Abstract
Toucans, with their garish colors and oversized beaks, are found in the wild in open wooded areas of tropical South America. There are 41 species of toucans and 7 genera. The Red-Breasted toucan, Ramphastos dicolorus, is also known as the Green-billed toucan. Although among the smaller toucan species in size and beak length, it is one of the most aggressive toucans.
In December 1978 a Red-breasted toucan was donated to the Phoenix Zoo by a local patron. While in quarantine, a laparotomy was performed revealing that our new resident was a male. He was exhibited by himself in an 8' x 20' x 10' enclosure of I" x 2" welded wire. After nearly two years of searching and advertising a second bird was finally located, but its sex was unknown.
While the newcomer was in quarantine, slight differences were noticed in the beak sizes of the two, which, in toucans, is usually indicative of sex difference. The
new bird's culmen had a slightly higher arch, making its beak appear a bit stouter and shorter than the male's. A difference in raspy vocalizations was also apparent; the male's was more intense and drawn out than the other's.
The two were visually and vocally introduced to each other in 4' x 5' x 5' cages set side by side, so that there was no physical contact possible until compatability could be assessed. Not only did he sit as close as possible to the other's perch and call constantly, but he also offered tidbits from his fruit bowl through the wire. All of this attention was seemingly ignored.
Before the two were relocated to their new exhibit, a 5' tall, 1 Y2' diameter date palm log was set in the cage. A cavity about 8" wide and 18" deep was hollowed out. A plywood lid closed the top, and a 4" entrance hole was punched in the side about 4" from the top. In the wild, toucans do not excavate their own nest sites (they use abandoned woodpecker cavities or
decayed trees), but rotted pieces of woo or debris may be removed or the entrance hole enlarged.
At their introduction in the toucan exhibit, there was no aggression between them, The new bird was preoccupied with getting familiar with the new surroundings; the male, however, immediately inspected the log, then proceeded to court the other bird in earnest. With each grating call, he would change his posture from stretching tall with beak extended to a low crouch. He hopped after the other persistently with food offerings in his beak, making a rolling click sound if he got its attention. Although the new bird seemed disinterested in his advances, after six weeks of courtship, activity around the nesting log inspired us to make a quick inspection which revealed two rounded white eggs (May 1981).
The incubation period for toucans is relatively short, only 16 to 19 days, depending on the species. Sixteen days after the eggs were discovered, "growling" noises were heard whenever one of the toucans entered the nest log. Their daily food ration was increased, and a fresh crock of food put in twice a day instead of just the usual morning delivery. Their diet consisted of a variety of chopped soft fruits and vegetables, small kibbles of dry dog food, mynahbird pellets and a mix of whole ground meats with added vitamins and minerals (referred to as bird-of-prey diet). The dog food and mynah pellets were offered both dry and soaked; before nesting the adult toucans preferred dry dog food, but fed the moistened foods to the young. Mice, mealworms and crickets offered to the toucans prior to the hatching were inspected but ignored. Once feeding the young, however, mice were taken but insects still refused. Interloping sparrows were avidly killed by the toucans, and pieces of them also fed to the young.
As the parents were attentive and feeding the young, and vocalizations could be heard, the keepers stayed away from the nest log to avoid upsetting the adults. Feeding was shared by both sexes. A morsel from the food crock would be taken to the nest entrance, where the bird perched and called to the young by a "ratchet" sound. (Later, after the young were gone from the nest, the male continued to exhibit this behavior).
One day, however, two weeks after the hatching, there was a message that, "There's this pink blob - maybe a bird - on the ground." Sure enough, one of the chicks was on the ground. I quickly returned it to the nest after checking it for injury, and while there discovered that there was a total of three nestlings. Two hours later the
blind, naked chick was on the ground again, and one of the parents was trying to kill it. Since the parents were obviously not going to accept it back in the nest again, we took it for hand-raising.
Still later that afternoon, a second chick was on the ground; it was also taken for hand-rearing. The third nestling was taken from the cavity but as it was plumper and seemed healthier than the other two, it was returned for the parents to raise. They continued to tend it for two more weeks, after which time the nestling died and the adults pulled it out of the cavity. Temperatures at that time were over 110° F, and though the log was in a shaded location and mistheads were spraying a fine, cooling mist, the temperature inside the log may have become excessive.
The two surviving toucan chicks were nestled into a deep cup-like depression in a large towel that we placed in a box. A folded paper towel at the bottom of the depression facilitated frequent cleaning, yet allowed the young to grip the sloping sides of the terrycloth, in nearly the same posture as they would have had in the nest log. When necessary, a heating pad was placed behind one side of the towel so that the chick could move toward or away from the warmth. For humidity, a small widemouthed dish with a water-saturated paper towel was placed in the box.
The box was partially covered with a towel, which not only kept the birds in darkness and prevented drafts, but also illustrated an interesting behavior of cavity nesting birds - nestlings raised in tree cavities respond dramatically to "shadowing," that is, the darkening of the cavity when the parent enters the hole of the nest
log. The darkness stimulates the young to instinctively begin gaping for food. At each feeding time, this shadowing effect was simulated by putting the towel completely over the box, then withdrawing it to feed once the chicks had responded.
When the young are newly hatched their first meals are regurgitated to them by their parents. Some of the parents' digestive enzymes are probably transferred as well. As these chicks were two weeks old, they were most likely receiving morsels directly down the throat.