We began this study after observing that flocks of American robins (Turdus migratorius) and cedar waxwings (
Bombycilla cedrorum) left behind seemingly ripe fruit after visiting patches of laurel cherry for days.
Most frugivores either supplement their diet with small amounts of animal food or other protein sources (e.g., cedar waxwings,
Bombycilla cedrorum; Witmer, 1998) or are able to subsist on little dietary protein (e.g., oilbirds, Steatornis caripensis; Snow, 1962).
Crabapple seeds also contain cyanide (Seigler 1976), and this poison can cause death when consumed in large amounts by Cedar Waxwings (
Bombycilla cedrorum, Woldemeskel and Styer 2010).
(Hylocichla) I Turdus migratorius 11 Ixoreus naevius Chamaea fasciata 2
Bombycilla cedrorum 2 Dendroica sp.
Indeed, during the winter of 2004-05, France witnessed a large and unexpected invasion of Bohemian waxwings (
Bombycilla garrulus) (10), a species known to migrate from circumpolar areas where pseudotuberculosis is endemic.
The following nine species were present in the unburned site, yet were absent in the burned site: Black-and-white Warbler, Eastern Phoebe, Hairy Woodpecker, Northern Flicker, Ruby-throated Hummingbird, Eastern Towhee, Northern Cardinal (Cardinalis cardinalis), Cedar Waxwing (
Bombycilla cedroruta), and Veery (Catharus fuscescens).
Among wintering birds are the pine grosbeak (Pinicola enucleator), the rough-legged buzzard (Buteo lagopus), the snow bunting (Plectrophenax nivalis), the shore lark (Eremophila alpestris), and the waxwing (
Bombycilla garrulus).
Trials with captive Cedar Waxwings (
Bombycilla cedrorum) demonstrated that (1) percentage recovery of microspheres is high, (2) all defecations containing seeds also contain microspheres, (3) relatively few microspheres are recovered in defecations not containing seeds, and (4) presence of microspheres on fruits does not affect fruit choice.
Bombycilla - waxwings