68 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



same size accounts for the existence of aggressiveness in all of the 

 individuals of the species. 



The Life of a Lizard 



In this section I want to describe what probably happens to a Uzard 

 throughout its life history in general tenns of its social relations and 

 its spatial distribution in a densely populated area. There are many 

 gaps in my information that I must bridge with hypotheses. Some 

 of the imagery may be wrong but it is the best I can do to demonstrate 

 as vividly as possible some of the gaps in our knowledge. 



A lizard hatches from an egg buried under a log, the edge of a rock, 

 or in leaf litter and soon settles into a home range; how far it wanders 

 before doing so we do not know. The initial activity range differs 

 from those of the adults. The former is smaller, and the hatchling 

 avoids large perches and is not attracted by the presence of an indi- 

 vidual of the other sex. The avoidance of large diameter perches is 

 adaptive since these are frequently occupied by adult males that eat 

 hatchlings when the adults can catch them. 



These hatchlings are aggressive and soon space themselves out so 

 that their home ranges do not overlap, though the home range of a 

 young lizard may be overlapped by those of several larger lizards. 

 As the young lizard grows, it enlarges its home range. At the same 

 time, there seems to be a shift in perch preference with the result that 

 the growing lizard begins to visit the usual perches of the larger 

 individuals. 



Initially, the young lizard is generally ignored by the larger neighbors 

 and avoids them. But as it grows larger and begins to visit their 

 perches, they begin to chase it, both when it visits one of their perches 

 and when they encoimter it elsewhere. At first the young lizard tol- 

 erates this behavior and flees the larger individual without changing 

 its activity range. Such a situation may last for several weeks and 

 perhaps several months. During this period the same lizard also is 

 chasing from its own activity range others smaller than itself, and it 

 may expand its activity range at the expense of another by chasing it 

 away. The young Uzard also may be forced to move by another 

 slightly larger lizard's moving into its area; I believe this action pro- 

 duces some of the long distance shifts recorded for juveniles. 



Even if another juvenile does not displace it, this lizard's continued 

 growth soon brings it into more serious conflict wdth the adults whose 

 activity ranges overlap its own — first, with adult females since they 

 are smaller than adult males. The decreasing diff'erence in size be- 

 tween the adult female resident and the more rapidly growing juvenile 

 seems to produce serious conflicts for two reasons. First, the female 



