Adult Seabird Survival

Most of the seabirds that nest on Tern Island are very long lived. Some of them up to 30 years and maybe beyond that. In a population like that each years chick survival isn't nearly as important to the whole population as is the survival of adults. All because of those long lives. Another way to think about it is that if a pair of birds lives 30 years and breeds 25 times only 2 chicks from all those attempts have to survive to maturity to maintain the population. Because of this fact catastrophic failure in any one nesting season becomes less important.