Sunday, September 21, 2008

Those Darn Jays! And one of their cousins.

Steller's Jay. Photo by David Powell

Seems like they are everywhere, and into everything. Just watching their antics brings a smile to most folks. Their raucous call is the first sound I hear when I pull into the drive at my Jemez home; the sentinel loudly proclaiming the arrival of the source of raw peanuts, one of their favored foods at my place. Steller’s Jays are the most common in the ponderosa pine forest, but several other species also reside in the Jemez valley and mountains including Western Scrub-jay, Pinyon Jay, Gray Jay, and Clark’s Nutcracker. Each fills a unique niche, and all reside in slightly different habitats. Some species are absent from, or highly inconspicuous, in the Jemez for at least part of the year.

All jays are members of the Corvid family of birds, which includes crows, ravens, magpies. The source of many legends and myths, they are the largest of the passerines, or perching birds, and as a group are considered to be among the most intelligent birds. Conspicuous in their presence, they are bold, active, noisy and aggressive. They are survivors in the avian world!

Those that are most frequently seen in the New Mexico highlands, the Steller’s, Pinyon, and Western Scrub-jay have noticeably blue plumage, almost iridescent in some light. Interestingly, there is no blue pigment in their feathers; the color is a purely structural effect dependent on the fine colorless framework of interlocking barbs in their feathers, and why the color varies relative to sunlight.

All jays are omnivores, eating a wide variety of plant and animal foods including insects, nuts, seeds, berries, fruits, small mammals, and eggs and young of smaller birds. Most jays also cache food such as nuts, by pushing it into crevices in the ground, or in the bark of trees. They loosen the soil with their bills, and sometimes even dig a small hole, insert a single food item, and then cover it with soil or vegetation. Interestingly, they can indeed return to the stash later to collect the hidden treasure.

Found in the higher elevation coniferous forest, particularly in ponderosa pine, Steller’s Jays are the largest of the western jays, and distinctive in their blue plumage and black crests, used for social interactions combined with a variety of postures and vocalizations. They habituate readily to humans, and are common at bird feeders and picnic areas. Possessing an extensive vocabulary, they also are mimics, and imitate raptors calls as well as those of other birds and mammals, including chickens and roosters, and dogs and cats. I once chased a Northern Goshawk through the forest, only to find a very vocal Stellar’s Jay at the end of my quest. Normally non-migratory, they will sometimes move to lower elevations during the winter months. They are monogamous, and pairs maintain a territory year-round. Independent young remain with their parents as a family group into the winter following hatching.

The Western Scrub-jay is generally found at lower elevations than the Steller’s Jay, and in more arid scrub and dry woodlands, including pinyon and juniper forests that are generally more open. I do; however, occasionally see them at my place. This medium-sized jay lacks a crest and has a long tail. It can be easily recognized by the dull blue upperparts with a patch of gray in the mid-back, and grayish-buff underpart. They also habituate easily to humans, and I often seem them near residences along the valley floor. Bold and confident around we two-legged featherless types, scrub-jays seem largely unaffected by our activities, and indeed their populations seem to be healthy in the western U.S. Monogamous pairs defend permanent, all-purpose territories, and share in territorial defense.

The behavior of the medium-sized Pinyon Jay differs considerably than either of the previous two jays. It is a highly social, cooperative-breeding, seed caching bird that often lives in permanent flocks that may contain 500 or more individuals. Although it is omnivorous, its ancestors evolved in close association with pine trees. Modern day Pinyon Jays are highly adapted for foraging on pine seeds, and have a number of adaptations that enable them to do so. Their bill is relatively long for removing seeds from cones, and they also possess an expandable esophagus, for storage of seeds. Individuals have an excellent memory that allows them uncanny accuracy when digging up hidden food stores months after caching them, and even beneath snow. Highly monogamous, divorce among this bird is extremely rare (< 3%). Extended family members, usually sons that were hatched the previous year, assist the parents with feeding, nest sanitation, and nest guarding. Pinyon Jays maintain large home ranges, and range widely throughout these areas year-round, always in a flock. Finding a flock is much like locating the proverbial needle in a haystack, thus limiting our ability to adequately assess numbers of birds as well as populations trends. They are primarily dependent on pinyon-juniper habitat, which is among the least appreciated of western woodland types, and is often targeted for removal or conversion to grassland. Additionally, the bark beetle infestation of the previous two years, that has killed a large number of pinyons may have an effect on populations.

Found in boreal and sub-alpine conif erous forest, the Gray Jay, is only rarely seen in the Jemez Mountains and only in the highest of elevations, generally during the winter months. Its range extends southward only into northern New Mexico. Adapted to a life in a hostile environment, it employs an unusual food storage behavior. Copious, sticky saliva, is used to fasten food items in trees, which are retrieved throughout the year.
Clark's Nutcracker. Photo by David Powell.

Also a pine seed specialist, the annual cycle of the Clark’s Nutcracker, is based on the availability of fresh and stored pine seeds. They begin consuming unripe seeds at high elevations in July, and by September are storing ripened seeds. In the fall, they often switch to new seed sources at at lower elevations, and by mid-winter, I find them at my suet feeders. Populations fluctuate between years, primarily in response to food availability, making this another difficult species to monitor. Their grating, noisy call is occasionally my reward at the end of a challenging, uphill hike to the escarpment of Virgin Mesa, which makes the sight of them at my water pan in winter ever more exciting.

Other larger cousins of these birds such as Black-billed Magpie, American Crow, and Common Raven also belong to the corvid family, and they are equally fascinating but fundamentally different than jays.

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