Blog #364 Why Ospreys are Colonizing Cayuga Lake

Osprey diving, compilation courtesy of bored panda [not original author]. 

Why Nest Around Cayuga? 

The rapid Osprey population expansion in the Greater Cayuga Lake Basin is probably  driven by three factors: ample fish, accessible fisheries, and abundant safe nesting  substrates surrounding the lake and refuge. Cayuga Lake has over 110 species of fish  and is stocked annually with high-protein sportfish like lake trout, brown trout, rainbow  trout, 

Osprey plunging into the water to catch a fish, courtesy of vit.org. 

Fully submerged Osprey rising with fish in talons, courtesy of YouTube. Ospreys can dive to 3 feet deep. 

and Atlantic salmon. The lake offers Osprey favorites such as largemouth and  smallmouth bass, brown bullheads, yellow perch, white suckers, carp, and various  sunfish. However, what good is having ample fish if you can’t catch them? 

When fishing, Ospreys have a success rate 70 percent, courtesy of Steven Bloom. 

Ospreys are keen fishers but can only dive underwater to 3 feet because of their  buoyancy. They fish everywhere they see a fish, but primarily feed in the weedy,  nearshore littoral zones of the lake home to young fish of many species. The north end  of Cayuga near MNWR has 5,800 acres of prime habitat that is 6 feet or less deep. On  the lake’s south end, a much smaller shelf extends northward from Ithaca for 0.25 mile.  Shallow 

Ospreys fish in the shallow Litoral zone and at the top of the Limnetic zones, map adapted from NOA. 

areas at the mouths of Cayuga's major tributaries, such as Taughannock and Salmon  Creeks, form limited, but important littoral zones for Osprey to fish. 

Osprey nesting pair on a dedicated nest platform, courtesy of Ann Murray. 

Traditionally, Ospreys nest in massive, strong trees near water that can support the  weight of a half-ton nest or on islands without predators. Most Ospreys in the  Adirondack Mountains nest on trees. However, suitable trees no longer exist elsewhere  because of the spread of human development. Ospreys adapted by nesting on  substrates like double-buck utility poles, pylons, communication towers, grain elevators,  athletic lights, channel markers, water towers, abandoned chimneys, and whatever else  they find. In just fifty years, the US Osprey population has changed its nesting  preference to these more stable substrates. No nests around Cayuga have been found  in trees despite the existence of a few appropriate flat-topped white pines around the  lake.  

The primary limiting factor for why Cayuga was colonized before the other Finger Lakes seems to be nesting substrates. Ospreys will nest on anything tall that is in the open to  guard against aerial ambushing predators. Lakeside communities around Cayuga use  double-buck utility poles to carry electricity to its customers. Due to different equipment  

requirements, the roads circling the other Finger Lakes have primarily far less desirable  single-armed poles. Excluding the nests at the Grenidge powerplant, most nests around  Seneca Lake and the other Finger Lakes are on cell towers. 

Nest on double-armed utility pole with a riser in Union Springs, NY. 

The expanding Osprey population in the greater Cayuga basin has witnessed explosive growth due to a number of favorable natural and human factors. The structural features  of Cayuga Lake including ample shallow shelves offering a plentiful food supply was  critical. One should not, however, overlook fortuitous human contributions. Over the last  20 years, NYSEG has erected dozens of dedicated Osprey platforms to welcome new  breeding pairs to the area. NYSEG also puts potentially hazardous nests on risers  elevating them safely above the live wires. Unfortunately, NYSEG’s aggressive pro Osprey efforts have been stalled by COVID restrictions and a heavy work schedule. 

What About the Future? 

Ospreys are extremely adaptable birds that will likely thrive despite predicted climate  changes provided they find adequate fish. Now they colonize the Finger Lakes, possibly for the first time. Osprey are considered a sentinel species used to detect environmental stress in aquatic ecosystems such as chemical contaminants dangerous to humans.

Maps showing the dramatic increase in the Osprey population in the Greater Cayuga Lake Basin  from 1999 until the present. The first Osprey nest in the area was built in 1979. 

These magnificent “fish hawks," once persecuted by hunters and tourists, have now  captured the hearts of residents and visitors to Cayuga Lake, who support their  conservation and protection. 

Eyes to the sky! 

Candace 

Candace E. Cornell 

Friends ofSaltPoint 

Lansing, NY 

Cayuga Lake Osprey Network 

NY cec222@gmail.com 

My thanks to Osprey scouts Fritzie Blizzard, Becky Sewell, Fred Bertram, Cindy and Karel Sedlacek, my  supportive husband Dave Collum, my mentor Alan Poole, and NYSEG’s Paul Paradine and crew for all 

their help. I especially appreciate the many birders who send me reports on Osprey sightings and nest  locations.