SOCIAL INHIBITION OF TERRITORIAL BEHAVIOR IN YEARLING MALE COLLARED LIZARDS, CROTAPHYTUS-COLLARIS

In central Oklahoma, collared lizard males display age-dependent diffe rences in social behaviour, whereby sexually mature first-year (yearli ng) males adopt subordinate tactics, and males 2 years and older estab lish and defend all-purpose territories. We tested the hypothesis that the social activities of adult males inhibit the expression of territ orial tactics in yearling males by recording the behaviour of yearling s in the presence of adult males, when all adult males were removed fr om study plots for 4 days, and then again when adult males were return ed to their territories. The rates of yearling male patrol, display an d intrasexual encounters increased during removals, especially during the last 2 days, following which the rates of these behaviour patterns declined when adult males were replaced. Yearling males also increase d the frequency with which they interacted with females when adult mal es were removed. Moreover, the duration of intersexual encounters duri ng the last 2 days of removal was over twice that during the first 2 d ays of removal, suggesting that females became more receptive to yearl ing males the longer adult males were absent. Our results suggest that the stable age-related behavioural differences in male collared lizar ds is governed by social feedback, where sexually mature yearling male s are capable of displaying territorial behaviour patterns but are inh ibited from doing so by the activities of adult males. (C) 1998 The As sociation for the Study of Animal Behaviour.