Download Osprey (Pandion haliaetus) - Michigan Breeding Bird Atlas

Osprey (Pandion haliaetus)
Sergej Postupalsky
Status: Special Concern (MNFI)
Kensington, MI. 4/25/2009 © Jim Ridley
The Osprey is a large, distinctive, fish-eating
raptor which obtains its prey by plunging feetfirst into the water from flight or a hover.
During the breeding season it carries the fish to
a perch, often with spectacular flying and vocal
display high in the sky. In boreal and temperate
regions Ospreys are migratory, moving to
tropical and subtropical areas for the winter
(Henny and Van Velzen 1972, Osterlof 1977).
In North America, it breeds from central Alaska
across Canada to Newfoundland, south to
western Mexico, the Rocky Mountain states;
east to the Great Lakes region and New
England; along the Atlantic Coast south to
Florida and the Bahamas; along the Gulf Coast
to Louisiana and Texas; and along the Yucatan
and Belize coastlines (Palmer 1988, Poole et al.
2002). Michigan Ospreys breed mainly in the
northern two-thirds of the state and are currently
expanding their range into the southern third.
Distribution
Prior to the 1960s, the Osprey’s status in
Michigan was poorly understood. Early
accounts stated that the species was “generally
distributed, but apparently nowhere abundant”
and that it “breeds” without citing specific nest
records (Gibbs 1879, Cook 1893, Barrows
1912). This was likely due to a lack of
(Click to view a comparison of Atlas I to II)
ornithological activity and record-keeping
before automobiles and good highways made
northern Michigan more accessible to
ornithologists, most of whom lived in southern
Michigan where the species had been eliminated
by loss of habitat and persecution. By the 1950s,
Osprey nests were reported in a dozen Michigan
counties and its status was described as “a rare
summer resident, principally in the northern half
of the state” (Zimmerman and Van Tyne 1959).
In the early 1960s, the Osprey population was
rapidly declining (Postupalsky 1977) due to
much reduced reproduction attributable to the
thin-eggshell syndrome caused by widespread
DDE (a metabolite of DDT) contamination of
aquatic food webs (Wiemeyer et al. 1975, Poole
1989). Osprey productivity in Michigan started
improving in the late 1960s and by 1971 had
reached estimated population maintenance
levels (Postupalsky 1977). Osprey numbers then
leveled off at about 80 pairs and in 1977 started
slowly increasing again.
In Michigan, Ospreys nest in dead trees found in
beaver ponds, man-made impoundments, or
along the fringes of lakes and streams. They
also nest in conifer swamps where nests are
built on top of tall pines, other conifers, or on
© 2011 Kalamazoo Nature Center
Osprey (Pandion haliaetus)
Status: Special Concern (MNFI)
snags, occasionally up to several miles from the
nearest water body. Ospreys readily accept nest
platforms provided for them (Postupalsky 1978)
in addition to power-transmission towers,
utility-line poles, light-poles, navigational aids
(Poole 1989), and telecommunication towers.
Fully 90 % of the nests in the LP are now on
man-made structures.
Breeding Biology
Most Ospreys arrive at their Michigan nest sites
in early April. Eggs (two to four, most
frequently three) are laid in late April and early
May. Most chicks hatch in the first half of June,
and young fledge from mid-July to early
August. Ospreys start departing from Michigan
in August and by October most have arrived on
their tropical wintering grounds. One-year-old
Ospreys remain in their wintering areas for at
least one year (Henny and Van Velzen 1972,
Osterlof 1977). Whereas some return as twoyear olds and a few may attempt nesting
(Englund and Greene 2008), most Ospreys do
not start breeding until at least age three
(Postupalsky
1989).
Factors
limiting
reproductive success include weather, changing
fish populations, increased weediness and water
turbidity of lakes and reservoirs, and predation
by Great Horned Owls and Bald Eagles.
