Iquitos Gnatcatcher Polioptila clementsi Scientific name definitions

The Iquitos Gnatcatcher is a newly described species of gnatcatcher known exclusively from a handful of white-sands patches in the Allpahuayo-Mishana Reserve, near Iquitos in northeastern Peru. It closely resembles the Guianan Gnatcatcher (Polioptila guianensis), but is geographically isolated, and differs in details of plumage and voice. It is apparently restricted to the canopy of white-sands forest (varillal), where it has primarily been observed accompanying mixed-species flocks. The Iquitos Gnatcatcher differs markedly from the Tropical Gnatcatcher (Polioptila plumbea), the only sympatric Gnatcatcher in that Iquitos Gnatcatcher lacks a black cap, is more uniformly gray on the body (especially the breast), shows distinct white eye arcs, and has white outer tail feathers. The song is quite different from Tropical’s song, but is similar to the sympatric Chestnut-shouldered Antwren (Euchrepomis humeralis), consisting of 2-3 introductory notes followed by a rapid trill. Little is known about the behavior and natural history of this species, but the dearth of observations has prompted extreme alarm over its conservation status. Prior to taxonomic revisions, BirdLife International treated the species as Critically Endangered, but today BirdLife considers the species to be conspecific with Guianan Gnatcatcher (Least Concern). The American Ornithological Society maintains the Iquitos Gnatcatcher as a distinct species, and Peruvian endangered species legislation has created a nascent recovery program for the species.

11 cm; 5–6 g. Adult male and female not definitely described, as all specimens collected to date showed incomplete ossification of skull, though some apparently adult behaviour; numerous other individuals observed showed no plumage differences, and adult plumage seems likely to be very similar to that recorded for immatures. Immature male has forehead, side of head, crown, nape, back and rump dark grey; narrow white eyering broken at front and back; remiges blackish, outer vanes finely edged with grey; tail black, outermost pair of rectrices two-thirds to four-fifths white terminally, next pair about two-thirds to three-quarters white, next pair mostly blackish with c. 5 mm of white at tip; extent of white on outer rectrices asymmetrical between left and right (such asymmetry exhibited also by some juveniles of P. californica and P. melanura, at least suggesting possibility that it may not persist in adult of present species); throat and breast medium grey, slightly paler than upperparts; belly and undertail-coverts white;.

Differs from very similar P. guianensis in having longer bill.

Iris

Variously described as “brown,” “greyish-brown,” or “pale brown, almost cream.” Variation in eye color, is seldom described within species of this genus, and warrants further study.

Bill

Upper mandible black, lower mandible grayish-horn.

Tarsi & Toes

Legs bluish-grey, footpads whitish.

Part of the P. guianensis species complex, that also contains P. guianensis, P. facilis and P. paraensis, and P. attenboroughi, all of which have at times been lumped into a polytypic P. guianensis (1 Atwood, J., Lerman, S. & Kirwan, G.M. (2019). Guianan Gnatcatcher (Polioptila guianensis). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Available from https://www.hbw.com/node/58988. Close ). Present species along with P. schistaceigula, however, makes such a grouping polyphyletic (2 Smith, B. T., R. W. Bryson, Jr., W. M. Mauck, III, J. Chaves, M. B. Robbins, A. Aleixo and J. Klicka (2018) Species delimitation and biogeography of the gnatcatchers and gnatwrens (Aves: Polioptilidae). Molecular Phylogenetics and Evolution 126: 45-57. Close ).

Monotypic.

Iquitos region (NC Loreto), in Amazon Basin of NE Peru.

Tall, humid varillal forest dominated by Catalpa, canopy height variable, 15–30 m; plant species composition and abundance variable over small spatial scales. Type locality on border of ecoregions characterized as Napo moist forest and Iquitos varzeá. Elevation at single locality of known occurrence 150 m.

No well known, but presumably similar to its congeners in most ways.

Actively forages in canopy and subcanopy (upper quarter of trees) with mixed-species flocks composed primarily of other insectivores, and usually including some small frugivores and nectarivores; possibly replaced by P. plumbea in some mixed flocks in canopy of varillal habitats. Forages mostly in terminal portions of live, leafy branches; techniques include gleaning, short stabbing reaches, and acrobatic chases of fleeing prey; tail held partially cocked, frequently flicked laterally and briefly opened slightly to expose white outer rectrices.

Stomach contents of one specimen included insect fragments and small, white arthropod eggs.

Song a distinctly two-part series, initial 3 notes high (maximum frequency c. 8 kHz), sharp (duration c. 0.12 seconds) and evenly paced (delivered at c. 0.2-second intervals), followed by a series of lower (dominant frequency c. 6 kHz), sharper (c. 0.025 seconds duration) notes evenly delivered at c. 0.06-second intervals. Brief, quiet chatter, first note distinctly louder and longer, all notes with harmonics, given in uncertain context. Also quiet, single-note calls (c. 3 kHz); sharp, high-frequency (c. 7 kHz) calls, in doublets in flight or irregularly while foraging; an agitated call in response to playback rendered as repeated series of cadenced notes, “chik-chéé-dee, chik- chéé-dee, chik- chéé-dee, chik- chéé-dee.”

The nest, eggs, and breeding behavior of Iquitos Gnatcatcher remain undescribed.

Specimens in mid-December and early April are probably juveniles (unossified skulls), with those collected in mid-Dec thought to have been giving food-begging calls (behaviour which in other gnatcatchers persists for only c. 1 month after fledging). No other information.

Previously, Iquitos Gnatcatcher was considered Critically Endangered (3 Atwood, J. L., and S. B. Lerman (2006) Family Polioptilidae (gnatcatchers) Pages 350-376 in Handbook of the birds of the world. Volume 11 (J. del Hoyo, A. Elliott and D. Christie, Editors). Lynx Edicions, Barcelona. Close ), but currently not recognized as a valid species by BirdLife International. Poorly known; apparently rare and local. Patchy in distribution, and sometimes absent from apparently suitable habitat contiguous with active territories. Entire known range (six localities, totalling c. 2000 ha 4 Whitney, B.M. and Álvarez, J.A. (2005). A new species of gnatcatcher from white-sand forests of northern Amazonian Peru with revision of the Polioptila guianensis complex. Wilson Bull. 117(2): 113–127. Close ) is officially protected by Allpahuayo-Mishana National Reserve (IUCN Cat. VI; 581 km²), but this is a sustainable-use area within which logging is permitted for construction, charcoal and fuel (4 Whitney, B.M. and Álvarez, J.A. (2005). A new species of gnatcatcher from white-sand forests of northern Amazonian Peru with revision of the Polioptila guianensis complex. Wilson Bull. 117(2): 113–127. Close ). By the end of 2012, however, 55 privately-owned properties in the eastern part of the reserve, with a combined area of 960 ha, had been donated to the National Protected Areas Service, SERNANP External link . Surveys of available habitat within the reserve have only located 15 pairs BirdLife International (2015) Species factsheet: Polioptila clementsi. Downloaded from http://www.birdlife.org on 20/03/2015. . Critically Endangered because of its small population size (fewer than 250 mature individuals estimated BirdLife International (2015) Species factsheet: Polioptila clementsi. Downloaded from http://www.birdlife.org on 20/03/2015. ) and past and continuing loss of apparently specialized white-sand forest habitat.