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1 October 2011 Immature Survival and Age at First Breeding of Damara Terns: Conservation from a Non-Breeding Perspective
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Protecting breeding sites should not be the only conservation measure for seabirds that exhibit delayed maturity and spend extended periods of time in their non-breeding areas. We investigated age at first breeding and immature survival of Damara Terns Sterna balaenarum which breed in southern Africa and migrate c. 4000 km to their non-breeding grounds in West Africa. Using multi-state capture—mark—recapture models adult annual survival was estimated to be 0.87 (95% confidence interval: 0.73–0.94). Mean annual immature survival of Damara Terns from nest stage to breeding was estimated to be 0.59 (95% confidence interval: 0.48–0.68). Immature survival contained an element of pre-fledging mortality since most individuals were ringed before fledging. Furthermore, our estimate could be biased low due to permanent emigration from the study area. The age at first breeding was three years (probability of 0.27), and all terns were breeding at four years. This is comparable to other plunge-diving migratory terns which have extended periods of post-fledging dependence. In the light of this we suggest that consideration be given regarding the protection of the species in its non-breeding countries in addition to the protection of current breeding sites.

Justine Braby, Sigrid J. Braby, Rodney J. Braby, and Res Altwegg "Immature Survival and Age at First Breeding of Damara Terns: Conservation from a Non-Breeding Perspective," Ardea 99(2), (1 October 2011).
Received: 16 February 2011; Accepted: 1 September 2011; Published: 1 October 2011

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