Captive Breeding 21
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383 Captive Breeding 21 JOSEPH B. PLATT In the early 1960s, Willoughby and Cade (1964) PCR Services Corp. demonstrated that it was feasible to breed American 1 Venture Suite 150, Irvine, CA 92692 U.S.A. Kestrels (F. sparverius) in large numbers for scientific study. The Raptor Research Foundation was formed in DAVID M. BIRD AND LINA BARDO 1966 by a group of falconers and biologists mainly Avian Science and Conservation Centre of McGill University focused on saving the Peregrine Falcon. Under its aegis, 21,111 Lakeshore Road, Ste. Anne de Bellevue information and ideas were exchanged between private Quebec, H9X 3V9 Canada breeders and institutions. In North America, govern- ment and institutional programs were begun; the largest included The Peregrine Fund at Cornell University, the U.S. Fish and Wildlife Service’s program at Patuxent, Maryland, the Canadian Wildlife Service’s facility in INTRODUCTION Wainwright, Alberta, the Saskatchewan Co-operative Falcon Project at the University of Saskatchewan, and Birds of prey have been held in captivity for thousands the Macdonald Raptor Research Centre at McGill Uni- of years by many cultures. However, it was not until the versity. At the same time Europe saw the creation of the 20th century that they were bred in captivity and manip- Hawk Trust in the United Kingdom, and various falcon- ulated in the manner of domestic species. In his review ry groups in Germany to promote breeding of large rap- of breeding records of aviculturists, zoos, and falconers, tors for falconry and conservation. Cade (1986) found reports of 15 species that had bred in Within 10 years significant progress had been made captivity by the 1950s, and 22 by 1965. None of these in understanding the behavior and management of occurrences was part of an organized or sustained pro- breeding pairs as well as the art of incubation and the gram. care of young. Survey articles by Cade (1986, 2000) It was the idea of saving a diminishing species that documented that hundreds of large falcons were being provided the catalyst to bring together the people and produced each year and at least 83 raptor species had resources needed to overcome the challenges of consis- been bred by 1985. tently breeding these highly aggressive birds. Peregrine The successes have continued. Captive breeding Falcons (Falco peregrinus) were disappearing from and the related manipulation of wild-produced eggs breeding sites in North America and Europe because of have proved critical in the re-establishment of at least the contamination of their prey by DDT (Ratcliffe 13 species. These include the California Condor 1980). Western nations were committed to clean up the (Gymnogyps californianus), Red Kite (Milvus milvus) food chain, but would declining species such as Pere- in Britain, Bald Eagle, White-tailed Eagle (H. albicilla) grine Falcons, Ospreys (Pandion haliaetus) and Bald in Scotland, Bearded Vulture (Gypaetus barbatus), Eagles (Haliaeetus leucocephalus) recover? Griffon Vulture (Gyps fulvus), Harris’s Hawk (Parabu- 384 CAPTIVE BREEDING teo unicinctus), Mauritius Kestrel (F. punctatus), Aplo- wild or to import them from other countries. Birds can mado Falcon (F. femoralis), Lanner Falcon (F. biarmi- be collected as eggs or fledglings and then hand-raised cus), Peregrine Falcon on two continents, Barn Owl or raised by existing captive pairs. These individuals (Tyto alba) and Eurasian Eagle-Owl (Bubo bubo) in grow up accustomed to their confinement and are gen- Europe. Another dozen species have been bred and erally well adjusted (Weaver and Cade 1985, Toone and released on a smaller scale (Cade 2000). Risser 1988, Jenny et al. 2004). Hand-rearing young to This chapter presents a summary of guidelines to fledging age can cause significant socialization prob- the successful breeding of captive birds of prey. Raptors lems due to imprinting and should be avoided if natural are a diverse group, one to which generalities do not pairing is intended. On the other hand, if nestlings are always apply. hand-reared in groups of two or more conspecifics, they Artificial insemination and the use of imprints is also will imprint on one another. If these nestlings are one aspect of breeding that came about because of close placed in groups in flight pens at post-fledging, the association between trained raptors and their handlers. human imprint phenomenon can be reversed, at least These birds, both male and females, accept humans as with American Kestrels (D. Bird, unpubl. obs.). Hand mates. They court, solicit copulation, and raise fostered puppets can also be used (see Condors and Vultures sec- young with humans. The mechanics of this specialized tion). aspect of breeding is well presented in the literature Some species will breed in captivity when caught as (Weaver and Cade 1985, Fox 1995) and is not discussed adults (e.g., California Condors [Wallace 1994, Harvey here. The raptors presented in this chapter are divided et al. 2003], American Kestrels [D. Bird, unpubl. obs.]), into six major categories: large falcons, small falcons, but this is less likely for larger falcons (Weaver and eagles, hawks, owls, and vultures and condors. Since Cade 1985). Injured, unreleasable wild owls frequently captive propagation of raptors began with the breeding have been used as natural breeders if not too severely of large falcons, we have placed an initial detailed compromised (McKeever 1979) and endangered raptors emphasis on these raptors, followed by descriptions of held in rehabilitation programs can be used as semen the variations in breeding practices for the remaining donors (Blanco et al. 2002). All newly acquired birds groups of species. Within each raptor group, aspects of should be quarantined and tested for disease and para- cage design, feeding methods, breeding behavior, and sites before being used in a breeding program (Toone natural and artificial incubation and brooding methods and Risser 1988). are discussed. No matter what group of raptors the read- Female raptors usually are larger and more aggres- er is interested in breeding, it is worthwhile to peruse sive than males. To reduce the risk of injury or death to the entire chapter for useful tips that are likely applica- the male, the male should be placed in the breeding pen ble across the board. several days or weeks before the female (Heidenreich All birds of prey are protected by government agen- 1997). This may allow the territorial male to exert a cer- cies and the importation of exotic species is highly reg- tain degree of dominance over the newly introduced ulated (see Chapter 25). One should always verify female. Even so, in some species such as Merlins, the which permits are necessary to set up a breeding facili- female will suddenly and explicably kill her long-time ty and to acquire and raise raptors before beginning the mate (D. Bird, unpubl. obs.). project. Security to protect the birds from predators, thieves, and vandals also must be considered in the design and operation of a facility. SEXING AND PEDIGREES Many raptors are size- or plumage-dimorphic, and thus ORIGINS OF BREEDING STOCK can be sexed easily (D’Aloria and Eastham 2000). A few, however, are size- or plumage-monomorphic. For the latter, breeders must resort to collecting blood or Acquiring the Birds excreta in order to perform radioimmunoassays to test Raptors for captive breeding can be acquired from sev- for the presence of testosterone or estrogen (Saint Jalme eral sources; some are taken from the wild, particularly 1999). Birds also can be sexed using standard DNA for species conservation programs (Cox et al. 1993). blood analyses and karyotyping (Saint Jalme 1999, Special permits are required to remove birds from the Leupin and Low 2001). Bald Eagles have been sexed CAPTIVE BREEDING 385 using laparoscopy (Mersmann et al. 1992, Parry-Jones on the interior wall and 4.2 m high on the outside wall. 2000). Observing the behavior and vocalizations of The outer wall is open and covered with two layers of interacting birds also can be an indication of their sex wire mesh on the outside and vertical bars of 1.3-cm thin (McKeever 1979). walled electrical conduit placed at 6.2-cm centers on the There always is a risk of inbreeding when working inside. The PVC bars prevent the birds from coming in with a small population. Stock secured from other cap- contact with the mesh, which is 15 cm beyond the bars. tive populations may already be inbred. Severely The roof is solid except for a 9 × 3-m panel of mesh and reduced wild populations also may be highly related. bars to allow light and air flow. The walls of the cham- Careful records should be kept and genetic fingerprint- bers are painted plywood, which provides a smooth ing (microsatellite marking) can be used to ascertain the washable surface. The floor and nest ledge are covered relationships between birds (Toone and Risser 1988). with pea-sized smooth gravel, which has smooth edges Programs such as KINSHIP have been used to test the and does not compact, thus providing a “giving” surface pedigree of potential pairs to ensure that inbreeding is for landing birds. The bottom meter of the outer wall is reduced (Gautschi et al. 2003). paneled with metal sheeting to keep out snow. Predator barriers are buried around the buildings to protect the birds from potential predators and rodents (Weaver and LARGE FALCONS Cade 1985). The service corridor runs down the center of the barn on the first and second floor, allowing keep- In 1983, The Peregrine Fund, Inc. (now based at the ers access to each pen for maintenance and observation World Center for Birds of Prey in Boise, Idaho) pro- of the breeding pairs. The floors of these corridors are duced a publication: Falcon propagation: a manual on soundproofed with carpeting.