Nestlings and News

Good morning from the grey and wet Eastern Shore!  Tropical Depression Andrea has come and gone, with no damage to our surroundings or our ospreys.  Although there was not much wind associated with Andrea, we received 4.5 inches (11 centimeters) of rain at our home. Our viewers will be very happy to know we weathered this first storm of the hurricane season with no ill effects. The really good news is that Chick #3 seems to be holding his/her own, and had a good meal this morning thanks to his perseverance, lots of fish from Tom and careful attention from Audrey.

We have been observing a very busy Tom all morning, who has been incredibly busy trying to obtain nesting materials from his surroundings.  Our next door neighbor has a few scraggly-looking trees, and Tom has been trying to snatch dead branches right off of them while in flight.  He has only been successful some of the time, but keeps trying.  Mr. Crazy Osprey Man has a ready supply of prefab osprey building materials, and will put some out this afternoon.  He will attach some construction tape to the sticks so we can track their use in the nest if Tom decides to use them.

Now to answer a couple of questions and comments from the Conservancy’s Facebook page:

One June 4, Anthony Nelson made a comment regarding some commotion at the nest, an angry-looking Audrey and a large shadow passing over the nest.  Well, Mrs. Crazy Osprey Man happened to be home from work, and observed the incident in question.  There was an osprey interloper in the area, and it was attempting to land in our nest during Audrey’s watch.  She raised the alarm, and quite vocally I might add.  The shadow that Mr. Nelson saw was cast by the unwanted visitor, that’s how close he was to the nest.  Tom was in the area, heard the alarm, and raced to the scene.  A chase ensued, and for a short time, Tom and the interloper engaged in a spectacular aerial display.  The offending osprey decided he really didn’t want to visit anymore, and off he flew.

If you have been watching the camera, we are sure you have seen Audrey shading the chicks by holding out her wings to provide protection from the elements.  This behavior occurs very frequently, and you will observe the adults doing this throughout the summer.

We have had a fair amount of contact with Dr. Spitzer in the past several days for a variety of reasons.  He has advised that at this point, the 4th egg will not hatch.  The adults are very busy taking care of the young ones, and egg incubation has gone by the wayside.  So we will still try to observe the last unhatched egg, and see if we can determine what actually happens to it.  If you notice anything regarding the egg, please post a comment on Facebook for all to see.

Dr. Spitzer has provided one of his wonderful essays about osprey behavior.  Here is a very interesting one for your reading pleasure that answers some of the questions and addresses some of the comments on Facebook:

 Chapter #4:  The Nestlings

 Of course they hatch very small and helpless, and it is hard to imagine that eight weeks later this will be a flying osprey.  Such are the miracles of life.

 Hatching time (thus laying time and subsequent nestling age) is closely tied to local Chesapeake climates.  The first eggs are laid in the very sheltered upper ends of great tidal rivers, near places like Denton, MD (Choptank), Seaford, DE (Nanticoke), and Tappahannock, VA (Rappahannock), which are also warmed early by the surrounding land mass.  Laying at these sites can be as early as the first week of April.  The last nests to lay and hatch are those out on the completely exposed Smith Island marshes in the lower Bay, the Martin National Wildlife Refuge colony of about 40 nests on low poles.  Here most eggs are laid in late April, fully three weeks later, and there are no early “outlier” clutches.  Winter lingers on the Bay, water gains heat slowly.  Wind and storms sweep across these vast, exposed marshes, posing a thermoregulatory challenge to incubating female ospreys.  These same principles hold true for the famous (but currently struggling, food-limited) osprey colony on outermost Gardiners Is., NY.

 Hatchlings are covered with a fine, soft, beige down, and are incubated almost constantly by the female.  Her nest defense behavior when small young are present often becomes more attentive and aggressive; and she may be reluctant to fly.  The male now provisions both her and the young; and she presents small nestlings with appropriately small bits of fish (not regurgitation).  During their first week to ten days, nestlings will also beg food from a human visitor to the nest.

 At 10 to 12 days all this changes:  Nestlings grow a second heavy gray down and take on a rather reptilian appearance.  Now they lie still and play dead when you visit the nest, but their eyes–now bright red–remain open, shining vigorously with life.  For the next few weeks, you can see their lifted, bobbing heads from a distance with binoculars or telescope, but they drop them instantly in response to parental alarm calls.

 During week three the body feathers and wing feathers start to grow, emerging from nourishing blood-rich keratin sheaths known as “blood quills”.  From then on, nestlings look and act more like ospreys with every passing week, and acquire a juvenile photogenic charm.  Because there are lengthy intervals between fresh fish deliveries, they have a storage organ at the top of their digestive system called the “crop”.  After they are fed, this bulges in the lower neck and upper breast, gradually subsiding as food passes into their stomach.

 Hunting demand on the male gradually increases as the young grow, and this is demonstrated by the female’s frequent, repetitive food-begging call.  As you will hear, this can be quite an annoying, nagging call, and you may want to turn the volume way down on your computer.  Ospreys can be noisy neighbors….

 Why don’t the young fall out of the nest?  Parents usually maintain a lip on the nest.  But there is also tremendous natural selection for careful nest behavior; it must be genetically hard-wired, because there is no learning curve, no second chance.  Many years ago, when I was transporting nestlings from the Chesapeake to Gardiners Island nests for brood-size experiments, I found that a very shallow box on the back seat of my car was enough to confine them; with a rim of perhaps four inches—such is the life-saving constraint of this behavior.  However, by the time I reached NY the interior of my car appeared as if iced with a big pastry gun.  Unfortunately, this was osprey guano; not so delectable as icing.  Fortunately most of the guanoed surfaces were vinyl, saving me from my youthful whimsy.  This brings us to the question of nest hygeine:  The young back up to the nest rim, and squirt long white streams of liquid excrement over it.  (Will this be an issue with the Osprey Cam?)

 This guano is crystalline uric acid; nitrogenous wastes that are far more concentrated than mammalian urine.  Osprey nestlings cannot drink, so water conservation is absolutely essential, and all water comes from their fishy food.  They also have a salt excretory gland in their forehead:  Hypersaline solution is ducted to their nostrils, and then evaporates or drips off the bill tip.  These two adaptations of avian physiology have enabled seabirds to become abundant around the world; and numerous birds are also successful in desert environments.

 Still:  As summer comes on, osprey nestlings are living on top of a pedestal in the constant, unrelenting sun, with no chance for a drink.  Once they do fledge, they may roost in shade where available, and drink Bay water.  They finally get off that exposed nest, but for weeks it may remain the focus for feeding by the adults—the predictable rendezvous known to both generations.  Ospreys are good hunters around dawn and dusk, in crepuscular light, so I often see noisy feeding of fledgings very early and late on simmering July days.  Watch and listen for this, if the Osprey Cam nest is successful.

 That’s the way to use Osprey Cam:  Just leave the tab open on your computer.  You will hear calls when something interesting is happening.  Take a break, hit the tab, watch the action.

 Osprey Cam might also show us English sparrows in action.  We think they sometimes feed in the nest on small food fragments and insects, working as a sanitary crew.  We do know they nest commonly underneath ospreys’ big bulky stick nests, gaining predator protection and shade.  If these downstairs tenants also provide maid service, this is a true Symbiosis.  And more evidence that “The Universe Insists upon Life” (John Hay).

 Paul Spitzer

Windy Hill on the Choptank

May 22, 2013

Fabulous insights, Dr. Spitzer!  Thank you so much!  That’s it for now from the Eastern Shore.  Until next time, we remain,

Crazy Osprey Man and Mrs. Crazy Osprey Man

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