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May 12, 2011: Food and Feathers

May 12, 2011: Food and Feathers

Credit: Bob Sallinger

by Bob Sallinger

kgw.com

Posted on May 12, 2011 at 8:40 PM

Updated Wednesday, Oct 30 at 7:56 AM

The hawks are now 20, 20 and 17 days old. The older nestlings are almost half way to their first flights! They are growing rapidly and the parents are bringing in food several times a day to keep them  well fed. You can now see their flight feathers and tail feathers beginning to emerge from under the down. At this stage they are called "blood feathers." They are still connected to the bird's circulatory system and are comprised of live cells. Up close they look like white tubes. The center of the tube is full of blood. They are soft and easy to break.  As they continue to grow the cells will die off and the feather shafts will become hard. The nestlings will preen these shafts with their beaks to remove a waxy sheath that covers the shaft and allow the rest of the feather to unfurl.

Watch Raptor Cam Live: KGW-Audubon Raptor Cam

More on Feathers: Cornell Lab of Ornithology

Note feathers emerging with yellow circle

 

Thanks to everybody who wrote in about what types of prey you have seen coming into the nest. So far the most common prey items have been city pigeons (rock doves) and rats. However, Red-tails actually eat a wide array of prey species. A compilation of 11 Red-tailed Hawk studies in the book, Hawks, Eagles and Owls of North America by Johnsgard showed that mammals average about 68% of their diet, birds averaged 17.5% of their diet and reptiles and amphibians (mostly snakes) averaged about 7% of their diet and invertebrates averaged about 3.2% (the remaining points are "other"). There is however significant variation from bird to bird and site to site. Based on what we are seeing with this pair it looks like the vast majority of their diet is city pigeon (rock dove) which which makes sense since they are super common in downtown Portland.

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