The Osprey

The Osprey
by Jerry Allen, FPS Volunteer

Migration
The estimated nesting population of the Osprey in the U.S in 1994 was determined by researcher Larry Houghton to be approximately 14,000 nesting pairs. Even with modern population inventory techniques, it is still difficult to make accurate nest site counts, and involves an extremely large task with researchers having to contend with budgeting and staffing limits.

Twenty percent of the U.S. Opsrey are located in New England, 20% in the Chesapeake Bay area, and 20% in Florida. The remainder are located in the northeast U.S. and some are found west of the Mississippi.

Osprey nesting in the New England and Chesapeake Bay areas migrate to the Caribbean, Central America and Northern S. America. The others east of the Mississippi migrate to Florida. Populations west of the Mississippi migrate to Mexico. Most Osprey along the GulfCoast, S. California, and S. Florida are year-round residents of those areas and do not migrate.

This includes those here on Honeymoon Island, the reason for their abundance here being the excellent habitat, nesting sites and food sources found here.

Fall migration begins in late August and September andends in mid October. Stop off points used by northern populations before migrating south include Hawk Mountain in PA, and Cape May in New Jersey, which extends south into the ocean. Many species of migratory birds congregate in these locations, and so many ornithologists, birders and casual observers gather during peak migration in order to witness the spectacle first-hand.

Hurricanes and Predators
Osprey migrating from these areas then proceed either directly over open water, or over land. Young Osprey often select the open water route, crossing long stretches of open ocean. Nearly 2/3 of the young will perish dues to storms.

While many birds build up stores of fat to live on during migration, the Osprey does not.. They hunt actively along the way, fishing as they go, sometimes carrying a “fish snack” with them. They tend to be solitary in migration, but mated pairs travel together, riding the wind currents and soaring on updrafts and thermals.

The mature birds migrate by instinct and navigate by eye, always aware of landmarks, returning to the same wintering grounds year after year. The fledglings too, will be driven by instinct, navigating by the ancestral “map” embedded within. The young that successfully manage the migration fly thousands of miles until they somehow recognize a place they have never been to before, and something within them will say “home”. Then they will settle into this ancient wintering ground, and partake inthe abundance of fish as they regain their strength after the strenuous migration. The ability to recognize a place they have never been to before is surely a fact stranger than fiction.

Winter Quarters
The return trip south takes about 1/3 the time it took tomigrate north, as they seem anxious to return to the nest and ready it for a new family. Once settled in, returning mated pairs tend their nests, and those without mates engage in courtship. Older pairs will rebuild their nest and newlyweds will work to build a new nest. Occasionally, established nests are damaged by storms, and the couple will select a new sight.

There is always the chance that the Great Horned Owl will select an Osprey nest and call it its own. The Owls leave the nestin ill repair, and badly soiled, being the “good renters” that they are.

By mid march, most wintering sites used by the Osprey that do migrate are ghost towns, barren of all but the yearling birds who continue to hone their hunting skills and gain experience. The cycle of life begins anew!

To experience the Osprey first hand, and learn more about their life history, join in on one of the Ranger-Led Osprey Trail walks, held each Saturday at the Picnic area at 11am, November through March.

Resources: Alan Poole, Biologist Larry Raymond and Stephen D. Capenteri, “The Fish Hawk Osprey”.