Birds of a Different Feather
Somber shading and a surprising behavior are part of this species' offbeat tale.
BY Wendy Perkins
Photography by Ken Bohn
Among the frequently flashy-hued birds that make up the parrot group, the palm cockatoo Probosciger aterrimus stands out by virtue of its somber coloring. These “tall, dark, and handsome” birds have a home in the Zoo’s Conrad Prebys Australian Outback, and they are really a sight to see!
The Subtle Approach
Native to northern Queensland, Australia, and New Guinea, this species is the largest of all cockatoos (measuring up to 25 inches from head to tail) and they also have the largest beak among their kind. A fine, white powder from exfoliated down feathers covers their body, making the black plumage appear dusky gray. The “bright spot” on a palm cockatoo’s face is the featherless patch of red skin under its ebony eyes. When the bird is excited, the spot flushes from dark pink to orange-red to scarlet in color.
With their big beak, these birds are able to crack the large, tough nut of the pandanus plant (often called a palm, but it’s not). Pandanus fruit is a palm cockatoo favorite. In fact, the birds’ common name comes from the fact they they are so often seen feeding in those trees (which, again, are not actually palms, but oh, well). They round out their diet with other types of fruits, nuts, and leaf buds.
Home Is Where the Hollow Is
Appearances aside, palm cockatoos differ from other parrots and cockatoos in other ways, too. They have a very slow life cycle, breeding every two years as opposed to the yearly breeding of their kin. And while they, like other cockatoos, raise their young in tree hollows, they have more specific nest requirements.
Palm cockatoos seek out hollow stumps that are open at the top. What happens when it rains? No roof, no problem. During nest preparation, the birds fetch thin sticks, break them into small pieces, and drop them into the cavity. The accumulation of broken bits forms a platform that keeps the precious egg elevated above any water that collects. A pair of palm cockatoos may make a number of nests within their territory, but only actually use one as the spot for eggs and chicks. Which is not to say the other spots go unused by the birds. A tree cavity not only makes for a cozy nest, but is key to a unique behavior in these birds: drumming.
The Beat Goes On
While a number of animals use tools, palm cockatoos are among the few that actually make a tool by breaking off a branch and, if needed, biting off bits until it is about eight inches long; they sometimes use a hard seedpod instead of a stick. Holding the instrument in one foot (almost always the left!), the bird bangs it repeatedly against the hollow section of the stump. Field researchers found that each male has its own rhythmic style, and recorded birds sometimes drumming 200 beats in a row. Like a lot of bird calls, the drumming probably serves as a territory announcement and a way to attract a mate. However females drum, too. It’s thought that drumming might also be a way a pair reinforces their bond after they have established their relationship.
The trees that are “just right” for these birds are usually around 100 years old and may be scarce, especially after humans alter the habitat. Logging, mining, and land clearing for agricultural and development purposes have left glaring scars on the forests palm cockatoos inhabit in New Guinea. Breeding these birds in managed care is helping to keep the gene pool active and diverse—a hedge against extinction.
A Bird in the Hand
Another difference between palm cockatoos and other types is that “palmies” (an Australian nickname) lay only a single egg (other cockatoos lay two or three). When the pair at the off-exhibit breeding area at the San Diego Zoo Safari Park laid their first egg in 2008, staff removed it, which triggered the birds to lay another. The first egg was carefully tended to in an incubator; after it hatched, the chick was sent to the Avian Propagation Center (APC) at the Zoo for hand rearing. It was the first time any of the APC team had raised the species, and they had been told it was difficult. Yet, channeling their passion for birds and determination to help the chick thrive, they dove into the research and hard work needed.
Hand-rearing the chick allowed the wildlife care specialists to observe and document all stages of the the little one’s development. As this particular chick’s feathers came in, it happened in an order that made it appear like he had sideburns, so the staff nicknamed him Elvis. Once he fledged, Elvis went to a “dating center” for palm cockatoos at the Sedgwick County Zoo in Kansas. This species is known to be particular when it comes to choosing and bonding with a mate. At the Kansas facility, the palm cockatoos are kept in groups to allow for optimum socialization and lots of choices for mate selection. Elvis did, indeed, find a female that suited his fancy—and vice versa—and the two returned to San Diego. They have their own territory in the koala area at the Zoo, where visitors delight in the pair’s activities and marvel at their beauty.