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Purpose
Lake Red Rock, Iowa
To establish nesting Ospreys, Pandion haliaeetus, in Marion County, using young birds provided
by the Minnesota and Wisconsin Departments of Natural Resources. Introduction of Ospreys as
nesting species in Iowa facilitates regional and national recovery. Eleven states have released
Ospreys, and Iowa’s effort complements a coast-to-coast linkage of the birds.
Iowa birds are banded with a silver
(Federal) and purple (Iowa) leg band.
Their wings are painted to help with
identification and monitoring purposes
once the birds begin to fly and perch
around Lake Red Rock.
Fundraising activities are always
welcomed by community civic
organizations and youth groups.
Contact: Marla Mertz: 641-627-5935
(Marion County Naturalist, MCCB)
or Larry Zirkelbach: 641-842-6008
(IDNR Park Ranger, Elk Rock State Park)
Sponsors and Acknowledgements
Den Adel Lumber, Pella
Beth Brown, Osceola
Dick Krayenbrink, Pella
Dwight Robuck, Knoxville
Godfather’s Pizza, Knoxville
Iowa Bow Fisherman’s Association
Jack Leachman, Leachman Lumber, Des Moines
Kirk Irwin, Chariton
Mid American Energy
Mike Kalkwarf, Otley
Audra Fabre, Pella Christian High School and
the 2005 Sophomore Biology Class
Newton Correctional Facility
Pat Schlarbaum, IDNR
Paula Purdy, Americorps
Pella Cooperative Electric
Spahn & Rose Lumber, Knoxville
Curt and Karen Schwanebeck, Knoxville
Wal-Mart, Pella & Knoxville
Local Fishermen, Commercial Fisherman
Dr. Burk, Knoxville Veterinary Clinic
U.S. Army Corps of Engineers
Kay Harsin, Knoxville
Denise Zirkelbach, Elk Rock
IDNR Law Enforcement, Parks, and Fisheries
Marion County Conservation Board
MacBride Raptor Center
Widowed People of Central Iowa
Dorothy Templeton, Knoxville
Vermeer Manufacturing, Pella
Heidi von Arb, Marion County Conservation Board
Identification
Ospreys, Pandion haliaeetus, commonly called fish hawks or fish eagles, are
neither a true hawk nor eagle, but are in the family of Kites. Ospreys have
worldwide range. Sexes are similar in appearance, but females tend to be 10%
larger than males. Also, coloration on females includes pronounced dark flecking
or “necklace” on their chests. Eyes are red/orange in immature birds and yellow in
adults. A distinctive blackish-brown strip extends across the eye and down the side
of the neck. Other field mark characteristics include wing linings that are white
with dark barring, and dark carpal patches at the wrist are noticeable when viewed
from below. Typical flight has wings angled back much like gulls. Osprey calls
consist of a series of shrill, staccato whistles, gradually rising in pitch, tewp, tewp,
teelee, teelee, tewp.
vulture
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Territory
Male Osprey show strong fidelity to ancestral breeding areas, preferring to nest
colonially where adults originated. Females may disperse hundreds of miles
from their origin to nest; however, males will generally return within 20 miles of
origin. Due to this very low dispersal tendency by males, young Osprey are prime
candidates for relocation. Projects are designed to spread young, geographically,
to areas where Ospreys have not nested in decades. This strategy will ultimately
improve nesting survival and complete historic, continental distribution.
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Hunting
Ospreys are superb at fishing by catching prey with their feet following
spectacular feet-first dives. Osprey wing joints are specialized to withstand 40-50
mph dives and usually enter the water completely. Ospreys’ pale bluish talons are
tipped with nature’s finest fishhooks: claws, sharp as needles. Their outer toes,
like those of owls, are reversible; this characteristic and the sharp protuberances
or “spicules” on the lower surface of the toes allow them to grasp slippery fish
and carry them to a nearby perch.
Nesting
Nest sites are usually in the top of dead trees, but nests are also placed on manmade structures such as duck blinds, channel markers, and navigation aids and
telephone poles. Ground nests occur, most frequently on islands. Osprey clutches
consist of three or four eggs that are creamy white and heavily spotted brown.
Eggs are laid at two-to-three day intervals in May and incubation proceeds for 38
days. The male provides food for the female and brood after hatching. The female
remains in the nest for the first 30 days providing protection from predators and the
elements. At 42 days, young can tear apart fish provided by parents and around 53
days, first flight occurs. Adults attain sexual maturity at three or four years of age
and average life expectancy is ten years.
Young of the year quickly acquire fishing skills and gradually expand their range until
migration in mid-September. Immature Ospreys spend up to 20 months at their overwintering areas in South America.
1 year
SOUTH AMERICA
2 years
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