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Montana Field Guide

Montana Field Guides

Bobolink - Dolichonyx oryzivorus

Image Copyright and Usage Information
Species of Concern
Native Species

Global Rank: G5
State Rank: S3B
(see State Rank Reason below)


Agency Status
USFWS: MBTA; BCC10; BCC11; BCC17
USFS:
BLM:
FWP SWAP: SGCN3
PIF: 3

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Copyright by: The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, NY, all rights reserved.
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
    Bobolink (Dolichonyx oryzivorus) Conservation Status Review
    Review Date = 12/20/2011
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    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

    CommentUnknown.

    Long-term Trend

    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.

    Short-term Trend

    ScoreC - Rapidly Declining. Decline of 30-50% in population, range, area occupied, and/or number or condition of occurrences

    CommentBreeding Bird Survey (BBS) 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.

    Threats

    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

    Intrinsic Vulnerability

    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).

    CommentNot Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has a high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance. Species has good dispersal capabilities such that extirpated populations generally become reestablished through natural recolonization.

    Environmental Specificity

    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

    Score 3.5 + 0.0 (geographic distribution) + 0.0 (environmental specificity) - 0.5 (short-term trend) + 0.0 (threats) = 3.0

 
General Description
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.

Diagnostic Characteristics
Breeding males are unique among North American passerines in being entirely black underneath and lighter above (Renfrew et al. 2015).

Species Range
Montana Range Range Descriptions

All Ranges
Summer
Migratory
(Click legend blocks to view individual ranges)

Western Hemisphere Range


eBird Occurrence Map

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Courtesy of eBird and Cornell Lab of Ornithology
 


Observations in Montana Natural Heritage Program Database
Number of Observations: 4447

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding

Indirect Evidence of Breeding

No Evidence of Breeding

WINTER (Dec 15 - Feb 15)
Regularly Observed

Not Regularly Observed


 

(Observations spanning multiple months or years are excluded from time charts)



Migration
In the Bozeman area, normal migration periods are May 20 to June 5 and August 15 to September 1.

Habitat
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 (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:
    1. 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);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
    4. 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.

    Literature Cited
    • 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.

Food Habits
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.

Ecology
Strongly territorial during the early breeding season, but social and highly gregarious the rest of the year (Renfrew et al. 2015).

Reproductive Characteristics
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.

Management
Bobolinks have declined in abundance by nearly 60% since 1970 (Renfrew et al. 2019). This is due largely to changes in land use, particularly loss of meadows and hay fields (Renfrew et al. 2015). Over the next two decades, it is predicted that populations of bobolinks will decline by 30%. This species depends on grasslands throughout its annual range, so conservation and management requires a geographically and biologically coordinated effort. Renfrew et al. (2019) identifies the strategies that merge biological, social, economic, and conservation needs and span a wide range of actions in greater detail in A Full Life Cycle Conservation Plan for Bobolink (Dolichonyx oryzivorus).

