Osprey Tales

Febuary 20, 2014

All bird feathers evolved from scales. In fact, birds still possess scales in the lower parts of their legs and feet. Feathers are the most complex structure found in present day vertebrates. They aid in flight, thermal insulation, waterproofing, and coloration.

There are two basic types of feathers:
1. Vaned feathers which cover the exterior of the body.
2. Down feathers which are underneath the vaned feathers.

Vaned feathers cover the whole body and give the bird its shape and color. They include both the flight feathers, and the tail feathers.
Down Feathers are smaller but lack the barbules and their accompanying hook-lets so they are not zipped together and do not look so neat. In fact they are soft and fluffy. They provide most of the insulation and are so good at this, that humans for years have collected the “down” from various birds to put into sleeping bags, pillows and quilts.

What is a Brood patch?

Brood patches are areas where the feathers fall out during or immediately prior to incubation of the eggs. These areas of bare skin on the bird’s abdomen are heavily infused with blood vessels and allow the incubating adult bird to transfer heat to the eggs, thus speeding up development of the embryo.

Brood patch on female pied flycatcher
Harriett’s friend agreed to show her Brood Patch. Name withheld

Although feathers are light, an osprey’s plumage weighs more than its skeleton. The bones of an osprey are hollow and contain air sacs. Color patterns serve as camouflage against predators looking for a meal, not to mention courtship displays. Ozzie remembers the Magenta streak in Angela’s brow. It was breathtaking. If Ozzie and Harriett hatch fledglings this year, you will be amazed with their coloration and camouflage.

In earlier post we discussed the evolution of birds. Birds branched off from reptilian dinosaurs in the late Cretaceous period, 100 to 200 million years before present. It is the presence of feathers that is unique to birds. Other animals can fly, other vertebrate animals have beaks or bills, other vertebrate animals lay eggs, but no other living animal has feathers. Every bird has feathers and everything that has feathers is a bird.

A typical contour feather.

Feathers have a basic form of a central hollow supporting shaft called a ‘rachis‘ and a number of fine side branches. These side branches have even finer sub-branches in contour feathers.

The side branches are called barbs and are linked together by a set of barbules and their hook-lets. Barbs have side branches of their own called barbules. The upper ones containing a series of hook-lets and the lower ones without hooks but slightly convex in form to catch the hook-lets of the barbules from the next barb along the shaft. This is perhaps best understood by examining this diagram.

The base of the feather – where there are no side branches – is called the quill and at the base of this is the hollow entrance that was used by blood veins to carry nutrients to the growing feather when it was alive.
The gripping effect of any one set of barbule hook-lets is not great, but like the threads that hold your clothes together the combined effect is sufficient to keep the feathers together. The overall presence of all these barbs and barbules together is called the vane of the wing. The rachis and the vane are the two parts of the feather you see with the naked eye.

Take a moment to examine the structure. Amazing? Yes. Now remember the osprey has voluntary and involuntary control of each and every muscle group that contain these feathers.

“Hope is the thing with feathers that perches in the soul – and sings the tunes without the words – and never stops at all”.
Emily Dickinson

The next post will require a one year leap in time. The entire year of 2013 must be left to future storytelling, since the homeward migration has begun in South America. I will certainly try to fill you in this summer if the action gets slow.

Thanks for reading,

The Doctor

Ozzie and Harriett reached sexual maturity in three years. Some ospreys take longer, but of course Ozzie did not.

The spring and summer of 2010 (Age 3 months – 18 months); was spent at Lake Maracaibo.

Their second breeding season, the spring and summer of 2011 (Age 20 months – 2 years); was spent on The Red Channel Marker, in the North River of Carteret County. Harriett wanted to go back to the Chesapeake Bay area, but it is the male who chooses the nesting site, and Ozzie choose Carteret County. The spring and summer of 2011 was The Summer of Fun.

The Summer of Fun was remarkable for:

– Migration home was easy that year.
– Ozzie and Harriett are head over heals in love with each other.
– They build a very nice nest for themselves on The Red Channel Marker.
– Harriett becomes an expert homemaker.
– Ozzie becomes an expert fisherman.
– Ozzie becomes poetic and recites a beautiful poem to Harriett.
– No eggs were laid, no chicks were born. It was not a nest failure, but a time of maturing love.

The spring and summer of 2012 (age 3 – 4 years); was different.

Ozzie’s return to the The Red Channel Marker was the most memorable and life altering experience of his life. Some birds, in retrospect, recall difficult, overwhelmingly painful times in their past, with nostalgia, and think of them as learning experiences. But what was about to come down in Ozzie’s life, can in no way be remembered as beneficial.

To be continued……………

    1.  Ospreys are birds of prey, whose diet is almost exclusively fish.

            There is no better fisherman on planet earth than the osprey.

2. The osprey is a raptor. Those of us from generation JurassicPark can’t help but think of the terrifying dinosaurs called Velociraptor.

3. Osprey mate for life.

4. The female is slightly larger that the male.  She wears a necklace.

5. North American ospreys migrate to South America every fall to “winter” for the season.  The mates take “separate vacations”.  They use the magnetic fields of the earth to navigate.

6. Ospreys have incredible eyesight. They can see eight times better than humans.  Ospreys are hunters, they must be able to see their prey, sometimes from great distances, and calculate just the right moment to strike. In fact, an osprey can spot a medium-sized flounder from at least one mile away.

7. A skein is the symmetric V-shaped flight formation of migratory birds. The V formation greatly boosts the efficiency and range of flying birds, particularly over long migratory routes.

8. Osprey pairs usually return to the same nest site year after year, and add new nest materials to the old nest each year.

9. The Osprey tolerates a wide variety of habitats, nesting in any location near a body of water providing an adequate food supply. It is found on all continents except Antarctica, although in South America it occurs only as a non-breeding migrant.

10. Human habitat is sometimes an aid to the osprey. The birds happily build large stick-and-sod nests on telephone poles, channel markers, and other such locations. Artificial nesting platforms are common in areas where preservationists are working to reestablish the birds.

11. North American osprey populations became endangered in the 1950s due to chemical pollutants such as DDT, which thinned their eggshells and hampered reproduction. Ospreys have rebounded significantly in recent decades, though they remain scarce in some locales.