Castelnau's antshrike

Castelnau's antshrike
Conservation status
Least Concern  (IUCN 3.1) [1]
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Thamnophilidae
Genus:	Thamnophilus
Species:	T. cryptoleucus
Binomial name
Thamnophilus cryptoleucus (Ménégaux & Hellmayr, 1906)

Castelnau's antshrike (Thamnophilus cryptoleucus) is a species of bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". ^[2] It is found in Brazil, Colombia, Ecuador, and Peru. ^[3]

Taxonomy and systematics

Castelnau's antshrike was originally described as Myrmelastes cryptoleucus. By the principle of priority, Myrmelastes is junior to Myrmeciza. In 1924 it was transferred to that genus and then in 1927 to its current Thamnophilus. Later some authors treated Castelnau's antshrike as a subspecies of the blackish-grey antshrike (T. nigrocinereus), but that approach was not widely accepted. They are now considered sister species. ^{[4] [5] [6]} Castelnau's antshrike is monotypic. ^[2]

Description

Castelnau's antshrike is 16 to 18 cm (6.3 to 7.1 in) long and weighs 30 to 35 g (1.1 to 1.2 oz). Members of genus Thamnophilus are largish members of the antbird family; all have stout bills with a hook like those of true shrikes. This species exhibits slight sexual dimorphism. Adult males are mostly black. They have a mostly hidden white patch between their scapulars, white tips on the scapulars, white tips and edges on their wing coverts, sometimes very small white tips on their flight feathers, and white underwing coverts. Their flanks and belly are dark gray. Adult females are similar to males but their scapulars and wing coverts are entirely black. Subadults are similar to adult females but browner. Both sexes have a brown iris, a black bill, and blue-gray legs and feet. ^{[4] [7] [8] [9] [10]}

Distribution and habitat

Castelnau's antshrike is found along the upper Amazon River and its major upstream tributaries. It occurs along the Rio Napo in Ecuador and Peru to where it enters the Amazon. In Ecuador it also occurs along the Río Pastaza and presumably further downstream on that river in Peru. In Peru it also occurs along the rios Marañón and Ucayali. In Colombia it occurs in the extreme south along the Amazon, and in Brazil along the Amazon almost to the Rio Negro. Castelnau's antshrike is found almost exclusively on river islands but also occurs on the "mainland" near the rivers. In all areas it occurs mostly in dense understorey but commonly into the mid-storey as well. In elevation it occurs only as high as about 300 m (1,000 ft). ^{[4] [7] [8] [9] [10]}

Behavior

Movement

Castelnau's antshrike is presumed to be a year-round resident throughout its range. ^[4]

Feeding

The diet of Castelnau's antshrike is not known in detail but includes insects and other arthropods. It usually forages singly or in pairs and seldom joins mixed-species feeding flocks. It usually forages between 1 and 3 m (3 and 10 ft) of the ground but does feed as high as 9 m (30 ft). It forages while hopping among branches, commonly reaching or making short jumps from a perch to glean prey. ^{[4] [8] [9]}

Breeding

Little is known about the breeding biology of Castelnau's antshrike. The only described nests were found during June and July in Peru; other evidence suggests that the species' breeding season extends from March to October. The nests were a cup made mostly of grass and suspended in a branch fork 1 to 3 m (3 to 10 ft) above the ground. The clutch size was two eggs. The incubation period, time to fledging, and details of parental care are not known. ^[4]

Songs and calls Listen to Castelnau's antshrike on xeno-canto

Vocalization

The song of Castelnau's antshrike has been described as "a short, fast, accelerating 'keoh, keoh, kuh-kuh-kuhkuhkuhkuhkuh' with [a] nasal, bouncing-ball quality" ^[8] and as "an accelerating, descending series of downslurred notes: kyuk kyuk-kyew-kew-kew'ku'ku'kukuku" ^[9] . Its calls include "a drawn-out 'kawh' " that is sometimes doubled or in a series and "a 'kowah, kr-r-r-' ". ^[8] These are also described as "a cawing raow [and] raow-brrrrrrrrr". ^[9]

Status

The IUCN originally in 2012 assessed Castlenau's antshrike as Near Threatened but in 2023 downlisted to being of Least Concern. It has a large range; its population size is not known and is believed to be decreasing. "The primary threat to this species is accelerating deforestation in the Amazon basin, as land is cleared for agricultural production. It is rendered particularly susceptible because of its reliance on islands and riparian forest, which are easily accessible and therefore subject to higher levels of human encroachment and logging activities." ^[1] "Human activity has little short-term direct effect on Castelnau's Antshrike, other than the local effects of habitat destruction; this species occupies successional habitats, however, and is tolerant of a low level of human disturbance. In the longer term, Castelnau's Antshrike potentially is vulnerable to widespread habitat loss, as might occur through perturbations of the Amazonian hydrological regime stemming from widespread deforestation, dam construction, or global climate change." ^[11]

References

1. BirdLife International (2023). "Castelnau's Antshrike Thamnophilus cryptoleucus". IUCN Red List of Threatened Species . 2023: e.T22701306A223801446. doi: 10.2305/IUCN.UK.2023-1.RLTS.T22701306A223801446.en . Retrieved 22 March 2024.
2. Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (January 2024). "Antbirds". IOC World Bird List. v 14.1. Retrieved 4 January 2024.
3. Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, G. Del-Rio, A. Jaramillo, D. F. Lane, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 4 March 2024. Species Lists of Birds for South American Countries and Territories. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved March 5, 2024
4. Schulenberg, T. S. and G. H. Rosenberg (2020). Castelnau's Antshrike (Thamnophilus cryptoleucus), version 1.0. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.casant1.01 retrieved March 22, 2024
5. Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, G. Del-Rio, A. Jaramillo, D. F. Lane, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 4 March 2024. A classification of the bird species of South America. American Ornithological Society. https://www.museum.lsu.edu/~Remsen/SACCBaseline.htm retrieved March 5, 2024
6. Brumfield, R.T. and Edwards, S.V. (2007). Evolution into and out of the Andes: a Bayesian analysis of historical diversification in Thamnophilus antshrikes. Evolution 61(2): 346–367.
7. McMullan, Miles; Donegan, Thomas M.; Quevedo, Alonso (2010). Field Guide to the Birds of Colombia. Bogotá: Fundación ProAves. p. 129. ISBN   978-0-9827615-0-2.
8. Ridgely, Robert S.; Greenfield, Paul J. (2001). The Birds of Ecuador: Field Guide. Vol. II. Ithaca: Cornell University Press. p. 394. ISBN   978-0-8014-8721-7.
9. Schulenberg, T.S., D.F. Stotz, D.F. Lane, J.P. O’Neill, and T.A. Parker III. 2010. Birds of Peru. Revised and updated edition. Princeton University Press, Princeton, New Jersey plate 159
10. van Perlo, Ber (2009). A Field Guide to the Birds of Brazil. New York: Oxford University Press. pp. 234–235. ISBN   978-0-19-530155-7.
11. Armacost, J.W., Jr. 2004. The nest, eggs, and nestlings of the Castelnau's Antshrike (Thamnophilus cryptoleucus), with notes on its ecology and conservation. Wilson Bulletin 116: 262-266.