Rock Wren (Salpinctes obsoletus)

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This article is about the North American bird. For the New Zealand bird, see New Zealand rock wren.
"Salpinctes" redirects here; this is also a junior synonym for Mandevilla, a genus of vines.

Rock wren
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Troglodytidae
Genus: Salpinctes
Cabanis, 1847
Species:
S. obsoletus
Binomial name
Salpinctes obsoletus
(Say, 1823)
Subspecies[2]
  Breeding
  Migration
  Year-round
  Nonbreeding
Synonyms[3]
  • Troglodytes obsoleta (Say, 1823)
  • Troglodytes latifasciatus (Deppe, 1830)

The rock wren (Salpinctes obsoletus) is a small songbird of the wren family native to the rocky areas of western North America. There are 8 subspecies of the rock wren, one extinct: the San Benedicto rock wren, as a result of the eruption of Volcán Bárcena. They are similar in size to other wrens, with a grey-brown coat, a brown rump, and a speckled white throat. They are noted for their variable song and song pattern, used for territory defense, as well as their habit of building "pavements" with flat rocks around their nest to help nestlings stay dry. Rock wrens are serially monogamous, forming pairs for nesting season. Nestbuilding usually begins in March, usually in crevices, and the first brood are laid late April to June, with a possible second brood later in June. They are largely terrestrial foragers, rarely flying. Their diet consists of insects, mostly weevils, during the spring and summer, shifting to grain during autumn and winter. They are a least-concern species, however, their population size has declined 13% in 10 years.

Taxonomy

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The rock wren was first described by Thomas Say, published in Edwin James' 1823 book "Account of an Expedition from Pittsburgh to the Rocky Mountains, Performed in the Years 1819 and '20" as Troglodytes obsoleta.[4] It was later moved to its own monotypic genus, Salpinctes, by Jean Cabanis in 1847, because of its straighter tail.[5] Salpinctes formerly included the canyon wren(synonym Thryothorus mexicanus), however it was later removed.[5]

The genus name, Salpinctes, comes from the Greek word for "trumpeter". Its specific epithet, obsoletus, is Latin for "worn out". There are 8 subspecies, split into 2 groups (obsoletus and guttatus).[2]

Northern group - obsoletus

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  • S. o. obsoletus (Say, 1822) — Nominate subspecies.[2]
  • S. o. guadeloupensis (Ridgway, 1876) — Found on Guadalupe Island, off western Baja California. Darker than other island populations, with longer, heavier bill and shorter wing and tail. Juveniles have barred, dusky backs. Its name, guadeloupensis, comes from its habitat, Guadalupe Island.[2]
  • S. o. tenuirostris (van Rossem, 1943) — Similar to nominate, but with thinner and longer bill. Found on San Benito Island. Its name comes from the Latin words tenuis and rostrum, meaning "slender" and "beak" respectively. [2]
  • S. o. exsul (Ridgway, 1903) — Extinct from the eruption of Volcán Bárcena. Formerly found on San Benedicto Island. Said to have been generally darker than nominate, along with more cinnamon-buff bars on outer rectrices. Its name comes from the Latin word exsul, meaning "exile".[2]
  • S. o. neglectus (Nelson, 1897) — Similar to nominate, but with barred flanks, darker, and with more spots on breast. Noted to be variable in appearance. Found in the highlands of southern Mexico. Name comes from Latin neglectus, meaning "overlooked".[2]

Southern group - guttatus

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  • S. o. guttatus (Salvin and Godman, 1891) — Flanks are spotted, instead of barred flanks like fasciatus. Found in the highlands of El Salvador. Name comes from Latin guttatus, meaning 'spotted'. [2]
  • S. o. fasciatus (Salvin and Godman, 1891) — Flanks are barred, instead of spotted flanks like guttatus. Found in the highlands of Nicaragua. Name comes from Latin fasciatus, meaning 'banded'.[2]
  • S. o. costaricensis (van Rossem, 1941) — Generally paler compared to fasciatus, as well as having a longer, larger bill. Found in the highlands of northwestern Costa Rica. The name comes from the name for Costa Rica.[2]

Description

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Rock wrens are 12.5–15 cm (4.9–5.9 in) in length and 22–24 cm (8.7–9.4 in) in wingspan. Bill length is 18.7 mm (0.74 in) and 17.8 mm (0.70 in) in males and females respectively. Wing length is 70.3 mm (2.77 in) in males, slightly less at 67.8 mm (2.67 in) in females, similarly for the tail length: 51.9 mm (2.04 in) and 47.8 mm (1.88 in) respectively. However, males weigh 15.7 g (0.55 oz), slightly less than females, who weigh 17.2 g (0.61 oz).[2][6]

