Abstract
Not much has been written about the nesting habits of wild populations of Hyacinth Macaws.
Much of what I have read about these magnificent creatures is contrary to my own observations. And, my observations of the 1988-89 breeding season are in conflict with those of the 1989-90 season. Nevertheless, I believe it useful to share a lot of questions and maybe even a few answers.
It is understandable that our knowledge of small, inconspicuous birds is limited. What is our excuse for near total ignorance of the natural history of one of the largest, loudest, and most valuable members of the parrot family?
As a parrot lover for over 40 years, two of Brazil's species have long piqued my interest - the Golden Conure and the Hyacinth Macaw. Having spent a lot of time and more money snooping around in Mexico, Central America and Venezuela in search of wild parrot adventure, I couldn't resist the opportunity to visit Brazil with the promise of seeing wild Hyacinths. The general aspects of my first two trips to Brazil are being reported elsewhere. Here, I would like to concentrate on the specifics of nesting habits as observed in January, June and October of 1989 and April 1990. All observations were made on a 36,500 acre cattle ranch in the state of Mato Grosso do Sul, about 75 miles northwest of the town of Aquidauna. The ranch is located on the flood plain of the Paraguay River system - "The Pantanal!' This basin is small by Amazon standards but large in ecological importance, being one of the world's largest wetlands. It has maintained much of its original wildlife because of its pattern of land use - low intensity grazing. According to the locals, and confirmed by our observations, the large macaws of this region of Brazil nest during the mid spring to early summer (October to February). This corresponds to the end of the dry season - beginning of the rainy season. The area studied is a southwesternmost corner of the Hyacinth range. It has been reported elsewhere that the Hyacinths of the northern part of their range nest earlier, with August being mentioned by Roth.
In January 1989, Bob Martins of Houston, Texas took a group to the ranch, where they video-taped partially feathered Hyacinth chicks coming to the openings of their nests. These young were probably four to eight weeks old and were in the three nest sites regularly used by pairs of Hyacinths who frequent a grove of trees about 200 yards north of the main ranch house.
On my three trips, we covered wide areas of the ranch during the midmorning to midday periods, but concentrated on the grove of trees nearest the ranch house during the early mornings and late afternoons. Here we were able to study the several pairs which seemed to center their lives near the ranch house.
In June 1989, pairs with one or two fledglings would start gathering into a group in several large trees, just north of the main ranch house before 5 a.m. After 12 to 18 had arrived, they would fly to palm trees inside the back yard of the ranch house. Usually, they gathered green palm nuts and ate them. Sometimes, they seemed to play games by swinging on the tips of palm fronds while hanging upside down by their feet and flapping their wings.
Fledglings often joined their parents in feeding and playing or sometimes played, rested or dozed off by themselves in one of the large, deciduous trees. More than half of the pairs we saw in June had offspring, about half of the pairs with offspring had two. This contradicts the reports of others who have said that two eggs are laid, but then only one chick is raised to fledge. It also contradicts reports that only a small percentage of mature Hyacinth pairs will breed in a given year.
In October, I was surprised to find most pairs still burdened with offspring that had to be nine to ten months old. I was also surprised to see little evidence of breeding activity by adult pairs. We saw pairs in trees with proven nest sites. We saw lots of mutual preening. We saw some pairs copulating. We saw no Hyacinths enter or leave a nest cavity.