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Numbers Matter for These Birds

By on May 27, 2017 in BirdWords
Tricolored Blackbird by David Bogener

Tricolored Blackbird photo by David Bogener

Last month local birders joined in a state-wide survey of tricolored blackbirds. These birds look much like their more common and widespread relatives, the red-winged blackbirds, and they are even found in similar marshy habitats. But the two speak different languages and have markedly different lifestyles.

These are the sounds of the Red-winged Blackbird:

These are the sounds of the Tricolored Blackbird:

The survey is conducted statewide in just three days. This all-at-once survey approach minimizes recounting the birds as they move. And move they do!

Tricolors begin nesting in early spring in southern California and the San Joaquin Valley. Then they move northward and by late spring and early summer are ready to undertake a second nesting, much of it in the Sacramento River watershed. This year the survey in early April found no tricolored blackbirds in southern Shasta County. Two weeks later the nesters moved in: 10,000+ were reported.

Those birds were descending on a field of Himalayan blackberry. Tricolors have been versatile, and as historical marshes of tules and cattails have gone dry, they have adopted a wide range of nesting vegetation, including nettles, mallows, triticale, and blackberries. When they find a field that looks promising, they swarm into it by the hundreds, thousands, and tens of thousands.

If you visit a local pond this time of year, you are apt to see a sprinkling of red-winged blackbirds perched on the tules, perhaps singing their reedy but musical song and showing off their bright epaulettes, vermillion edged with yellow. Below them are the females, hidden with their brown plumage as they warm their eggs in reed-hung hide-aways.

These red-wing colonies might stretch thirty feet from one perched male to the next. Tricolors, on the other hand, go for high-density. The males are likely perched a mere yard from one another, and there are probably two females on two nests beneath each male. This high-density nesting offers a potential advantage.

While the bright and busy colony, along with the tricolors’ raucous, obnoxious blatting, may draw predators, the sheer number of birds overwhelms most local predators. The nearby cats and snakes can only eat so many nestlings. The vast majority survive.

Unless the killing is mechanized. The flock of over 10,000 that arrived in our county seems huge, but surveys in the 1930’s documented colonies with a quarter to a half million nests! Since then, numbers have steadily tumbled. When triticale replaced tules, tricolors adopted the new fields; farmers reacted to the hungry hordes with poisoned grain and market hunts. Those actions are now outlawed, but, despite many positive farmer-conservationist collaborations, harvesting of grain while birds are still in their nests sometimes continues, wiping out entire reproductive colonies. Most irrevocably, the inexorable conversion of marshes into row crops, orchards, homes, and shopping centers reduces habitat on a wide and lasting scale.

Still, 10,000 birds is enough to make a successful colony. Enough, in fact, to raise the seamy side of reproductive abundance. Tricolors try to nest near plenty of grain and insects, but their numbers can overwhelm not only local predators, but also local food supplies. This creates hunger at home, a problem that different species face differently. Underfed eagle and owl chicks eat their younger siblings. Wolves reduce their offspring by limiting reproduction to one pair in the pack. Observations indicate that tricolored blackbird mothers, rather than starve their whole broods, will remove some chicks to be able to feed the others. It’s not a pleasant reality, but one that successful reproduction can force.

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Never Out of Season

By on May 1, 2017 in BirdWords

Northern Mockingbird Displaying

You’ve heard them. Maybe in the day, maybe all day. Maybe at night, when it seems decent creatures should be in bed. Maybe they’ve added sweet melody to your spring morning. Maybe they’ve kept you wondering at night. Northern Mockingbirds are singers.

They have their own style of delivery, but Mimus polyglottos, the many-tongued mimics, learn their songs from other birds, animals, and even machines around them. They sing their playlists round and round, a wheel of chirps, chortles, squawks and trills that dominate the local soundwaves. With age and experience, they keep learning new songs. Males, the louder and more relentless singers, may learn up to 200 songs in their lives. Their musical variety, then, can attract long-term mates who know that they have been around and have the stuff to survive.
The trilling you’ve heard through the night is usually a less satisfied bird, a lovelorn bachelor still seeking someone to nest with.

Mockingbirds’ feathers seem less flamboyant than their songs, but they hold their own surprises. Wings folded, the birds are nondescript tan and gray, as unremarkable as newsprint. But then, when the birds fly, bold black-and-white abruptly flashes out on wings and tail, a sort of optical shout, like a meaningful story. Then the birds land and go visually mute once more, like a pause for thought.

Dull colors might seem like useful camouflage, but mockingbirds don’t settle for dull. Even standing on the ground they frequently flash their wings out. The standard explanation for this display is that the bright white wing patches startle bugs, causing them to move and be more easily seen and eaten. But this effect is unobserved. Test it, with, say, a small piece of paper. Do bugs move when you flash it at them? Apparently other species of mockingbirds who lack the bright patches also flash their wings. So it seems the biggest known effect of flashing wing patches is to make people wonder why they do it.

