Friends of Smith Mountain Lake State Park
Monday, September 25, 2017

Osprey Watch 4

 

 

Two eggs have hatched!  The first chick came out of its shell on May10th.  The second chick arrived on May 11th, Mother’s Day.  Two more to go, hopefully.  The osprey chicks arrive weak, wet and helpless.  Down covers most of their bodies and their eyes open within a few hours of hatching.  At this point they begin to take food from their parents. The whole game now is survival of the fittest, or as some say, survival of the first.  The first born has a lead on the second born and a bigger lead on the chicks to follow.  This first born has been eating and getting stronger for a day before the second hatched. 

 

When the male brings a fish to the nest, he has already eaten the head .  He gives it to the female to tear up into bite size pieces, the oldest and strongest chick is able to push its way to the front of the line thus assuring it will get fed first.  The last born is the weakest and last to be fed.  If food is in short supply, there is a greater likelihood that the last born will not get enough food and therefore starve.  At Smith Mountain Lake, there is plenty of food and a good chance that all the chicks will get fed and grow to fledge.

Small broods demand less food than do large broods, and there is a significant loss of weight in adults, especially females, when too many chicks are begging for food.  Competition among chicks, and caution on the part of osprey parents, are the major reasons why ospreys don’t raise large broods in the manner of ducks or chickens.

The young osprey quickly develops a second coating of light down, usually about 10 days after hatching.  After about two weeks of age, feathers start to replace down.  Within 30 days, the ospreys will increase in size to about 75% of their adult body weight.  To achieve this rate of growth, the male usually spends 35% of his day foraging.  The fully grown osprey will weigh 2 ½ to 4 pounds with the female being the larger of the two birds. 

by Jim Gearhart
Friends of Smith Mountain Lake State Park