Once you know something about a group of animals, you come to expect that they will eat particular things. When one thinks of the family Parulidae (New World Warblers) and their diet, the first thing that comes to mind are insects or other small invertebrates and most warblers have fine thin bills ideally suited for catching these things. Also, anyone who has watched these hyper-energetic little birds forage can’t but be impressed by how actively they search out their prey.
In terms of being energetic, the Parulidae are perhaps outdone only by the hummingbirds. Maybe it shouldn’t be surprising then that like the hummingbirds warblers might occasionally put their fine thin bills to use collecting floral nectar to satisfy their energetic needs. While the evidence that warblers do this is circumstantial — I know of no experiments or close observations ruling out the possibility that they are instead visiting flowers to catch small invertebrates — this evidence suggests that it is more likely that many are collecting nectar than not.
In the literature we find that Palm (Setophaga palmarum), Cape May (Setophaga tigrina), Yellow-rumped (Setophaga coronata), Northern Parula (Setophaga americana), Tennessee (Oreothlypis peregrina), and Nashville (Oreothlypis ruficapilla) warblers all have been recorded collecting nectar. Audubon’s Online Guide to North American Birds indicates that among North American warblers Townsend’s (Setophaga townsendi), Orange-crowned (Oreothlypis celata), and Black-throated Blue (Setophaga caerulescens) warblers also collect nectar. This same source states that Painted Redstarts (Myioborus pictus) visit hummingbird feeders suggesting they too might visit flowers. Finally, one researcher suggests that records of Bachman’s Warbler (Vermivora bachmanii) foraging in the flowers of majagua trees (Hibiscus elatus) raises the possibility that this warbler too might have collected nectar.
Most warblers that collect nectar appear to do this only occasionally — even though they they may defend these temporary resources — and most commonly during migration or on their wintering grounds. Tennessee warblers, however, regularly visit and defend flowers where they winter in the tropics.
Recently I observed a pair of Tropical Parulas (Setophaga pitiayumi) visiting some jocotes (Spondias purpurea) that are now blooming here at Cuixmala..
J. Andrew Boyle has very nice photos of a Northern Parula (Setophaga americana) collecting nectar from the long red tubular flowers of Firespike (Thyrsacanthus tubaeformis) in Florida. While I could not find online photos of a Tropical Parula doing this, Oiseaux-Birds states that this warbler “occasionally consume[s] some berries and nectar from flowers”.
The birds feed early in the morning but mostly late in the afternoon after the Streak-backed orioles (Icterus pustulatus — adult female and then juvenile shown below) reduced their nectar-foraging activity.
References and Additional Sources
Bent, A. C. 1963. Life histories of North American wood warblers. Part One. Dover Publications, Inc., New York, NY.
Hamel, Paul. B. Bachman’s Warbler. In Audubon Wildlife Report: 1988-1989. Edited by William J. Chandler. 848 pp., apps., 1988. Academic Press, San Diego, Calif.
Morton, E. S. 1980. Adaptations to seasonal changes by migrant land birds in the Panama Canal Zone. In A. Keast and E. S. Morton, eds., Migrant birds in the Neotropics. Washington, D.C. Smithsonian Institution Press, pp. 437- 453.
Rogers, L. L. 1997. Nectar-feeding by Cape May, Tennessee, and Nashville Warblers in Minnesota. The Loon 69(2):55-56.
Sealy, S. G. 1989. Defense of nectar resources by migrating Cape May Warblers. Journal of Field. Ornithology 60(1):89-93.
Wunderle, J. M. 1978. Territorial defense of a nectar source by a Palm Warbler. Wilson Bull. 90:297-299.