Prairie Restoration Brings Back Declining Songbirds
Baskett Slough National Wildlife Refuge - 2004
When Baskett Slough National Wildlife Refuge personnel recently intensified efforts to improve prairie and oak savanna habitat for threatened and endangered butterflies and plants, they also reaped important benefits for songbirds.
Western bluebirds are associated with oak savannas in Oregon's Willamette Valley. They experienced drastic population declines in mid-20th century, probably due to intensified agricultural practices. In 2001, refuge staff placed several nest boxes in oak savanna habitat on the west slope of Baskett Butte in hope of attracting western bluebirds.
Although bluebirds are sometimes present on the refuge during the winter, they had not been known to nest here in recent memory. Tree and violet-green swallows, black-capped chickadees, and house wrens immediately took up residence in the boxes. For the past two years, a pair of white-breasted nuthatches, another species that has shown serious population declines in the Willamette Valley, used one of the boxes. Both years, a pair of tree swallows waited patiently near the box for weeks. When the nuthatches fledged in late May, the swallows immediately moved into the box to start their own nest. Nest cavities are obviously in high demand!
From 2001 to 2003, refuge staff cleared brush and mowed invasive grasses. In the fall of 2003, restoration efforts culminated in a prescribed burn. These actions created a prairie containing fewer shrubs, with lower-growing grasses and less thatch. The intended effect of an increased Fender's blue butterfly population was achieved. In addition, in the spring of 2004, western bluebirds nested in one of the boxes and fledged young! It appears that this success was a side effect of management actions that improved foraging habitat for bluebirds in the oak savanna.
Another area, near the wildlife observation platform at the top of Baskett Butte, has received the same type of treatment in the last few years. Staff cleared brush, removed small trees, and mowed invasive grasses. They also restored a nearby agricultural field to native prairie. Last spring, they sprayed the field with herbicides to control weeds and non-native grasses.
Birders hiking the trail to the platform during the 2004 nesting season were almost certain to see and hear a pair of territorial western meadowlarks that occupied the area around the platform. The Oregon state bird has declined at a higher rate than any other bird in the Willamette Valley over the past 35 years. This pair was the first known to nest on the refuge in many years. Prairie restoration work helped to create a large area of grassland with diverse grass structure that meadowlarks need for foraging and nesting.
Work will continue in the coming years to protect and restore upland prairie and oak savanna at Baskett Slough NWR. This work should continue to improve habitat for a variety of plant and wildlife species associated with these habitats.
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