Abundance and Population Trends
By 1992, the statewide population had tripled to
227 known pairs: 152 in the UP and 75 in the
northern LP. During 1993-1998, the number of
nesting pairs dropped to a low of 180 known
pairs (113 in the UP and 67 in the LP). This
decline was observed over most of the Osprey’s
Michigan breeding range and was also noted in
Wisconsin (Eckstein et al. 2009). The cause of
this negative trend remains unknown. Osprey
reproduction in the 1990s continued at adequate
levels, therefore one is left to postulate
increased mortality during migration or on the
wintering grounds in Central and northwestern
South America, where wildlife protection and
anti-pollution laws go largely unenforced, and
Sergej Postupalsky
where fish-eating birds are routinely shot at
aquaculture facilities (Bechard and Reyes 2003).
Some partial recovery was noted by 2000 when
200 nesting pairs were located: 124 in the UP
(including Isle Royale) and 76 in the LP
(Postupalsky pers. obs.).
In 2008, 110 nesting pairs were identified in the
LP (87 in the north and 23 in the south)
representing a substantial increase from the 60
pairs reported in MBBA I (Postupalsky and
Weinrich, pers. obs.). The growing population
in the southern LP has become established only
during the last decade, aided by an introduction
program conducted by the DNR, Huron-Clinton
Metroparks and the Detroit Zoo. During 19982007, about 50 Osprey nestlings were taken
from nests in northern Michigan and hacked out
at four locations in the southern LP. In 2000, the
most recent year of a statewide survey, 124
nesting pairs were found in the UP, an increase
from the 100 pairs reported in MBBA I.
Throughout the 36-year monitoring period,
nesting Ospreys were more numerous in the
eastern UP than in the western part. About 50
accessible breeding sites across the UP continue
to be monitored. Osprey numbers at these sites
appear to be stable, except on Seney NWR
where an increase has occurred in recent years.
As most of the monitored nests are on platforms
and other man-made structures at accessible
locations, the sample may not be representative
of the entire UP Osprey population. Large, more
remote parts of the UP are no longer being
monitored for Osprey nesting, as the DNR
discontinued aerial surveys after 2000. Five to
six pairs have nested on Isle Royale in recent
years (Peterson and Vucetich 2006, Vucetich
and Peterson 2007). The map shows Ospreys
nesting in 13 of the UP’s 15 counties; only
Ontonagon, Houghton, and the mainland portion
of Keweenaw County show no nesting. In the
northern LP confirmed nesting is indicated for
21 counties. In the southern LP, nests are thinly
distributed over 17 counties. This southward
extension of the Osprey’s breeding range is the
© 2011 Kalamazoo Nature Center
Osprey (Pandion haliaetus)
Status: Special Concern (MNFI)
most significant change occurring since MBBA
I.
Conservation Needs
In Michigan, the Osprey was listed as threatened
by the DNR until 2009 when it was removed
from the state endangered species list. While its
population has made an encouraging recovery in
recent years, the unexplained dip in numbers
during the mid-1990s is cause for concern.
Well-designed nesting platforms appropriately
placed near productive water bodies enable the
Osprey to breed in areas lacking suitable nest
supports. Power companies have erected
platforms on top of isolated poles to keep
Ospreys from nesting on utility towers and
poles, and the U.S. Coast Guard has installed
platforms on top of channel markers and rangelight towers to prevent the birds’ nests from
obstructing the lights. Such measures permit
Ospreys to persist in an increasingly humandominated landscape; however monitoring of
their effectiveness needs to continue. Because
the Osprey is a top predator in aquatic
ecosystems it is vulnerable to bioaccumulation
of environmental pollutants (Wiemeyer et al.
1975). Therefore continued vigilance of the
long-term effects of chemical pollutants is
necessary.
Literature Cited
Barrows, W.B. 1912. Michigan Bird Life.
Special Bulletin. Michigan Agricultural
College. Lansing, Michigan, USA.
Bechard, M.J., and C.-M. Reyes. 2003.
Mortality of wintering Ospreys and other
birds at aquaculture facilities in Colombia.
Journal of Raptor Research 37:292-298.
Cook, A.J. 1893. Birds of Michigan, 2nd
edition. Bulletin 94. Michigan Agricultural
Experimental Station. Lansing, Michigan,
USA.
