Osprey - Pandion haliaetus
(see State Rank Reason below)
State Rank Reason (see State Rank above)
Species is relatively common within suitable habitat and widely distributed across portions of the state
- Details on Status Ranking and Review
ScoreD - 1,000-2,500 individuals
CommentA total of 640 element occurrences or nesting territories are documented in the Montana Natural Heritage Program's database. This likely indicates a population of between 1,000-2,500 reproductive individuals.
ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment353, 645 square kilometers based on Natural Heritage Program range maps that appear on the Montana Field Guide
Area of Occupancy
ScoreU - Unknown
ScoreE - Relatively Stable (±25% change)
CommentPopulations declined after European arrival, but have rebounded and are probably best recognized as stable within +/- 25% since European arrival.
ScoreF - Increasing. Increase of >10% in population, range, area occupied, and/or number or condition of occurrences
CommentRaptor survey routes for Montana between 1976 and 2011 have shown a steady increasing trend which has stabilized in the past 10 years. Breeding Bird Survey data for Montana is of moderate credibility and shows a significant increase of +6.3% per year or 84% increase per decade. Surrounding states and provinces all show increases with varying levels of significance and support.
ScoreF - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.
CommentContaminants, electrocution, and to a lesser extent baling twine all represent threats to populations in Montana.
SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
CommentSpecies seems to be doing well and has shown the ability to recover.
ScopeModerate - 20-60% of total population or area affected
CommentProbably 20-60% of the population is being impacted by threats at any given time.
ImmediacyModerate - Threat is likely to be operational within 2-5 years.
ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
CommentModerately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance within 5-20 years or 2-5 generations. Species has good dispersal capabilities such that extirpated populations generally become reestablished through natural recolonization.
ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.
CommentNarrow Specialist. Obligate piscivore. Need suitable nest sight near foraging areas.
Raw Conservation Status Score
3.5 – 0.25 (population size) + 0.0 (geographic distribution) + 0.25 (short-term trend) + 0.0 (threats)
Ospreys are dark brown above and white below, with a barred tail. The head is white with a prominent brown eye stripe extending from the eye to the shoulders. Females and immature birds have brown streaking on the breast. Immature ospreys have light feather edges on the tops of their wings, giving them a speckled look. Ospreys have long, narrow wings, which are bent at the wrist when soaring. The underside of the wing often appears two-toned, with white along the leading edge of it (except for dark wrist patches), and brown-barred flight feathers. They have a loud whistled call. Ospreys range in length from 21 to 24 inches, and have a wingspan of 54 to 72 inches. A large diurnal raptor with long narrow wings, dark brown upperparts, white underparts, a white head with a prominent dark eye streak, and dark wrist patches (visible in flight) on the underside of the wings; immatures have pale buff edging on the dark feathers of the upper surface; females are more likely than males to have a necklace of dark streaking; average length 56 to 64 cm, wingspan 147 to 183 cm.
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Bald Eagles are much larger and hold their wings straight out when soaring. Eagles have dark brown bellies and wings, in contrast to the white belly and barred wings of the Osprey. Differs from other hawks in having all of the following characteristics: white belly, dark wrist patches, and a white head with a prominent dark eye streak. other hawks do not habitually plunge feet-first into water to obtain prey.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(direct evidence "B")
(indirect evidence "b")
No evidence of Breeding
(regular observations "W")
(at least one obs. "w")
(Observations spanning multiple months or years are excluded from time charts)
Osprey depart by October for wintering areas in Central and South America. Bozeman area migration: April 20 to May 1 and September 15 to 30 (Skaar 1969). Migrates to CA, TX, FL or farther south.
Ospreys nest mainly near large lakes, reservoirs, and rivers in Montana. On upper Missouri, nest tree height variable but always as tall or taller than other trees. Presence of a flat, stable surface for nesting more important than tree species (Grover 1983).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Nearly all of their diet consists of fish, primarily rough fish such as suckers. On upper Missouri, catastomids most common prey, with salmonids and cyprinids eaten in similar quantities. Perch also eaten, but relative frequency not calculated (Grover 1983).
Upper Missouri nesting density = 0.03 occupied/km free flowing river, 0.54 occupied/km impounded river (Grover 1983). Becoming rare in Fortine area. Considered common 100 years ago in Gallatin valley; uncommon today (Skaar 1969).
Ospreys build their large nests on trees, power poles, docks, and other man-made structures. Ospreys prefer to build their nest at the top of dead, broken-topped trees, unlike eagles, which usually build nests in live trees below the tree canopy. Ospreys often build "frustration" nests if their first nest fails, although they rarely lay eggs a second time. Ospreys arrive in Montana in March and April, and lay one to four eggs in April or May. The young leave the nest in July and August, when about two months old. Upper Missouri average clutch size is 2.71; two-thirds of pre-fledglings killed were blown out. Successful nests = 52% of total occupied. Brood size of successful nests = 2.16. No eggs layed in 21.7% of occupied nests (Grover 1983). Nest dates April to July.
- Literature Cited AboveLegend: View Online Publication
- Grover, K.E. 1983. Ecology of the osprey on the upper Missouri River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 58 p.
- Marks, J.S., P. Hendricks, and D. Casey. 2016. Birds of Montana. Arrington, VA. Buteo Books. 659 pages.
- Skaar, P.D. 1969. Birds of the Bozeman latilong: a compilation of data concerning the birds which occur between 45 and 46 N. latitude and 111 and 112 W. longitude, with current lists for Idaho, Montana, Wyoming, impinging Montana counties and Yellowstone National Park. Bozeman, MT. 132 p.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
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