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Archive for February, 2012

Cats and birds are natural enemies, predator and prey.  Except, of course, in Edward Lear’s nonsense poem “The Owl and the Pussycat”.  This video, however, shows that even they can get along.  So maybe there is hope for the world after all.

Obviously the cat and the owl in this video are friendly.  Even when the cat leaps at the owl I sense it is more for play than prey. 

The jesses (strips of leather) hanging from the owls legs suggest this owl belongs to a falconer.  The cat, probably a family pet, is comfortable with the owl.

CTRL + Click :     http://www.wimp.com/catowl/   

 

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Whenever I do a lot of writing or typing I guarantee there will be typos and mis-spellings.  I was an undergraduate engineer and everyone knows engineers can barely speak English.  I can calculate formulas to three decimal places but can’t spell with any accuracy. 

Spell Checker is my best friend.  That’s why I am happy to share the following

                  Ode to My Spell Checker

I yews a spelling cheque

It came with my pee sea

It  plainly marques four my revue

Miss takes I can knot see

 

I’ve run this poem threw it

I’m shore yaw pleased to no

It’s letter perfect in its weigh

 My chequer tolled me sew

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Today’s  Science Times section of the New York Times reported the following story:

Marriage, infidelity and divorce:  these intimate matters are familiar to humans.  But oddly enough, birds deal with them as well.  Now researchers have found that avian infidelity is more common in severe or uncertain weather.

Dr. Carlos Botero published data on more than 80 bird species including swallow, chickadee, bluebirds, falcons, gulls and geese.

In birds, infidelity is measured through DNA testing of off spring.  Divorce is measured by how birds pair off.  When two birds are paired one year but seek a new partner the next, they are considered divorced.

Dr. Botero found that promiscuity increases when weather changes, because birds seek different traits in their mates as conditions change.

For instance, in a climate where rain is abundant and there many fruits, birds might rely on small, soft seeds for food.  In this case, a female might be attracted to a male with a short, narrow bill capable of easily eating these seeds.

But if conditions turn dry and only hard seeds are available, a bird with a stronger, bigger beak might be more capable – and more alluring as a mate.

The researchers believe that as the climate changes, birds may be reckoning with increased marital strife

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The recent mild temperatures make it seem more like spring than mid-winter.  One of my traditional spring cleaning chores is cleaning out the bird house.  I remove last year’s nest and clean the inside with a diluted solution of bleach or ammonia.

That has been the classic cleaning recommendation for as long as I can remember.  There is a concern that some of the nest parasites might survive the winter cold and could, then, prey on this year’s vulnerable nestlings.  And there haven’t been many nights cold enough to kill all parasites. 

However, in recent years some ornithologists have begun to question the need for the traditional spring cleaning.  Those birds that use bird houses (less 10% of all species will) are known as cavity nesters.  In the wild they might build their nest in an old woodpecker hole, a rotten tree trunk or any natural cavity.

Our man-made bird houses emulate these natural cavities.  Who, the scientists now ask, cleans out those natural cavities every year.  No one.  And the birds have been using them for eons and seem to do just fine without spring cleaning.  So maybe it isn’t necessary.

Me?  I am still a traditionalist and will do the spring chore.  Just to be sure the young will live to come back again next year.

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Spring is coming

Today I heard the first reports of Red-winged Blackbirds for the year.  They are always one of the earliest migrants to return from down south.  But mid-February seem exceptionally early.  Maybe it is the mild weather.

Male Red-wings return before the females, often 3-4 weeks before the females show up.  They act like a bunch of teen-aged boys they have nothing to do so they just hang around in large groups and eat a lot.  Often they will join with a similar group of male grackles and starlings creating huge mobs of black birds.  Numbers can be as high as hundreds of birds. 

If a group arrives in your yard, they will empty your bird feeder in no time at all.   They are insatiable.  They will devour all your seed leaving nothing for the “pretty” birds.  Fortunately there is one way you can stop them from eating all your seed and let the others eat.  Fill your feeder with Safflower Seed.  Blackbirds don’t like, but all the other birds do, cardinal, chickadees, finches.  You can still attract the colorful birds while avoid all the blackbirds.

In a few weeks the large flocks of male blackbirds begin to disperse as individual males select and begin to defend a nesting territory waiting the females to return for the south.   Walk near the appropriate marshy areas and you will hear the males pouting out their song hoping to attract a mate.  They flaunt their red wing patches like headlight trying to lure in a passing female. 

Then you know that spring has truly begun.  Love is in the air.  Flowers will soon appear.

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The Great Backyard Bird Count(GBBC), which runs over President’s Day Weekend, Friday Feb 17 to Monday Feb 20,  is a great way to learn about and enjoy your local birds, engage with family and friends, and join thousands across the country in submitting observations to the GBBC database. 

