Bobolink (Dolichonyx oryzivorus) Conservation Status Review
Review Date = 12/20/2011
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
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.
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).
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.
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