June 16, 2005
Osprey Observations
First a personal note: I'll be going on vacation to the Outer Banks of North Carolina from June 18-25. During that time, we will not have any Gallery updates or new Web Log posts, but please feel free to continue sending Gallery submissions and questions, as I'll be checking in occasionally. We'll get caught up completely when I return.
Also, our cam technician will be keeping a close eye on the equipment, but with one less person on duty, we might not be as speedy to notice a problem, so we ask for your patience if any technical glitches occur.
On Friday, we'll do a Gallery update, and we'll be posting some interesting photos we've received over the last few days. In one photo we could just make out the bulging crop on the little chick, showing it's well fed. Also we saw the female shading the young from the hot sun (the weather is finally cooling down on Thursday). And we saw one shot where it looked like the female came incredibly close to whitewashing the camera lens -- she really had it in her sights. :-)
Another photo worth highlighting is the shot to the right, which relates to a question we received from a cam watcher who wanted to know why the ospreys cock their heads while looking skyward.
As some might remember from the Eagle Cam Web Log, we mentioned that unlike humans, raptors have two foveae (or centers of focus) in each eye, and these two foveae let them see both forwards and to the side at the same time.
The deep fovea has a line of sight that points forwards and about 45 degrees to the left or right of the head axis, and the shallow fovea has a line of sight that points forward but only covers about 15 degrees to the left or right. Of the two centers of focus, the deep fovea has the higher acuity.
Raptors have large eyes for their headsize, and it limits their eyeball movement (check out this photo of an imitation osprey skull, which shows how much of the skull is taken up by the eye sockets). So when an osprey wants to get a good look at a distant airborne threat, it has to cock its head at an angle to expose the target to the deep fovea of its eye, which offers maximum keenness. Researchers have observed that the more distant the object, the more likely the raptor will spend time looking at it sideways.
The greatest threat to our cam ospreys is from the air, so when a bird passes overhead, the osprey parents normally want to have a good look at it to decide if it's friend or foe. A few years ago, the osprey parents got an eyeful as a bald eagle made a dive at the platform. People in the Visitor Center saw it from the observation window, and we got questions from cam watchers asking if the birds were all right as they looked highly agitated. Fortunately, the eagle left without making contact with the ospreys, but it showed that any parent on the platform is wise to closely examine objects overhead. So keep those eyes to the skies. :-)
See you after June 25,
Lisa - webmaster