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Montana Field Guide

Montana Field Guides

Bobolink - Dolichonyx oryzivorus

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 is somewhat common across grasslands and valley bottoms state-wide. It appears to be stable or declining and faces threats from habitat loss due to conversion of native grasslands to row crop agriculture and a warming climate. Additionally, it suffers loss of nests in hay fields when hay is cut before young have fledged.
Bobolink (Dolichonyx oryzivorus) Conservation Status Summary
State Rank: S3B
Review Date = 12/03/2024
How we calculate Conservation Status
Rarity: VeryUncommonVeryCommon Threats: HighlyThreatenedUnthreatened Trends: RapidlyDecliningDecliningStableIncreasing Rank: S1 S2 S3 S4 S5 CriticallyImperiledSecure

See the complete Conservation Status Report
 
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

Click the map for more info.
Courtesy of eBird and Cornell Lab of Ornithology
 


Observations in Montana Natural Heritage Program Database
Number of Observations: 5403

(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).

Stewardship Responsibility

Based on the Montana Natural Heritage Program's latest predicted habitat suitability model

Total species' range in Montana 381,161 km2 (100% of Montana)
Area predicted to have
some level of suitable habitat
179,533 km2 (47% of Montana)

Stewardship responsibility for the predicted area of suitable habitat can be broken down as follows

  Total Suitable Optimal Suitability Moderate Suitability Low Suitability
Federal 11% <1% 2% 9%
State 6% <1% 1% 5%
Local <1% <1% <1% <1%
Conservation Lands/Easements 2% <1% <1% 2%
Private/Tribal/Unknown 80% 1% 20% 59%

See the Habitat Suitability for Biodiversity task in Map Viewer for a more detailed look at stewardship responsibilities within a variety of local jurisdictions.


References
  •  Literature Cited Above
  •  Additional References
  •  Web Search Engines for Articles on "Bobolink"
  •  Additional Sources of Information Related to "Birds"
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Citation for data on this website:
Bobolink — Dolichonyx oryzivorus.  Montana Field Guide.  .  Retrieved on , from