As forward as these birds can be with just borrowed songs and black-and-whites, mockingbirds are no less shy in tending their territories. They dive-bomb cats, dogs, and crows who wander too near. Less riskily, with encroachments from their own kind males have developed a bill-up and chest-to-chest dance at their territorial border. That ritual rarely deteriorates into a pecking battle, and allows both birds to make peace and move on without too much loss or humiliation.

The successful male mockingbird chooses a nesting site. Several of them, actually, where he frames several nests of twigs. Then the female makes her choice, and finishes the one she’ll use with grasses and other soft linings. She lays a handful of eggs, which in 12-13 days hatch into blind, naked nestlings. Both parents help the young into their first feathers, and then she will often start a second brood while he continues to tend the first.

In the 19th century, before radios or today’s Pandora, mockingbirds were captured to provide music in people’s homes. Those nearly year-round singers—the literature lists them as singing February to August, and then again September to November—were so popularly caged that they began to disappear from East Coast yards. Since then they have rebounded, doing well in suburbia’s mix of open areas and trees with fruits and berries. Now, in the era of expanded pesticide use and domestic cats, they are declining again, but their song remains the headline show in gardens across America.

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Birds Get Down, and More, for Winter

By on February 7, 2017 in BirdWords
Ruby-crowned Kinglet Male

Ruby-crowned Kinglet Male

On frosty winter mornings when just a few minutes outside has your cold fingers complaining and refusing nimbleness, think of the hummingbird. This creature no bigger than your pinky has perched outside all through the starry night, and before the frost is gone will be darting about lapping up nectar and snapping up insects. How do they do it?

Birds are wonderfully well adapted to dealing with cold. Most creatures become inactive when the temperature drops low. Insects may survive as hidden eggs or cocoons. Lizards lie motionless under a log. But like us mammals, birds are warm-blooded, and warm-bloodedness allows activity even in the cold. Of course, like any furnace, warm-bloodedness requires energy. Birds must eat!

Little birds especially, with their limited capacity for fat storage and the greater exposure of small things to the elements, seem almost constantly ravenous throughout the daylight hours. Tiny hummingbirds can devour up to three times their weight in a day. Kinglets flitter nonstop in their almost frantic hunt for winter insects. Rolling packs of chickadees glean over fir needles, green in their snowy mountain homes. A robin may be the size of your pet boa, but it must dine more, and more often.

Warm-bloodedness also needs insulation to be effective. Naked scales might work for our cold-blooded relatives, but mammals have fur and birds have feathers, nature’s finest insulation. Beneath their outer contour feathers, birds wear the thin but dense layer of down that traps still air, keeping their bodies at a comfortable 104 degrees even as winter chases less robust creatures, like grizzly bears, into protected hideaways. When the cold bites especially hard, birds can fluff their feathers to increase insulation, and pull their heads down on their shoulders, or tuck them under a wing.

Of course, their feathers must be kept dry. Like us, most birds have natural body oil. They spread this oil from a gland at the base of their tails, keeping their feathers glistening, both beautiful and waterproof.

Double-crested Cormorant

Double-crested Cormorant Wings Spread

Most water birds produce plenty of this preening oil, but oddly one of our diving birds produces hardly any. Apparently the advantage of pursuing fish without the buoyancy of dry feathers can compensate for getting wet. Instead of preening, however, cormorants stand in the sun with their wings held out to dry, a performance visible all along the Sacramento River.

Birds are also vulnerable to cold through their unfeathered feet. Long-legged herons and egrets are particularly exposed. Handily, the birds have a built-in heat-exchanger. Arteries carrying warm blood from the feathered body are intertwined in the legs with veins carrying chilled blood from the feet. Heat naturally dissipates, warming the veins and cooling the arteries. The result is that some heat is quickly returned to the warm core, and, especially in icy habitats, the feet just live at much colder temperatures than the rest of the body. Birds handle this by keeping their heat-loving muscles in their warm bodies, with little more than bones and tendons nakedly exposed. Also, watch a heron or egret. They frequently stand on just one leg, tucking the other up into their feathers, warming their toes and reducing heat loss.

Great Blue Heron

Great Blue Heron

Different birds undertake a variety of other strategies to survive the cold. Watch a robin face the morning sun, catching that warmth full on. Little nuthatches huddle together in tree cavities. Hummingbirds can actually go into overnight torpor, a mini-hibernation in which their body temperature drops as much as 50 degrees and their heart-rate slows from 500 to 50 beats per minute, saving precious energy. Poorwills, the western cousins of the whip-poor-will, can enter that state of torpor for weeks at a time.

Migration, of course, is perhaps the grandest adaptation to cold. But with birds, so well suited to handling Earth’s normal chills, migration may reflect the pursuit of food more immediately than the temperature change. Birds cannot survive when seeds are covered by snow, or fish by ice, or when fruits are picked clean or insects have ceased to crawl and flutter. Without food, it’s time to go. But a chill morning? Pah! Put on your coat and watch them!

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Quail Live the Good Life

By on December 31, 2016 in BirdWords

California Quail Male

If your True Love went local, and instead of offering an Old World “partridge in a pear tree” gave you their California native counterparts, be glad! A quail in a crab apple brings much to enjoy!

