02225nas a2200205   4500008004100000020001400041245014200055210006900197260001000266300001200276490000700288520157000295653002101865653001101886653001301897653002201910653002401932100002101956856004201977       2009                        eng d  a0908-885700aNest excavation does not reduce harmful effects of ectoparasitism: an experiment with a woodpecker, the northern flicker Colaptes auratus0 aNest excavation does not reduce harmful effects of ectoparasitis  cMarch  a166-1720 v403 aIt has been hypothesized that it is adaptive for birds to build new nests annually in order to avoid the accumulation of ectoparasites. Previous studies on costs of ectoparasitism have focused on cavity nesters in nestboxes while largely ignoring reproductive consequences in natural tree cavity nests, the context where nest selection strategies presumably evolved. To see whether ectoparasitism could be a driving selective force in the evolution of nest excavation in a woodpecker, I experimentally fumigated a subset of freshly excavated cavities and a subset of reused cavities of the northern flicker Colaptes auratus and compared reproductive performance with a set of control nests. The main ectoparasite of nestlings, a blood-sucking fly Carnus hemapterus, may have appeared one or two days earlier in reused nests but there was no difference between fresh and reused nests in intensities of flies one week post-hatching. Prevalence of parasitism reached 100% in both reused and freshly-excavated control nests in the second week. Nestlings from control nests had lower body mass residuals than those from fumigated nests after 15 d and fledged at a lower weight, suggesting that ectoparasitism by C. hemapterus was costly. However, fresh nest construction was no benefit, likely because the high dispersal ability of the ectoparasite meant all nests were colonized rapidly. Parents did not adjust provisioning effort according to parasitism as delivery rates did not differ between control and fumigated nests but delivery rates increased with brood size.10aBritish Columbia10aCanada10aCarnidae10aCarnus hemapterus10aon Colaptes auratus1 aWiebe, Karen, L.  u<Go to ISI>://ZOOREC:ZOOR14508048374 