On Osprey Time

Water temperature in Cayuga Lake in the winter, modified from geoearth.com.  The wind has been howling all day across the lake and snow squalls shrouded us in  snow up until a half-hour ago. As the sky clears, the east shore slowly comes into view.  What is it like living in the depths below Cayuga’s cold and stormy surface?  At the beginning of winter water temperatures in Cayuga Lake are a uniform 39ºF.  Plunging temperatures and winds chill the water surface until it is 32ºF causing it to freeze. Ice is about 9% less dense than water—one of water’s stranger properties— causing the ice to float. These thermal stratifications or layers remain throughout the  winter. If water were most dense as a solid, lakes would freeze from the bottom up,  eventually freezing solid. In that case, little or nothing would survive in the lake. Winter  stratification persists because ice and snow cover prevents blowing winds from mixing  the water and acts to ...

How do animals like Ospreys navigate during long migrations? Studies suggest that most, if not all, rely on redundant location systems and orient using one or more of the following: the sun, celestial patterns, Earth’s magnetic field, olfactory maps, weather patterns, surface topography, ocean wave patterns, and low-frequency acoustics. Although advances in animal tracking, meteorological monitoring, magnetic modeling,  and computer processing have helped us understand, conflicting interpretations and the complexity of studying animal movements have left the mechanisms of animal navigation an enduring mystery of biology.  Young Osprey on spring migration, courtesy of Dana Nesiti.  Imagine how grueling and improbable it is for a juvenile Osprey to cross the Caribbean on their way to South America—a continuous 1,800 mile overwater flight during both  day and night in the absence of visual landmarks, stop-over locations, and foraging  habitats. Ospreys are diurnal...

Arrows indicate fall migration, reverse the arrows for the spring migration, courtesy of RSP.  The global range of Ospreys is impressive, with representatives found around the  world except for in Antarctica. Although non-migratory Osprey populations occur in  Australia, the Caribbean, and the southern US, most Ospreys breed in the northern  hemisphere and fly south to over-winter. These 2,000–4,000 mile journeys are difficult  and dangerous; evolution would only tolerate such risky behavior if there was a  considerable upside.   On migration, Ospreys can fly over 250 miles in one day in fair weather. In North  America, Ospreys travel as far as Central and South America and winter as far south as  Argentina ( see map below ). Osprey breeding throughout Europe and Scandinavia overwinter in West African countries like Senegal and Gambia where the climate is pleasant and fish are plentiful. Eastern European and some Russian Ospreys migrate...