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Archive for January, 2013

Tool-using Birds

Scientists rate the ability to create and utilize tools as a measure of a speicies’ intelligence. Humans score well on this measurement. How about birds?

Some crows are tool users. In order to reach insects buried deep inside holes in tree trunks, crows are known to make and use “spears”. First they pick a twig of the proper length and they sharpen one end to a point. Then they poke this spear into the hole to get insects. That takes some degree of intelligence.

Watch this video to observe more avian intelligence. A heron uses a tool (a fishing lure) to catch a meal.
http://www.youtube.com/watch?v=uBuPiC3ArL8

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black & turkey vultures - 2Birds are found everywhere. From the driest desert to the rain forest, from the highest mountains to lowest valleys. In cities and in the country.

Today I was driving on fumes. So I stopped at a gas station to fill up. As I was filling the tank I looked up and saw a Black Vulture soaring overhead. I didn’t expect it. It surprised me.

Turkey Vultures are the common vulture in this area, but Black Vultures are showing up here and there more frequently. Both are big black soaring birds. The Black Vulture has shorter but wider wings. They also have white on the outer tips of the wings, as opposed to the Turkey Vulture which has white on the trailing edge of the wing. Turkey Vultures have red heads, Black Vultures, black heads.

Turkey Vultures soar with the wings held at an angle, forming something of a V shape. Black Vultures hold their wings flat.
The important factor is to keep your eyes open. You never know when you may see an interesting bird.

I remember once being at the NY Botanical Garden and noticing a Robin sitting on a nest on a branch that was just 10 feet above a main path. Most of the people walk right under the nest and never realized the nest was there. As Sherlock Holmes would say, they looked but they did not see.

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To survive a cold winter night a bird looks for a sheltered, warm place to sleep, such as a hole in a tree or a dense evergreen.  On really cold nights several birds might all pile into one birdhouse and snuggle up to share body heat.  Studies show that when 2 kinglet size birds snuggle up on a 32 degree evening, each reduced its heat loss by 23%.  In groups of three, each reduced its heat loss by 37%.  So if you are cold, hug a friend.

 Large birds have an advantage over smaller birds because the have a relatively smaller surface area for their mass.   

 Ptarmigan and grouse, birds of snowy areas, will plunge under loose snow and sleep under the snow cover.  It is warmer under the snow than in the open air.  In Alaska, small Snow Buntings may stay under snow both night and day.  Air temperature above the snow might reach – 30 degrees but two feet under the snow it will be a relatively balmy zero degree.

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 A bird’s normal body temperature is higher than a human’s, typically around 103 degrees.  They must eat a lot of food to maintain that temperature especially when the outside temperature is low.  Studies show that on in 85 degree summer temperatures a House Sparrow can survive 67 hours without eating.   However, in winter temperatures of 5 degrees they can survive for only about 15 hours, or about the length of a long, cold  winter night.

 Scientists have studied the lowest temperatures that bird can endure.  The European yellowfinch can survive temperatures as low as –36C for 24 hours.  I can’t.

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Chilly Day

Cold Temperatures Arrive Winter has been unusually warm so far but today colder temperatures have arrived with even colder temperatures on the way. Time to break out the winter coat, hats and gloves. Birds can’t don heavy clothing. So they make other changes to conserve heat on cold days. First, birds have more feathers in winter than in summer. And, if you ever had a down-filled coat, you know feathers make wonderful insulation. Birds fluff up their feathers to trap layers of air between feathers providing greater insulation. On a cold day a chickadee may look twice as fat as on a warmer day. Unlike many animals, birds do not have any exposed fleshy parts such as ears, tails or legs that lose a lot of body heat. Ducks have extra layers of fat to provide insulation. When perching, a bird may stand on one leg and tuck the other foot into its belly feathers. Some birds bury their horny beak into feathers to save heat. Shivering is another short term adjustment to cold that converts muscular energy into heat. However, the lost energy must be soon be replaced by eating.

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This morning I joined a large group (30-35 people) for a winter birdwalk at Croton Point Park. Although I could only devote a short amount of time, I was rewarded with 4 new species for my 2013 Bird List.

That included the first Bald Eagle of the year (actually, we saw four eagles.) The weather has been so mild that I feared we might not see any eagle this year. It takes cold winter weather to drive eagles into Westchester. The average person does not realize that an eagle’s favorite food is fish, especially dead fish. They like to sit in tall tree next to a body of water and wait for a dead fish to float past. Then they swoop down and scoop the dead fish off of the surface of the water. (That kind of spoils their image as a fierce hunter)

When cold winter temperatures freeze lake and streams farther north, eagles are force to move south to open water. That brings them to Westchester, especially along the Hudson River, which is usually free of ice.
As the weather gets colder, more eagles appear. Four years ago there were 93 eagles between Croton Point Park and the Bear Mountain Bridge.

The annual Hudson River EagleFest is scheduled for Saturday, Feb. 9th. If you have never attended, you have missed a great event. For details about this event, organized by Teatown Lake Reservation go to
                                www.teatown.org

Last year almost 5,000 people attended. Most activities and programs are free of charge. Some have a small fee. The major programs sell out early. So sign up early if you are interested.

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Hard-Boiled Eggs

Ostrich  vs Chicken EggMy recent blog post comparing the size of an Ostrich egg to the typical chicken egg prompted an interesting response from a reader, a reader with a culinary bent.

She pointed out that the traditional method for cooking the perfect hard-boiled (chicken) egg calls for bringing a pot of water just to the boiling point, then immersing the egg in the hot water for 5 minutes. Perfect results every time.

An Ostrich egg dwarfs a chicken egg. But you follow pretty much the same recipe to achieve a perfect hard-boiled Ostrich egg. Except you leave the egg in hot water for two hours, not five minutes.

Then you can make egg-salad sandwiches for an army.

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