LC
Western Grebe Aechmophorus occidentalis



Justification

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 very 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.

Population justification
The population is estimated to number 130,000 individuals.

Trend justification
The overall population trend is decreasing, although some populations have unknown trends (Wetlands International 2006). This species has undergone a small or statistically insignificant decrease over the last 40 years in North America (data for Aechmophorus occidentalis and A. clarkii combined, from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).

Acknowledgements

Text account compilers
Ekstrom, J., Butchart, S.


Recommended citation
BirdLife International (2017) Species factsheet: Aechmophorus occidentalis. Downloaded from http://www.birdlife.org on 20/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 20/10/2017.