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.
Declines have been noted in the USA (del Hoyo et al. 2004), and as a result an overall population decline is suspected. However, local trends could represent fluctuations, especially considering the number of both positive and negative processes acting on the population (del Hoyo et al. 2004).
Text account compilers
Ekstrom, J., Butchart, S.
BirdLife International (2019) Species factsheet: Tyrannus forficatus. Downloaded from http://www.birdlife.org on 16/09/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/09/2019.