Blog # 312 Orpheus Sees Three Eggs

Female Osprey doing a belly dance, a behavior indicating great interest in a subject. 

The good news is Ophelia laid her third egg—an orangish beauty—on Saturday, April  24, and we are off to a good start for the breeding season. She and Orpheus are  keeping them safe and warm during incubation. Orpheus, has gotten more eager to  incubate over the years, which gives Ophelia needed breaks. Ophelia has laid three 

eggs every year since she and Orpheus began nesting on Salt Point in 2013.* The first  hatchling should appear around the May 24. 

Meanwhile, Orpheus’s ailing eye shows some improvement. He could clearly see his  three eggs in the nest today as he rolled and fussed with them. For the last two and a  half weeks Orpheus has been favoring his left eye keeping shut as if injured. This is  worrisome as Ospreys are visual hunters and his fishing prowess has not been up to  par lately. Fish deliveries for Ophelia arrive only once or twice a day instead of the usual  three times. The good news is that he does open it a little more now than before,  suggesting it might be healing. Now that there are three eggs in the nest, Orpheus will  have to step up his game. If he is not healed by the time the eggs hatch, will he be able  to provide for himself and his family? Don’t Ospreys see as we do, relying on binocular  vision to hunt? 

Binocular vision is the field of overlap between the right and left eye, courtesy of Scientific American. 

The first question is rhetorical: we’ll have to wait and see. The second question made  me think; what sort of sensory world does the Osprey live in and what behaviors do  these factors trigger during fishing. People are often tempted to think that since birds  and humans generally share a reliance upon visual information for many of their  interactions with the world, that they see the same things. Untrue. 

Most birds like Ospreys live and see another world, one with ultraviolet light, olfactory,  and magnetic and touch signals, temperature and pressure gradients, and other  sensory perceptions to navigate daily activities. Birds from different habitats need  different sensitivities of visual acuity. For example, double-crested cormorants living in  turbid water have poor eyesight. (There is no sense having superior receptors if there is  no light in the water.) Ospreys, on the other hand, live in clean environments and  consequently possess vision superior to ours: not only do they have 4 times the visual  acuity of humans, they also “see” in the ultraviolet and magnetoreception perceptions.

Eye placement on an Osprey-front facing sides like a white stork (below). 

As illustrated above and below, Eye placement and visual capabilities differs among  species and affords different visual capabilities in different species. Birds with eyes on  their sides have a very wide visual range where as it is more narrow in a front facing owl  and humans. Osprey eyes are frontward facing like the crane below, which is why they  frequently move their heads around. 

Visual field of a buzzard, human, and a white stork as determined by eye placement on head. 

After reading research papers on binocular vision in Ospreys, the news is sobering. Ospreys employ binocular vision during the last few seconds of the hunt before prey  seizure. It is instrumental in overcoming the defraction of water, an optical illusion of 

bending light rays, making things in water appear where they are not. Orpheus should  have no trouble doing most things, such as flying around, landing on a perch, bathing,  and eating, etc. However, he can’t hunt efficiently if he’s lost his binocular capacity.  Other Ospreys with eye injuries tend to blunder into a fish, but that’s not a sustainable fishing technique. Orpheus is skilled at catching brown bullheads in a murky Salmon  Creek after storms. He must use other sensory cues to detect their location, in the mud. Perhaps an air bubble is all that need to give the catfish away. 

In time, I believe we will find many more subtle differences in visual capacity in birds  that explain different behaviors in Ospreys and other birds. In short, there are many different ‘‘bird eye views’’; proceed generalizing with caution and always bear in mind that there is more to a bird’s world than meets your eyes.” 

Eyes to the sky!  

Candace 

Candace E. Cornell  

Friends of Salt Point & 

Cayuga Osprey Network  

Lansing, NY  

cec222@gmail.com 

*The pair did not reproduce in 2019 due to disturbances at the nest.

HELP PROTECT OSPREYS: 

• Keep a distance (100-300 feet) from active nests in the breeding season. If an  animal vocalizes when you are near, you are too close! BACK OFF IMMEDIATELY. • Carry binoculars to view wildlife from a distance. 

• Help keep local waters clean and healthy. Preserve and clean shorelines. • Recycle or dispose of used fishing line and other materials that can entangle  Ospreys and other aquatic animals.

• Volunteer to monitor Osprey nests with the Cayuga Osprey Network. Write to:  cec222@gmail.com.  

EYES ON OSPREYS 

WATCH! 

Salt Point Osprey Nest Cam 2021 

READ! 

On Osprey Time—a blog on the Ospreys of Salt Point 

VISIT! 

Cayuga Lake Osprey Trail