Slaty-capped shrike-vireo

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Slaty-capped shrike-vireo
Vireolanius leucotis - Slaty-capped Shrike-Vireo.JPG
at Apiacás, Mato Grosso state, Brazil
Vireolanius leucotis - Slaty-capped Shrike-Vireo
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Vireonidae
Genus: Vireolanius
Species:
V. leucotis
Binomial name
Vireolanius leucotis
(Swainson, 1838)
Vireolanius leucotis map.svg
Range of V. leucotis sensu stricto (without V. l. mikettae). See the Taxonomy and Distribution sections.

The slaty-capped shrike-vireo (Vireolanius leucotis) is a species of bird in the family Vireonidae, the vireos, greenlets, and shrike-babblers. [3] It is found in every mainland South American country except Argentina, Chile, Paraguay, and Uruguay. [4]

Contents

Taxonomy and systematics

The slaty-capped shrike-vireo was originally described in 1838 as Malaconotus leucotis. [5] It was eventually placed in genus Vireolanius but for a time in the early twentieth century it was placed in genus Smaragdolanius and its own family, Vireolaniidae. By the 1970s Smaragdolanius had been merged into Vireolanius and included in the family Vireonidae. [6]

The slaty-capped shrike-vireo's further taxonomy is unsettled. The IOC, the Clements taxonomy, and AviList assign it these four subspecies: [3] [7] [8]

BirdLife International's Handbook of the Birds of the World (HBW) follows as 2014 publication and treats V. l. mikettae as a separate species, the pale-legged shrike-vireo. [9] [10] Clements recognizes that it is distinctive within the larger species by calling it the "slaty-capped shrike-vireo (pale-legged)". [7] AviList also recognizes that this treatment as a separate species might be correct but is awaiting further evidence. [8]

This article follows the one-species, four-subspecies model.

Vireolanius leucotis Keulemans 1878 VireolaniusLeucotisKeulemans.jpg
Vireolanius leucotis Keulemans 1878

Description

The slaty-capped shrike-vireo is 14 to 15 cm (5.5 to 5.9 in) long; the nominate subspecies V. l. leucotis weighs 21.5 to 30 g (0.76 to 1.1 oz). The sexes have the same plumage. Adults of the nominate subspecies have a blue-gray crown and nape. They have a bright yellow forehead, supercilium, and crescent below the eye. Their lores are dull blackish gray. They have a deep grayish blue stripe through the eye and "moustache" on an otherwise dull white face. Their upperparts and tail are bright olive-green. Their flight feathers are mostly dull blackish gray with olive-green outer webs that show as a bright patch on the closed wing. Their chin, throat, and breast are bright lemon yellow, their belly a duller lemon yellow, their flanks duller greenish yellow, and their undertail coverts lemon yellow. [11]

Subspecies V. l. simplex has a light green band on its forehead, a greenish front to the moustache, and an otherwise light gray face. Their nape is paler than the nominate's and their back is duller green with a grayish tinge. V. l. bolivianus has a blackish border across the forehead that continues above the supercilium; it is otherwise like the nominate. V. l. mikettae has a facial pattern like the nominate's but is olive where it is dull white. The yellow of its supercilium and underparts is deeper and brighter than the nominate's and its flanks are a darker olive green. All subspecies except V. l. mikettae have a pale green or lime-green iris, a black maxilla, a pale gray or leaden blue mandible, and pale gray or leaden blue legs and feet. V. l. mikettae has yellow to pinkish yellow legs and feet. [11]

Distribution and habitat

The slaty-capped shrike-vireo has a disjunct distribution; the range of V. l. mikettae is separate from the contiguous ranges of the other three subspecies. The subspecies are found thus: [11]

The slaty-capped shrike-vireo inhabits the canopy and edges of humid forest in the lowlands, foothills and lower parts of the highlands. [11] In both Peru and Venezuela it is more common at the higher elevations than in the lowlands. [12] [13] In elevation it ranges from sea level to 1,800 m (5,900 ft) in Brazil. [14] It is found between 300 and 2,000 m (1,000 and 6,600 ft) in Colombia, mostly below 1,100 m (3,600 ft) in Ecuador, up to 1,400 m (4,600 ft) in Peru, and between 200 and 1,300 m (700 and 4,300 ft) in Venezuela. [15] [16] [12] [13]

Behavior

Movement

The slaty-capped shrike-vireo is apparently a sedentary year-round resident. [11]

Feeding

The slaty-capped shrike-vireo feeds on arthropods and apparently favors caterpillars. It forages mostly from the forest's mid-story to its canopy. It typically forages singly, in pairs, or family groups and frequently leads mixed-species feeding flocks. It takes most prey from the underside of leaves and twigs. [11] [16]

Breeding

Nothing is known about the slaty-capped shrike-vireo's breeding biology. [11]

