Malheur: Home to the Largest Population of Breeding Bobolinks in Oregon

by Teresa Wicks, Eastern Oregon Field Coordinator

The spring soundtrack of Malheur National Wildlife Refuge is filled with the sounds of migration, territorial song battles, courtship, and joy. As spring progresses from primarily waterfowl and migratory bird–dominated to breeding-bird dominated, the soundtrack transitions from the drums, baritones, and horns of waterfowl to the flutes, clarinets, and altos of breeding passerine bird species. But one bird, whose voice is more common over the tallgrass prairies of the Midwest, lends a bit of an electronic flair with their song.

The Bobolink, the backward-tuxedo-wearing star of Malheur’s flood-irrigated wet meadows, has a fairly bubbly, mechanical song, whose echo-like quality often creates the illusion of multiple birds singing at once. The easiest way to find Bobolinks is by listening for their mechanical song over the fields of the southern end of Malheur, north of P Ranch. Males tend to sing while perched in the top of willow and other woody riparian vegetation, or while performing their flight display. These flight displays are achieved when the males fly high up into the air and then move, almost mothlike, in a gliding pattern while stiffly fluttering their wings.

Bobolink with worm in bill and dark green blurred background
Bobolink, photo by Christian Fritschi.

Malheur National Wildlife Refuge is home to the largest breeding population of Bobolinks in Oregon, which also happens to be the largest westernmost breeding population in North America. Bobolinks are related to blackbirds and meadowlarks and are similarly tied to North American grasslands and wetlands. In the Midwest, Bobolinks breed in mixed tallgrass prairie and spend the post-breeding season in and near wetlands, where they molt before heading south 12,500 miles to South America.

Unfortunately, throughout most of their range, Bobolink populations are declining. According to the Breeding Bird Survey, the Bobolink breeding population declined by 65% from 1966 to 2015. Most of this population decline has been linked to habitat loss associated with development and land-use change. Today, Bobolinks are more common in agricultural fields of mixed grasses and broadleaf plants, particularly legumes. At Malheur, this relationship is often between Bobolinks and Thermopsis species, commonly called false lupine.

As meadows and hayfields are converted to other forms of agriculture, houses, energy production sites like solar farms, etc., habitat for Bobolinks is lost. Additionally, according to climate and population models, much of the breeding habitat available to Bobolinks is predicted to decline as temperatures warm and annual precipitation becomes more variable.

Here at Malheur, Bobolink populations thankfully go against the national trend and appear to be stable or slightly increasing. In an effort to understand how to best support Bobolink populations at Malheur, Bird Alliance of Oregon has been working with refuge staff and Klamath Bird Observatory to create a vegetation survey protocol. This protocol will record vegetation and land management metrics associated with the flood-irrigated wet meadows where Bobolinks breed at the refuge. These variables can then be analyzed in conjunction with landbird data, including Bobolink population data, to develop a better understanding of what management variables will best support a climate-resilient and continuing population of Bobolinks at Malheur National Wildlife Refuge.