1976] 
A /cock — Populations of Centris pallida 
123 
Table 1 
Recapture data on samples of marked males of Centris pallida. 
Number 
Marked 
Number 
Recaptured 
on Another Day 
Patrolling Males 
Study Site 1 
153 
83 (54%) 
Study Site 2 
76 
58 (76%) 
Copulating Males 
Study Site 1 
20 
13 (65%) 
Study Site 2 
41 
26 (63%) 
Hovering Males 
Study Site 1 
47 
18 (38%) 
evenly; it is not uncommon for a location 10 m 2 to have several 
dozen males swirling over it while an adjacent area of equivalent 
size has fewer than ten individuals. The samples of males were 
taken for marking from limited areas (rarely covering more than 
20 m 2 and usually less) where males were relatively abundant. 
Follow-up searches on subsequent days were concentrated in these 
areas and they quickly revealed that many marked individuals 
returned day after day to the same limited portion of the total 
emergence site. A large majority of the marked patrolling males 
were seen again on at least one other day (Table 1) and for the 
population as a whole, the average interval between the day of 
capture and the day of last sighting was 3.44 days (Fig. 1). Because 
patrolling males tend to return to the same area but do not defend 
it they can be said to possess home ranges (patrolling males ignore 
other flying males but will fight intensely for a specific digging 
site containing a pre-emergent female). 
If we analyze the recapture frequencies of patrolling and copu- 
lating males in Site 1 vs. Site 2 (lumping copulating males with 
patrollers because copulating males had been patrolling prior to 
their capture in copula) we find that patrollers were significantly 
more likely to have been recaptured after marking in Site 2 than 
Site 1 (X 2 = 6.61, d.f. = 1, P<.01). This difference probably re- 
flects higher mortality experienced by males in the first study area. 
There were two heavy rains accompanied by unusually cold weather 