Rock wrens have grey-brown upperparts with small black and white spots and pale grey underparts with a light brown rump.[7] Additional features include a light grey line extending through the eye, a long and sharp bill,[8] a speckled light gray throat, a long barred tail, zebra-striped undertail coverts, and dark legs.[2] Juvenile plumage is similar to adult, except for a slightly more vibrant buff, similar to a washed-out cinnamon color, fluffier body feathers, and absence dark streak and spots on the underparts.[2]

They are very distinct in their habitat, however, it is possible to confuse them with the canyon wren, which have superficially similar coloring, however, their solid white throats, and their generally brighter, less muddled colors, are notable differences.[2][9]

Distribution and habitat

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Rock wrens are permanent residents in the south of their range, including California, western Washington, northern Nevada, Arizona, and New Mexico, southern Guatemala and Nicaragua, northwestern Costa Rica and Panama, as well as inland Mexico, including Baja California.[2][10] They are also residents of Guadalupe Island and San Benito Island.[2] They are occasional vagrants in the eastern United States. During the breeding season their range extends to the southern interior of British Columbia, as well as Wyoming, Montana, Idaho, and Utah.[11] They are commonly found in rocky open habitats, on exposed rock, canyons, cliffs, and similar, however, rock is not a firm requremaent, as they can also be found in large eroded sandbanks.[2] Rock wrens are rare in urban areas like roads or buildings, instead preferring rocky areas with a minimal amount of verticality, enough shrubbery to forage in, and ample crevices for nesting.[2] The rock wren is very tolerant of altitudes, breeding from 60 m (200 ft) to 3,600 m (11,800 ft) above sea level,[12][13] however, they are most common below 2,000 m (6,600 ft).[2]

Behavior

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Rock wrens are serially monogamous. Males court by bringing food to females. During nesting season, males are territorial, guarding their area around 1.8 hectares (4.4 acres) acres in size,[14] defending them with songs, calls, and threat displays such as bobbing.[14][2]

Breeding

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Nest-building begins in March, and the first brood occurs late April to June, and a second brood can occur from mid-June to early August, with up to 3 broods per year. Rock wrens nest in crevices, cavities, or other similar sheltered areas, on stone surfaces. They lay 5-6 eggs per clutch, with incubation being around 14-16 days.[14] Incubation is handled by the female alone, however males will occasionally bring food.[2]

Eggs are ovate, usually 18.6 cm × 14.8 cm (7.3 in × 5.8 in) in size, and around 2.27 g (0.080 oz) in mass.[15][16] One egg is laid per day.[17]

A fledgling rock wren

The outsides of the nests are roughly 8.9 cm (3.5 in) in diameter and 3.4 cm (1.3 in) in depth, with the inside 6.7 cm (2.6 in) and 2.9 cm (1.1 in) in diameter and depth respectively.[18] Nests are usually built in cavities with openings around 2 times the bird's height, or 10.2 cm (4.0 in).[19] They are built on top of a stone foundation, similar to the pavement, and consist of stones, plant material, trash, and other debris.[20] Nests often include a "pavement" made with stones leading up to the nest that may help keep the nest and nestlings dry, helping them maintain their body temperature.[21] Pavements consist of flat stones, around 3.1 grams in weight, 27 by 18 mm in width and length, and 5 mm thick. Stones weighted on average 20% of the bird's body mass, with on average 230 stones per nest. The amount of stones varied with the size of the nest cavity, larger cavities having more stones.[22]

Nestlings left the nest around 14-16 days old, moving to a different rock within 75 m (246 ft) from the nest, continuing to receive care from parents for about 1 week, and remained on the parent's territory for 4 more weeks. Nestlings molted at 28-35 days, however, they still possessed gape flanges.[19]

Feeding

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A rock wren with a spider in its beak

Rock wrens are largely terrestrial, only flying for short durations, instead using a very rapid gait to move around.[9][2] They probe with their bill as their extraction tool, and eat insects, such as leafhoppers, ants, and weevils, as well as occasionally other arthropods like spiders, and rarely seeds.[9][2] Rock wrens mainly forage during the day on open ground, scavenging the surface of rocks and soil, and probing crevices.[2]

Nestlings were observed to mainly feed on grasshoppers along with other insects, however, large portions of the prey could not be identified due to their size.[23]

Vocalizations

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Dickcissel male perched on a metal pole singing, with neck stretched and beak open.

