Justification of Red List Category
This species has a very 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 stable, 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 has not been quantified, but it is not believed to 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 global population size has not been quantified given recent taxonomic splits. Prior to being split, the species has been described as uncommon to common (del Hoyo et al. 2004).
The population trend has not been investigated. Tree cover loss within the range is very low (<2% over ten years; Global Forest Watch 2021, using Hansen et al.  data and methods disclosed therein). Given the species' apparent tolerance of some habitat degradation and open habitats (Jones 2020), deforestation is unlikely to drive a population decline. Therefore, in the absence of evidence for any substantial threats, the population is suspected to be stable.
Text account compilers
Butchart, S., Wheatley, H. & Ekstrom, J.
BirdLife International (2023) Species factsheet: Zimmerius improbus. Downloaded from http://www.birdlife.org on 24/03/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/03/2023.