Mishana Tyrannulet is known only from poor-soil forests in northern Peru, with two disjunct populations. To date, the lowland population is known only from the Nanay and Tigre river basins west of Iquitos, Peru. Recent records (Díaz-Alván et al. 2017) have extended the known distribution substantially northward within the Tigre River Basin, and the species should be looked for in poor-soil hilltop forest across northern Peru (and perhaps southern Ecuador).
The second population occurs in low-stature or scrubby forests in the Mayo and Huallaga river valleys of San Martín, Peru, at elevations up to 1100 meters above sea level (Schulenberg et al. 2010).
Despite significant field effort, the species is unrecorded from white-sands forests along the Morona River in western Loreto, suggesting that the species is genuinely absent from that area, creating a sizable disjunction between the two known populations.
Distribution outside the Americas
Endemic to the Americas.
Both populations of Mishana Tyrannulet are restricted to stunted or scrubby forests. The Nanay-Tigre population is most common in forest growing on pure white-sand soils. White-sand forests vary considerably in their structural and floristic characteristics, and while Mishana Tyrannulet occurs across the full range of white-sand forest types, ideal habitat for the species is moderately stunted forest that can be recognized by the presence of the visually distinctive tree Dicymbe uaiparuensis (Alvarez Alonso 2003). Recent fieldwork has found Mishana Tyrannulet on other poor-soil habitats in the Tigre River Basin, including forest on highly weathered clay-soil terraces and stunted forest on domed ombrotrophic peatlands (Díaz-Alván et al. 2017). Mishana Tyrannulet apparently is less common in these habitats compared to white-sand forest, but is potentially much more widespread than currently is known. Weathered clay terraces are ubiquitous across the Nauta Formation of northern Peru (Higgins et al. 2011), and so-called "peatland pole forests" are widely scattered across the vast swamps of the Ucamara Depression (Draper et al. 2014). Further work is required to elucidate the full extent of the distribution of Mishana Tyrannulet distribution in these habitats.
The San Martín population also occurs in stunted or scrubby forests. In the Mayo and Huallaga Valleys, these include semi-dry forests, degraded or secondary forests, and forest growing on sandy soils or low ridgetops.
Historical baseline data do not exist to infer changes. Deforested white-sand areas on the western outskirts of Iquitos presumably once held this species. Likewise, deforested white-sand areas along the Amazon downstream from the mouth of the Nanay River may have once held the species. Extensive deforestation in the Mayo and Huallaga valleys presumably has affected the San Martín population, though it has been recorded from secondary forest and scrub.
No fossil material exists for the Mishana Tyrannulet (Jessica Oswald, 2017 personal communication).
Socolar, J. (2018). Mishana Tyrannulet (Zimmerius villarejoi), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/nb.mistyr1.01