Eckstein, R., G. Dahl, S. Easterly, B. Ishmael, J.
Nelson, P. Manthey, M. Meyer, L. Tesky, D.
Goltz, and B. Glenzinski. [date unknown].
Sergej Postupalsky
Wisconsin Bald Eagle and Osprey Surveys,
2008. Unpublished report, Wisconsin DNR,
Rhinelander, Wisconsin, USA.
Englund , J.V., and V.L. Greene. 2008. Twoyear-old nesting behavior and extra-pair
copulation in a reintroduced Osprey
population. Journal of Raptor Research
42:119-124.
Gibbs, M. 1879. Annotated list of the birds of
Michigan. Bulletin of the U.S. Geological
and Geographical Survey of the Territories
5:481-497.
Henny, C.J., and W.T. Van Velzen. 1972.
Migration patterns and wintering localities
of American Ospreys. Journal of Wildlife
Management 36:1133-1141.
Osterlof, S. 1977. Migration, wintering area
and site tenacity of European Osprey
Pandion haliaetus (L.). Ornis Scandinavica
8:61-78.
Palmer, R.S., editor. 1988. Handbook of North
American Birds. Volume 4. Diurnal raptors
(Part 1). Yale University Press, New Haven,
Connecticut, USA.
Peterson, R.O., and J.A. Vucetich.
2006.
Ecological Studies of Wolves on Isle
Royale.
Annual
report
2005-2006.
Michigan
Technological
University,
Houghton, Michigan, USA.
Poole, A.F. 1989. Ospreys: A Natural and
Unnatural History. Cambridge University
Press, Cambridge, United Kingdom.
Poole, A.F., R.O. Bierregaard, and M.S. Martell.
2002. Osprey (Pandion haliaetus). Account
683 in A. Poole and F. Gill, editors. The
Birds of North America. The Birds of North
America, Inc., Philadelphia, Pennsylvania,
USA.
Postupalsky, S. 1977. Status of the Osprey in
Michigan. Pages 153-165 in J.C. Ogden,
editor. Transactions of the North American
Osprey Research Conference.
US
Department of Interior, National Park
Service, Series 2, Washington, D.C., USA.
Postupalsky, S.
1978.
Artificial nesting
platforms for Ospreys and Bald Eagles.
© 2011 Kalamazoo Nature Center
Osprey (Pandion haliaetus)
Status: Special Concern (MNFI)
Pages 34-35 in S.A. Temple, editor.
Endangered Birds: Management Techniques
for Threatened Species.
University of
Wisconsin Press, Madison, Wisconsin,
USA.
Postupalsky, S. 1989. Osprey. Pages 297-313
in I. Newton, editor. Lifetime Reproduction
in Birds. Academic Press, London, United
Kingdom.
Vucetich, J.A., and R.O. Peterson.
2007.
Ecological Studies of Wolves on Isle
Royale.
Annual
report
2006-2007.
Michigan
Technological
University,
Houghton, Michigan, USA.
Wiemeyer, S.N., P.R. Spitzer, W.C. Krantz,
T.G. Lamont, and E. Cromartie. 1975.
Effects of environmental pollutants on
Connecticut and Maryland Ospreys. Journal
of Wildlife Management 39:124-139.
Zimmerman, D.A., and J. Van Tyne. 1959. A
Distributional Checklist of the Birds of
Michigan.
Occasional Paper 608.
University of Michigan Museum of
Zoology. Ann Arbor, Michigan, USA.
Suggested Citation
Postupalsky, S.
2011. Osprey (Pandion
haliaetus). In Chartier, A.T., J.J. Baldy, and
J.M. Brenneman, editors.
The Second
Michigan Breeding Bird Atlas. Kalamazoo
Nature Center. Kalamazoo, Michigan, USA.
Accessed online at: <www.mibirdatlas.org
/Portals/12/MBA2010/OSPRaccount.pdf >.
© 2011 Kalamazoo Nature Center
Sergej Postupalsky