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). The population trend appears to be increasing, and hence the species does not 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 increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007).
Regulus calendula occurs throughout North America, in the U.S.A., Canada, Mexico and Guatemala (del Hoyo et al. 2006). The subspecies obscurus, endemic to Mexico's Guadalupe Island, was last recorded in 1953 and is now considered extinct (Barton et al. 2004).
Text account compilers
Butchart, S., Ekstrom, J., Khwaja, N.
BirdLife International (2019) Species factsheet: Regulus calendula. Downloaded from http://www.birdlife.org on 26/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/08/2019.