Blog #309 Orpheus Does the Hanky Panky

 Pair at the Inlet nest, courtesy of Cindy and Karel Sedlacek. 

The rule of thumb is that Ospreys are monogamous. Their fidelity to their nest site is  absolute and their commitment to their mate endures a lifetime. The biological  imperative to nest—to build a home near their natal grounds—is written deep in their  genetic code and vital to their reproductive success. However, on rare occasions the  cards will get shuffled, and a male will attempt polygyny—breeding with two females. 

Trio on the Salt Point nest. L-R Orpheus, Ophelia, and Madame O.

Is that what is going on at Salt Point? Has Orpheus taken a second female? If he has,  he’s entered into a rare sexual relationship. Polygyny (from the Neo-Greek poly- means  "many", and gyne means "woman" or "wife") is a mating system where one male mates  with several females in a breeding season. This type of mating is seen in lions, deer,  some primates, some birds, and many systems where there is a dominant alpha male.  

Courting Osprey in tandem flight, courtesy of Karel and Cindy Sedlacek. 

This is the second time that Orpheus has showed polygynous leanings (see Blog #69  Two Nests, Two Females, and Two-timing). In mid-April, 2015, while Ophelia was busy  tending to her nest, a second female—I’ll call her Madame O—arrived in the area taking  great interest in the new Salmon Creek Osprey platform. Since the trees had no leaves,  Orpheus was able to watch both platforms from a cottonwood on the Myers Park side of  the creek. Orpheus remained attentive to Ophelia, but guarded both nest sites. Madame  O put a few sticks in the Salmon Creek nest as did Orpheus, but he transferred some of  her sticks to the Salt Point nest. On several occasions, Orpheus was seen flying around  his primary nest platform with Madame O in tow. As anticipated from previous reports,  

Orpheus lost interest in the second nest once the trees leafed out and his ability to see  both nests ended. He went back to fishing solely for Ophelia and sharing incubation  duties with Ophelia. In polygynous relationships, the second nest always loses out, but the primary nest also suffers from the male’s lack of attention. 

Why does a monogamous species occasionally switch to polygyny? Why do secondary  females put up with mates that rarely feed them? It would be easy for male ospreys to  be polygynous if available nests were limited. Secondary females put up with polygyny  because the population dynamics limits their choices and hopes to become the primary  female. Secondary females stay around because they don’t want to risk losing their  nests, and those that wait patiently eventually takeover successfully when primary  females fail to breed or die. Polygyny is limited in most populations because it requires  special circumstances, namely an undefended nest nearby the primary nest.  

Ophelia’s begging for food is ignored by Orpheus. 

It can be hard to watch a male Osprey ignoring one of the females as she begs for food  while incubating. Ospreys are not being "bad" for engaging in polygamy. We should not  project anthropomorphic moralistic ideas upon these wild birds. The male is making  decisions about his own survival, and how much energy he has to provide for two  families.  

Then why did he start an affair? (Oops. There I go applying moral values.) Ornithologists think Ospreys are largely motivated by two instincts—to survive and to  reproduce—the same instincts that motivate humans. When an opportunity arises to  reproduce with a second female, some males will take advantage of it. Again, similar  behavior to that of humans. Polygyny is thought to become more likely when nests are  too close together. Having an empty, undefended nest nearby is too much of a  temptation to pass up. Normally, females would chase away another female, but if the 

male is allowing it, it sends a signal to his mate. Nature is probably filled with subtle  signals that humans neither perceive nor understand. We are learning as we go. 

Eyes to the sky!  

Candace 

Candace E. Cornell  

Friends of Salt Point & 

Cayuga Osprey Network  

Lansing, NY  

cec222@gmail.com 

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

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