ABSTRACT

In many species of woodpeckers (Picidae), males and females segregate on the feeding substrate. White-headed Woodpeckers (Picoides albolarvatus) segregate sexually in some locations but not in others. During July and August 1986, 102 foraging observations of these birds were made in the southern Sierra Nevada Mountains of California on trees ranging from 3 to 100 m tall. Males tended to forage in the upper one-third of the trees while females tended to forage in the lower one-third, regardless of the total height of the trees. This pattern of segregation differs from that described in previous studies of woodpeckers and shows that foraging behavior differs among populations of White-headed Woodpeckers. Studies of the adaptive value of observed behavior and morphology must, therefore, consider temporal and spatial variation in these traits.