Eared Grebe (Podiceps nigricollis) Conservation Status Review
Review Date = 12/22/2011
ScoreE - 2,500-10,000 individuals
CommentBased on the 118 records over approximately 80 locations of breeding in the Montan Natural Heritage Programs's database, and an average colony size of 4 from the 2010 waterbird report, the probable population size in Montana is somewhere between 1,000 and 10,000 individuals.
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)
CommentLarge numbers of reservoirs have been created across Montana and many provide habitat for this species, so the population is likely stable within +/- 25% of pre-European levels.
ScoreU - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.
CommentBreeding Bird Survey data is of low credibility in Montana and shows a nonsignificant increase of -4.0% per year or 34% decrease per decade. Surrounding states and provinces show both positive and negative trends and most are of low credibility and nonsignificant.
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.
CommentContaminants, fish stocking, drought related to climate change, and habitat loss all represent threats.
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.
CommentHabitat could recover relatively quickly and Eared Grebes should be able to respond in turn.
ScopeModerate - 20-60% of total population or area affected
Comment>20% of sites are likely impacted by drought, fish stocking, or some sort of habitat loss/alteration.
ImmediacyModerate - Threat is likely to be operational within 2-5 years.
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. Species breeds on shallow lakes and ponds with emergent vegetation and highly productive macroinvertebrate communities.