Quail, after all, are a lesson in living the good life!

For starters, they enjoy music. They sing to one another, a hello call that is usually rendered Chi-CA-go, although the North State dialect sounds more like Lake-SHAS-ta. Pairs sing together, duets in which the female maintains the hello refrain and the male fits high grace notes into the spaces of her song.

Quail are dedicated parents, too. They have large families, 10-16 eggs in a clutch, or more if a neighbor contributes. They help their children explore the world, watching dutifully as the young leave the nest within a day of hatching to start poking at the world, beak first. The parents are, of course, unable to produce milk, but their chicks, no more discerning than human infants, pick through the adults’ feces and, just as humans acquire valuable antibodies through nursing, they swallow protozoans that help in digestion.

Families of quail typically neighbor up to form a covey, a community for living and child-rearing that unsurprisingly increases adult life expectancy. The covey keeps together with an ongoing low pit-pit chatter: I’m right here – Don’t go away – We’re OK.

Sometimes a male will perch prominently on a bush, boulder, or fencepost , but he is not alone. He is watching for danger, and if he becomes alerted his calls grow louder and more urgent. Other males in the covey may join him to peck at a small predator, or the quail may all flee. Once the chicks can fly, which begins at about day ten, the covey’s wings create a burst of thunderous flutter as the birds explode into their short flights from peril.

The high-perched male is certainly watching for predators, but he might also be showing off a bit. Quail are stylish, and, while the female wears the muted tones common to avian patterns of nest camouflage, the male sports a striking attire of scaled grays, chestnut, cream, black and white, all under a burgundy crown decorated with a black plume that might inspire royalty, or punk rockers, or a praetorian guard.

Beyond sharing the cultural pleasures of music, family, community, and flair, quail take care of their individual physical needs, too. They eat a healthy diet, up to 30% lean meat, but mostly vegetables—seeds and such. They also get enough sleep. Particularly in winter, while hordes of daybreak sparrows flitter through yards and under feeders, quail become scarce, seeming content to sleep late through the cold hours of the season. Their coveys, numbering scores or hundreds of birds, provide plenty of eyes and ears to attend to safety in their brushy hideaways and protective trees.

This good life seems to be serving the quail well. In a time when many species are declining, California quail have slightly increased their population, even while sustaining a statewide shotgun harvest of a million birds per year.

If you have brush close by, California quail may troop to your backyard bird feeder. And if they pass an old crab apple tree that still struggles along the fenceline, perhaps you’ll hear them chuckle a low song of satisfaction.

Science Celebrities Visit Redding

By on December 3, 2016 in BirdWords
Dark-eyed Junco

Dark-eyed Junco “Oregon” Subspecies

The flit of little gray birds with a conspicuous flash of white outer tail feathers signals the arrival of our charming winter visitors, the Dark-eyed Juncos. Look more closely, and you will see a sparrow-shaped bird with a whitish bill and belly, gray central tail feathers, a rusty back and a black head. The female has a similar plumage pattern only more muted. In this part of the country, juncos migrate vertically. They nest in the high mountains – I’ve seen pairs on Mt. Lassen during the summer – then move downward to spend the winter in the valley.

Dark-eyed Juncos build a nest of grass, moss, rootlets, bark and twigs in a shallow depression with overhead protection. The three to five white eggs with reddish-brown markings are laid by the female and incubated by both parents for about 12 days; then the initially naked and helpless young are cared for for another 9-13 days before leaving the nest. Nestling juncos’ feet develop rapidly, so even before they are able to fly, they can run away if threatened by a predator.

Juncos are lively birds to watch at bird feeders this time of year. Most of the adult diet consists of seeds of various kinds. Juncos can also be seen in open woods, undergrowth and roadsides, and can frequently be found in parks such as Lema Ranch. In winter, flocks of 10-30 occupy a foraging territory, so your yard may have its own flock. Within a flock, each bird will have a definite social ranking with the “top bird” getting first crack at the edibles. See if you can tell who is who in your yard!

This common little bird is a “rock star” in scientific circles. Juncos easily accommodate to laboratory aviaries and so have been the subject of avian behavioral studies in courtship and nesting, care of young, and status of individuals in flocks.

Juncos have even been caught in the midst of evolving. At the University of California San Diego, a study is being performed to compare the “city” juncos on campus with “country” juncos in the nearby mountains. Differences have been found in the tolerance for proximity to humans, and those differences have proven to be inheritable. Also associated have been subtle physical differences, which, as time goes on could lead to separate subspecies. Evolution is often thought to take many, many years, but in fact changing conditions frequently cause rapid changes in species. In this case, it’s happening right before the researchers’ eyes!

Different populations in various geographical areas are highly variable, so much so that the western juncos were once split into four distinct species. Deeper studies revealed that the different groups can interbreed freely and are now considered to be one complex species. Thus, juncos are very interesting for genetic investigation.

So, this ordinary familiar little harbinger of winter is actually famous in scientific circles, and a very important bird in the furthering of human knowledge. Enjoy these avian celebrities in your yard and neighborhood until spring when they return to the mountains to produce the next generation.