Red-cockaded Woodpecker Home Range 



47 



was greatest in December for four species of tits and greatest in 

 February for a fifth species. Our finding that red-cockaded woodpeckers 

 were least active during the winter is not evidence against the hypothesis 

 that winter is the principal time of resource limitation for red-cockaded 

 woodpeckers. It may reflect avoidance of unfavorable conditions by 

 remaining in the cavity. In winter, the birds generally did not leave their 

 cavities until the sun reached the trees, and then they often basked. 

 Thus they may avoid pre-sunrise activity that is expensive for small 

 birds (Morse 1970). The absolute number of hours spent foraging need 

 not be greatest in the period of food limitation. In winter, activity is 

 limited by daylight, and sufficient energy must be acquired to survive 

 the night. As days lengthen, the potential for more activity increased 

 (e.g. cavity construction, territorial defense, reproduction). Thus the 

 energy budget increases and the absolute foraging time increases to meet 

 these needs. Presumably this is offset, to some unknown degree, by 

 differences in temperature and food abundance. Strain on the energy 

 budget is probably best reflected by the percentage of the activity 

 budget spent foraging. This was greatest during December and January. 



1.0 



uj 0.4 



X 

 O 



Z 0.2 



0.0 



GROUP B 



GROUP A / 



\ / 



i » i | I I I I I I I 



A/79 SONDJ FMAMJ J/80 



MONTH 



Fig. I. Overlap in foraging substrate use between the sexes within 5-minute 

 observation bouts. 



