Conservation breeding for reintroductions: assessing survival in a captiveflock of houbara bustards

Conservation breeding for reintroduction is becoming a popular option for r estoring threatened populations. Whereas post-release results are widely re ported in the conservation literature, little empirical information is pres ented on the captive populations that often make such releases possible, ev en though fecundity, fertility and survival rates can have an impact on the outcome and cost of wild population re-establishment. We present results o f survival analyses carried out on a captive population of houbara bustards to determine peak periods of mortality, and by identifying sources of vari ations in mortality to recognize the potential impact of management practic es on productivity. There were two main mortality peaks: during incubation (53% survival of fertile eggs), and by 6 months posthatching (75% survival of hatchlings). Management-related variables influencing survival of eggs a nd chicks included the year when laid, the cohort of females laying them, a nd possibly sex. Most posthatching deaths were due to trauma and infectious diseases. Trauma-related deaths usually follow collisions with cages, and imply selection for the captive environment, an undesirable trend in popula tions maintained for reintroductions. Reducing losses during incubation wou ld have the largest impact on production of birds for reintroduction, enabl ing the release of more birds, and reducing the overall costs of the projec t.