BC Conservation Data Centre: Conservation Status Report
Dolichonyx oryzivorus
Bobolink
| Scientific Name: | Dolichonyx oryzivorus |
|---|---|
| English Name: | Bobolink |
| Provincial Status Summary | |
| Status: | S2?B |
| Date Status Assigned: | March 25, 2022 |
| Date Last Reviewed: | March 25, 2022 |
| Reasons: | This is a species with a scattered, limited distribution, small population size and some threats to its habitat and overwintering areas (COSEWIC in prep). |
| Range | |
| Range Extent: | F = 20,000-200,000 square km |
| Range Extent Estimate (km2): | 104,000 square km |
| Range Extent Comments: | Range extent calculated based on confirmed and probable breeding locations on the BC Breeding Bird Atlas (Siddle, 2015) Breeding is locally distributed in the main valley bottoms in the southern and central interior, from the Similkameen east to Creston and north to the Chilcotin. |
| Area of Occupancy (km2): | D = 6-25 |
| Area of Occupancy Comments: | 22 known sites, widely scattered in lowland s. BC (van Damme 1999) |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | There are 22 known breeding sites, mainly in hayfields and riparian meadows (Van Damme, 1999). |
| Number of Occurrences with Good Viability / Ecological Integrity: | Rank Factor not assessed |
| Number of Occurrences Appropriately Protected & Managed: | B = 1 - 3 |
| Comments: | Almost entirely dependant on agricultural areas, especially hay fields and other forage crops (Sidde 2015) . Small population at the Creston Valley Wildlife Managment Area. |
| Population Size: | CD = 250 - 2,500 individuals |
| Comments: | Van Damme (1999) estimates the British Columbia breeding population at between 500 and 1100 individuals. This is much lower than the estimates compiled by Partners in Flight (2019) and presented in the most recent COSEWIC status report (in prep) which have the BC population estimated at 15,000 (95% CL 3000 to 37000) |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | BC = High - medium |
| Comments: | Moderately threatened by habitat loss due to urbanization, particularly in the Okanagan Valley. Increasingly intensive haying practices and conversion from grass to alfalfa hay crops also negatively impacts breeding populations. Hay-cropping during incubation and early nestling stage results in 100% loss of offspring (Martin and Gavin 1995). Application of insecticides to breeding areas both reduces and contaminates their primary food source, impacting both juvenile and adult birds (Van Damme 2019). |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | CD = Decline of 50-80% |
| Comments: | Breeding bird survey results for British Columbia indicate a 83.4% decline (-94.5 to -56.0 95%CI)over the last 2001 to 2021 ( A. Smith pers comm to M. Gabhauer 2020). This is a rapid recent decline after Bobolinks colonized British Columbia shortly after the turn of the century (Cannings et al. 1987), likely by taking advantage of newly-created agricultural habitats (Bollinger and Gavin 1992). |
| Long-Term Trend: | I = Increase of >25% |
| Comments: | Assuming that the species has colonized British Columbia in historic times as a response developing hayfields and pastures. |
| Other Factors | |
| Intrinsic Vulnerability: | Rank Factor not assessed |
| Environmental Specificity: | Rank Factor not assessed |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | Identification of nesting habitats is needed within the suspected range using standards for terrestrial ecosystem mapping (Ecosystems Working Group 1995). Standardized surveys (Resour. Inventory Comm. 1997 #15) for singing males in high suitability habitats should then be undertaken in areas identified by habitat mapping, to determine provincial distribution, centres of abundance, and relative densities. Recent expansion into irrigated fields has been seen in arid eastern Oregon (Wittenberger 1976, cited in Martin and Gavin 1995) and southern Alberta (D. Fraser, pers. obs.) and may occur in British Columbia. |
| Stewardship | |
| Protection: | The species is listed in the proposed Identified Wildlife Management Strategy under the Forest Practices Code of British Columbia Act. Procedures for the establishment of Wildlife Habitat Areas on critical nesting habitats, and General Wildlife Measures to determine appropriate management practices within established areas should be made available to resource managers. However, very few breeding sites are on Crown Land. |
| Management: | It is therefore very important to cooperate with landowners to develop and implement land management guidelines designed to protect nesting habitats on private lands. Delay hay-cropping until after birds leave in August to prevent nesting failure. Avoid use of pesticides on breeding grounds. Secure and manage a number of breeding sites that show consistent and substantial annual breeding activity. Hayfields supporting this species should be mowed annually, but not until after fledging in early July (Martin and Gavin 1995). Even later mowings would permit a second brood. In cooperation with the Canadian Wildlife Service, a comprehensive management plan for neotropical migrants in British Columbia should be developed that also addresses the conservation needs of Bobolinks. Siddle (2015) suggests that earlier mowings that may result from climate change could cause further declines. Renfrew et al. (2020) summarizes the literature on threats, including shooting as pests of rice in South America, hunting for food and capture for the pet trade, |
| Version | |
| Author: | S. Cannings and L. Ramsay updated by D.F.Fraser |
| Date: | January 17, 2022 |
| References | |
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Bollinger, E.K. and T.A. Gavin. 1992. Eastern Bobolink populations: ecology and conservation in an agricultural landscape. 497-508pp. in Hagan, J.M. and D.W. Johnston (EDS.) Ecology and conservation of neotropical migrant landbirds. Smithsonian Institution Press, Washington, D.C.
