Perceived predation risk and its effect on population

Perceived Predation Risk Reduces the Number of Offspring Songbirds Produce per Year

Liana Y. Zanette,Aija F. White,Marek C. Allen and Michael Clinchy

Science 9 December 2011: 
Vol. 334 no. 6061 pp. 1398-1401

Traditionally predator effects on prey demography are associated with direct killing in studies of population ecology and wildlife management. In this paper the researchers show that perception of predation risk itself can act as a big damper on population.

The researchers isolated effects of perceived predation risk in a population of free living sparrows by actively eliminating direct predation. They then played back predator recorded calls and sounds to manipulate perceived risk. The researchers found that perception of predation risk alone brought down number of offspring by 40%.

The researchers conclude that predation risk perception should be given greater consideration in vertebrate conservation and management