Cassowaries

Abstract

Cassowaries are large, black, omnivorous, flightless birds (ratites) that are found in the rain forests of New Guinea and Northern Australia. There are three species, and numerous subspecies. The double-wattled cassowary, Casuarius casuarius, is probably the most abundant and, therefore, the most commonly seen in captivity, the other two species are practically non-existent in collections in North America, being represented only sporadically in 3 or 4 collections.

Adult double-wattled cassowaries are 4 to 5 feet in height and will weigh 100 to 120 pounds when fully grown. The young assume adult coloration at approximately 2 years, and reach sexual maturity between 5 and 7 years of age. All cassowaries have a very poor, sporadic breeding record in captivity. They generally lay 4 to 7 large, lime to avocado-green eggs. The incubation period for these eggs is approximately 46-50 days. Cassowaries adapt quite well to captivity and thrive in a variety of climates throughout the world, however are extremely sensitive to cold and must be protected from severe weather or frost bite and death can result. They love water, relish being sprayed with a hose and are expert swimmers.

Cassowaries have many unique features. The head is crowned by a large casque which is helpful in breaking through dense underbrush. In most species the neck is decorated by brilliantly colored

patches of skin of various hues. Their almost non-existent wings are distinguished by large, veinless feather shafts that resemble knitting needles. Each of the bird's three-toed feet is highlighted by a large talon-like nail that is often used as a weapon for defense.

Cassowaries have been displayed in U.S. zoos for over 100 years. Individual birds are relatively easy to maintain in captivity. A large enclosure with some shade trees and a proper diet will suffice to maintain these birds for a long period of time. One female lived over 21 years as an adult in a zoo, and a breeding male was 31 years old when he first mated. Problems arise when one attempts to keep more than one bird together or attempts to breed them. The main problem in breeding stems from the fact that the male and female are solitary in the wild, except during breeding season, and do not usually get along well together in captivity even in large enclosures. There have been many attempts to exhibit male and female cassowaries together and many humorous tales are told about such introductions. More often than not, tragic occurrences have resulted, and exhibits of single cassowaries are common sights in many zoos.

The breeding of cassowaries in captivity has been very uncommon. The London Zoo first bred them in 1862 and again in

1863. One chick was produced each year and neither survived. This feat was not accomplished again until 1957 when the San Diego Zoo reared one chick. This success was later duplicated by two zoos and two private individuals during the early 1970's. In 1977, the Denver Zoo became the sixth place in the United States to hatch a cassowary. This accomplishment has only been attained by 8 other institutions in the world. Two other zoos have thus far hatched single specimens in 1980 in the U.S., and a private zoo has produced young yearly the past three years. By far the most successful propagation program has been that of the Edinburgh Zoo in Scotland, where at least one bird has been reared every year since the early 1960s. Normally, successful rearings have occurred by allowing the male to incubate and rear the young. Few people have artifically incubated eggs, fewer still have hatched young and a complete artificial rearing program has been almost non-existent.

The Denver Zoo's history with cassowaries is rather unique and interesting. In 1974, while building Bird World, we decided that we should exhibit these most unusual flightless birds. After locating a "pair" in another zoo, we proceeded to arrange to pick them up. During the return trip to Denver a discussion ensued as to which bird was the female, as there was confusion during the crating of

the birds. Thus the seed of doubt was planted. Six months later (on of all days, Easter Sunday), we had our own bright lime-green Easter egg! Within a week our worst fears were confirmed when we began obtaining 2 eggs a day. We had two females. The search for a male began and continued throughout that summer and into the following spring. At last a male cassowary (far from a perfect physical specimen) was available on loan from another zoo, this particular bird had a very colorful and well-traveled history, far too complicated to describe here. After a long wait, he finally arrived but too late for the 1976 breeding season.

We immediately began the long and often hectic introductory process. We introduced the male bird to both females simultaeously. They chased and literally kicked him over the fence. We then introduced him to each female separately with the same results. We had decided that we would continue this process in the hope that he would assert his male dominance. Finally, in the spring of 1977, one of the females accepted him and mating was observed. Thus we began a 3 year attempt to accomplish what few other zoos had done in the past; to artificially hatch and raise cassowaries.

Cassowary rearing does not differ significantly from the other ratites. The main problem in raising them is the establishment of a proper growth rate and weight gain. An imbalance of minerals in the young birds, generally brought about by abnormally fast body growth, can cause leg or tendon displacement. In other words, the birds gain weight so rapidly that their legs cannot adequately support them. The hatching problem was also causing us great concern since cassowary hatchings in the wild, and for the most part in captivity, are the result of male parental incubation of the eggs. At the Denver zoo we were quite certain we would have to rely on artificial incubation. Temperatures and humidity levels for artificial incubation are well established for many species, but not for cassowaries.

Cassowary courtship is an extremely long involved process that is fascinating to observe. The male will begin by erecting his feathers over his entire body and then very vigorously shake his entire body. This produces the only sound in the entire process. This is believed to be an attention getting device. The male then very cautiously and slowly approaches the female from the back towards one side of the head. If not spurned at this point he begins a very deliberate, gentle stroking, pecking of the head and neck region, that resembles a grooming procedure. This stroking continues for a considerable period of time

(up to 20-30 minutes) and proceeds down the female's side and progresses up to the base of her neck and down her back. If nothing disturbs the courtship, (if anything does, the whole process stops immediately and may or may not start again) this gentle grooming has a mesmerizing effect on the female and she will slowly sink to the ground. At this time the male will mount her and copulation takes place. Sometimes the male will not be successful in having the female lie down and will proceed to groom her on the opposite side and continue until mating is accomplished.

Cassowaries generally have a small clutch of eggs for their large size. Clutches are generally 4 eggs but very frequently will be as large as 7. Both of our laying females were exceptional and laid an average of 14 eggs. The fact that all eggs were collected as soon as they were laid, contributes to this unusually large clutch size. The eggs average 143 mm x 90 mm in size and weigh an average of 634 gms. The diet of our adult cassowaries consist of the following: chopped apples and chopped bananas spread over ratite diet. 1 The fruit is sprinkled with Vionate2 and bone meal. Periodically, whole adult mice are offered and rapidly accepted. The ratite diet is offered free choice at all times.