178 
Brattstrom 
The present results indicate that (1) 
lizards can learn to use their thermal en- 
vironment rapidly and efficiently; (2) lizards 
become more precise in their behavioral 
thermoregulation Avith increased exposure to 
the environment; (3) in thermal gradient 
studies (especially those dealing with prefer- 
red body temperatures), there must be at 
least a standard number of days for a lizard 
to be in the gradient, and a record of daily 
preferred body temperatures. For such ex- 
periments it would be desirable for workers 
to use the same size and shape thermal 
gradient with the same thermal parameters, 
but this is impractical. It is essential to state 
(1) the gradient size; (2) its thermal para- 
meters including detailed descriptions of the 
heat source; (3) duration of time animals 
are in the gradient; and (4) the previous 
thermal and feeding history of the animals. 
Some workers feed their animals in the 
gradient, but Regal (1966) has shown that 
preferred body temperatures are higher 
after feeding. Further, it is important to 
have standardized photoperiods and, in view 
of rhythmic changes, to record temperatures 
at the same time each day. It is mandatory 
that only one lizard be in the gradient at 
one time as it was shown by Regal (1971, 
1974) that the dominance relationship be- 
tween lizards in a thermal gradiant can 
affect both their activity and preferred body 
temperatures. 
WHEEL RUNNING 
In an attempt to develop methods for 
measuring the effort and energy used in be- 
havioral temperature regulation, I tried to 
get a lizard to run in a “hamster exercise 
wheel.” Four Cnemidophorus tigris (num- 
bered 1 to 4 in order of social dominance) 
were placed in a 110-gallon terrarium with 
sand, rocks, and a 250 w white-bulb infrared 
lamp at one end. The lamp and room lights 
were on from 0700 to 1900 hours. After 
several weeks, two hamster exercise wheels 
(6 inches in diameter) were placed in the 
cage. The lizards would not run when placed 
inside the wheel even when it was lined with 
sandpaper. Each lizard (except #2) was 
placed on th'e outside of the wheel for 1 
minute. Occasionally the wheel would turn 
a bit while the lizard was on it. On subse- 
quent days the lizards would spontaneously 
crawl on the wheel and keep it turning while 
facing the heat lamp, often with the tail 
braced against the ground. Wheel running 
data for the above experiment are presented 
in Table 2. Interestingly, the most subordin- 
ate lizard (#4) did not use the wheel. He 
would emerge from his burrow only when 
other lizards were inactive. The dominant 
and largest lizard often left the wheel to 
chase one of the subdominants or to patrol 
the terrarium. He, therefore, spent less time 
on the wheel than the subdominants, but 
moved the wheel faster. 
This simple experiment has possibilities 
for investigating a variety of time/activity/ 
energy problems with lizards. It has con- 
vinced me that lizards can be taught to do a 
wide variety of tasks if the tasks are related 
to their natural activities in the field. 
“UNREWARDED” EXPLORATION AND 
LEARNING OF COMPLEX MAZES 
Exploratory behavior occupies a consider- 
able portion of an animal’s time. While food, 
heat, and mates may be found in the course 
of this activity, much of such behavior is 
unrewarded. Yet, in the process, the animal 
learns much about its environment and may, 
when needed, utilize this information to ob- 
TABLE 2 
Wheel running in the whiptail lizard, Cnemi- 
dophorus tigris. 
Lizard number* 
1 2 3 4 
Av. length of time 
on wheel in 
seconds 24.6 41.3 32.3 0 
Av. # revolutions/ 
sec. .78 .67 .65 0 
Speed, inches-sec. 14.04 12.06 11.70 0 
*in order of dominance, #1 highest. 
