Spring is here and ospreys have returned to raise a family near the water. When the birds first arrive, they often looked exhausted. For good reason, migration isn’t easy.
Ospreys travel as individuals, not in flocks, from wintering grounds in the tropics. A 2014 study published by Mark S. Martell and others in the Journal of Raptor Research, shows that many of our east coast ospreys winter in South America with smaller amounts in Florida or in the Caribbean. As spring approaches, wintering ospreys in South America make a long distance journey past the Gulf of Venezuela and over the Caribbean Sea, a trip of between 400 and 700 miles, to briefly rest in Haiti, Jamaica, or Cuba. It’s a tiring flight that typically takes 27 to 40 hours and involves risky nighttime travel. Once across the Caribbean Sea, nearly all ospreys will cross Cuba to the Florida Keys and then northward to breeding grounds. An amazing journey that normally takes two to three weeks from start to finish.
Along the way, ospreys have many dangers. One is the weather, especially when crossing large bodies of water. Birds can be blown off course or get caught up in a severe thunderstorm. This drains fat and puts an osprey at risk of being too weak to continue. Another risk is an osprey getting shot. This happens when a hungry osprey tries to take a fish from a private or commercial fish farm in the Dominican Republic, Haiti or Cuba. Many poor farmers do not take kindly to someone, even a bird, “stealing” a fish.
If an osprey can survive the trip, its partner will hopefully be there to greet it, something that unfortunately doesn’t always occur, especially if one partner is late. A high probability exists that the first to arrive to the nest will be attracted to a new mate, since the need to breed is stronger than the instinct to wait for a partner that might not arrive. Although ospreys generally mate for life, it’s a bond that needs to be reinforced each spring.
Recent studies on migrating ospreys by the National Parks of New York Harbor Conservancy and Gateway National Recreation Area indicate that late returning ospreys frequently have clashes with ambitious new birds in the nest. Conflicts are usually short, as the bond between old mates is stronger than a newly formed pair, especially if the new mate is a young bird.
After a rapid decline in population from 1950 to 1980 due to the over-use of DDT, a toxic pesticide, osprey numbers are increasing throughout the United States. This is great news! Ospreys are top-level predators that feed mostly on fish, and a healthy population of top predators means the overall ecosystem is healthy to support the food chain. Are there things we can do now, however, to make sure their long winged migration isn’t so death-defying?