Southern Stone Curlews (1980)

Southern Stone Curlews (Burhinus magnirostris), a form of shorebird, are native to Australia, where they inhabit grassy woodlands throughout most of the continent. They are often found where land usage is of low intensity, as in the Northern Territory on Cape York Peninsula. They are nocturnal and largely predatory, with invertebrates making up the bulk of their diet. The young are produced in the spring of the year and are semi-precocial. Adult birds are monomorphic, that is, both sexes are similar in appearance, showing no sexual dimorphism. Immatures are similar to adults but the coloration is paler. Mature birds are approximately 550mm in length, which includes a 180mm tail and a 45mm bill. Southern Stone Curlews are also known as the Bush Thick Knee, Bush Curlew, Scrub Curlew, Southern Stone Plover and the WeeLoo. Stone Curlews are usually seen in single pairs during the breeding season but often congregate in flocks during the nonbreeding season. The birds are basically sedentary, and do not migrate. Although ground invertebrates are important dietary items they have been observed to eat small birds and mice. Nesting takes place during the months of January through August. A scrape or small clearing is made on the bare ground and generally only two eggs are laid. Quite often the nest is near a bush or tree or behind a fallen tree which offers added protection and seclusion. The eggs are a light stone or pale buff color, blotched with various shades of brown. The eggs are incubated by the hen and the young are fed by both parents for several days after hatching. The bird collection in the San Diego Zoo currently contains two adult pairs of Southern Stone Curlews, in additon to one young raised in 1975 and five in 1979. The first adult pair was received August 31, 1967 from the Adelaide Zoo, Adelaide, South Australia. A second pair, approximately two years old, arrived at the zoo during the month of June 1978, originating from the Perth Zoo, Perth, West Australia. After arriving, the birds had to pass the usual 30 day quarantine period at the zoo hospital before being placed on public display. So far, only the Adelaide pair has successful produced offspring. The breeding pair of Stone Curlews is housed in a planted aviary near the Rondoval Pool near the Zoo's bus depot. The aviary measures 10 feet by 20 feet by 7 feet tall. The aviary is planted with a dense cover of New Zealand Christmas Trees (Metrosideros excelsus). They presently share the exhibit with a pair of Little Friarbird (Philemon citreogularis). Adult birds are fed what we refer to as a wet-dry pan. This includes a combination of several food items; ground dog food (260Jo protein), ground horse meat, trout chow (400Jo protein), dried shrimp meal, millet seed, a 260Jo protein laying mash (Layena, manufactured by Ralston Purina), grated hard boiled egg and a few meal worms as supplemental to the diet. This diet is fed as a mix in a round stainless steel pan. The adult hen usually begins laying during the month of April. A two egg clutch is laid, with an interval of three days between the first and second egg. The eggs are usually artificially incubated, but in the past, the adult birds have been allowed to incubate naturally. The advantage of artificial incubation is that more young can be produced from a given pair of birds per breeding season. The incubation period is 24 to 25 days. When eggs are laid, they are collected daily and stored under optimum conditions. Prior to setting, the eggs are fumigated with a formadahyde gas. This gas is produced by mixing potassium permangante and formalin (370Jo) at a temperature of at least 70.0°F. and a high humidity. These ingredients are mixed together in a small earthenware container in a box of about 2 cubic feet volume, and the eggs are exposed to the gas in this box for about 30 minutes. The fumigation procedure is used to eliminate bacteria which might be adhering to the surface of the egg shell. Since eggs are an excellent medium for bacterial growth, especially under the conditions of incubation (heat and humidity), it is essential to keep the eggs as free of bacteria as possible, prior to, and during the incubation process. The eggs are incubated in a Petersime incubator which automatically turns the eggs every two hours. The incubation temperature and humidity are 99 .5 °F. and 85.0°F. wet bulb, respectively. Approximately three days prior to hatching the eggs are transferred to a separate hatching unit where they are allowed to hatch. After breaking out of the shell completely, the young curlews remain in the unit for about 24 hours before they are placed in a brooder. The Stone Curlew chicks are brooded in a wooden box brooder for the first three or four weeks after hatching. The flooring substrate is green astro-turf. The turf is frequently cleaned, which helps prevent disease problems. Heat is provided by both an electrical heat cone and a light bulb. The brooding temperature is 95.0°F. for the first week and is decreased by 5 .0°F. per week until the brooding temperature reaches ambient temperature. After about four weeks of age the young birds are transferred to a floor pen brooder. This allows the birds more room for exercise. The diet of the young curlews include: finely chopped white fish, ground horse meat, dried shrimp meal, soaked dry dog food (26% protein), hard boiled egg yolk, trout chow (40% protein), Gerbers high protein baby cereal, bone meal, a vitamin supplement (Vet-Nutri, manufactured by Squibb and Sons) and a few meal worms. Water is added to the above ingredients until the mixture is in a liquid suspension. The bone meal is added to provide additional calcium to the diet, since the calcium to phosphorus ratio of the red horse meat is insufficient for normal bone growth and development. Water is provided by an inverted canning jar with a plastic base reservoir. A very interesting point about Southern Stone Curlew chicks is that they have to be handfed for several days after hatching. This time period may last as long as three or four weeks before they begin to eat on their own. The best method for feeding them is from the tip of a pair of forceps. Since the food ingredients are in a liquid suspension, the initial feedings consist of dangling the larger chunks above their beaks until they open. They are fed about every three hours for the first week after hatching. As they grow, the time interval for feeding is decreased to about three times per day. The young curlews are not fed during the night hours, but the first feeding takes place at seven in the morning and the last feeding at four in the afternoon. A food pan is always available to the birds, starting from the first day after hatching. The birds seen to thrive on this method of rearing and grow at a rapid rate. Our first Southern Stone Curlew was successfully raised in 1975 and was appropriately and affectionately named, Stretch. Subsequently, during the 1979 breeding season five additional birds were also artificially reared. Although the adult pair originating from the Perth Zoo has not yet laid, we are looking forward to the time when they also present the zoo with offspring.