Behavioral Responses of Two Species Passerine to Predation Risk During Breeding Period

Life-history theory predicts that differences in reproductive effort and residual reproductive value among species should result in differences in the level of risk that parents are willing to tolerate to themselves versus their offspring. Here,we tested the prediction that parental investment decisions were correlated with nest sites by comparing risk - taking behaviour in two species of passerines (small skylark Alauda gulgula and horned lark Eremophila alpestris) in alpine meadow, from 2002 to 2004. We experimentally manipulated predation risk by presenting models and measured the willingness of parents to feed nestlings. The results shown:Response of the horned lark to human intrusion was a significantly stronger than the small skylark;Both species responded to predators by decreasing the length of attendance time,reducing the feeding rate and increasing the length of elapsed time;There was significantly difference between the reproductive behaviour in the small skylark and horned lark in the natural condition,whereas,no difference in the predator condition;Males of both species had lower willingness to tolerate risk to themselves than females. Thus,those passerine species responded to predators by reducing investment in current reproduction and increasing probability of future survival. Our experimental results support the above prediction.