212 
Greenberg 
of cold can be dissociated from the effect of 
cold on activity (Boycott, Gray, and Guillery, 
1961). Daily variations in low temperature 
tolerance (indicated by a loss of the righting 
reflex) were described by Spellerberg and 
Hoffmann (1972), who attributed the 
changes to short-term acclimation during the 
cold night hours as well as an endogenous 
daily rhythm. 
Cabanac (1971) observed that body tem- 
perature and arousal are so intimately re- 
lated as to require a knowledge of the 
animal’s internal state when considering its 
responses to various stimuli. He has ventured 
the term “alliesthesia” for the phenomenon 
of changing stimulus value with variations 
in the animal’s internal state. For example, 
Garrick (1974) has observed that the selec- 
tion of body temperature by two species of 
lizard is affected by the animals’ reproduc- 
tive and hormonal state. Other species re- 
spond to bacterial infection by selecting 
warmer microhabitats and effectively devel- 
oping a “fever” (Kluger, Ringler, and 
Anver, 1975) which may be important to 
survival (Bernheim and Kluger, 1976). 
In a study of blue spiny lizards, thermal 
radio transmitters were used to monitor the 
lizards’ body temperatures during various 
activities (Greenberg, 1976a). It was of 
interest that these lizards basked until their 
body temperatures attained the maximum 
voluntary level, after which they were rela- 
tively passive in regard to the thermal quali- 
ties of their microhabitats (Fig. 7). This 
suggested that after an initial “warming 
up,” behavioral thermoregulation would not 
compete with or complicate an interpretation 
of subsequent activities. Such a eurythermic 
species seemed at first to be an ideal labora- 
tory subject, until the body temperature cor- 
relates of feeding and foraging were anal- 
yzed (Fig. 8). 
Feeding occurred across a wide range of 
body temperatures, but foraging occurred in 
a relatively narrow range of elevated body 
temperature. It is reasonable to assume that 
a lizard would be both a better predator, as 
well as a less vulnerable prey, if it limited 
forays to times at which body temperatures 
Basking 
Full Basking 
Lateral To 
2468 10 12 |246 |246 j2468 
NUMBER OF RECORDS 
Figure 7. The body temperatures associated with 
two basking postures, the transition from basking 
to perching, and the perching “range.” Most bask- 
ing and all other temperatures were obtained by 
use of temperature sensitive miniature radio 
transmitters implanted in three lizards. (Adapted 
from Greenberg, 1976a). 
are elevated to levels conducive to both 
maximum alertness and action. 
These observations suggest that if one 
provided only the minimum conditions neces- 
sary to keep a lizard feeding well and appar- 
ently healthy, one might be misled in an 
interpretation of spontaneous activity. 
Basking and Perching 
Basking is a commonly employed thermo- 
regulatory behavior among diurnal lizards. 
It can be defined as an activity in which 
