Territorial behaviour and population dynamics in red grouse Lagopus lagopus scoticus. II. Population models

1) Recent experiments on cyclic red grouse populations discovered that aggressiveness, induced by testosterone implants, depressed population density for more than a year after the implants were exhausted. 2) This confirms the observation, also made in previous studies of this territorial species, that aggressiveness can determine population density. Additionally, it hints at a form of social memory that sustains the effect of episodes of high aggressiveness after their cause has ceased to exist. […].

Jason Matthiopoulos, Robert Moss, Francois Mougeot, Xavier Lambin and Steve M. Redpath, Journal of Animal Ecology 2003 72, 1083-1096