Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The population is estimated to number c.430,000-520,000 individuals (Wetlands International 2014).
This species has undergone a small or statistically insignificant decrease over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) and is listed as declining by Wetlands International (2014).
Reduction in discards from fisheries has greatly reduced available food in parts of the species range that had seen rapid increases in the previous century. Egging continues to the present day in rural parts of New Brunswick and Nova Scotia, and by indigenous people from Alberta to Labrador but rates are thought to be unlikely to be driving declines (Nisbet et al. 2017). Control programmes are in place at many airports, to prevent damage to aircraft, but the impact is not thought to be significant (Nisbet et al. 2017). The closely related European Herring Gull, ecologically and behaviourally equivalent, was the most frequently recorded casualty to collisions with wind turbines in a study of 4.7 km of the English coastline over 11 years (Newton and Little 2009). It is also likely to experience a change in suitable habitat due to the effects of climate change however, the effect of this is not currently known.
Text account compilers
Butchart, S., Hatchett, J., Calvert, R., Malpas, L., Ekstrom, J., Martin, R., Stuart, A., Symes, A., Taylor, J.
BirdLife International (2019) Species factsheet: Larus smithsonianus. Downloaded from http://www.birdlife.org on 18/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/11/2019.