 Photo by Terry R. Steele |
Birds of the
By Pepper Trail |
wrapped in feathery insulation especially for Winter delivery.
- Hal Borland, "Questions," Sundial of the Seasons
It is a November day in the Colestin Valley. A gray winter fog fills this hollow in the eastern foothills of the Siskiyou Mountains, deadening sound. But the silence cannot last. It is abruptly shattered by an explosion of avian outrage. A group of acorn woodpeckers is in full cry, calling for reinforcements to defend their granary tree - their precious storehouse of acorns - from a marauding black-billed magpie. The black and white wings of defenders and attacker flash around and around the tall pine snag, until the magpie finally swoops away, a hard-won acorn clamped in its beak.
This confrontation could occur nowhere else on earth than in our very own Klamath-Siskiyou region. Acorn woodpeckers are the quintessential birds of California's golden oak-covered hills. Black-billed magpies are the spirit of an entirely different world, the raw-boned interior West of junipers and sagebrush. It's like watching a group of Silicon Valley investors in a showdown with a high plains drifter. These birds, and their environments, are separated for most of their range by the towering barrier of the Sierra Nevada and Cascade Range. But there is a gap in this mountain wall north of Mount Shasta, and through this gap flows a river of life, creating a great biological whirlpool that stirs the Great Basin together with the Pacific Coast, and enriches the treasure-trove of biodiversity that is the Klamath-Siskiyou.
This treasure-trove holds a total of 392 bird species, as documented by a recent review of published and unpublished records. Of these birds, 189 have been confirmed to nest somewhere within the region (this compares, for example, to approximately 255 breeding species for all of Oregon!). The mobility and adaptability of birds means that, in contrast to plants, there are no bird species completely restricted to the Klamath-Siskiyou. However, the region is the range limit for many birds, emphasizing the area's ancient status as a refuge in an ever-changing world. Birds flock to the Klamath-Siskiyou from all directions. The accompanying table summarizes some of the species that reach the limit of their distribution in the region, and the environments that they favor.
Much remains to be learned about the breeding distributions and habitat requirements of birds in our region. A small sample of the birds whose breeding range in the Klamath-Siskiyou is poorly known include: hooded merganser, band-tailed pigeon, flammulated owl, calliope hummingbird, canyon wren, vesper sparrow, and evening grosbeak. A major initiative, the Klamath Demographic Monitoring Network, has recently begun to fill in the gaps in our knowledge. This group, coordinated by the Redwood Sciences Laboratory at Humboldt State University in Arcata, is a consortium of private, local, state, and federal organizations involved in bird survey and monitoring in the region. The network operates more than 8,000 point count stations and mist-netting sites, extending from the headwaters of the Rogue and Klamath Rivers on the north and east to the Sacramento and the Eel Rivers on the east and south. The goal of the effort is to inventory bird populations, document changes in these populations over time, and investigate factors that may be responsible for population change.
The region's complex patchwork of habitats provides many opportunities for research on ecological relations, competition, and coexistence among birds. For example, the Siskiyous are one of the few places in North America where four members of the chickadee family occur together: the oak titmouse, black-capped chickadee, chestnut-backed chickadee, and mountain chickadee. How do these species, all of a similar size and with similar feeding habits, manage to coexist? Another fascinating puzzle is the range boundary between the very similar rufous and Allen's hummingbirds in south-coastal Oregon. What environmental changes in this narrow zone tip the competitive balance from favoring rufous hummingbirds north of the Bandon area, to favoring Allen's hummers south of it?
Questions like these are not merely of scientific interest. To understand how to conserve our birds, we need to know how adaptation, competition, and reproduction operate, particularly in small populations. Populations of many North American birds are declining due to continued habitat loss and fragmentation. Logging roads and clearcuts expose forest interior species to threats including starlings (a major nest competitor), brown-headed cowbirds (a brood parasite), and opossums (a voracious predator on eggs and nestlings). In the face of these threats, populations of vulnerable species such as the hermit warbler, olive-sided flycatcher, and western tanager could ultimately become too small and inbred to survive.
Because of the Klamath-Siskiyou bird community's diversity and variability, its preservation is an essential part of any overall effort to protect the avian biodiversity of North America. Unfortunately, the existing system of designated wilderness areas and other preserves is not an adequate sanctuary for our birds. There is a critical need for more protected land, particularly at low elevations, in the coastal strip, and in wetland habitats, as well as for more extensive biological corridors to maintain connections between scattered populations of higher elevation species. Some specific areas that are known to provide vital bird habitat but are not adequately protected include the Klamath River canyon, the Shasta and Scott Valleys, Lake Earl near Crescent City, and the eastern Siskiyou crest.
The good news is that the Klamath-Siskiyou, with its long biological history and diversity of habitats, appears to be a stronghold of genetic variety. To date, the genetics of only two bird species have been examined in the Klamath-Siskiyou, and both exhibited very high levels of genetic diversity compared to other populations of these species across the West. Even more than a treasure trove of species, the Klamath-Siskiyou region may represent a reservoir of genetic variation. This rich variability could prove crucial in the ability of species to respond to long-term environmental changes, such as global warming.
For as long as human beings have lifted their heads to watch an eagle cross the sky, or paused to listen to the melody of a wren, birds have nourished our spirits. They are the most familiar and the most appreciated of an wild creatures, and a world without them would be barren indeed. In the Klamath-Siskiyou, we are blessed with a great company of these feathered companions. We must work with understanding, care, and love to assure that we will always be able to enjoy that pure and unconditional gift: the song of wild birds.
Selected bird species reaching a range limit in the Klamath-Siskiyou, with their primary habitats.