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Vultures Soar to do the Dirty Work

By on July 3, 2017 in BirdWords

Turkey Vulture Adult and Juvenile

Summer is the season for soaring. Thermals, the warm air rising from the earth’s heated surface, can lift birds thousands of feet into the air with no more effort than spreading their wings. Larger birds, particularly raptors, for whom the quick flutter of small-bird wings would be physiologically impossible, are particularly famous for riding on thermals. The reigning champions of hot-air flight are, arguably, turkey vultures.

They’re ungainly, maybe disgusting. They can’t sing, only argue over food with a breathy hiss. They’re folklore symbols of doom and death. But supremacy in the air helps vultures prosper and decorate the sky through our sultry summer days. Some 90% of the soaring birds we see are apt to be not birds of prey but turkey vultures.

These vultures can be identified at a great distance. They hold their wings up in a V, a gift of their initial letter that hawks and eagles cannot replicate. The V shape, known in aviation as a dihedral, helps stabilize the birds in windy weather. When winter buffets the north state, the resident vultures ride the winds that replace the lazier-seeming currents of summer. Other turkey vultures will honor autumn tradition and head south—but they will still sail the winds, as they can ride as far down-continent as ever-blustery Tierra del Fuego.

Wherever they are, turkey vultures must soar to find their food with the most efficiency. Unlike most birds, they hunt with a keen sense of smell. Eagle-eyed predators can spot a salmon below the river’s ripple. Owls can hear a mouse squeak a football-field away. Vultures’ food, already dead, will not squeak or scurry for the ear or eye. Turkey vultures hunt mainly by smell. Their acute olfactory sense will not only find their carrion dinner, but will tell them whether it is too rotten to interest a civilized vulture. Indeed, while large owls, with their absent sense of smell, may gulp down a skunk, vultures will regularly discard at least the skunk’s scent gland.

But they really are not delicate diners. Vulture beaks are sharp and strong, but when particularly tough hides must be pierced, they may need to wait for early decay or a bigger predator to open the carcass. Since they will then be eating meals past their expiration date, and since they seem to prefer eating entrails from the anus up, vultures are heavily exposed to toxins. Fortunately, they are adapted to the dangers. Their naked heads not only keep feathers from being matted with contaminants, but also allow their skin bacteria, thicker and harsher than our own, to attack microbes in the meat, averting facial infection. The birds seem to be immune to effects from many biotoxins, and their own exceptionally virulent intestinal bacteria help them finish the job.

Their job is in fact a substantial service. Vultures find and scavenge about 90% of sizable dead animals in their range, reducing both disease and cleanup costs we would otherwise face.

Their condor cousins, with the rise of lead shot in carcasses and, longer term, no more mega-fauna to clean up, have been teetering on the edge of extinction for some time. Turkey vultures, on the other hand, perhaps responding to clearing of forests, an increase in roadkill, and a warming climate, have been extending both their breeding and wintering ranges northward.

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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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A Message From David Yarnold, President and CEO of the National Audubon Society

By on March 11, 2017 in Conservation, In the News

If your in-box looks like mine, you’ve received a lot of email about the administration’s first draft of a budget outline. There’s a lot of bold-faced or bright red type on those emails and they make it sound like the proposed budget cuts are a done deal. Audubon thinks you deserve a more thoughtful response. Those emails would also lead you to believe that an executive order to begin the long process of undoing the Clean Power Plan is the end of the line. In fact, the administration’s budget proposal was designed to generate headlines about living up to campaign promises, but it also divided Americans on core values like clean air and clean water. The executive orders are just the beginning of a years-long process that will test the Audubon network’s commitment to science, community and fairness.

Keep in mind a president’s budget proposal is just that: an opening bid. More details will emerge in the coming weeks. Those details will be debated for months in Congress. As we’ve seen in recent weeks on issues ranging from privatizing public lands to health care, you have a chance as constituents to influence how that budget gets shaped. As the voice of birds, Audubon will be by your side. We’ve worked to protect funding for the places birds need for 111 years—with Democrat and Republican presidents and across party lines in Congress. And in the coming weeks and months, we will work harder than ever with our elected representatives on both sides of the political aisle to make sure we continue to protect the clean air, clean water, and stable climate birds and people need to thrive.

It’s clear that this administration, left unchecked, will fundamentally step back from all of those protections in the name of reducing the role of government. While it’s the nature of bureaucracies to need an occasional pruning, other agendas are at work, serving special interests like big oil and coal as well as the super-wealthy.

Audubon’s leadership chooses to engage with this administration as we have with 28 that preceded it. We simply won’t stand aside while the future of the Arctic Wilderness or Endangered Species Act gets decided. But we’re under no illusions about how hard the fight will be in the face of many in the administration who equate caring conservation with economic hardship. That cynical and, some would say, blasphemous world view is a complete distortion of the values that drove Republicans from Teddy Roosevelt to Richard Nixon to create national parks and bedrock environmental protections.

At every step of the budget process, Audubon—with your continued help and support—will fight to protect funding that’s critical to advancing our conservation work.

How can we do it? We’re a credible voice for commonsense conservation, and that transcends party or politics. The Atlantic magazine recently described Audubon as “one of the oldest and most centrist of conservation-minded groups” in the country. In a polarized political climate, Audubon’s membership is unique, with members and donors from across the political spectrum,including Democrats, Republicans and independents. We are community builders, not community dividers because birds create common ground. When I meet with chapters, I see committed conservationists and I can’t readily tell R’s from I’s or D’s.

You, our diverse members, make us an effective organization—in the communities we call home and in Washington D.C. Your representatives need to hear why funding conservation work is so important to you and to Audubon’s efforts across the country. You can be confident that in the coming weeks and months we will offer you opportunities to raise your powerful voice at the crucial points when it matters most.

Remember, now more than ever, you’re what hope looks like to a bird. Get involved and take action today.

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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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