Nest-site characteristics and nesting success of the greater pewee in Arizona

We provide information on nest-site characteristics and nesting success of the greater pewee, Contopus pertinax, in the Huachuca Mountains of southeas tern Arizona. Primary breeding habitats include montane pine-oak forests an d sycamore or cottonwood riparian forests. Nests (n = 19) were found betwee n 14 May and 29 June 1997, and between 31 May and 6 July 1998. Egg dates fo r combined years were between 12 May and 15 July; successful nests fledged young between 21 June and 17 July. Nest predation on greater pewee nests (4 7.4%) was the principal cause of reproductive failure. No greater pewee nes ts were parasitized by cowbirds, whereas cowbird parasitism ranged between 11% and 32% of host populations on the same sites. For all species monitore d at both sites (n = 203) the frequency of cowbird parasitism did not vary between years; however nest predation was significantly higher in 1998 than 1997. While there was no year effect of nest failure among greater pewees, during the year of low nest predation frequency (1997) greater pewees had significantly higher nest success than other species on the same site. Over all, greater pewees fledged a mean of 0.8 +/- 1.0 (SE) fledglings per nest, n = 19. Mean nest height was 11.6 +/- 0.8 m in mature stage pines (DBH 46. 6 +/- 2.6 cm, mean nest tree height 19.7 +/- 0.9 m). Greater pewees nested in trees that were significantly taller than canopy trees found in non-use sites. A combination. of high nest placement and aggressive nest defense ma y account for the lack of brood parasitism and low rate of nesting failure caused by predation during low predation years.