April 26, 2004
Couple Dynamics & Weather
Nest Update: We currently have three eggs in the nest. Last year we also had three eggs, and two hatched. Hopefully, all three will produce young this year.
Pic of the Week: Norman Porter was the first watcher to send in a pic of the third egg, so he has our Pic of the Week. Also, be sure to visit the gallery where we've added new pics of the eggs and nest activity. And much thanks to those who are sending in these wonderful shots.
Now that the couple have a family on the way, their nest behavior has changed. During the present egg stage, both parents will spend time sitting on the eggs, although the female will do it most often. While the female sits on the eggs, the male will do the hunting for both of them, often bringing a headless fish to the nest for her to eat (he eats the head).
On April 22 (Earth Day), we saw this sequence play out. The female had taken a break from sitting on the eggs. The male came back to the nest with a headless fish in his talons. He left the fish on the side of the nest, where the female retrieved it and took it out of view to eat (probably to a nearby perch). The male then took her place on the eggs.
Osprey expert Alan Poole has noted that individual male ospreys show great variation in how much time they spend incubating; for example, male ospreys in Scotland spend as little as 20% of their time on the eggs, while male ospreys in New England spend as much as 66% of their time on the eggs. Poole has observed that the males who incubate less do not deliver more food nor do they spend more time hunting -- they just hang out and perch more than the dutiful males.
Once the eggs hatch at the cam nest, the female will rarely leave the nest, and the male will have to hunt for the entire family, which will keep him busy if all three eggs produce young.
In the osprey world, one of the most crucial factors affecting nest productivity is the weather. Storms can reduce the osprey's foraging success by making fishing more difficult. Alan Poole has noted that high winds, rippling water, extended cloud cover, and long periods of cold rain can affect the male's ability to catch fish, causing chicks to starve or females to abandon their nests.
Last year Blackwater Refuge experienced a cold, wet spring, which lowered production on the 30 artificial nest structures at the Refuge. In 2002, the nest structures yielded 70 fledglings, while in 2003 the number was down to 42. The Blackwater biologists also noted that the 2003 season had one of the highest rates of renesting (starting over) due to lack of first-nest success. Fortunately, the cam nest had a good year in 2003, producing two young after seeing only one chick in both the 2001 and 2002 seasons.
Until next time,
Lisa - webmaster (contact)
Submitted by Norman Porter