Population status

Black Turnstone
(Arenaria melanocephala)

Black Turnstones are distributed along the rocky shorelines of British Columbia in winter. It is likely that large proportions of the total population use Canadian coastlines during this time (Gratto-Trevor et al. 2011). Data from the Christmas Bird Count (CBC) capture only a small fraction of the range-wide population, but they are the only long-term data available, and the species is present in small but consistent groups in predictable habitat that tends to be regularly accessed by surveyors. In Canada, CBC results are based on only 40 count circles. Neverthess, the trend is precise, and suggests little overall change in the Canadian population since about 1970. Continental CBC results, which have a larger sample size (125 circles), suggest a trend that is borderline between little change and moderate decrease (-25%). The majority of this more negative trend comes from the Oregon coast (Meehan et al. 2018). The British Columbia Coastal Waterbird Survey corroborates the CBC results for Canada, indicating little change in the regional population between 1999 and 2016. Overall, the population may be best considered as having shown little overall change in Canada relative to 1970, though the reliability of this assessment is considered medium. The Black Turnstone is at an acceptable level relative to its national population goal (see Canada graph below).

 

Population goal and acceptable levels of variation

Species/groupGoalLower levelUpper level
Black TurnstoneMean abundance (first 5 years of survey)Goal minus 25% Not applicable

Picture of logo Christmas Bird Count (CBC)

Additional information on: Christmas Bird Count (CBC)

Table 1: Population trends by geographic area
Geographic areaTime PeriodAnnual Trend Table 1 - footnote 1 Limits
LowerUpper
Canada Select to view graph of the geographic area: Canada 1970-2016; Christmas Bird Count (CBC)1970-20160.2-1.31.59
North America Select to view graph of the geographic area: North America 1970-2016; Christmas Bird Count (CBC)1970-2016-0.6-1.70.294
 

British Columbia Coastal Waterbird Survey

Additional information on: British Columbia Coastal Waterbird Survey

Table 2: Population trends by geographic area
Geographic areaTime PeriodAnnual Trend Table 2 - footnote 1 Limits
LowerUpper
British Columbia coast1999-2016-1.2-4.62.4
 

References