References
  • 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
    • Renfrew, R.B., K.A. Peters, J.R. Herkert, K.R. VanBeek, and T.Will. 2019. A full life cycle conservation plan for bobolink (Dolichonyx oryzivorus). U.S. Fish and Wildlife Service. 216 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • American Ornithologists’ Union [AOU]. 1998. Check-list of North American birds, 7th edition. American Ornithologists’ Union, Washington, D.C. 829 p.
    • Becker, D.M. 1984. Reproductive ecology and habitat utilization of Richardson's merlins in southeastern Montana. M.Sc. Thesis. Missoula, MT: University of Montana. 62 p.
    • Bent, A.C. 1958. Life histories of North American blackbirds, orioles, tanagers, and their allies. U.S. Natl. Mus. Bull. 211. Washington, D.C.
    • Bird Conservancy of the Rockies. 2017. Pocket Guide to Northern Prairie Birds. Brighton, CO: Bird Conservancy of the Rockies. 98 p.
    • Bramblett, R.G., and A.V. Zale. 2002. Montana Prairie Riparian Native Species Report. Montana Cooperative Fishery Research Unit, Montana State University - Bozeman.
    • Casey, D. 2000. Partners in Flight Draft Bird Conservation Plan Montana. Version 1.0. 287 pp.
    • Casey, D. 2005. Rocky Mountain Front avian inventory. Final report. Prepared for the U.S. Fish and Wildlife Service and The Nature Conservancy by the American Bird Conservancy, Kalispell, Montana.
    • Clawson, M.R. 199. An investigation of factors that may affect nest success in CRP lands and other grassland habitats in an agricultural landscape. M.Sc. Thesis. Bozeman, MT: Montana State University. 45 p.
    • Confluence Consulting Inc. 2011. Montana Department of Transportation Wetland Mitigation Monitoring Reports (various sites). MDT Helena, MT.
    • Dechant, J. A., M. L. Sondreal, D. H. Johnson, L. D. Igl, C. M. Goldade, A. L. Zimmerman, and B. R. Euliss. 2003k. Effects of management practices on grassland birds: Bobolink. Northern Prairie Wildlife Research Center, Jamestown, ND. Northern Prairie Wildlife Research Center
    • Dickson, D.C. 1991. Systematic wildlife observations on the Blackfoot-Clearwater Wildlife Management Area. Montana Department of Fish, Wildlife and Parks. Missoula, MT. 14 pp. plus appendices and photographs.
    • Dobkin, D. S. 1992. Neotropical migrant landbirds in the Northern Rockies and Great Plains. U.S.D.A. For. Serv. N. Region Publ. R1-93-34. Missoula, Mont.
    • Dobkin, D.S. 1994. Conservation and management of neotropical migrant landbirds in the Northern Rockies and Great Plains. Univ. Idaho Press, Moscow, Idaho. 220 pp.
    • Ehrlich, P., D. Dobkin, and D. Wheye. 1988. The birder’s handbook: a field guide to the natural history of North American birds. Simon and Schuster Inc. New York. 785 pp.
    • Faanes, C.A. 1983. Breeding birds of wooded draws in western North Dakota. Prairie Nat. 15(4): 173-187.
    • Flath, Dennis and David Dickson. 1994 Systematic wildlife observations on the Blackfoot-Clearwater Wildlife Management Area 1991-1993. Montana Department of Fish, Wildlife and Parks.
    • Gillihan, SW. and T. VerCauteren. 2015. Pocket Guide to Prairie Birds. Brighton, CO: Bird Conservancy of the Rockies. 91 p.
    • Gniadek, S. 1983. Southwest Glendive Wildlife Baseline Inventory. Miles City, Mont: Bureau of Land Management, Miles City District Office. 56 pp with appendices.
    • Hays, R., R.L. Eng, and C.V. Davis (preparers). 1984. A list of Montana birds. Helena, MT: MT Dept. of Fish, Wildlife & Parks.
    • Hendricks, P, S. Lenard, and C. Currier. 2012. Grassland Bird Surveys in North Valley County and Northwest Phillips County, Montana: 2011 Summary. Report to the USDI Bureau of Land Management. Montana Natural Heritage Program. Helena, MT. 7pp.
    • Hendricks, P. 2000. Roadside bird counts on BLM lands in Petroleum and Fergus Counties, Montana. Montana Natural Heritage Program, Helena, MT. 57pp.
    • Hendricks, P., G.M. Kudray, S. Lenard, and B.A. Maxell. 2007. A Multi-Scale Analysis Linking Prairie Breeding Birds to Site and Landscape Factors Including USGS GAP Data. Helena, Mont: Montana Natural Heritage Program.
    • Hendricks, P., S. Lenard, C. Currier, and J. Carlson. 2007. Grassland bird surveys in north Valley County, Montana: 2001-2006. Report to the Bureau of Land Management, Glasgow Field Office. Montana Natural Heritage Program, Helena, Montana. 19 pp. plus appendices.
    • Hendricks, P., S. Lenard, D.M. Stagliano, and B.A. Maxell. 2013. Baseline nongame wildlife surveys on the Fort Peck Indian Reservation. Report to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. Montana Natural Heritage Program, Helena, MT. 83 p.
