With early fall migrants returning and before late summer residents leave, the oak woodlands, wastewater treatment pond, Stillwater Ck. riparian, and open fields should support a wide variety of species. Meet in Shasta College’s north parking lot for this 1⁄2 day trip that is open to the public. Bill Oliver and Connie Word will co-leaders.
Tag Archives | birds
Jaybirds—Thieves and Oak-farmers
Western Scrub-Jay
Common as dirt and all around us, anyone who sets foot outdoors must have seen the Western Scrub Jay, boldly sitting atop the highest tree, scolding raucously, or flying with an acorn in its beak. Sometimes mistakenly called “Blue Jay”—that’s its cousin east of the Rocky Mountains who sports a perky blue crest—the Western Scrub Jay is a foot-long crestless jay with blue on head, wings and tail, a pale brownish-gray back, and a gray-white throat.
The male and female form a long-term pair bond and raise 3 to 6 young per year in a nest built of sticks. Rather than picking sticks up off the ground, I have seen them break sticks off a tree, often discarding any that don’t meet their standards.
Although the diet of the Western Scrub Jay includes fruit, seeds, insects, small animals (and it does rob nests), its mainstay is acorns which it often buries in the ground for consumption later, a practice called caching.
I watched a jay stick an acorn into the soft soil of the front of my vegetable garden. Immediately, another jay showed up and swiped the acorn and buried it in back in a tomato cage. Then jay number 3 flew in after the same acorn, but was chased off by the second jay.
Similar lunchtime observations of jays’ thieving by a research scientist at UC Davis led her to an investigation in the lab. She found that individuals that stole food from other jays’ caches spent much more time moving and reburying the same piece of food than non-thieves did. So, thieves suspect that everybody else is a thief, too.
Acorn Woodpeckers, who cooperatively make their own caches, or “granaries,” of acorns in holes in trees, are also on to the tendency of Western Scrub Jays to steal nuts. The woodpeckers always have a member of their group on guard and if a jay comes near, the woodpeckers go into noisy “red alert,” and several fly in to chase the potential raider away.
Another ramification of Western Scrub Jays’ and related species’ habit of caching acorns relates to their importance in the scrub oak woodlands. Of course, the birds never find all the acorns that they’ve buried and many remain to sprout into oak seedlings.
Researchers recorded that the related Blue Jay cached significant numbers of acorns – 50 jays cached 150,000 acorns in 4 weeks, leading to speculations that the swift extension of oak forests as the ice retreated at the end of the last ice age was due to the activity of the jays.
A botanist looked at this more closely. He superimposed a map of the world-wide distribution of oaks upon a map of the occurrence of acorn-caching jays of various species and found that no oaks were found where there were no jays, although the jays survived in areas without oaks. His conclusion was that oak forests are entirely dependent upon jays for their reproductive survival. So, our local feathered rascal has an important job to do for our oak forests!
Western Scrub Jays are common in our neighborhoods and woodlands, so watching them in action takes little more than patience and curiosity.
Discover Birding at Turtle Bay
Our youth/beginner bird walks are conducted on the first Saturday of every month throughout the year. Wintu Audubon can provide binoculars and field guides. Call Dan Greaney, 276-9693, with questions or for more information. Please remember that we now assemble at the Venture Properties parking lot. Take the first left before the Redding Civic Auditorium.
Discover Birding at Turtle Bay
Our youth/beginner bird walks are conducted on the first Saturday of every month throughout the year. Wintu Audubon can provide binoculars and field guides. Call Dan Greaney, 276-9693, with questions or for more information. Please remember that we now assemble at the Venture Properties parking lot. Take the first left before the Redding Civic Auditorium.
Nesting Season Showcases Variety in Bird Homes
Mama bank swallow and her chick gaze out over the Sacramento River from their cliff-bank burrow – photo courtesy of David Bogener
Spring is in the air and birds are in the creative construction business. The homes they build, where they will lay and incubate their eggs and raise their young, come in many styles, shapes, and sizes.
The simplest is almost nothing – a mere scrape on the ground such as the Killdeer use—and is abandoned as soon as the eggs hatch and the precocious babies follow their parents and pick up their own food. More complicated is the floating platform, such as the rafts that Pied-billed Grebes construct on local ponds, allowing these swimmers to live their entire lives without ever setting foot on land.
Simple elevated nests are the familiar cups that many songbirds such as the beloved American Robin build in bushes and trees. A robin’s sturdy home is formed with twigs, then cemented with mud– so if you see a female robin with mud on her chest you can bet that her nest is nearby. Robin babies hatch blind, naked, and helpless, so she lines the nest with grass to make a soft cradle for the nestlings in the weeks that their parents fly food to them. Even after the young fledge, the parents continue to feed them for some time.
Bird nests are unique to each species, so the builder of an old abandoned nest can often be identified by the materials, size, placement, and other construction features of the nest. There’s no confusing the tiny, dainty hummingbird’s nest, woven of moss and spider webs, with the massive stick-built home of the Bald Eagle! I once observed a Bald Eagle in Seattle land on a sizeable tree branch and keep on flying, snapping the branch and heading off toward the nest the pair was constructing – no picking up old sticks from the ground for this mighty bird!
Many birds are cavity nesters, using holes in trees that they have chiseled out themselves or reused after the original makers have moved on. All of the woodpeckers excavate their own cavities, although sometimes even they will start housekeeping in a provided nesting box.
To a certain extent we can select nesting box tenants by sizing the hole in the birdhouse. Entrances up to 1 ¼ inch round will admit wrens, titmice, and nuthatches. Bluebirds and tree swallows will use 1 ½ inch doorways. Larger holes will invite the nonnative European starlings, and so are not advised.
Unusual cavity nesters are the Belted Kingfishers, who dig long tunnels in river banks to house their eggs and chicks, and the Bank Swallows, who seem to use their burrows in courtship. The males dig two foot tunnels into a riverbank cliff, and the females check the sites out before selecting a package deal of mate and burrow. Their cousins, the Northern Rough-winged Swallows, will similarly burrow or can be seen nesting in the weep-holes of the concrete Bella Vista water intake downstream from the Sundial Bridge.
The master architects of the local bird world build complex nests such as the hanging basket of the Bullock’s Oriole. The Bushtit builds a woven construction more like a long sock with a tiny entrance hole up above the ankle. When the parent birds come to feed their chicks, the sock does the shimmy as the babies eagerly take their meal.
So, enjoy the season and the beauty of its diverse lives and homes! With your eyes open maybe you will see a bird carrying a piece of material to line its nest, and you’ll know that parent birds are preparing to raise their young ones!
Article by Linda Aldrich