Birds
of Prey and Their Prey
Nocturnal and diurnal predators are ever-present in the
grasslands. Coyotes are present daily and the more reclusive
Bobcats and Gray Fox are thought to forage each night. Also
present year-round are Red-tailed Hawk, Red-shouldered Hawk,
Cooper’s Hawk, Greater Roadrunner, Turkey Vulture,
White-tailed Kite, American Kestrel, Barn Owl, and Great
Horned Owl. Additional predators in winter include Burrowing
Owl (see Map 7, Grasshopper Sparrow and Burrowing Owl),
Northern Harrier, Sharp-shinned Hawk, Merlin, and Zone-tailed
Hawk.
Because
the prey preferences of these predators is rather well established,
we can surmise that certain prey are in ample supply on
San Marcos Foothills. Burrowing Owl feed primarily on Jerusalem
Crickets. California Voles are the preferred prey of White-tailed
Kite, pairs of which use the West Mesa and the Cieneguitas
Creek Grasslands. Other small mammal fauna, so important
in support of the birds of prey assemblage, are poorly known
on San Marcos Foothills. Brush Rabbits may be the principal
prey for Red-tailed Hawk. Other small mammals (Deer Mouse,
California Mouse, pocket mice, shrews, and snakes) must
be present in ample abundance but the lack of any formal
investigations on small mammals does not allow us to detail
the prey base for the predators on San Marcos Foothills.
Mourning Dove and Western Meadowlark are heavily preyed
upon, probably by Coyote and Red-tailed Hawk. Greater Roadrunner
eats almost anything up to one-third its body size: lizards,
snakes, nesting and nestling birds, small mammals, and large
insects. There are few places other than San Marcos Foothills
in Santa Barbara County where one can reliably see a Greater
Roadrunner.
Droughts
in our regions are profoundly stressful events for birds.
Because the bird breeding season is compressed for most
species between late April and early July (beyond most of
the rainy season), habitats that retain moisture are those
that support most bird reproduction. This explains why riparian
habitats support a very high proportion of nesting birds
in southern California. Each wetland habitat is important
in proportion to its size, persistence, water chemistry,
and association with other habitats. Insects, soil micro-organisms,
amphibians, and plant communities are the primary beneficiaries
of wetlands; reptiles, small mammals, and birds are in turn
supported. Surface wetlands are therefore important contributors
to ecosystem functions in the semi-arid Santa Barbara region.
|
Table
3. Birds of Prey Assemlage
on San Marcos Foothills
|
| Breeding
Season (February to August) |
Non-breeding
Season |
| Turkey
Vulture |
Turkey
Vulture |
| White-tailed
Kite |
Northern
Harrier |
| Cooper's
Hawk |
Sharp-shinned
Hawk |
| Red-tailed
Hawk |
Red-tailed
Hawk |
| Red-shouldered
Hawk |
Red-shouldered
Hawk |
| American
Kestrel |
Zoned-tailed
Hawk |
| Barn
Owl |
American
Kestrel |
| Great
Horned Own |
Merlin |
| Western
Screech-Owl |
Burrowing
Owl |
| |
Western
Screech-Owl |
| |
Loggerhead
Shrike |
| |
| More
than any other group, small mammals (voles, gophers,
various mouse species, White-footed Woodrat, Merriam’s
Chipmunk, and California Ground Squirrel) support the
SMF bird-of-prey community. Protecting birds of prey
requires an understanding of these smaller animals —
the habitats they use and the passage corridors to other
habitats they depend upon – so that stewardship
practices may be compatible with their needs. Learning
more about small mammals is one of our top inventory
objectives should we acquire the property. |
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