Red-faced Warbler Life History

Habitat

In the United States, Red-faced Warblers breed in higher elevations (6,500–9,200 feet) of mountains in Arizona and New Mexico, mostly in forests with pine, oak, and fir trees. Over most of their range, they favor canyons and places with streams, but they do occur in forests on level terrain. At the high end of their elevational range, they breed in forests with Douglas-fir, quaking aspen, Engelmann spruce, and canyon maple. Migrants may occur at much lower elevations but tend to select similar forests, often along stream corridors. On the wintering grounds in Mexico and northern Central America they use similar habitats, normally above 4,000 feet elevation, where pine, oak fir, alder, and arbutus are predominant.

Food

Red-faced Warblers forage in coniferous trees and occasionally deciduous trees, where they flit along branches and twigs in the midstory. The usually keep to the outer edge of the foliage, where they investigate needle clusters for small insects and their larvae. They take most prey by gleaning or hover-gleaning, but they also pursue insects in flight. Red-faced Warblers flick the tail frequently, possibly to startle insect prey into moving. They eat caterpillars, flies (and larvae), aphids, scale insects, leafhoppers, treehoppers, planthoppers, and spittlebugs. They may also eat some beetles or beetle larvae.

Nesting

Nest Placement

The female chooses the nest site, a small hole in the ground, often with an overhanging rock, vegetation, or other feature to provide shelter. Many nests are set at the base of a tree or on a slope.

Nest Description

The female builds the nest, a cup of bark, leaves, and pine needles lined with grass and animal hair. Males do not assist but sometimes build a separate nest that does not get used. Nests average about 3.8 inches across and 2.1 inches tall, with interior cup 2.2 inches across and 1.6 inches deep.

Nesting Facts

Behavior

As soon as they return to nesting grounds, male Red-faced Warblers begin to sing in order to establish a territory and attract a mate. Males display to females by raising, lowering, and spreading the tail, quivering the wings, and raising the head, showing off the striking red face and also the contrasting white rump. A responsive female may perform a similar display, which is an invitation to mating. This occurs often once she has selected the nest site and then frequently up until egg-laying. Males guard females closely not just through egg-laying but right through the end of incubation (rather unusual in a songbird). Both males and females seek mating opportunities with birds other than their primary partner, such that in most nests the young are of mixed parentage. The Red-faced Warbler is nevertheless “socially monogamous” in its mating system, with the young raised by the female parent and the male territory holder only. Most pairs repartner with the mate from the previous nesting season in or near the same territory. After the nesting season, family groups may forage together for a few weeks, sometimes joining other family groups and other woodland birds in small flocks. On the wintering grounds, Red-faced Warblers regularly join mixed-species flocks of woodland birds, but they tend to be aggressive toward members of their own species in such flocks.

Conservation

Red-faced Warbler population trends are not known. Partners in Flight estimates the global breeding population at 350,000, rates the species a 14 out of 20 on the Continental Concern Score, and includes it on the Yellow Watch List for species with restricted ranges. Red-faced Warblers are sensitive to logging, and may decline in numbers after logging or disappear from the habitat entirely. Habitat modification and destruction are the chief known conservation threats to this species.

Credits

Martin, Thomas E. and Patricia M. Barber. (1995). Red-faced Warbler (Cardellina rubrifrons), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Pyle, P. (1997). Identification Guide to North American Birds. Part I. Slate Creek Press, Bolinas, CA, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

Stephenson, T. and S. Whittle (2013). The Warbler Guide. Princeton University Press, New Jersey, USA.

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