Hog Island Ospreys Rachel and Steve are protecting their three eggs in their love nest high above Muscongas Bay. To share more about our feather friends, Osprey expert Dr. Rob Bierregaard answers a few of your raptor-related questions!
Q. Can you talk about Rachel’s vocalization? There seems to be an: “I’m hungry call!” But what about, “I love you!”
Rachel’s vocalizations to her mate are about hunger and those to other ospreys are aggression. I don’t believe love comes into it.
Q. One of the male ospreys around earlier had a relatively light plumage. It looked quite mottled as well. Does plumage color change occasionally during the molt?
That very light bird was one who was not molting properly. The feathers were bleached out. Remember that Ospreys are out in the sun all day long! Most birds molt all their body, or contour feathers every year, and most small birds molt all their flight feathers every year. Some large birds, like Ospreys take more than a year to replace all their flight feathers (wing and tail). That light bird was several years into such a process and not keeping up with the wear and tear.
Q. How long does the process of molting take for male (during the winter in South America) and the female (during summer in the north)?
Both sexes of Ospreys will start to molt probably late in the nesting cycle. They may delay the molt during migration and complete it down on their wintering grounds. I don’t think there’s a big difference between males and females.
Q. Do osprey only mate in their nests?
No, they will copulate around the nest on favorite perches perhaps. But it’s easiest on the nest.
Q. How common is it that all chicks would die in a nest?
It’s rare but not unprecedented. On Martha’s Vineyard we usually have about 25% of the nests fail each year. Even if fish are being brought in, it may not be enough. Hard to call that one from a distance. Pollution or disease might be a factor.
Q. Have you tracked any mating osprey and if so what new information have you learned? What is the furthest you have seen an osprey go to find fish?
We have tagged a number of adults and found lots of interesting info. We have a male in the Chesapeake Bay that is flying 40 miles each way (!) to fish up in Salisbury ME. This is “Quin” if you go on my website (www.ospreytrax.com). That’s pretty extreme. Bob Kennedy tagged a male Osprey in Jamaica Bay that spent almost the entire breeding season in the Bay, which is a very small area. 10 miles is no big deal for Ospreys to go to fish.
Q. In a hard winter like this past one is there a particular deterrent to delay osprey return? The difficultly in fishing might, but would cold or any other factor play a part?
The Ospreys don’t know what kind of winter we’ve had. They just show up when they normally do. Sometimes they may retreat back south if they find everything frozen over. But this year it seemed at least some of the hard core birds in southern New England showed up and toughed it out.
Stay tuned for another Q&A, and read more of Dr. B’s recent insights into ospreys here.