In terms of how many caterpillars birds eat, I have a 1995 brochure, "Save our
Birds -- Save our Forests," from the US Forest Service, Pacific Northwest
Research Station, discussing bird species known to eat the larvae
(caterpillars) of Western Spruce Budworm and Douglas-Fir Tussock Moth. It says,
". . . some species eat as many as 300 insects per day during the summer
months. A breeding pair of evening grosbeaks can devour 25,000 to 50,000
caterpillars just in the period it takes them to raise a family!" Results from
one of their experements have suggested that birds ate five of every six
budworms. While it's not about tent caterpillars, it's quite fascinating. The
brochure has a table of species known to eat the larvae, showing which birds
eat which of the two larvae, but I will just combine them for simplicity's
sake.

American Robin, Black-headed Grosbeak, Black-capped Chickadee, Brown-headed
Cowbird, Bushtit, Cassin's Finch, Chestnut-backed Chickadee, Chipping Sparrow,
Dark-eyed Junco, Evening Grosbeak, Flammulated Owl, Golden-crowned Kinglet,
Hammonds Flycatcher, House Wren, Lincoln's Sparrow, MacGillivray's Warbler,
Mountain Chickadee, Northern Flicker, Pileated Woodpecker, Pine Siskin,
Red-breasted Nuthatch, Ruby-crowned Kinglet, Solitary Vireo, Swainson's Thrush,
Townsend's Warbler, Vaux's Swift, Veery, Warbling Vireo, Western Tanager,
White-crowned Sparrow, White-headed Woodpecker, Wilson's Warbler and Yellow
Warbler.

Lisa Godina
Lacey, WA
mailto: LMGodina at reachone.com