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Campbell, R.W., N.K. Dawe, I.McT. Cowan, J.M. Cooper, G.W. Kaiser, M.C.E. McNall, and G.E.J. Smith. 1999. The Birds of British Columbia. Vol. 3, Passerines: Flycatchers through Vireos. Can. Wildl. Serv., Delta, and B.C. Minist. Environ., Lands and Parks, Victoria.
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Cannings, R.A., R.J. Cannings, and S.G. Cannings. 1987. Birds of the Okanagan Valley, B.C. Royal B.C. Mus., Victoria, BC. 420pp.
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Cannings, R.J. 1998. The Birds of British Columbia - a taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria, Wildl. Bull. B-86. 266pp.
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COSEWIC. 2010e. COSEWIC assessment and status report on the Bobolink Dolichonyx oryzivorus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vi + 42 pp. (www.sararegistry.gc.ca/status/status_e.cfm).
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Donovan, T. M., F. R. Thompson, J. Faaborg, and J. R. Probst. 1995. Reproductive success of migratory birds in habitat sources and sinks. Conservation Biology 9:1380-1395.
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Downes, C.M., and B.T. Collins. 2007. Canadian Bird Trends Web site Version 2.2. Canadian Wildlife Service, Environment Canada, Gatineau, Quebec, K1A 0H3.
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Godfrey, W.E. 1986. The Birds of Canada, rev. ed. Natl. Mus. Can., Ottawa, ON. 595pp.
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Martin, S.G. and T.A. Gavin. 1995. Bobolink (DOLICHONYX ORYZIVORUS). In The Birds of North America, No. 176 (A. Poole and F. Gill, eds.). The Acad. Nat. Sci., Philadelphia, PA, and The Am. Ornithol. Union, Washington, DC. 24pp.
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Murphy Creek Power Corporation. 2012. Murphy Creek Investigative Plan Template. Murphy Creek Power Corporation, 1885 Marine Drive, North Drive, Vancouver B.C.
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Resource Inventory Committee. 1995. Standards for terrestrial ecosystem mapping in British Columbia: review draft. Ecosystems Working Group, B.C. Minist. Environ., Lands and Parks, Victoria, BC. 222pp.
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Resource Inventory Committee. 1997. Standardized Inventory Methodologies for Components of British Columbia's Biodiversity: Forest and Grassland Songbirds, version 1.1. Prepared for the Resour. Inventory Comm., B.C. Minist. Environ., Lands and Parks, Victoria, BC. 20pp.
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Sauer, J. R., J. E. Hines, and J. Fallon. 2007. The North American Breeding Bird Survey, Results and Analysis 1966 - 2006. Version 10.13.2007. USGS Patuxent Wildlife Research Center, Laurel, MD
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Sauer, J.R., et al. 1997. The North American breeding bird survey results and analysis. Version 96.4. Patuxent Wildl. Res. Center, Laurel, MD. Online. Available: http://www.mbr-pwrc.usgs.gov/bbs/bbs.html
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Tews, J., D. G. Bert, and P. Mineau. 2013. Estimated mortality of selected migratory bird species from mowing and other mechanical operations in Canadian agriculture. Avian Conservation and Ecology 8(2): 8.
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Van Damme, L.M. 1999. Status of the Bobolink in British Columbia. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. 28 pp. Working Report WR-93.
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Wittenberger, J.F. 1976. Habitat selection and the evolution of polygyny in Bobolinks (Dolichonyx oryzivorus). Ph.D. diss., Univ. Calif. at Davis, Davis, CA.
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Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.
Suggested Citation:
B.C. Conservation Data Centre. 2022. Conservation Status Report: Dolichonyx oryzivorus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Aug 19, 2025).