Bobolink - Dolichonyx oryzivorus
State Rank Reason (see State Rank above)
Species has undergone recent large population declines in Montana and a patchwork of declines and increases have been documented in surrounding states and provinces.
- Details on Status Ranking and Review
ScoreU - Unknown
ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment380,531 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)
CommentSpecies requires higher cover wetter grasslands with taller grasses. Some wetlands have been lost, but irrigation has increased since European arrival so overall trend is probably stable within +/-25% since European arrival.
ScoreC - Rapidly Declining. Decline of 30-50% in population, range, area occupied, and/or number or condition of occurrences
CommentBBS data for Montana is of highest credibility and shows a -6.4% decline per year or 48% decline per decade. Patchwork of declines and increases for surrounding states and provinces. There are stable trends for percentages of point counts and abundances on North Valley County Point Counts between 2001 and 2008.
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.
CommentHabitat loss, drought in relation to climate change, and mowing are probably the greatest threats to the species.
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 capable of responding quickly when water is returned to allow denser taller grasses.
ScopeHigh - > 60% of total population or area affected
Comment>60% of population is impacted by drought and/or mowing/grazing.
ImmediacyModerate - Threat is likely to be operational within 2-5 years.
CommentOngoing and accelerating
ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).
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. Need deep cover grasslands which are very limited in Montana so in Montana their specificity is narrow.
Raw Conservation Status Score
3.5 + 0.0 (geographic distribution) + 0.0 (environmental specificity) - 0.5 (short-term trend) + 0.0 (threats) = 3.0
How Scores are Calculated
The Bobolink is approximately 18 centimeters long with a stout, relatively short, pointed bill and sharply pointed tail feathers. The breeding male is black below, with a buff to whitish hind-neck, white scapulars, and white rump; early in spring the male has pale feather edgings. The breeding female is buffy with dark streaks on the back, rump, sides, and head. The juvenile resembles the breeding female but lacks streaks below. Fall adults and immatures resemble breeding female but are darker above and richer buff below. (Renfrew et al. 2015)
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.
Breeding males are unique among North American passerines in being entirely black underneath and lighter above (Renfrew et al. 2015).
Western Hemisphere Range
eBird Occurrence Map
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Summary of Observations Submitted for Montana
Number of Observations:
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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)
In the Bozeman area, normal migration periods are May 20 to June 5 and August 15 to September 1.
Nests built in tall grass and mixed-grass prairies. Prefers "old" hay fields with high grass-to-legume ratios.
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 (high, medium, or low) 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 2001, 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 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 associated as using 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 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.
High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.
If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at email@example.com
or (406) 444-3655.
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: http://mtnhp.org/requests/default.asp
) 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. 2001. The wild mammals of Montana. Special Publication No. 12. Lawrence, KS: The American Society of Mammalogists. 278 p.
- 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.
During the breeding season, diet consists of weed seeds and a large variety of larvae and insects. During the winter, diet consists of wild and domesticated rice, oats, other small grains, corn, tassels, weed seeds, and occasional insects.
Strongly territorial during the early breeding season, but social and highly gregarious the rest of the year (Renfrew et al. 2015).
Single brooded species with five to six eggs per brood. Incubation period 10 to 13 days. Young able to fly after 10 to 14 days.
Bobolinks have declined in abundance, largely because of changes in land use, particularly loss of meadows and hay fields (Renfrew et al. 2015).
- Literature Cited AboveLegend: View Online Publication
- Marks, J.S., P. Hendricks, and D. Casey. 2016. Birds of Montana. Arrington, VA. Buteo Books. 659 pages.
- Renfrew, R., A.M. Strong, N.G. Perlut, S.G. Martin, and T.A. Gavin. 2015. Bobolink (Dolichonyx oryzivorus). The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/176
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
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- Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
- Roy F. Weston, Inc., Bozeman, MT., and Western Technology and Engineering, Inc., Helena, MT., 1989, Stillwater PGM Resources East Boulder Project Addendum F: Supplemental Biological Studies. Final Report. December 1989.
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- Sibley, D. 2014. The Sibley guide to birds. Alfred A. Knopf, New York, NY. 598 pp.
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- 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.
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