Songs and calls
Listen to Rock wren on xeno-canto

Female rock wrens do not sing, however, males have large repertoires of 69–119 song types, each song a 1–2.5 second trill of repeated syllables, with 3–5 seconds between songs.[14][2] Rock wrens have five call types: a two-part tic-ear/spit-tee sometimes used to warn of intruders; a rough trill, sometimes following a spit, used as an alarm; an agitated chatter; and an aggressive k'chee used during confrontations.[2]

Rock wrens sing with a distinctive pattern intermediate between 'eventual variety' (repeating one song type before switching) and 'immediate variety' (never repeating). A male typically sings each song type three to four times within a burst of 10–15 songs, rarely repeating the same song consecutively — transcribed, it would look like ABCBDCBDEFDEFGEHGEHGEHGI.[24] Song is primarily used for territorial defense, with males having greater repertoire size and pitch variety being more effective at deterring rivals.[23][2]

Conservation

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The rock wren is a least-concern species on the IUCN Red List, however, the population is slowly declining, with a 13% decrease in population from 2010 to 2020.[25] The cause of this is unknown.[14] Little is known about the causes of mortality or lifespan in adults,[26] however, nests are subject to predation.[2] Observed nest predators included the striped racer snake, the desert woodrat, and the white-tailed antelope squirrel,[2] as well as bullsnakes and prairie rattlesnakes.[27]

