Effects of residence time on displays during territory establishment in a lizard.

We know little about how signals are used during territory establishment, particularly when potential competitors are separated by distances that are typical of those between neighbours. I studied the effects of residence time on the display behaviour of male Anolis sagrei lizards in long- and short-distance contexts. In the long-distance context, the habitat patches of two male lizards were 5 m apart, separating the males by a distance typical of that in territorial neighbourhoods. For the short-distance context, I placed two males in one habitat patch. In both contexts, either 1-day residents were paired with new arrivals, or both individuals were new arrivals. In the long-distance contexts only, I also created situations in which both individuals were 1-day residents. Residence time affected the relative frequencies of headbob displays ('bobbing displays' and 'nodding displays'). However, the direction of the effect depended on opponent proximity. In long-distance contexts, 1-day residents performed fewer bobbing displays relative to nodding displays than did new arrivals; in short-distance contexts 1-day residents performed more bobbing displays relative to nodding displays than did new arrivals. The results suggest that signalling during territory establishment is governed by a qualitatively different set of rules when potential competitors are at short versus long distances. Copyright 2000 The Association for the Study of Animal Behaviour.

Plasma corticosterone and testosterone levels during the annual reproductive cycle of male brown anoles (Anolis sagrei).

The objective of the present study was to determine the plasma levels of testosterone and corticosterone in male Anolis sagrei during the annual reproductive cycle and to examine the relationships between seasonal change in the levels of these hormones, male reproductive activity, and body condition. Both testosterone and corticosterone levels in adult males captured in the Miami, Florida, area varied significantly with month and with season (i.e., breeding vs. nonbreeding period), although they were not significantly correlated with each other or with body mass. Mean monthly testosterone levels were higher during the breeding season (March-August) than during the nonbreeding season, with the one exception that the highest mean testosterone level occurred in February immediately before the beginning of the breeding season. Testosterone levels in the overall sample of 144 males were significantly correlated with testes mass but not with any of the other measured variables. Corticosterone levels were highest during the nonbreeding season and lowest during the breeding season. Corticosterone levels on a monthly basis were negatively correlated with monthly changes in testes mass and positively correlated with monthly changes in abdominal fat-body mass.