    • Johnsgard, P.A. 1979. Birds of the Great Plains: breeding species and their distribution. University of Nebraska Press, Lincoln. 539 pp.
    • Johnsgard, P.A. 1992. Birds of the Rocky Mountains with particular reference to national parks in the northern Rocky Mountain region. Lincoln: University of Nebraska Press. xi + 504 pp.
    • Johnson, D. H., and L. D. Igl. 1995. Contributions of the Conservation Reserve Program to populations of breeding birds in North Dakota. Wilson Bulletin 107(4):709-718.
    • Johnson, R.G., and S.A. Temple. 1990. Nest predation and brood parasitism of tallgrass prairie birds. Journal of Wildlife Management 54:106-111.
    • Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
    • Kantrud, H.A. 1982. Maps of distribution and abundance of selected species of birds on uncultivated native upland grasslands and shrubsteppe in the northern Great Plains. U.S. Dept. Int., Fish and Wildl. Serv. FWS/OBS-82/31. 31 p.
    • Land & Water Consulting, Inc., Missoula, MT., 2002, Montana Dept. of Transportation Wetland Mitigation Monitoring Report, Year 2001: Musgrave Lake, Montana. Proj. No. 130091.019. July 2002. In 2001 Wetland Mitigation Monitoring Reports, Vol. II.
    • Lenard, S. 2006. Birds of Blaine County, Riparian Point Count Surveys 2005. Report to the Bureau of LandManagement, Havre Field Station, Havre, Montana. Montana Natural Heritage Program, Helena, MT. 16pp.plus appendices.
    • Lenard, S. and P. Hendricks. 2005. Birds of selected grassland and riparian plots along the Rocky Mountain Front. Montana Natural Heritage Program for US Fish and Wildlife Service and The Nature Conservancy. 17pp + maps.
    • Lenard, S., J. Carlson, J. Ellis, C. Jones, and C. Tilly. 2003. P. D. Skaar's Montana bird distribution, 6th edition. Montana Audubon, Helena, MT. 144 pp.
    • Martin, S.G. and T.A. Gavin. 1995. Bobolink (Dolichonyx oryzivorus). Species Account Number 176. The Birds of North America Online (A. Poole, Ed.). Ithaca, NY: Cornell Laboratory of Ornithology; Retrieved 3/25/2008 from The Birds of North America Online database
    • Maxell, B.A. 2016. Northern Goshawk surveys on the Beartooth, Ashland, and Sioux Districts of the Custer-Gallatin National Forest: 2012-2014. Montana Natural Heritage Program. Helena, MT. 114pp.
    • Montana Bird Distribution Committee. 2012. P.D. Skaar's Montana bird distribution. 7th Edition. Montana Audubon, Helena, Montana. 208 pp. + foldout map.
    • MT Fish, Wildlife & Parks. No date. Blackfoot-Clearwater Wildlife Management Area checklist.
    • Oechsli, L.M. 2000. Ex-urban development in the Rocky Mountain West: consequences for native vegetation, wildlife diversity, and land-use planning in Big Sky, Montana. M.Sc. Thesis. Montana State University, Bozeman. 73 p.
    • Pavlacky Jr., D.C., et al. 2021. Landscape-scale conservation mitigates the biodiversity loss of grassland birds. Ecological Applications e2548. 17 p.
    • Ralph, J.C., J.R. Sauer, and S. Droege. 1995. Monitoring bird populations by point counts. Gen. Tech. Rep. PSW-GTR-149. Albany, CA: USDA Pacific Southwest Research Station. 181 p.
    • Richmond, C.W. and F.H. Knowlton. 1894. Birds of south-central Montana. Auk 11:298-308.
    • 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.
    • Sater, S. 2022. The insects of Sevenmile Creek, a pictorial guide to their diversity and ecology. Undergraduate Thesis. Helena, MT: Carroll College. 242 p.
    • Saunders, A. A. 1912. A horseback trip across Montana. Condor 14(6):215-220.
    • Saunders, A.A. 1921. A distributional list of the birds of Montana: With notes on the migration and nesting of the better known species. Pacific Coast Avifauna No. 14. pp. 38-39, 118-119.
    • Sibley, D. 2014. The Sibley guide to birds. Alfred A. Knopf, New York, NY. 598 pp.
    • Skaar, P. D., D. L. Flath, and L. S. Thompson. 1985. Montana bird distribution. Montana Academy of Sciences Monograph 3(44): ii-69.
    • 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.
    • Stewart, R.E. 1975. Breeding birds of North Dakota. Tri-College Center for Environmental Studies, Fargo, North Dakota. 295 pp.
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    • Waldt, R. 1995. The Pine Butte Swamp Preserve bird list. Choteau, MT: The Nature Conservancy. Updated August 1995.
    • Watts, C.R. and L.C. Eichhorn. 1981. Changes in the birds of central Montana. Proceedings of the Montana Academy of Sciences 40:31-40.
    • Wittenberger, J.F. 1978. The breeding biology of an isolated bobolink population in Oregon. Condor 80: 355-371.
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Citation for data on this website:
Bobolink — Dolichonyx oryzivorus.  Montana Field Guide.  .  Retrieved on , from