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I usually like to work a little wordplay into my titles, in hopes of catching the eye of casual readers.  But when the topic is Ospreys, no cleverness is necessary.  They are just plain cool.  And damn good looking.


Today a group of Bay Area Kossacks will welcome realalaskan and Mrs. realalaskan, and take them on a grand tour of Point Reyes and other bits of birdy West Marin.  Sure, it's beautiful.  But the real attraction (let's be honest here) is the Ospreys.  They probably love West Marin because it's beautiful, so it all works out.

So besides the looks factor, why are Osprey so cool?  Well, for one thing they're truly one of a kind.  Taxanomically, they stand alone.  Most the diurnal birds of prey out there - hawks, eagles, kites, harriers - are grouped together in the family Accipitridae; the falcons and caracaras are part of Falconidae.  And then there's the Osprey - the only species in the only genus in the family Pandionidae.  They're like the Bernie Sanders of raptors.


Like that other exceptionally cool raptor, the Peregrine Falcon, they are found on every continent except Antarctica.  They breed near water, using a large stick nest.  They will build their nests on trees and rock ledges, but will also use man-made structures like power poles, antennas and bridges.  (My husband is a broadcast engineer, and his trade magazines occasionally print articles on ospreys at transmitter sites.)  In many locations, nesting platforms designed specifically for osprey have been erected, and the birds use them readily.  

ospr m v f
Though there is some overlap, you can generally tell males from females by plumage; females have a darker breastband (or necklace), whereas males are clearbreasted or have a faint necklace.  Like many other raptors, Osprey females are larger than males.

Why would people build nesting platforms for Osprey?  (Aside from the fact that they're so cool that of course you want to encourage them to hang out.)  Well, they were one of the species hard hit by DDT; it built up in watersheds across the land, got into streams and lakes, concentrated in the fish, and affected all the birds who ate those fish.  Another problem is that Osprey like waterfront real estate, and so do people.  People tend to be much more disruptive when they move in, though.  And for a number of years, osprey were shot like so many other raptors.  Osprey populations crashed in the middle of the last century, but have rebounded pretty well over the past 20-30 years.

Ospreys are also built pretty cool.  A few years ago, I had the opportunity to prepare one as a study specimen which let me see some of its unique adaptations for fish hunting.  (The bird died at a rehab center where it had been taken after being found tangled in fishing line.  They cut most of the line off, but some of it had actually cut into the flesh on the bird's wing.  Heartbreaking.)  Most raptors talons look like the letter "D" in cross-section, rounded on the outside edge, but flat on the inside; Osprey have an oval cross-section shape.  I was told this helps puncture fish more easily.  Even more remarkable (to me, anyway) was the texture of their feet.  The soles of their feet are covered with spicules - little spikes - that feel like extra coarse sandpaper, and help them hold onto their slippery prey.


Their foot structure is very different than other raptors, with all the toes the same length; in other hawks, the rear talon is much larger, and the three forward facing toes are different lengths (with the center toe longest).  Even more unusual - unique among diurnal raptors - they can swing one of their front toes around to the back so that they have two front and two back talons, allowing them a more even grip on their fish.  

They spot fish by sight and make (generally) shallow dives to grab the fish in with their feet.  If the fish is larger, they will adjust it in flight so that it is facing forward and more aerodynamic.  They are capable of carrying fish that weigh almost as much as they do - the Cornell Lab website says the record observed capture was a 2.5 lb fish, pretty impressive considering that the birds weigh about 3.5 lbs.


They lift the fish from the water with assistance from crazy-long crazy-flexible wings.  This photo I took of an osprey chasing a redtail from its territory really shows the difference in wing shape well - something that can help you ID that distant bird.

ospr rtha_0117

Wish us luck today as we look for these magnificent birds (and all of their feathered cousins).  Maybe we can share a photo from the road.

Originally posted to lineatus on Sun Mar 17, 2013 at 06:00 AM PDT.

Also republished by Birds and Birdwatching.

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