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Author Archive | Dan Greaney

Bird Migration Fueled by Fall Bounty

By on September 28, 2016 in BirdWords
Yellow Warbler

Yellow Warblers surge down local riversides in September feeding on abundant insects from streamside vegetation

Salmon will be arriving soon, and the birds will know it. Turkey vultures know the smells, and will congregate in bare trees at fish-rich creeksites. Experienced eagles will displace the vultures at sand-spit carcasses. Mergansers and cormorants will swallow salmon fragments in the water. Herons and egrets will ply the shorelines where carcasses wash up. Sandpipers may join them. Insects will quickly colonize the dead fish, and their swarming hordes will feed the thrushes, warblers, and flycatchers who come to share in the salmon bounty.

The fall run of Chinook salmon to north state rivers and creeks delivers a huge, valuable load of Pacific Ocean protein and calories that benefit a wide range of wildlife—bears, foxes, otters, fishers, raccoons, skunks, coyotes, bobcats, and a variety of insects that in turn feed more mammals, reptiles, amphibians, and fish. For many birds, the salmon calories are especially important.

Birds that migrate long distances can as much as double their weight in preparation for the trip. In the weeks before flight, they go into hyperphagia, a profound over-eating binge that can see their weight increase as much as 10% per day. They store the energy as fat, which concentrates their necessary fuel in a form lighter than carbohydrates or muscle. The birds then burn this fuel in flight, arriving at their wintering grounds once again slim and hungry.

Of local birds that eat salmon, perhaps the most fish tonnage goes into turkey vultures. Some vultures spend winters in the north state, but most still migrate to Mexico or throughout South America, up to 6000 miles from Redding. Even soaring most of the way, as vultures do, the calorie requirement is high.

Smaller birds cannot soar their way south, but must flap almost nonstop. For numerous songbirds, riversides are highways full of calories. Right now they are hungrily devouring insects, from salmon, from oak trees, from cottonwoods; they are not particular. In addition to insects many songbirds devour the grapes, blackberries, and pokeberries scattered along autumn shorelines. Thrushes, waxwings, tanagers, orioles, vireos, and flycatchers all wolf down this wealth of food to enable their flights south.

Some of our most numerous gems flocking downriver right now are yellow warblers. Relying on insects, they are swarming through Shasta County streamside woodlands, bulking up their little third-of-an-ounce bodies for a flight of two to three thousand miles. They are on the move, and may appear just as flashes of yellow through the pale September foliage, but scores of them can sometimes be seen in a brief streamside stroll.

Fortunately our departing birds do not exhaust the food supplies. Many birds that summered in Canada’s prairies or forests, or in the high arctic will soon flock hungrily into Shasta County, and they should find plenty to eat. Ducks and gulls will feed on salmon that still wash to the riverbanks. Robins and hermit thrushes will eat grapes hanging high in cottonwood trees. Little bushtits, who nested here, will now stay the winter, finding sustenance in the insect larvae and eggs tucked into crevices of leaves and twigs. The bounty of autumn rivers keeps on giving.

Western Kingbirds on Field Patrol

By on June 25, 2016 in BirdWords

Western Kingbird

Most birds are more sensible. They gather their food from the ground, or leaves, or something solid, or at least liquid! But flycatchers make a living on the wing, plucking insects—not necessarily flies—right out of the air.

The flycatchers are a large group of birds that thrive in many habitats. Some are small, greenish, and tucked in close to riparian brush. Some hunt in woodlands or forest canopies. Some flash brightly along open fields.

But all of them share their hunting behavior. They scan from a perch, fly out in pursuit of an aerial insect, and, with any luck, snatch the bug with their beak and return to a perch to dine. If you see a bird fly out, squiggle in the air, and return to a post or prominent branch, you are almost certainly watching flycatching.

Our largest flycatcher, the western kingbird, is frequently seen on roadside fence-wires. The fences make perfect perches from which to hunt over the fields they prefer. A nearby oak or telephone pole will provide a nesting site, and the kingbirds are good to go!

Not shy at all, western kingbirds decorate their neighborhoods with bright flashes of color from their lemon-yellow bellies, and loud, rubber-ducky chattering. They will tolerate nearby nests of what they judge as gentler birds, such as robins and doves, but aggressively harass hawks, owls, and nest predators such as ravens, crows, and magpies. While defending their nesting territories, kingbirds may become aroused, causing their head feathers to stand erect and revealing the crimson crown that is normally completely hidden but earns the kingbird its name.

