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.
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).
This species is found in the USA and Canada. The nominate subspecies breweri occurs in the arid intermountain west of the USA (stretching north into south-east Alberta and south-west Saskatchewan, Canada) (Rotenberry 1999, Byers et al. 1995). Further north it is replaced by the subspecies S. b. taverneri (Rotenberry 1999, Byers et al. 1995), which occurs into south-eastern Alaska.
This species breeds on sagebrush flats and other open scrubby areas. It winters from just south of the breeding range in south-western USA to central Mexico (Rotenberry 1999, Byers et al. 1995), though the wintering grounds of S.b. taverneri remain largely unknown.
Habitat loss has accelerated owing to the invasion of exotic plants, particularly cheatgrass Bromus tectorum, which has increased fire frequency and altered post-fire successional pathways (Rotenberry 1998).
Text account compilers
Bird, J., Harding, M., Mahood, S., Butchart, S.
BirdLife International (2019) Species factsheet: Spizella breweri. Downloaded from http://www.birdlife.org on 18/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/10/2019.