The Ovenbird (Seiurus aurocapillus) is often heard before it is seen, a loud ringing “tea-cher, TEA-cher, TEA-CHER!” broadcast from close to the forest floor through much of the eastern U.S. and Canada during the nesting season. Ovenbirds are large warblers, no relation to the Ovenbird family Furnariidae found in the tropics. However, both the warbler and the family share a basic brown color palette, and are named for their curious domed, Dutch oven-like nests which, in the case of the warbler, are build on the ground.
Ovenbirds winter primarily in the Caribbean and Central America. There, they forage on or close to the ground, where much of their diet is comprised of ants. This habit of scratching and leaf-flicking on the forest floor has earned them the name “Betsy Kick-up” in Jamaica! Ovenbirds are frequently found in shade coffee plantations, where they may also feed on female coffee berry borers that are laying eggs in fallen coffee cherries, thus performing a great service to coffee farmers.
Migrant (and resident) bird species have been monitored in Puerto Rico since 1973 in a study where Ovenbirds have been one of the most common species. Their numbers have declined to less than 20% of their original abundance. Some of the declines are related to variable rainfall patterns (which will be exacerbated by climate change), and some to conditions on their breeding grounds (see below). But similar declines in resident Puerto Rican birds in the same study indicate there are undiscovered factors occurring on the wintering grounds as well.
On their North American breeding grounds, Ovenbirds need large forests to breed in, and habitat loss and fragmentation has taken its toll. Even in large forests in northern regions, declines in reproductive success are tied to, believe it or not, earthworms.
Due to the last glaciation, Canada, the upper Midwest, and New England have no native earthworms — all of the worms are introduced. Their efficient consumption of leaf litter on the forest floor has greatly altered many forests. Plants that require a thick organic layer in some forests have declined, leaving less cover for Ovenbird nests, which then fall to predators. Ovenbirds also rely on the insects and invertebrates that live in leaf litter, which are also far less abundant in habitats invaded by non-native worms. These factors are thought to be driving declines in some breeding populations of Ovenbirds.
Ovenbirds found on shade coffee farms help farmers by eating pests, and have found safe haven in winter. Choosing shade-grown coffee can help support populations of this charismatic songbird so that future generations can enjoy its distinctive summer song.
More coffee birds here.
Ovenbird photo by Julie Craves, all rights reserved. Banded by the Rouge River Bird Observatory, Dearborn, MI.