Local Osprey Building Nest by Jim Cruce
It has now been 26 days since the osprey returned from their long migration and many people are wondering when they are going to lay their first eggs. Typically this pair has laid their eggs during the last week of April so we may still be a few days away. They will have spend approximately a month preparing their nest and going through their courtship rituals. This morning the pair spent some time removing material from the nest . The mail was walking around while the female looked on picking up small branches and other materieas and tossing them over the side. He then copulated with the female and took off. Guess they felt the nest needs some redecorating. It is pretty amazing to see how meticulous they are about how things are placed in the nest---they don't just come in and drop the nest branch onto the pile--They are constantly placing and replacing materials. You can almost imagine them talking to one another saying "no honey that's not quite right, theat branch would really look better over on the other side of the nest next to the string and moss" Osprey Feng Shui!
Osprey will incorporate all kinds of stuff into their nest. Alan Poole in his book, Osprey: A Natural and Unnatural History notes a bunch of very interesting materials that have been found in osprey nests including rag dolls, hula hoops, rubber boots, an oilskin raincoat, a feather duster and a toy sailboat with its sail still intact.
One question we have received is how the murky water in the Willamette River might affect the osprey. The Willamette is running particularly high this year and the water is extremely cloudy. Osprey hunt almost exclusively for fish and the clarity of the water does indeed affect their ability to find their meals. They will hunt high above the water at heights ranging from 30 to more than 100 feet. When they observe a fish they will tuck their wings and plunge into the water after their prey. The more murkey the water the less successful their hunting is likely to be. Even factors such as cloud cover and surface rippling can impact osprey nesting success. The are many cases around the country where biogists have attributed osprey nest failures to local water conditions but it is very difficult to draw a direct causal relationship in these kinds of situations since there are so many different factors that can impact nesting success. The male has been bringing a regular supply of fish to the female at South Waterfront, but is is hard to tell at this point whether water conditions are significantly affecting their hunting success.