Osprey Fall Migration

Osprey also called Fish Hawk or Sea Hawk

(Pandion haliaetus)

Late Summer and Autumn is Migration time for Ospreys!

Written by Joseph Reynolds, President of Save Coastal Wildlife

Fall is a restless time for many coastal animals along the Jersey Shore. They have an uncontrollable urge to move and migrate, traveling hundreds and sometimes thousands of miles, past hungry predators, strong winds, and stormy weather to get to the promised land - a place to call home for the during winter in the Northern Hemisphere, or that half of Earth which is located north of the Equator.

Numerous stories have been told of wild migrations for monarch butterflies, American eels, humpback whales, and striped bass. But ospreys or fish hawks are also players during fall migration.

During fall migration, many people would like to think all juvenile birds grow up in a family that lives together and migrates together, like Canada geese, but this isn't always true.

One of the most amazing aspects of fall migration for ospreys is that young ospreys are entirely on their own. Soon after they are able to fly and capture food, first year ospreys need to take care of themselves, including during migration. All young ospreys fly solo. How they know where to go and how to get there is one of great migration mysteries that has yet to be answered.

Adult ospreys nurture their offspring until the young are able to feed themselves, but then their role as parents is complete. Mother osprey typically leaves the nest first soon after the young fledge. She becomes less and less of a presence around the nest starting sometime in August before finally taking off by herself. Her critical role in raising the young is completed and she will spend the next month or so feeding and gaining that was lost during the nesting period, as she offered much of the food to her young. Alan Poole, one of the worlds great experts on ospreys, shares with us in his book entitled, Ospreys: The Revival of a Global Raptor (2019) that adult female ospreys lose “at least 10% - 15% of their body mass during the nesting period…it seems likely that the female parents are hungry much of the time they are raising young, especially as the young get older and take more food.” It also seems that their mate or the father loses much less body mass, usually taking a good chunk of each fish for himself. As the famous English rock singer-songwriter Nick Lowe declares in his song, Born a Women, “Cause if you're born a woman, you're born to be hurt,” and that’s true even for female ospreys.

But Father osprey is not done yet with caring for his young. He will continue to bring food to the nest a few weeks after the female until the young have achieved some degree of fishing skills to become some what capable hunters. Alan Poole tell us, “the male stays on, and his role is critical in bringing fledging ospreys to independence.”

By early September, most if not all resident osprey parents will have departed the nest and surrounding area, migrating to the Southern Hemisphere well before their offspring.

Ultimately, a young osprey will be on his or her own to polish flying and foraging skills and to increase energy stores before starting a long winged journey single-handedly down to southern portion of the Earth, without any help from another osprey. The young ospreys will amazingly have to fly thousands of miles to a place in the Southern Hemisphere they have never been before unaided by parents, siblings, friends, or even a map.

A migrating adult osprey taking a break during a rainy day.

How Do Young Ospreys Know Where to Go?

While there are lots of theories, there are not a lot of absolute answers. Migration is still a mystery. Instinct almost certainly plays a big role. A sixth sense that will urge an inexperienced bird to move southward. 

A fall migration route from Jamaica Bay in New York City to Lake Valencia in Venezuela.

Over the years, wildlife biologists have tracked ospreys that have nested in Jamaica Bay, NY with miniature satellite transmitters during fall migration.  These scientific studies have at least revealed an osprey's general flight path. The birds will follow the sun, stars, and coastline of North American to the tip of Florida, then cross the Straits of Florida to Cuba before heading east to Haiti and the Dominican Republic. From there, young ospreys will usually fly 500 miles over open water to winter in northern South America, in places along rainforest rivers and lakes into the Amazon Basin ranging from Brazil, Venezuela, or Columbia.  It's more than a 3,500 mile journey, perhaps as much as 5,000 miles depending on which route a particular young osprey may take. These young-of-the-year birds will then typically spend  18 months in South America before making their return migration northward to find a partner, nest, and raise of family of their own.

The Cornell Lab of Ornithology also tells us that a single osprey may log more than 160,000 air miles during its 15-to-20-year lifetime traveling from its wintering home in the tropics to its breeding home in North America. For example, during thirteen days in 2008, one osprey flew 2,700 miles, from Martha's Vineyard, Massachusetts, to French Guiana, South America.

Dangers & Threats

There are many dangers for young first-time ospreys during fall migration. They can get hit by a car or ship, get tangled up in power lines, get shot at by an angry aquaculture farmer in the Caribbean or South America, get blown off course by storms and hurricanes, and even get lost when crossing the open ocean. The good news is that statistically those young ospreys that do survive their first year have a better chance of surviving future migrations.

Recovery

In the past, the sight of an osprey was a rarity due to reproductive failure from pesticide contamination (largely from D.D.T), nest disturbance and shooting for sport. Thankfully, osprey numbers are increasing today and individuals are returning to formerly vacated breeding grounds, as well as expanding into new areas including in Coney Island and Jamaica Bay, New York, Raritan Bay in New Jersey, and inland up the Connecticut and Quinnipac rivers in Connecticut.

Improving water quality, protection of habitat and for birds, restoration efforts in floodplain areas and near coastal waters, as well as the construction of artificial nesting platforms by conservation groups and volunteers, have all helped in the osprey’s recovery and have provided safe nesting locations. Of course there is still more work to be done to clean up local waters and restore habitat for this beautiful fish hawk to endure. 

A juvenile osprey at its birth nesting platform.