On Osprey Time

  A female juvenile on migration, courtesy of Cynthia Sedlacek. When the urge to migrate calls, overwhelming instincts steer each Osprey to fly south. This fall migration is primarily triggered by dwindling daylight hours and colder temperatures driving the Osprey’s prey— fresh and saltwater fish—to warmer, deeper, and inaccessible depths. Impending hunger drives the birds on these fantastic journeys. Ospreys are able to perform their remarkable long-distance migrations by alternating between two types of flight methods—gliding flight which is ultimately fueled by solar energy and energy-intensive flapping flight. These diurnal raptors begin their southward flights in the morning as the sun warms the cool night air forming thermals—rising columns  of buoyant air that transfers heat energy upwards.   Ospreys and other gliding birds catch thermal up-drafts close to the ground and ride the rising air currents hundreds of feet aloft. When they reach the peak, the birds soar forward and gli

  Map 1. World-wide autumnal migration patterns of Ospreys, courtesy of Roy Dennis. Where in the world are our Ospreys? Can we say that an Osprey breeding on Cayuga Lake is “our” Osprey or does that honor go to the South American country where they over-winter? Personally, I think the honor goes to their natal site, where the bird was born and returns to breed. Ospreys have a global distribution although many countries have only a few breeding pairs.  Ospreys are evolutionarily far removed from all other raptor species, and placed in their own family,  Pandionidae . The scientific name of the Osprey is  Pandion haliaetus.  There are four subspecies listed below: two are migratory and two are not. North American Osprey, courtesy of Birds of the World. •  North American Osprey,  Pandion haliaetus carolinensis ,  breeds from Alaska to Nova Scotia, south to the Great Lakes states, and along both coasts of the United States. In Minnesota, they are common on northern lakes and along the St.