Habitat selection and reproductive success of Lewis’s Woodpecker in the South Okanagan Valley

Lewis’s Woodpecker (Melanerpes lewis) has been listed as a species of special concern due to its range-wide decline in population numbers, possibly as a result of habitat loss and degradation. Management plans for this species need information on habitat requirements. However, little is understood about how habitat features affect nest site selection and reproductive success. I conducted the first study of the species in Canada, in the South Okanagan Valley, British Columbia, during 2004-2005 in an effort to fill this gap. I examined the habitat features influencing nest site selection using multiple logistic regression models. I also evaluated effects of habitat features and clutch initiation date on nest success using multiple Weibull regression models. Nest tree decay class and total basal area of large trees (DBH[greater than or equal to]50cm)/ha were the most important factors for nest site selection. Of the 57 nests monitored, 34 were located in snags, 22 in dead-top trees, and only one in a live tree. Despite the importance of large, decayed trees and newly-burned forest for nest site selection, these factors were unrelated to the subsequent nest success. The Mayfield estimate of overall nest success was 0.52 ± 0.08 (mean±S.E. n=57 nests). Early and late clutch initiations had higher nest success than intermediate clutch initiations, possibly due to seasonal variation in nest predation and cavity competition. But early clutch initiations were more likely to produce large clutches and fledged broods than late clutch initiations. Deep cavities with small entrances were able to effectively lower predation risk especially during the peak of nest predation. Overall, my results suggest that: (1) the habitat features related to nest site selection were not correlated with nest success; (2) early clutch initiations allowed the bird to gain the highest annual production rate; and (3) nest predation and cavity competition appeared to be important limiting factors to the species in the South Okanagan Valley. Key words: Lewis’s Woodpecker, cavity nesting bird, habitat attribute, nest site selection, reproductive ecology.Science, Faculty ofZoology, Department ofGraduat