Pk. Kleintjes et Dl. Dahlsten, FORAGING BEHAVIOR AND NESTLING DIET OF CHESTNUT-BACKED CHICKADEES IN MONTEREY PINE, The Condor, 96(3), 1994, pp. 647-653
The foraging behavior and nestling diet of Chestnut-backed Chickadees
(Parus rufescens) was studied during the breeding season (March-May) i
n a Monterey pine (Pinus radiata) plantation, 1991-1992. Adult birds s
pent 79% (+/-7.1 SD) of their foraging time on Monterey pine as a resu
lt of prey availability. The majority of this time was spent perch gle
aning and hang gleaning prey from the outer needles of the upper tree
crown. Nestling diet was composed of approximately 43% Monterey pine s
awfly larvae (Acantholyda burkei, Hymenoptera: Pamphiliidae) and 17% t
ree camel crickets (Gammarotettix bilobatus, Orthoptera: Ehaphidophori
dae). Both insects feed upon Monterey pine foliage. Spiders and indivi
dual Homoptera, Hemiptera, Coleoptera, Lepidoptera, and Diptera specie
s comprised the remaining 40% of the diet. Monterey pine serves as an
important foraging resource for Chestnut-backed Chickadees during the
breeding season and may have contributed to the range expansion and po
pulation increase of this species in the San Francisco Bay region.