The chestnut-headed nunlet (''Nonnula amaurocephala'') is a species of

near-passerine Near passerines and higher land-bird assemblage are terms of traditional, pre-cladistic taxonomy that have often been given to tree-dwelling birds or those most often believed to be related to the true passerines (order Passeriformes) owing to mor ...

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

in the family

Bucconidae The puffbirds and their relatives in the family Bucconidae are tropical tree-dwelling insectivorous birds that are found from South America up to Mexico. Together with their closest relatives, the jacamars, they form a divergent lineage within th ...

, the puffbirds, nunlets, and nunbirds. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

Taxonomy and systematics

The chestnut-headed nunlet is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

. It, the rufous-capped nunlet (''N. ruficapilla''), and the grey-cheeked nunlet (''N. frontalis'') form a

superspecies In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

.Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, A. Jaramillo, D. F. Lane, J. F. Pacheco, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 24 August 2021. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved August 24, 2021

Description

The chestnut-headed nunlet is long and weighs . Its entire head, upper mantle, breast, and upper belly are bright rufous. Its back, wings, and tail are plain dull brown; the rump has an olive wash. The rufous upper belly grades to whitish on the lower belly. The bill is mostly black, the eye red, and the feet lead gray.

Distribution and habitat

The chestnut-headed nunlet is found only in a small part of Brazil's Amazonas state, north of the Amazon River and west of the

Negro River In the English language, the term ''negro'' (or sometimes ''negress'' for a female) is a term historically used to refer to people of Black people, Black African heritage. The term ''negro'' means the color black in Spanish and Portuguese (from ...

. It almost exclusively inhabits the understory of seasonally flooded ''

igapó (, from Tupi language, Old Tupi: "root forest") is a word used in Brazil for Blackwater river, blackwater-flooded forests in the Amazon biome. These forests and similar swamp forests are seasonally inundated with freshwater. They typically occur ...

'' forest, usually up to about above the ground but sometimes as high as .

Behavior

Feeding

The chestnut-headed nunlet has been observed sallying from a perch, presumably to catch invertebrate prey, but no details of its feeding behavior or diet have been published.

Breeding

No details of the chestnut-headed nunlet's breeding

phenology Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonal and interannual variations in climate, as well as habitat factors (such as elevation). Examples include the date of emergence of leav ...

have been published.

Vocalization

No recordings or description of the chestnut-headed nunlet's vocalizations are available as of late 2021.

Status

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

originally assessed the chestnut-headed nunlet in 1988 as Near Threatened but since 2004 has rated it as being of

Least Concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

. It has a very small range and unquantified population that is believed to be decreasing. Its ''igapó'' habitat is widespread and under little human pressure, and the species is probably undercounted due to its quiet and sedentary nature.

References

{{Taxonbar, from=Q1270689 Nonnula Birds of Northern Amazonia Birds of the Brazilian Amazon Endemic birds of Brazil Birds described in 1921 Taxonomy articles created by Polbot