Like other flycatchers, kingbirds must be strong flyers. To support their aerobatics, they have a keeled breastbone—picture a fin of bone extending out from your breastbone. This structure allows the strong muscles that move the wings to anchor farther forward, giving them better leverage for power and agility. A less pronounced version of the keeled breastbone may be seen in your chicken dinner.

Unlike chickens, kingbirds migrate a long way. Most western kingbirds winter in Central America. In March and April they flap a couple thousand miles into the western US or Canada. There they build a nest of soft plant material, usually high in a tree or human construction, and incubate a handful of camo-blotched eggs. The number of eggs per clutch and the number of clutches attempted vary with the abundance of food.

The hatchlings emerge naked in about eighteen days, and set about gaping for food and growing their muscle, bone, and feathers—gray head and back, yellow belly, and black tail with fine white edgings. If all goes well and the nest predators are kept at bay, in just three more weeks a new generation of western kingbirds is ready to try its skill at hunting the bugs that buzz our fields.

Robins Grace our Days

By on February 27, 2016 in BirdWords
American Robin

American Robin

John James Audubon reports that when at the age of eighteen he emigrated from France to the New World, “The first land-bird seen by me, when I stepped upon the rugged shores of Labrador, was the Robin, and its joyful notes were the first that saluted my ear… I could scarcely refrain from shedding tears when I heard the song of the Thrush, sent there as if to reconcile me to…the barren aspect of all around.”

While the age of birdsong eliciting tears has largely been buried by hastier technologies, Audubon’s raw experience is something most of us can still find in our own backyards and parks. Reported to be the second most numerous land bird living in North America today, the robin remains a soulful beauty, so common as to be almost overlooked.

As Audubon noted, the robin is a thrush, a family that includes bluebirds and several speckle-breasted singers of deep forests. More than any other thrushes the robin has accommodated human civilization. It thrives wherever there is moist earth, trees and shrubs, and a supply of fruit, berries, and insects. From those places it seems to greet us vigorously. Its song, often the first in the morning and the last at night, is not the haunting flute of its thrush cousins but rather a lengthy and cheerful burbling punctuated with lively chirps. Nor does the robin confine itself to woodsy shadows. Most of us see it out in the open, pulling worms from a rain-wet lawn, or gracing the day from a skyward perch.

Robins range over most of the continent, wintering across the US and well into Mexico, and extending their nesting range high into Canadian forests. Redding often hosts large flocks in winter. Sometimes thousands of them will roost together high in cottonwood trees along the river, joining in avian lullabies at dusk—a treat for Turtle Bay visitors. As spring comes, the winter migrants will fan back northward. The flocks disappear. The locals pair up.

Alert observers may notice clear differences among different robins. All adults have yellow bills, and in some birds the white around the eye is striking. Their breast feathers may show a deep chestnut color, or brick red, or pale orange. Some birds will flash a glimpse of white at the corners of their tails. In general, female birds are paler, which serves well as they tend the nest. Other differences occur geographically. Robins are grouped into seven subspecies, but they interbreed, so their differences are not abrupt but rather blend from one to the other.

Females build the nest, mostly of grass and mud. She incubates 3-5 blue eggs for twelve to fourteen days. She will leave the eggs briefly to find food, but the male feeding his mate on the nest has been observed. Both parents care for the young through their fledging in another two weeks. Then the male may continue to look after the fledglings while the female, if weather and the insect supply permit, starts a second or even third nest.

Feral Cats Drive Songbird Decline

By on February 2, 2016 in BirdWords
Feral Cat Feeding Station

Feral Cat Feeding Station

Cats can be great pets, low maintenance purring machines. Unfortunately, they are also active and effective predators.

There are many ways for birds to die. Among the human causes in the US, window collisions may kill a billion birds a year. Cars kill a fraction as many, some 200 million. Pesticides, power line and cell tower collisions, wind turbines, hunting, and oil spills may kill another 200 million.

But the big killer in the US is cats. It is estimated that outdoor cats kill 2.4 billion birds a year in our country. With the exception of habitat loss, this number dwarfs all other current human-caused bird mortality combined.

Many of the studies are small, but they reveal a grim pattern. Cats kill nearly 50% of suburban songbird fledglings. Pet cats average one wildlife kill per fifty-six hours outdoors. They eat or abandon most of their kills at the kill site, not on the owner’s doorstep – belying many owners’ hopes that their pet is too domesticated to follow its instincts. A University of Nebraska study pins thirty-three bird extinctions on cat predation worldwide.

