Captive Propagation of Scarlet Macaws

Abstract

The scarlet macaw (Ara macao) is among the largest and most vividly marked members of the parrot family. With origins from Mexico to Brazil the scarlet macaw has been rapidly decreasing in number through non-restrictive exportation and non-selective destruction of habitat. Currently, the scarlet macaw retains ''protected'' status in several South American countries. In essence, the survival of this once numerous colorful species in the years fonhcoming will be dependent upon captive propagation programs by dedicated aviculturists.

In conjunction with intensive breeding programs, hybridization of those potentially endangered parrots must be kept to a bare minimum or completely eliminated in order to maintain an accurate species genome in our captive populations. The data and procedures submitted in the following text are for the benefit of those who share an interest in propagating potentially endangered or threatened species of psittacine birds. Currently at our facilities at Avicultural Research, pairs of hyacinthine, green wing and blue and gold macaws are nesting under identical conditions described for the scarlet macaws.

Mating and Egg Laying Behavior

Two wild-caught adult scarlet macaws housed in a large common flight with other psittacine birds were noted to show strong pairing behavior and aggressive/ defensive interaction with the other psittacines in the flight enclosure. We observed these birds to become aggres-

sively territorial and possessive of feeding bowls and perch areas in what had previously been an open and casual flight. These birds were never surgically sexed, however a sexual pair was suspected based on the observed behavior.

In the fall of 1980, the pair was placed in an electronically controlled environmental breeding chamber four feet wide, five feet deep and six feet high. A nest box was constructed of wood with dimensions of four feet wide, two feet deep, two feet high and was an integral part of the internal area of the breeding chamber. The next box was lined with pine shavings which were periodically sprayed with water to augment the system humidifier in maintaining a relative nest box humidity content of approximately 60 % .

OnJune 6, 1981, after three weeks of a 14 hour photoperiod, the female laid her first clutch of three eggs, of which two were fertile. Egg laying was suspected to be close at hand because of a change in stool coloration (to dark brown or black) and increased time spent within the nest box. A new egg was discovered approximately every 48 hours. Fertility was determined by removing the eggs, candling and returning the eggs to the nest box.

In the following 12 months of the study the pair produced a total of five clutches. The first four clutches were left with the parents for incubation and the fifth clutch was artificially incubated and hatched in our laboratory facilities.

Mating behavior and subsequent egg

laying for the five clutches was artificially induced by gradually shortening the photoperiod from a base line of 12 hours to a minimum of seven hours over a period of 10 days. This minimum photo period was then held for a duration of 14 days and followed by a one-half hour photoperiod increase per day until the photoperiod reached its maximum duration of 14 hours. Egg laying usually commenced within 20 days after this maximum point was reached.

Typically, the pair produced three fertile eggs per clutch. Eggs were laid every other day (48 hour intervals) and usually discovered by us during early morning hours. Our mean incubation period was 24 days, which from our review of the literature, is perhaps four days short of the norm (Bates and Busenbark 1969). However, our average weight of newly hatched chicks did correspond to the 24 .0 grams typically cited in psittacine breeding references.

We experienced early hatching (as much as one week premature of the 28 day norm), both when the eggs were left with the parents, and when the eggs were artificially incubated. However, this phenomenon could be specific to this particular pair of macaws. Eggs left in the box were sprayed with warm water every other day during the incubation stage to augment humidity content. The parents would typically move off the eggs during this procedure and considered the water spraying of eggs and nesting media a ritual which they would tolerate with some reluctance.

Artificial Incubation Techniques

Artificially incubated eggs were weighed to .01 gram every other day on an OHAUS solid/liquid beam balance model 7401-02 and were rotated between a "wet" and "dry" incubator as dictated by weight in order to keep the developing embryo within our extrapolated weight loss curve. It has been determined that a weight loss of 16% during the incubation period is congruent with a successful hatch (Stoodley 1982). This value can vary as much as 4 % above or below the theoretical value of 16 % (Stoodley 1982). However, with the proper equipment and care we found we could hold our weight perimeter within ± 2%.

We utilized the Marsh Farms Roll-X automatic incubators with manual turn and have experienced a 100% hatch rate. Extreme care was maintained during the egg turning procedure by initially marking the eggs with pencil to designate an "A" side and a "B" side. In addition, rotational marks were noted so that the

egg was not continuously rotated in one direction thus causing embryo strangulation.

Eggs were turned every two hours for a total of seven times per day. The egg was turned an odd number of turns to insure that it ''slept'' on an opposite side during the night.

Eggs were candled every other day and pencil lines were placed tracing the outer limits of the air sac space. The average humidity requirement of our eggs was between 50 to 70 % relative humidity. All incubator humidity measurements were obtained by using a wet bulb ther-

mometer and converting the relative humidity values with a conversion table available in most standard incubation reference books. Our incubation temperature was 98. 5 °F with a flux variation of ± . 75 °F. Incubator humidity requirements are completely dependent upon varying weight measurements which are primarily dependent upon individual egg transpiration rates. It was noted that each egg must be tracked individually to insure a successful hatch rate.