- 1 species worldwide
- DR personal total: 1 species (100%), 1 photo'd
| The Osprey (left) has traditionally been considered to belong to its own monotypic family,
the Pandionidae. This arrangement emphasizes several unique features of
this "fish-hawk:" numerous adaptations for a life of fishing (reversible
outer toe, spiny foot pads, nasal valves that close underwater, and more).
Its fossil record goes back 15 million years (Poole 1994), and its adaptations
as a fish-eating specialist have made it one of the most successful birds
on earth. It has one of the widest ranges of all birds — it is found on
every continent (except Antarctica). In the Old World it breeds as far
north as Norway and as far south as Australia, and winters widely in Africa.
In the New World it breeds from Alaska to the Caribbean, and winters in
South America. It eats both freshwater and saltwater fish, permitting it
to exist in a very wide range of water-margin habitats.
Because it is so widespread and is conspicuous around the margins of
lakes, swamps, and on coastlines, Ospreys have been widely studied, and
much is known about their ecology, behavior, biology, and migrations. Bretagnolle
& Thibault (1993), for example, conducted a two year study on Osprey
communications on Corsica. The identified 11 visual displays that are used
to communicate in a semi-colonial environment without feeding territories.
Protecting the young in the large exposed nests (bulky nests built atop
drowned trees in many cases) is a key element in these communications.
Poole (1994) lists four subspecies of Osprey: migratory populations
in North America and Asia (P.h. carolinensis and nominate halietus,
respectively) and two non-migratory populations (P.h. ridgwayi in
the Caribbean; cristatus from Java and New Guinea through Australia).
Poole (1994) points to an interesting fact: despite its long history, Osprey
has not evolved into different species. The fish-eating Haliaeetus sea-eagles, in contrast, have evolved into 8 separate species over a range
nearly identical to that of the Osprey. Most of these eagles are, however,
non-migratory, allowing for isolation and speciation. The long-distance
migration of much of the Osprey population has permitted interchange between
populations and less chance for subspecies to become isolated and evolve
as species over time.
it is a worldwide bird, this is surely the easiest of all monotypic
families to locate! This one (right, in a fine shot by John Van de
Graaff) is of the North American race carolinensis, in the Florida Everglades.
Osprey's wings are long and rather narrow (left), and held sharply
angled at the carpal joints. This wing structure allows for long
migrations on strong wingbeats and short glides, rather than a reliance
of thermals. The large black carpal patches and the black line through
the eye to the hindneck are its most distinctive plumage patterns. It
is always very impressive to watch an Osprey hunting low over a lake,
and then grabbing a large fish with its feet! Sometimes it then has to
battle aerial pirates — including Bald Eagles — to bring the fish to a
favored perch for consumption. [This particular Osprey has just
initiated wing and tail molt, as can be seen by the still very short
feathers growing in the gaps.]
The local status of Osprey has been of some concern in many locales.
Major declines in the northeastern United States in the 1960s-1970s were
tied to DDT and other pesticides. After the banning of DDT, there were
major efforts to re-establish Ospreys in coastal lagoons along all of the
east coast by building nesting structures; today an International
Osprey Society continues these efforts (web cams at nest sites are
featured from time to time. Where I live in Monterey County, California,
Osprey is a scarce but widespread migrant and winter visitor. A few winter
on Elkhorn Slough every year. This is near where nesting was known, just
over the border in Santa Cruz County, a century ago. Efforts to have nesting
Ospreys in Monterey County (e.g., by building nest platforms at Elkhorn
Slough Estuarine Reserve) have yet to succeed, but I wouldn't be surprised
to learn of a nest here or somewhere on Lake San Antonio sometime in the
future (see Roberson 2002 for more on local status).
Photos: The perced Osprey Pandion
haliaetus at the top was at the Salton Sea, California, on 28 July 2008. The Everglades bird was taken by John Van de Graaff in Florida
in Dec 2001. The photo of the Osprey in flight
was over the Salinas River near San Ardo on 29 Mar 2010. All photos © D.
Roberson except that photo © John Van de Graaff; all rights reserved.
Poole (1989) is an entire book on the life history and ecology of Osprey;
we might think of it as a family book. An excellent introduction to this
family, incorporated much research and extensively illustrated with great
photos, is in Poole (1994).
Other literature cited:
Bretagnolle, V., and J-C. Thibault. 1993. Communicative behavior
in breeding Ospreys (Pandion haliaetus): description and relationship of
signals to life history. Auk 110:736-751.
Poole, A.F. 1989. Ospreys. Cambridge Univ. Press, Cambridge, U.K.
Poole, A.F. 1994. Family Pandionidae (Osprey), pp. 42-51 in del
Hoyo, J., A. Elliott, & J. Sargatal, eds. Handbook of the Birds of
the World. Vol. 2, Lynx Edicions, Barcelona.
Roberson, D. 2002. Monterey Birds, 2d ed. Monterey Pen. Audubon Soc.,