Vocalization

The slaty-capped shrike-vireo's song is a "single loud melodious descending whistle tyeer or eear, seemingly endless repeated", with some variation among the subspecies. That of subspecies V. l. mikettae is the most distinctive; its whistles are longer than the others' and are on almost the same pitch rather than descending. The species also makes a "short nasal steeply downslurred note tjew" and a "short grating low-pitched note" written as "Rrek". The species sings especially when leading a mixed-species flock throughout the morning; it apparently functions to allow the flock to maintain itself. [11]

Status

The IUCN follows HBW taxonomy and so has separately assessed the slaty-capped sensu stricto and "pale-legged" shrike-vireos. Both are assesses as being of Least Concern. The population size of neither is known and both are believed to be decreasing. No immediate threats to either have been identified. [1] [2] It is considered uncommon in Colombia and Peru, uncommon to fairly common in Venezuela, and "frequent to uncommon" in Brazil. [15] [12] [13] [14] It occurs in several protected areas. [11]

References

  1. 1 2 BirdLife International (2025). "Slaty-capped Shrike-vireo Vireolanius leucotis". IUCN Red List of Threatened Species . 2025 e.T103693756A281039827. doi: 10.2305/IUCN.UK.2025-2.RLTS.T103693756A281039827.en . Retrieved 15 November 2025.
  2. 1 2 BirdLife International (2024). "Pale-legged Shrike-vireo Vireolanius mikettae". IUCN Red List of Threatened Species . 2024 e.T103693760A264420167. doi: 10.2305/IUCN.UK.2024-2.RLTS.T103693760A264420167.en . Retrieved 15 November 2025.
  3. 1 2 Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (March 2025). "Vireos, shrike-babblers". IOC World Bird List. v 15.1. Retrieved 3 March 2025.
  4. ↑ Remsen, J. V., Jr., J. I. Areta, E. Bonaccorso, S. Claramunt, D. F. Lane, L, N. Naka, M. B. Robbins, F. G. Stiles, and K. J. Zimmer. Version 29 September 2025. Species Lists of Birds for South American Countries and Territories. South American Classification Committee associated with the International Ornithological Union. https://www.museum.lsu.edu/~Remsen/SACCCountryLists.htm retrieved September 29, 2025
  5. ↑ Swainson, William (1838). Animals in menageries. Printed for Longman, Orme, Brown, Green, & Longmans, and John Taylor. pp. 341–342. Retrieved November 15, 2025.
  6. ↑ Garcia, K. (2020). Green Shrike-Vireo (Vireolanius pulchellus), 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.grsvir1.01 retrieved November 14, 2025
  7. 1 2 Clements, J. F., P. C. Rasmussen, T. S. Schulenberg, M. J. Iliff, J. A. Gerbracht, D. Lepage, A. Spencer, S. M. Billerman, B. L. Sullivan, M. Smith, and C. L. Wood. 2025. The eBird/Clements checklist of Birds of the World: v2025. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/ retrieved November 3, 2025
  8. 1 2 AviList Core Team. 2025. AviList: The Global Avian Checklist, v2025. https://doi.org/10.2173/avilist.v2025 retrieved June 11, 2025
  9. ↑ Slager, D. L., C. J. Battey, R. W. Bryson, G. Voelker, and J. Klicka (2014). "A multilocus phylogeny of a major New World avian radiation: the Vireonidae". Molecular Phylogenetics and Evolution 80:95–104.
  10. ↑ HBW and BirdLife International (2025). Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 10. Available at: https://datazone.birdlife.org/about-our-science/taxonomy#birdlife-s-taxonomic-checklist retrieved October 12, 2025
  11. 1 2 3 4 5 6 7 8 9 Brewer, D., J. del Hoyo, G. M. Kirwan, N. Collar, and P. F. D. Boesman (2022). Slaty-capped Shrike-Vireo ('Vireolanius leucotis), version 1.1. In Birds of the World (B. K. Keeney, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.scsvir1.01.1 retrieved November 15, 2025
  12. 1 2 3 Schulenberg, T.S.; Stotz, D.F.; Lane, D.F.; O'Neill, J.P.; Parker, T.A. III (2010). Birds of Peru. Princeton Field Guides (revised and updated ed.). Princeton, NJ: Princeton University Press. p. 506. ISBN   978-0691130231.
  13. 1 2 3 Hilty, Steven L. (2003). Birds of Venezuela (second ed.). Princeton NJ: Princeton University Press. p. 674.
  14. 1 2 van Perlo, Ber (2009). A Field Guide to the Birds of Brazil. New York: Oxford University Press. pp. 336–337. ISBN   978-0-19-530155-7.
  15. 1 2 McMullan, Miles; Donegan, Thomas M.; Quevedo, Alonso (2010). Field Guide to the Birds of Colombia. Bogotá: Fundación ProAves. p. 177. ISBN   978-0-9827615-0-2.
  16. 1 2 Ridgely, Robert S.; Greenfield, Paul J. (2001). The Birds of Ecuador: Field Guide. Vol. II. Ithaca: Cornell University Press. p. 567. ISBN   978-0-8014-8721-7.
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