References

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  1. ^ BirdLife International (2016). "Salpinctes obsoletus". IUCN Red List of Threatened Species. 2016 e.T22711332A94289509. doi:10.2305/IUCN.UK.2016-3.RLTS.T22711332A94289509.en. Retrieved 11 November 2021.
  2. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac Benedict, Lauryn; Warning, Nathanial B.; Najar, Nadje A.; Pitt, Stephanie G.; Lowther, Peter E.; Kroodsma, Donald E.; Farley, Greg H. (2021). "Rock Wren (Salpinctes obsoletus), version 2.0". Birds of the World. doi:10.2173/bow.rocwre.02. ISSN 2771-3105.
  3. ^ "Salpinctes obsoletus (Rock Wren) - Avibase". avibase.bsc-eoc.org. Retrieved 2026-01-07.
  4. ^ James, Edwin; Say, Thomas; Long, Stephen H.; United States (1823). Account of an expedition from Pittsburgh to the Rocky Mountains, performed in the years 1819 and '20, by order of the Hon. J. C. Calhoun, sec'y of war: under the command of Major Stephen H. Long. From the notes of Major Long, Mr. T. Say, and other gentlemen of the party. Vol. 2. London: Longman, Hurst, Pees, Orre & Brown. p. 358. Genus Troglodytes, Cuvier — T. obsoleta, Say. Above dusky-brownish, slightly undulated with pale, tinted with dull ferruginous on the top of the head and superior portion of the back; sides of the head dull whitish, with a broad brown line passing through the eye to the origin of the neck; primaries plain, being entirely destitute of undulations or spots; tail coverts pale, each with four or five fuscous bands; chin, neck beneath, and breast whitish, each feather marked by a longitudinal line of light brown; belly white; flanks a little tinged with ferruginous; inferior tail coverts white, each feather bifasciate with black-brown; tail simple, broadly tipped with ferruginous-yellow, and with black before the tip, the remaining portion color of the wings, and obsoletely banded; these bands are more distinct on the two middle feathers, which are destitute of the black and yellowish termination; exterior plume marked by four yellowish white spots on the exterior web, and by two larger ones on the inner web; the tip is dusky, length six inches; bill, from the corner of the mouth, rather more than one inch.
  5. ^ a b Cabanis, Jean Louis (1847). Ornithologische Notizen: I und II (in German).
  6. ^ Dunning, John B., ed. (2008). CRC handbook of avian body masses (2nd ed.). Boca Raton: CRC Press. ISBN 978-1-4200-6444-5.
  7. ^ "Rock Wren Identification, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2020-09-28.
  8. ^ "Bird of the Month: Rock Wren (Salpinctes obsoletus)". Audubon Southwest. 2024-03-14. Retrieved 2025-12-29. This small, compact bird ranges from 5 to 6 ½ inches in length from its long, sharp bill to its moderately long, squared-tipped tail.
  9. ^ a b c Tramontano, John Philip (1964). "Comparative studies of the Rock Wren and the Canyon Wren" (PDF). University of Arizona.
  10. ^ "Rock Wren | Audubon Field Guide". www.audubon.org. Retrieved 2025-12-29. Strongly migratory, departing from northern part of range for the winter. Strays sometimes wander east in fall, and have even reached the Atlantic Coast.
  11. ^ "Bird of the Month: Rock Wren (Salpinctes obsoletus)". Audubon Southwest. 2024-03-14. Retrieved 2025-12-29.
  12. ^ Patten, Michael A. (1995). "Status and Distribution of California Birds California Birds: Their Status and Distribution Arnold Small". The Condor. 97 (2): 608–611. doi:10.2307/1369052. ISSN 1938-5129.
  13. ^ Smith, Michael Roger; Mattocks, Philip Ward; Cassidy, Kelly Michela (1997). Breeding Birds of Washington State: Location Data and Predicted Distributions. Seattle Audubon Society. ISBN 978-0-914516-09-5.
  14. ^ a b c d e "Rock Wren Life History, All About Birds, Cornell Lab of Ornithology". www.allaboutbirds.org. Retrieved 2025-12-29.
  15. ^ Bent, Arthur (1948-01-01). "Life Histories of North American Nuthatches, Wrens, Thrashers And Their Allies: Order Passeriformes". Papers in Ornithology.
  16. ^ Bent, Arthur (1948-01-01). "Life Histories of North American Nuthatches, Wrens, Thrashers And Their Allies: Order Passeriformes". Papers in Ornithology.
  17. ^ Matiasek, Jennifer (1998-04-21). "Nest-Site Selection and Breeding Behavior of the Migratory Rock Wren (Salpinctes Obsoletus) in Western Kansas". Master's Theses. doi:10.58809/LIXP8848.
  18. ^ Harrison, Hal H. (1979). A field guide to western birds' nests: of 520 species found breeding in the U. S. west of the Mississippi River. The Peterson field guide series. Mada Harrison. Boston: Houghton Mifflin. ISBN 978-0-395-27629-7.
  19. ^ a b Matiasek, Jennifer (1998-04-21). "Nest-Site Selection and Breeding Behavior of the Migratory Rock Wren (Salpinctes Obsoletus) in Western Kansas". Master's Theses. doi:10.58809/LIXP8848.
  20. ^ Bailey, Florence (1904-05-01). "Twelve Rock Wren Nests in New Mexico". Condor. 6 (3): 68–70. doi:10.2307/1361099. JSTOR 1361099.
  21. ^ Warning, Nathanial; Benedict, Lauryn (January 2015). "Paving the way: Multifunctional nest architecture of the Rock Wren". The Auk. 132 (1): 288–299. doi:10.1642/AUK-14-186.1. ISSN 0004-8038. Archived from the original on 2022-03-02.
  22. ^ Warning, Nathanial; Benedict, Lauryn (2016-03-01). "Facultative Nest Modification by Rock Wrens (Salpinctes obsoletus)". Avian Biology Research. 9 (1): 58–65. doi:10.3184/175815516X14447553481564. ISSN 1758-1559.
  23. ^ a b Pitt, Stephanie (2018-05-01). "Why Sing so Many Songs? Testing the Function of Song Type Repertoires in Rock Wrens Using Playback Experiments and Behavioral Observations". Master's Theses.
  24. ^ Kroodsma, Donald E. (1975). "Song Patterning in the Rock Wren". The Condor. 77 (3): 294–303. doi:10.2307/1366225. ISSN 0010-5422. JSTOR 1366225.
  25. ^ BirdLife International (BirdLife International) (2020-11-02). "IUCN Red List of Threatened Species: Salpinctes obsoletus". IUCN Red List of Threatened Species. Archived from the original on 2025-05-06.
  26. ^ Benedict, Lauryn; Warning, Nathanial B.; Najar, Nadje A.; Pitt, Stephanie G.; Lowther, Peter E.; Kroodsma, Donald E.; Farley, Greg H. (2021). "Rock Wren (Salpinctes obsoletus), version 2.0". Birds of the World. doi:10.2173/bow.rocwre.02. ISSN 2771-3105. No information on longevity, as few birds are banded and recaptured. Of 1,104 individuals banded in the United States between 1960 and 2018, only 1 individual was subsequently recaptured at a new location.
  27. ^ Pitt, Stephanie Gobert; Benedict, Lauryn (2022-06-01). "Breeding biology and reproductive success of Rock Wrens (Salpinctes obsoletus) in northern Colorado". The Wilson Journal of Ornithology. 134 (2): 260–268. doi:10.1676/21-00077. ISSN 1559-4491.
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See also

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  • Volcán Bárcena, the volcano that caused the San Benedicto rock wren (a subspecies of Salpinctes) to go extinct in 1952

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Synonyms

  • ROWR

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