Measurements
Both Sexes
- Length
- 4.3–5.1 in
11–13 cm - Weight
- 0.4–0.5 oz
12–14 g
Other Names
- Paruline vermivore (French)
- Chipe gusanero (Spanish)
Cool Facts
- Late in incubation the female Worm-eating Warbler sits so tight on her nest that only touching her will flush her. Her cryptic coloring makes immobility a safe strategy. If she is flushed, she will flutter across the ground with her wings and tail spread, acting helpless to lure predators away from the nest.
- Young Worm-eating Warblers typically leave their nest 8-10 days after hatching. Chicks as young as five days old have been observed leaving the nest and surviving, although they cannot fly at that age.
- Although the Worm-eating Warbler forages in the understory near the ground and nests on the ground, it does not spend much time on the forest floor. It does not forage there, and when on the ground it hops instead of walking.
- The oldest recorded Worm-eating Warbler was a male, and at least 8 years, 1 month old when he was recaptured and rereleased during banding operations in Connecticut.
Habitat
Forest
- Breeds in mature deciduous or mixed deciduous-coniferous forest with patches of dense understory, usually on steep hillside.
- Winters in tropical forests.
Food
Insects
Arthropods, spiders, slugs, and especially caterpillars.
Nesting
Nesting Facts
- Clutch Size
- 3–6 eggs
- Egg Description
- White to pink, with brown speckles.
- Condition at Hatching
- Helpless and naked.
Nest Description
Nest a cup of skeletonized leaves lined with moss, placed on ground.
Nest Placement
Ground
Behavior
Foliage Gleaner
Gleans in low shrubs, but only rarely on ground. Probes into hanging dead leaf clusters and foliage.
Conservation
Least Concern
Overall, Worm-eating Warbler populations remained stable between 1966 and 2014—with some areas experiencing declines, and others, increases— according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 830,000, with 100% breeding in the U.S., and 35% wintering in Mexico. This is a U.S.-Canada Stewardship species, and rates a 12 out of 20 on the Continental Concern Score. Worm-eating warbler is not on the 2014 State of the Birds Watch List. Dependence on large forests for nesting make this species vulnerable to population decreases due to habitat loss.
Credits
- Hanners, L. A., and S. R. Patton. 1998. Worm-eating Warbler (Helmitheros vermivorus). In The Birds of North America, No. 367 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
- North American Bird Conservation Initiative, U.S. Committee. 2014. State of the Birds 2014 Report. U.S. Department of Interior, Washington, DC.
- Partners in Flight. 2012. Species assessment database.
- USGS Patuxent Wildlife Research Center. 2015. Longevity records of North American Birds.
- USGS Patuxent Wildlife Research Center. 2014. North American Breeding Bird Survey 1966–2014 Analysis.