Sunday, February 26, 2012

Birds on Wires

European starlings, Sturnus vulagaris, on wires -- click to enlarge. 
It was very windy in Brooklyn yesterday. Birds on wires were all facing in the same direction. On a still day or in sheltered areas, birds sit facing any direction. But when the wind is blowing they turn to face it -- not just on wires but also on beaches, on branches, in fields, at feeders, on fences, and everywhere else. They are streamlined and the wind flows smoothly around them. If they faced the other way, it would ruffle up their feathers and let cold air under, and it might push them off balance. Like airplanes, birds land into the wind. They take off into the wind like airplanes too, and for the same reason -- they get aerodynamic lift. As they sit facing the wind, they are ready to step into the air and fly.

Sunday, February 19, 2012

American Black Duck

The male American Black Duck, Anas rubripes, has a dark body and light head, orange-red legs, unblemished yellowish bill, and a black-bordered bluish purple speculum (the brightly colored patch of feathers on the wing). 
I was walking in Brooklyn Bridge park yesterday when I heard splashing and thrashing in the pond. I got there just in time to see a male mallard duck fly away and a pair of ducks in the pond swimming excitedly and shaking their feathers. I may have just missed a duck fight! The male mallard circled overhead and splash-landed in the pond. He was chased away immediately as the duck pictured above rushed at him threateningly. This time the mallard flew away and did not return. The victorious duck bathed with exaggerated wing thrashing and water splashing.

A duck celebrates victory after chasing another duck away. 

The pair of ducks that remained soon settled down in the shallows to preen their feathers. They were a male American black duck and a female mallard. Despite being different species they behaved like a couple. She followed him around the pond, and, as explained, he was chasing male ducks away.

The Mallard duck female, Anas platyrhynchos, at lower right has a blue speculum bordered with white. Her beak is orange with black splotches.  

Male mallards occasionally breed with female black ducks and produce hybrid offspring. The mating displays of the two species are identical. But most of the mixed couples are a mallard male and a black duck female. I haven't seen reports of male black ducks with mallard females, but I haven't searched extensively. If any of my readers can speak about this, please post a comment. Meanwhile, I will consult with ornithologists I know and report back. I hope the ducks continue to visit the pond so I can keep an eye on them and let you know what I see.

The black duck stretches his wing, showing off his speculum and bright foot. The color of the speculum seems to change with the light. This is the same bird as above. Click to enlarge. 

Sunday, February 12, 2012

Squirrels in High Places

There is Republican primary coverage on television. Through the window near the TV, I see a squirrel  tightrope walking on the porch fence.

The juxtaposition reminds me of Ronald Reagan and the White House squirrels. He fed them, and they reportedly gathered outside the Oval Office and looked in at White House doors and windows, anticipating treats. The President brought back acorns for them from Camp David, the presidential country retreat in Maryland. The Reagans' 1984 Christmas card, a painting by Jaimie Wyeth, called "Christmas Morning at the White House," shows a squirrel leaving a trail of footprints in snow on its way to the White House door. (Click here to look at one that's being sold for $85.00!)

The relationship of the White House squirrels with other human occupants has been both good and bad. In 1921, President Harding's first lady, Florence, championed animal welfare, including the protection of squirrels on the White House grounds. President Truman fed the squirrels while taking his meals outside on the south porch. The nation was charmed when in 1949 a five-year-old visitor expressed concerns about the White House squirrels, and Truman appointed him to feed them (at no cost to the taxpayers). The story appeared in newspapers across the country; click here to read one.

The chummy relationship came to an abrupt end with the Eisenhower administration. Eisenhower was a golfer. When he had a putting green installed on the lawn a short distance from the Oval Office, the squirrels started burying nuts there. Eisenhower was reportedly infuriated about all the holes and bumps. After attempts to scare the squirrels away failed, a few were trapped and released somewhere else. Boy did he get in trouble for that! His opponents in Congress depicted him as an enemy of wildlife. The squirrel trapping campaign was suspended.

During the Carter administration, the National Park Service studied squirrels in downtown Washington. They found that Lafayette Park, the seven-acre park across Pennsylvania Avenue north of the White House, had an extremely high number of squirrels -- more than 100 -- probably supported by the constant stream of squirrel-feeding and snack-dropping tourists.

The George H.W. Bush years were challenging for the squirrels -- the Bush family dog, a Springer Spaniel named Millie, habitually chased the squirrels. During the Clinton years, when squirrels attacked the White House tulips, the gardeners placed peanut-filled feeders on the South Lawn and in the Rose Garden to draw them away from the flower beds. Like deja vu, George W. Bush's dogs also chased the White House squirrels.

I wonder how the squirrels are getting on with the Obamas. Is Bo a squirrel chaser? The President mentioned the squirrels last year during an East Room ceremony celebrating America's Great Outdoors -- you can watch the video clip by clicking here. (Sorry about the ad before the clip.) But does he feed them?

Sunday, February 5, 2012

The American Crow

The American Crow, Corvus brachyrhynchos.
In one of Aesop's Fables, a thirsty crow finds a tall pitcher with water in the bottom, beyond its reach. The crow drops pebbles into the pitcher to raise the water level, and drinks.  The moral of the tale is that necessity is the mother of invention. Another message is that even the ancients realized that crows are smart.

One of my favorite scientific debates is about a smart thing that crows do. Some scientists think the birds drop nuts onto roads from the air so that cars will crush them open; other scientists insist that crows are dropping nuts on hard roads surfaces to break them as they always do, but that cars are coincidental and not part of the nut-cracking plan.

Regardless of how the car debate is resolved, there is no question that crows drop nuts from the air to break them open. And it's more complicated than you might expect. Nuts may not crack on the first drop, but they weaken with each drop and break open eventually. Nuts break differently when dropped on different surfaces. Another crow might dash in and steal the broken nut.

A scientific study compared the way crows dropped hard California walnuts and softer English walnuts. (You can read the original paper by by clicking here.) The scientists observed and documented that crows drop harder nuts from greater heights, drop the same nut from decreasing heights on subsequent drops, and drop both kinds of nuts closer to hard roads. If other crows are watching, they drop from lower altitudes, on guard for possible thieves. How smart is that!

Stiff bristly feathers on the beak. 
The American crow is a large glossy black bird up to about 20 inches long. Its bill is heavy, shiny, and black; the top of the bill near the face is covered with stiff short bristly feathers. In adults, even the inside of the mouth is black. It calls a familiar caw-caw-caw. It breeds from central Canada south through most of the United States.

Crows spend winters in most of the parts of their breeding range inside the United States. During winter when less of their natural food is available they are more likely to visit landfills and dumpsters. They masterfully exploit urban food sources. They don't just eat trash -- they open lunch bags and unwrap the contents. I have watched them around outdoor lunch tables and trash cans at the Bronx Zoo. They pecked open unused ketchup packets, up-ended unfinished milk containers to drink the remains, and stuck their heads inside discarded potato chip bags to finish off the crumbs.

One study found that crows spend more time watching for danger while foraging around denser human populations than in rural areas; they share vigilance by forming groups and may depend on that more in cities, where line-of-sight can be short. I can attest that they are hard to photograph; they seem only casually aware of me, but I never seem to be able to get close. As I advance, using maximum stealth, they find interesting things to do just a few steps further away.

Click to enlarge. 
There is a nursery rhyme called Counting Crows, in which the number of crows you see predicts a future event. There seem to be endless version. Here is one --
One for sadness, two for mirth;
Three for marriage, four for birth;
Five for laughing, six for crying;
Seven for sickness, eight for dying;
Nine for silver, ten for gold;
Eleven for a secret that will never by told.