46 Richard R. Repasky and Phillip D. Doerr 



Niche overlap. Maximum overlap between sexes occurred at 

 different times for the two groups (Fig. 1). For group A, overlap was 

 greatest in May, when nestlings were tended and the male foraged 

 uncharacteristically low and upon the trunk. Overlap in group B was 

 greatest in October, when pine cones were used by both sexes and the 

 female foraged uncharacteristically high upon the trunk. Minimum 

 overlap between the sexes occurred in the late fall and early winter and 

 then again during summer (Fig. 1). 



Sex-specific foraging is a means by which sexes can reduce 

 competition for resources (Selander 1966, Ligon 1968). Overlap is 

 expected to decrease as food becomes less abundant (Wallace 1974, 

 Hogstad 1977), although Winkler (1979) noted that Strickland's 

 woodpecker, Picoides stricklandi (Malherbe), exhibited the least amount 

 of overlap when opportunistic conditions permitted sex-specific foraging. 

 Lack (1954) suggested that winter and the post-fledging portion of 

 summer may be times of food limitation for birds. Reduced overlap 

 during summer does not seem to reflect opportunistic use of resources, 

 for no such activity was recorded in the component variables. It may 

 reflect resource partitioning with increased group size after fledging. 

 This may seem an unlikely necessity because Hooper et al. (1982) 

 concluded that some home ranges contain more resources than 

 necessary. However, the problem of resource depletion within the 

 proximity of a predator (Charnov et al. 1976) is magnified with 

 increasing group size, and reduced foraging overlap may be a solution 

 to that problem. It is also an alternative to changing home range size in 

 times of relative food scarcity (Selander 1966). 



Foraging time. Red-cockaded woodpeckers were active during 

 most of the available daylight hours. The interval between leaving 

 cavities in the morning and roosting averaged 93% of the time from 

 sunrise to sunset, ranging monthly from 83% to 100% (Table 5). Only 

 the means for January, February, and March were less than 90%. The 

 percentage of active time spent foraging was least in May and June and 

 greatest during December and January (Table 5). The number of hours 

 of foraging per day, calculated as the product of the number of active 

 hours and the proportion of time spent foraging, corresponded closely 

 with the number of active hours per day (Table 5), being greatest in 

 summer and least in winter. 



Foraging activities should reflect the availability of food relative to 

 needs. The proportion of daylight time spent in activity and foraging as 

 a proportion of active time are expected to be greatest during the period 

 of resource limitation. Hinde (1952) found that tits (Parus spp.) increased 

 the proportion of daylight hours in which they were active during the 

 winter. Gibb (1954) found that the proportion of time spent foraging 



