Small mammals are critical to the conservation of raptors and wading birds. Shrews, mice, and especially Townsend’s vole are prey for these predatory birds. Some raptors, like the Northern Harrier and Rough-legged Hawk, feed almost exclusively on Townsend’s voles. Small mammals are most abundant when there is ample vegetation to conceal them. To ensure that there is an abundance of small mammals for raptors and wading birds, Delta Farmland & Wildlife Trust encourages farmers to leave tall grass fields on their farms; these Grassland Set-asides soon become colonized with small mammals, the most common being Townsend’s vole. Voles will even colonize fields that have been planted with a Winter Cover Crop of clover. Many of the mammals are rodents, but some are insectivorous, like the shrew. Shrews are the smallest mammals and feed on worms, beetles, and any other invertebrate they can catch. The drainage ditches of Delta farms also provide habitat for small mammals, including muskrats and beavers. Beavers can be troublesome for farmers because they can dam drainage ditches, causing fields to flood.
Some of the small mammals that can be found on Delta farms are (click the link to view the species profile):
- Townsend’s vole
- Vagrant shrew
- Deer mouse
- House mouse
- Muskrat
- Beaver