Feral cats number between 30 to 80 million in the US, according to World Animal Foundation estimates. If their kill rate equals that of pet cats, simple arithmetic indicates kills of small animals – birds, lizards, voles, etc. – of nearly 8 billion per year.

Despite being an invasive species, domestic cats are often maintained in the wild. Well-meaning people develop feeding stations that create unnaturally dense colonies. These colonies turn city parks and neighborhoods into native species kill zones, contributing hugely to the declines of American songbirds.

Further, these feral cat concentrations create sinks for the spread of disease and suffering, Feline leukemia and panleukopenia are highly contagious, disabling diseases of outdoor cats. FIV – the cat version of the AIDS virus – spreads mostly through saliva in cat-fight bites.

People, too, are at risk from cat-spread disease. Rabies is found in three times as many cats as dogs, possibly because of their greater involvement with wild animals and the lack of vaccination.

The toxoplasmosis parasite, famous for warnings to pregnant women against cleaning cat litter, can infect any warm-blooded being but only reproduces in cats. Over 70% of cats are expected to carry the parasite at some point in their lives, and they release hundreds of millions of oocytes that can deliver the disease for years through gardens and parks where they defecate. In people, our immune system usually prevents symptoms. But the parasite attacks the brain and is associated with deafness, eye lesions, and a wide range of behavior disorders including Alzheimer’s, autism, obsessive-compulsive disorder, and schizophrenia.

Some solutions to these bird kill and public health problems are easy. Pet owners who keep their cats indoors will protect both wildlife and their cats.

Feral cat problems are tougher to tackle. Trap-Neuter-Release programs have been shown to be ineffective. Neutered cats still kill birds and spread disease, and neutering efforts do not keep pace with the influx of new cats. A single breeding pair can produce 400,000 offspring over seven years.

US governments spend over $50 million a year to reduce the problems posed by feral and stray animals. In Redding, city land is being used to support feral cat colonies.

Climate Change is Beginning to Take Its Toll on Bird Populations

By on June 3, 2015 in BirdWords, Conservation, In the News
Western Meadowlark

Western Meadowlark

Last month I wrote about insect-eating birds swarming into Shasta County to raise their young. Unfortunately, I was indulging in a bit of optimistic nostalgia. The migration itself is as real as ever, but our nesting numbers are dismally down.

It can’t really be a surprise. Everything needs its habitat, and in actions that seemed reasonable, we have converted much wildland to more prosaic purposes. But the yellow-headed blackbird can’t nest where the marsh is drained, nor can the meadowlark make a home where grasslands are converted to row crops. The thrasher can’t sing where the chaparral is cut for houses, or the pet cat kills its young. The kestrel can’t nest where old woodpecker holes have been cut down to reduce hazards, and the pygmy owl can’t stalk grasshoppers where the woodland is paved into yet another retail center.

Driving up the valley as a kid it seemed there was a hawk on every telephone pole. But we reasonably want produce, and farmers pragmatically maximize their production. So after forty years of our plowing through the lairs of fieldmice, gophers, and snakes, of course the hawk numbers are down; after forty years of pesticides to kill hungry insects, of course the songbirds are reduced; after more recent advances to mow right to the fenceline, of course the hedgerow birds are gone.

Unfortunately, our personal perceptions of too-quiet treetops, empty telephone poles, and vacant fencelines are confirmed by research around the globe. Complementing the 115 year old Christmas Bird Count, the North American Breeding Bird Survey has run each May since 1966. It documents declines of 40-60% in a quarter of our birds, and up to 96%, depending on the species and region.

And that’s what has happened already. Now farm produce is being bio-engineered to withstand yet more pesticides, and their application has begun. Climate change is beginning to take its toll. At current carbon emission projections, 314 of 588 species studied by Audubon will lose at least half their seasonal habitat within the lifetime of this year’s graduates.

Many birds will face challenges as seasons unsynchronize: hummingbirds can’t sip on flowers that have already fruited, and fields gone dry offer fewer insects to bring to the nest. Some birds will be unable to shift northward as quickly as this climate change is demanding—especially if they need vegetation that moves north more slowly. Those who successfully shift will encroach on existing nesting grounds; ravens, which eat eggs and nestlings, are already increasing in the arctic, and invaded tundra birds have no Farther North to flee to.

As in most places, in Shasta County we have not, to my knowledge, lost any entire bird species in recent history. But the music is fainter, the voices fewer. Not so long ago, when the canaries started dying we recognized a problem and acted on it. We should be so wise and disciplined today.