WAZA magazine Vol 13/2012
California Condor
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Fig. 1 Ventral view of mature California condor showing tag and transmitter. © Mike Wallace/San Diego Zoo Global
In the wild, both Andean and California condors lay one egg, on average, every two years due to the long parental dependency period. If the single clutch egg is lost through predation or accident early in the 57-day incubation period, the pair will often “recycle” and lay a replacement egg in about 30 days. Capitalising on this trait, we removed the first, and sometimes the second, egg laid to artificial incubators for hatching and were able to get the captive pairs to lay more eggs than they normally would. Called double or triple clutching, we were able to increase the reproductive rate four to six times; a significant breakthrough in saving this normally slow reproducing bird. With the genetic status of each individual known, we were able to maximise out-breeding when forming pairs that normally mate for life in the wild.
To maintain adequate chick behaviour during the ontogeny of the extra chicks, life-like puppets were employed to mimic the behaviour and movements of parents in this highly social species. This artificial parental substitution effectively bridged the gap until, at about six months of age, the fledgling could be introduced to a more socially natural group of older birds that included an adult mentor to help maintain social order. Another tool employed to increase success in new, inexperienced pairs was the use of fake eggs to allow them risk-free time to learn the temporal rhythm of swapping incubation duties in unproven mates. When incubation behaviour improved to an adequate level, the real egg was surreptitiously replaced. Risk to genetically
valuable eggs or hatchlings was also reduced by allowing many of the new pairs to first practice the hatching process with less endangered and available Andean condor eggs in their first reproductive efforts. Over several seasons competent pairs were eventually allowed to raise their own offspring. Also, early on in the programme, the eggs of genetically valuable pairs were often reared artificially or given to more reliable pairs. The goal was to maximise production while concurrently training pairs to be reliable enough to raise their own young without undue risk to the eggs or chicks.