Blog # 462 If You Build It, Will They Come?

A white-chested male balancing on limb, courtesy of Gary Seloff.

Having an Osprey nest platform right off your deck is rather heady stuff for hawk lovers, especially an Osprey aficionado like me. My husband and I went with the “if you build it, they will come” philosophy, erecting a 35-foot Osprey platform last fall just offshore in Cayuga Lake. The months passed slowly as the leaves dropped and winter white caps buffeted the empty nest platform.

Watching Ospreys requires patience I reminded myself. They are stubborn and exacting, demanding precise criteria for their nesting sites. The birds must have a clear view around their nests with no tall trees nearby to prevent nocturnal ambushes by great horned owls. Similarly, the poles should be wrapped in flashing to block nest access from climbing predatory snakes and racoons. Two perches arising from the nest box allow the adults to guard the nest when the nestlings take up much of the nest.

Seeding the new nest is crucial to success. We wired a half dozen sticks to the nest box wire floor to prevent them from blowing out in a storm. The sight of these sticks encourages unbred Ospreys to investigate the nest. Nests should be located where fish. are accessible in shallow areas although they will travel up to 12 miles for fish. Even

if the nest platform is ideally located (according to our point of view) it may take years to be claimed.

Pair return to their nest of many years, 2016 Osprey Nesting Survey PA eBird.

The first wave of Cayuga Lake’s resident Ospreys returned to their nests rather early, beginning in mid-March. By early April, a second wave of Ospreys—unbred mature adults and two-year old birds on their first spring migration—began to arrive. These unbred birds, referred to as “intruders” or “floaters,” refresh the colony by filling nest vacancies left by mates that did not return from spring migration. Intruders challenge breeding pairs, testing their resolve and strength of their bonds to their mates and nests.

Depending on their age, physical strength, and determination, intruders can overpower and expel a nest owner. Intruders repeatedly pester breeding pairs and, in extreme circumstances, can disrupt their breeding cycle entirely. It’s estimated that intruders make up about 30% of the entire population. A colony of 100 breeding individuals on 50 nest sites could have several dozen floaters.

Intruder attacking a nest with the female defending it, courtesy of Darren Dawson.

Spring arrived slowly with cold and rainy days throughout much of April. We completed the spring count of active nests for my annual nest survey in the Greater Cayuga Lake Basin. It was heartwarming to see so many Ospreys returned safely for another season. This year there are 165 available nesting sites, including ten unused platforms, with most sites already occupied and new nests still being built. Nonetheless, the nest box off our deck remained empty except for the half-dozen sticks wired to the box to “seed” the nest. All we could do was wait and hope that a pair of intruders would eventually claim it.

If a pair was to breed in the platform this year it had to be soon. It takes an average of 35–42 days to incubate eggs and another 60 days for the nestlings to grow and learn to fly. Fathers continue to feed the fledglings as they learn to fish for up to two months or until they migrate. Thus, eggs must be laid before mid-May to have any hope of developing. Time was running out for us to get an Osprey nest this breeding season.

Finally—finally! —on April 11 a male Osprey finally “claimed” the nest box. Triumph! we thought. Our spirits were high. Surely this handsome male with the crisp white breast will claim the nest and attract a female in no time. I eagerly checked our motion-activated camera recordings throughout the day to see what the male, temporarily nicknamed Opie, was doing. The answer was a little perplexing at first, but the inevitable outcome became obvious as the days passed.

“Opie,” the male Osprey who “claimed” our platform offshore in Cayuga Lake with a fish.

Opie would perch or sit in the nest box for only an hour or so a day before vanishing: no shows were common for him. Opie was not madly collecting sticks like the other male nesters on the lake. For him, nest building wasn’t even a part-time job instead of its true life-and-death significance. Occasionally, he brought fish to the nest to eat it.

Osprey pair flying as part of their courtship.

After thirteen days of lackluster advertising for a mate, a female arrived at the nest on the morning of April 23. My fingers were crossed for this match. The two birds

immediately courted, flying in pairs, and playfully chasing each other in the air. She frequently sat in the nest box, looking quite at home. After two hours of demonstrative courting, it came to a sudden end. When the female attempted to sit next to Opie in the nest box, he suddenly turned on her. Opie aggressively flopped on his back, flashing his talons at her, and screaming to drive her away. It was clear that this awkward male was not worth her more mature attentions, and she disappeared to find another potential nest.

Three weeks since his arrival, Opie continues to sit in the empty nest box or perch in the trees, hoping for another female…but still no luck. No young fillies sniffing around his barn. Why should they?

Contrary to other breeding males on Cayuga, Opie seems clueless. He makes no attempt to strut his stuff to entice a female: he hasn’t even built a rudimentary nest! This is likely a young, immature bird, freshly returned from his first spring migration and clearly in need of another season to mature. Chances are good we’ll see a nesting pair in our nest box next year.

Eyes to the sky!

Candace

Candace E. Cornell

Cayuga Lake Osprey Network

cec222@gmail.com

A black and white drawing of an eagle

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