Simply count any birds you observe in your backyard, local park or other location for just 15 minutes on one or more days between February 17 and 20, and report your findings online at http://birdcount.org. Learn more about participating in the GBBC at http://www.birdsource.org/gbbc/howto.html.

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Albino Birds

Albino birds are rare.  I’ve never seen one although I’ve seen many photos.  Once I did see a partial albino House Sparrow in a flock of sparrows at my feeder.  One bird, same size and shape as the others, had a white head.  It certainly was distinctive.

That is why I was amazed by these photos of an albino hummingbird.  The bird is said to be a Ruby-throated Hummingbird although I don’t know how they identified the species since no field marks are visible.  Photos were taken in Virginia so, based on location, it probably is a Ruby-throated.

I loved to see any albino bird, but seeing an albino hummingbird would be something special

  

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Not so Eagle-Eyed

I have read stories of eagles, particularly in the open spaces of the mountain west, being killed by flying into power lines.  But if eagles have such wonderful vision, why don’t they see the power lines and avoid them?

The explanation is that the power line appears as a pencil thin 2-dimensional line not as a 3-dimensional object.  It is almost like looking thru a picture window than has a single strand of a spider web in one corner.   You never focus on the thin strand.  Instead, you easily disregard it as you gaze at the vast panorama image until it is too late.  In the wide open spaces of the west a tiny line is easily overlooked.

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At the EagleFest children often ask about how well can an eagle see.

The terms “eagle-eye” or “hawk-eye” are often used to describe exceptional vision.  There is much truth (and science) to the belief that raptors have much better vision than humans.  A red-tailed hawk is said to be able to spot a mouse at a distance of one-half mile or more.  I can’t do that, even with binoculars.

All birds have good vision.  They have to in order to survive.  Birds do not have a good sense of smell, so they must rely on sight to find food and to spot a potential predator or other dangers.  Not only are their eyes large compared to their overall body size they have greater image gathering ability.

It’s impossible to know for sure what the world looks like to an eagle, but we know from studying the anatomy of their eyes that their view must be enlarged and magnified compared to our view. Eagle eyes are the same size (weight) as human eyes (though a full grown adult Bald Eagle weighs no more than about 14 pounds!) But an eagle eye has a much different shape from ours. The back is flatter and larger than the back of our eye, giving an eagle a much larger image than we can see. And its retina has many more concentrated rod and cone cells-the cells that send sight information to the brain. Some animals, including humans, have a special area on their retina called the fovea where there is an enormous concentration of these vision cells. In a human, the fovea has 200,000 cones per millimeter, giving us wonderful vision. In the central fovea of an eagle there are about a MILLION cones per millimeter. That’s about the same number of visual cells jammed into a square millimeter as the finest computer monitor has on its entire screen when set at its highest resolution. 

 

While there is no official eye exam for birds, they do have superior vision to human.  When you go birding, you can be sure that they will see you before you see them.

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Only one real surprise at the EagleFest.  The mild weather attracted a lot of people on Saturday (about 4,000 attendees)  However, it also kept many eagles farther north.   Last year there were about 110 Bald Eagles between Croton Point Park and the Bear Mountain Bridge.   This year, maybe 20-25.  

I was the trip leader for the first BirdWalk of the EagleFest and we were fortunate to spot two Bald Eagles.  The mid-morning walk was most productive yielding 8 Bald Eagles, 1 N. Harrier and a handful of E. Bluebirds.

My biggest surprise of the day was the following explanation as to how Croton Point was the birthplace of the modern field guide. 

In 1931 Roger Tory Peterson, who was studying art in New York City, was an active member of the Bronx Bird Club.  The club made a field trip to Croton Point.  During their trip Roger identified a flock of Pippits as they flew overhead.  That greatly impressed another member of the club, Bill Vogt, who asked “How did you know what they were?”  In those days birders still identified most birds by shotgun, shooting them and then examining them closely while holding their dead bodies.  Roger explained his technique of looking for key field marks as a good way to ID birds without shooting them.  Vogt, who was a successful drama critic and novelist, was amazed and encouraged Peterson to put his technique into book form.  “I can get it published for you” he told Roger.

Peterson went to work and three years later the first modern Field Guide to Birds was ready.  Vogt had to contact several publishers before Houghton-Mifflin agreed to publish the book.  You have to remember that 1934 was the height of the great depression so publishing any book was a risk.   Amazingly, the first press run of 2,000 copies sold out in less than a week.  Additional copies were printed immediately and Peterson Field Guide to Birds has been continuously in print ever since (almost 70 years), selling millions of copies.   The price of the first edition was $2.75.  I checked the internet and found you can still buy a copy for $600-$700.

And, if you believe this version, the idea for the first modern field guide, the guide credited with making birding accessible to the general public, was first hatched at Croton Point Park.

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