Here are brief overviews of the species that we have observed in our projects, and of other species that are found on California farms and ranches that could use raptor perches. Links will take you to the Cornell Lab of Ornithology's All About Birds website, where you will find detailed information about each species and photos.
We regularly observe American kestrels utilizing raptor perches, especially in open habitat away from trees. Kestrels appear to hunt from the perches, regularly returning to the same perch over and over again, and often carrying prey to eat on the perch. Kestrels eat large insects (such as grasshoppers), small mammals (such as mice and voles), reptiles (lizards and small snakes) and songbirds.
Red-tailed hawks use raptor perches to rest and to hunt from. These large hawks like to hunt from a perch and the addition of perches in agricultural landscapes is likely to increase the time red-tailed hawks spend hunting in those areas. Red-tailed hawks are day-time hunters and primarily hunt for mammals- their prey ranges in size from mice and voles to rabbits and ground squirrels. They will also opportunistically hunt for birds and reptiles.
Golden eagles are the largest birds we have observed using raptor perches in California. They hunt for large mammalian prey such as rabbits and ground-squirrels. They will also opportunistically hunt for birds and reptiles.
Turkey vultures sometimes use artificial perches. They are carrion-eaters and play a critical role in cleaning up already-dead livestock and other dead animals.
Barn owls are valuable providers of pest-control for farmers and homeowners across the American West. There have been numerous studies demonstrating that barn owls hunt almost exclusively for rodents that are considered pests by farmers (in Yolo County, over 99% of prey items were animals that were considered pests). We have found barn owls utilizing our raptor perches at night, and their inclusion on farms and ranches is likely to help owls access more of the production land on a farm. Barn owls are cavity nesters and benefit from allowing natural cavities to remain, but can be attracted to an area through building artificial nest boxes.
great horned owl
Large and aggressive, great horned owls rule the night. These owls co-opt the nests of other large birds for their nest sites. Their diet in working landscapes primarily includes rodents, gophers, and rabbits.
Ravens are not raptors, but they are omnivorous birds that will sometimes hunt for small mammals and therefore provide farmers with pest-control services. The photo here shows a pair of ravens with a mouse they have caught.