Friday, November 6, 2015

For the birds...

Some of the photos are mine and some are borrowed... all are common bay area species...
Everybody knows this one...
Judy and I are not serious bird people - we like birds - but have never taken the time to seriously learn the names of many different species.  But we decided to set up a simple platform bird feeder out the back window.  All kinds of "generic  birds" showed up and after a while we learned to distinguish White Crown Sparrows from English Sparrows, Towies, Doves, Scrub jays (they are easy) Robins, Crows, Mocking birds, and many more.  Last year we were invaded by Band tailed pigeons for a time - but they have long gone. In mid winter we get bands of opertunistic migrants - like Cedar wax wings ... they linger for a while then move on...

As we walk the pups we see a great variety of water birds, egrets, herons, ducks, geese, avocets...also hawks, owls ( late), flickers, wood peckers, vultures, and. and pelicans.

In our mountain adventures we see still a wider variety...

Mourning dove
Next we put up a net sock filled with finch food - and we started getting a whole bunch of Lesser Goldfinches (they may be 'lesser' but they have interesting behavior and color non the less).  We also put up a couple of humming bird feeders - but instead of nice gentle little humming birds we have wild aggressive ones that don’t play well with others - they dive bomb and act in a very unfriendly manner.

English sparrow

Michelangelo had a great interest in observing birds in flight -but even though he attempted to learn from flying birds his flying machine never got it right. Now we know that on the down stroke of a bird wing two things happen - there is a forward thrust through the air (like a swimming motion). 

Rosy Finches
And due to the shape of the wing, the air that travels above the wing is made to produce lower pressure and the air flowing under the wing creates a higher pressure - and lift occurs.  Next time you see a seagull in flight see if you can notice the active thrust process - then when it is gliding the air moving differently above and below creates the lift to keep them in flight.

Band tailed pigeons

I am also amazed by the breathing system of birds - they can both inhale and exhale at the same time!  They have no diaphragm like us but have air sacs.  Muscles in the chest cause the sternum to be pushed out - making a negative pressure in the air sacs, so air enters from outside. Other muscles push the expired air out by a different route .. Air flows in only one direction through the bird lungs - and as a result they can inhale and exhale in one continuous process, more efficiently than mammals.

Towee - they hunt seeds as a mated pair - cheeping to each other

Birds of course do not have teeth - (Scarce as hens teeth) ...They swallow seeds, bugs, and worms whole... and they go to a two chambered gizzard, which precedes the stomach.  The bird picks up small stones or for small birds tiny pebbles that physically help to break down the food. 
Lesser Gold Finches
Strong digest enzymes are present here - and as the food is ground around by the strong muscular action, these enzymes aide in chemically  breaking down the food.  My first lessons in anatomy took place as I observed my mother clean fresh killed chickens - removing the gizzard, cutting it open, and washing out the stones inside.  I liked eating the tough cooked gizzards.
But why so many different varieties of birds?  The business of forming a new species requires a great many generations.  A bird population does not 'decide' to separate into new groups.  Something causes a separation to occur - a new formed wide river, emergence of a great ice flow, rising mountain range... Now the isolated groups face somewhat different conditions and what it takes to be successful and to survive will vary...

California  scrub Jay

Those organisms in each setting best suited to survival will do so - those not so fit will die out ... there is no decision on the part of the bird population to change.  Adapting to different food sources, different predators, different climates determine who is best suited and who not... after time the two groups are no longer even able to breed together - they have become distinct species with different size, color, diet...

Then there are the fascinating similarities between dinosaurs and birds.  As the world collection of dinosaur fossils grows, more and more can be learned about their bones, tissues, eggs, and even life style can be surmised.  As I observe a Canada goose I can well imagine that I am looking at a modern day descendant of a dinosaur.  The similarities are amazing:

White crown sparrow

1.  Dinosaurs have been found with birdlike eggs inside
2.  Feathers
3.  feet structures
4.  Wish bones structures
5.  similar breathing systems
6.  Similar scaly skin
7.  Similar protein composition
8.  Growing evidence that some dinosaurs were warm blooded
9.  Protective care of nest with eggs

Fossil reptile with feathers, beak, and bird like bones and feet

It has been a common put down to call some one a bird brain - but on going research has found that the brains of birds are capable of amazing processes... While there are species differences, birds are capable of solving abstract problems, memorizing many different song patterns, recognizing people and places, mimicking speech patterns of humans... and much more... The greatest discovery is to realize that bird brains are 'set up' differently than mammal brains and unexpected regions have unanticipated functions.

Suggested references: Scroll down to see individual species

My favorite:,4/