Blog # 459 A World of Ospreys

 

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. Croix River.

Satellite telemetry was used to determine their three main flyways Ospreys (Map 2). The western flyway follows the lower Columbia River between Oregon and Washington before it splits, heading down California to overwinter or continuing to Mexico and points south. 88% of these Osprey overwinter in Mexico, 6% in El Salvador, and 6% in Honduras or South America.

Midwestern Ospreys migrate south to Texas, the Caribbean Islands, and on to Central and South America. The eastern flyway hugs the mountain ranges and coastline from Canada down through New England, Pennsylvania, and the southern states to the Florida Keys. From there they island hop to South America as far south as Argentina. A small number of Osprey are non-migratory, spending their lives in Texas, South Carolina, Florida, and in Mexico along the Gulf Coast.

Map 2. North American Osprey flyways, courtesy of the Americas Avian Report

• Western Osprey, Pandion haliaetus, the nominate subspecies, are the only Ospreys found in Europe, Africa, Asia, Southeast Asia, and the Indian Subcontinent. All migrate to Africa. They have darker breast marks and bandit masks unlike their North American counterparts. This form is smaller, lighter bodied, and has a darker breast than the European nominate haliaetus.

Ospreys flourished along the coasts and rivers of Europe and Eurasia for millennia, although they were hunted as were most birds of prey. Since the 18th century, Osprey numbers started to drop due to over-hunting and egg collecting. Legislation, such as the Protection of Birds Act 1954 and Wildlife and Countryside Act 1981 in the United Kingdom, has made it illegal to collect wild birds' eggs. In the U.K., it is only legal to

Western Osprey, courtesy of Wikipedia.

possess a wild-bird's egg if it predates 1954, or with a permit for scientific research. Unfortunately, the centuries-old practice of egg collecting, or egging, still continues in the U.K. and Europe today. In the 1980s and 1990s, fines were only a moderate deterrent to egg collectors. However, the Countryside and Rights of Way Act 2000 brought imprisonment for the possession of the wild bird eggs and for attempting to buy egg collections.

Even the Catholic Church “preyed” on Ospreys. During frequent religious fasting consuming warm-blooded meat was forbidden, but eating cold-blooded fish was permitted. Seen as serious competitors for fish, the Church deemed Ospreys an enemy and promoted shooting them.

Today’s Ospreys are seeing a resurgence in some areas of Europe, notably along the Scottish coast and to a lesser degree in England, Germany, Wales, Italy, France, and Corsican coastal routes. In the fall, thousands of Ospreys migrate from Scandinavia across central and southern Europe on their way to Africa. Others from Russia and Asia travel to India and Southeast Asia. The largest populations on the continent remain in Sweden (about 4,100 pairs), Finland (up to 1,300 pairs), and 4,000 pairs in northern Russia.

The Partners in Flight Science Committee (2021) estimates 400,000 breeding pairs in North America. Bird Life International estimates the Europe has 9,500-13,500 breeding pairs or approximately 14% of the global population. These numbers are breeding pairs, excluding nonbreeding juveniles and intruders.

• Caribbean or Ridgway's Osprey, Pandion haliaetus ridgwayi, is a non-migratory subspecies living in Central America and some Caribbean islands. This paler form has a white head and breast with a weak to no eye mask.

Ridgway's Osprey, courtesy of CCNAB.

• Australian or Eastern Osprey, Pandion haliaetus cristatus, is non-migratory living on the coastlines and large rivers of Australia, Tasmania, and in some S.E. Asian islands. P.h. cristatus is the smallest subspecies.

Pandion haliaetus cristatus, courtesy of Wikipedia.

We are fortunate to have any Ospreys in the U.S. While Northern Canada, Scandinavia, and Russia retained their large populations, the highly toxic insecticide DDT almost eliminated the enormous North American populations in the 1950-60’s. With the cessation of DDT, the introduction of hacking efforts, and erecting artificial breeding platforms, many U.S. populations have rebounded along coastlines and expanded inland to lakes and rivers.

There are an estimated 50,000 breeding pairs worldwide with another 100,000 non-breeding juveniles and older birds that are unable to find nests or mates—so-called “floaters” (Poole, 2019). Floaters may represent a considerable fraction of the population, especially among males. Another obstacle to obtaining accurate population numbers is the lack of reliable data on bird populations in repressed areas and conflict zones.

Eyes to the sky!

Candace

Candace E. Cornell

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network cec222@gmail.com

EYES ON OSPREYS

WATCH!

Salt Point Osprey Nest Cam 2022-23

READ!

 On Osprey Time: Ospreys of the Finger Lakes

VISIT!

Cayuga Lake Osprey Trail Nests Driving Tour

Complete Cayuga Lake Osprey Trail

  HELP PROTECT OSPREYS:

•Stay 300 feet away from nests during the breeding season.

If the Osprey vocalizes, you are too close! BACK OFF IMMEDIATELY.

•Carry binoculars to view wildlife from afar.

•Recycle used fishing lines, twine, and nets, which can kill Osprey.

•Join the Cayuga Osprey Network: cec222@gmail.com.

•Help keep local waters clean, healthy, and safe. Pick up trash and do not litter.

Trash stays in the ecosystem a long time before it disintegrates.

Plastic just breaks down into smaller pieces.

Copyright @ 2023