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| Cranes Their Biology, Husbandry and Conservation - Sample Chapter |
The age of sexual maturity and the initial appearance of reproductive behavior varies between species and individuals, and is strongly influenced by rearing history and management within species. In general, cranes form mating pairs when two to three years old and begin to reproduce when three to five years old. With rare exceptions. Females lay eggs only when paired. Pair bonds persist and egg production continues (although sometimes at a lesser rate) even when members of a pair are separated into adjacent pens (Gee and Sexton 1979). Egg production usually begins one to two years after formation of a pair bond. Laying as early as two years of age has been occasionally reported in captive Wattled, Red-crowned, Eastern Sarus, and Sandhill Cranes, and is common in Mississippi Sandhill Cranes (25% of two-year-old females; Nicolich 1993).
For most species, captive cranes achieve reproductive success earlier than wild cranes. For some species, however, captivity appears to delay egg production. Captive Whooping Cranes generally start laying at 5-7 years of age, even though wild birds lay as early as three years of age (Kuyt and Gossen 1987). The mean age of first breeding is decreasing as management improves (Mirande 1994 unpubl.) Until a few years ago, most captive Siberian Cranes bred at seven years of age or older. However, with improved rearing and pairing techniques. Siberian Cranes are now breeding as early as four to six years of age (Panchenko 1993 unpubl.).
Sperm production generally begins at 2-3 years of age with regular production of quality semen usually occurring the following year. Unlike females that lay eggs only when mated, even unmated males produce sperm.
Captive cranes can live long and have an extended reproductive lifespan. A male Siberian crane at ICF lived to be at least 78 years of age and produced sperm until at least age 75. A pair of White-naped Cranes and a pair of Demoiselle Cranes produced young when both adults in each pair were at least 60 years of age. Great longevity has important management implications(see Chapter 9). . . |
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