Ospreys Traditional Cache

Ospreys are nesting on light poles. The cache is between two nests, like geocaches 0.1 mile apart.

The osprey (Pandion haliaetus) — also called fish eagle, sea hawk, river hawk, and fish hawk — is a diurnal, fish-eating bird of prey with a cosmopolitan range. It is a large raptor, reaching more than 60 cm (24 in) in length and 180 cm (71 in) across the wings. It is brown on the upperparts and predominantly greyish on the head and underparts.

The osprey tolerates a wide variety of habitats, nesting in any location near a body of water providing an adequate food supply. It is found on all continents except Antarctica, although in South America it occurs only as a non-breeding migrant.

The osprey is unusual in that it is a single living species that occurs nearly worldwide. Even the few subspecies are not unequivocally separable.

As its other common names suggest, the osprey's diet consists almost exclusively of fish. It possesses specialised physical characteristics and exhibits unique behaviour to assist in hunting and catching prey. As a result of these unique characteristics, it has been given its own taxonomic genus, Pandion and family, Pandionidae. Four subspecies are usually recognized, one of which has recently been given full species status (see below). Despite its propensity to nest near water, the osprey is not classed as a sea eagle.

The osprey differs in several respects from other diurnal birds of prey. Its toes are of equal length, its tarsi are reticulate, and its talons are rounded, rather than grooved. The osprey and owls are the only raptors whose outer toe is reversible, allowing them to grasp their prey with two toes in front and two behind. This is particularly helpful when they grab slippery fish. It has always presented something of a riddle to taxonomists, but here it is treated as the sole living member of the family Pandionidae, and the family listed in its traditional place as part of the order Falconiformes.

The osprey breeds near freshwater lakes and rivers, and sometimes on coastal brackish waters. Many nests are renovated each season, and some have been used for 70 years. The nest is a large heap of sticks, driftwood, turf or seaweed built in forks of trees, rocky outcrops, utility poles, artificial platforms or offshore islets. As wide as 2 meters and weighing about 135 kg, large nests on utility poles may be fire hazards and have caused power outages.

Generally, ospreys reach sexual maturity and begin breeding around the age of three to four, though in some regions with high osprey densities, such as Chesapeake Bay in the U.S., they may not start breeding until five to seven years old, and there may be a shortage of suitable tall structures. If there are no nesting sites available, young ospreys may be forced to delay breeding. To ease this problem, posts are sometimes erected to provide more sites suitable for nest building.

Ospreys usually mate for life. Rarely, polyandry has been recorded

The typical lifespan is 7–10 years, though rarely individuals can grow to as old as 20–25 years. The oldest European wild osprey on record lived to be over thirty years of age. In North America, great horned owls (Bubo virginianus), golden eagles (Aquila chrysaetos), and bald eagles (Haliaeetus leucocephalus) are the only major predators of ospreys, capable of taking both nestlings and adults. However, kleptoparasitism by bald eagles, where the larger raptor steals the osprey's catch, is more common than predation. 

The osprey has several adaptations that suit its piscivorous lifestyle :

    •    reversible outer toes,

    •    sharp spicules on the underside of the toes,

    •    closable nostrils to keep out water during dives, and

    •    backwards-facing scales on the talons which act as barbs to help hold its catch.

    •    dense plumage which is oily and prevents its feathers from getting waterlogged.

European breeders winter in Africa. American and Canadian breeders winter in South America, although some stay in the southernmost U.S. states such as Florida and California. Some ospreys from Florida migrate to South America. Australasian ospreys tend not to migrate.

In the late 19th and early 20th centuries, the main threats to osprey populations were egg collectors and hunting of the adults along with other birds of prey, but osprey populations declined drastically in many areas in the 1950s and 1960s; this appeared to be in part due to the toxic effects of insecticides such as DDT on reproduction. The pesticide interfered with the bird's calcium metabolism which resulted in thin-shelled, easily broken or infertile eggs. Possibly because of the banning of DDT in many countries in the early 1970s, together with reduced persecution, the osprey, as well as other affected bird of prey species, have made significant recoveries.

The cache is a tied in, camoed, "micro" pill bottle, the push hard to open and close kind. Please put everything back as you found it, including the rubber band and the sealed plastic bag, and replace or better the camo. BYOP!