Justification of Red List Category
This recently described species has a very small population, which is likely to be declining owing to habitat loss and degradation resulting from continuing timber extraction. The species consequently qualifies as Vulnerable.
Uncommon (Álvarez et al. 2012). The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.
This species is suspected to lose 21.4% of suitable habitat within its distribution over three generations (11 years) based on a model of Amazonian deforestation (Soares-Filho et al. 2006, Bird et al. 2011). It is therefore suspected to decline by <25% over three generations.
Zimmerius villarejoi is known only from an extremely limited habitat type in the río Nanay drainage near Iquitos, Loreto, the lower río Mayo and middle río Huallaga, San Martín (J. Díaz in litt. 2012), and a 1912 specimen taken from Moyobamba, San Martín, Peru.
It is confined to 'varillal' habitat - poorly drained, 12-18 m tall forest on white sand soils. The species's distribution seems to coincide with that of two or three tree species. It is uncommon and very patchily distributed. The diet includes small arthropods and fruit, notably the berries of the mistletoe Oryctanthus alveolatus.
Most of the known range is within a protected area. However, the limited extent of appropriate varillal habitat, and the continuing extraction of trees for building materials and posts, means that much of the population is threatened or at least compromised. Outside the protected area, the few varillales in which the species is known to occur (on the upper Rio Nanay) are completely unprotected, and are currently being heavily exploited for timber and other products.
Conservation Actions Underway
It occurs within the recently created Allpahuayo-Mishana National Reserve (c.580 km2).
10 cm. Rather non-descript greenish-yellow tyrannulet. Uniform olive upperparts. Most of underparts also olive, but this grades into yellow on the belly and undertail coverts. Wings dull black with faint olive cast and fringed (along with median and greater coverts) with yellow. Similar spp. Differs from sympatric Slender-footed Tyrannulet Z. gracilipes in having pinkish lower mandible. Voice Song is a simple series of two to four evenly spaced notes, the first being longest and each subsequent note being shorter.
Text account compilers
Benstead, P., Pople, R., Sharpe, C J, Symes, A., Wege, D.
Díaz Alván, J.
BirdLife International (2021) Species factsheet: Zimmerius villarejoi. Downloaded from http://www.birdlife.org on 09/12/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/12/2021.