through a soft release, where the cage is opened and they fly out on their own.
“We leave food for them on top of the cage, just in case, but within a few days they leave the area, as they follow the wild birds and disperse,” said Mr. Hislop.
Since the captive-bred birds are banded, the Turtle Farm is able to track where the approximately 50 captive-bred white-crowned pigeons released by the breeding program end up. One of the few island birds that migrate, white-crowned pigeons typically fly between Grand Cayman, the Brac and Cuba. However, over the years many of the birds released by the farm have stayed close to home, establishing an urban flock around West Bay. The flock appears to be comfortably breeding and flourishing side-by-side with people, offering the birds relative safety from hunters in their suburban environment.