Isthmian Wren Cantorchilus elutus Scientific name definitions

Isthmian Wren formerly was known as "Plain Wren", and included with two taxa that now are recognized as separate species, Cabanis's Wren (Cantorchilus modestus) and Canebrake Wren (Cantorchilus zeledoni). "Plain Wren" indeed was a good name of this species, as it possesses rather few obviously distinguishing field marks. This overall similarity is one reason why Cabanis's, Canebrake, and Isthmian wrens were considered conspecific until phylogenetic analyses revealed that each was more distantly related to each other than previously was thought; this genetic divergence also is complemented by differences in their songs. Isthmian Wren has a rather restricted distribution, occurring from southwestern Costa Rica south into Panama. Cabanis's Wren is present on the Pacific coast of northwestern Costa Rica; Cabanis's and Isthmian wrens probably were allopatric, but they may be coming into contact now, in the wake of deforestation in this region. Isthmian Wren builds two different types of nests, a thin-walled, cylinder-like construction that is used by the birds for roosting, and a much more substantial, elliptical structure with a downward-facing entrance, which serves for breeding.

12·5–14 cm. Overall, Isthmian Wren is rather featureless and dull-colored , without strong facial markings or prominent barring or streaking. Adults of both sexes ares similar and have a narrow white supercilium, gray-brown lores and eyestripe; cheeks and ear-coverts mottled dark grayish-brown and gray-white; crown dull gray-brown, back gray-brown, rump pale russet; primaries and secondaries warm brown with obscure darker bars; rectrices dull russet brown with narrow darker bars; throat white, chest pale grayish, center of belly grayish-white, flanks, belly side and undertail-coverts buffy cinnamon (1 Bangs, O. (1902) On a second collection of birds made in Chiriqui, by W. W. Brown, Jr. Proceedings of the New England Zoölogical Club 3:15–70. Close ).

Differs from C. zeledoni in smaller size, much warmer coloration, and is generally duller and paler than C. modestus. Compared with the latter it has a longer bill and shorter tail (2 Kroodsma, D. and D. Brewer (2019). Plain Wren (Cantorchilus modestus). In Handbook of the Birds of the World Alive (del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie and E. de Juana), Lynx Edicions, Barcelona, Spain. pp. Available from https://www.hbw.com/node/58143. Close ).

Iris

reddish-brown (3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close ), not yellow as previously asserted (4 Kroodsma, D. and D. Brewer (2005). Plain Wren (Thryothorus modestus). In Handbook of the Birds of the World Volume 10: Cuckoo-shrikes to Thrushes (del Hoyo, J., A. Elliott and D. A. Christie), Lynx Edicions, Barcelona, Spain. pp. 428. Close )

Bill

maxilla black, mandible grayish

Tarsi and Toes

legs bluish-slate to dull gray

Males

wing 58.6-65 mm (mean 61.4 mm); tail 46-54.5 mm (mean 50 mm); exposed culmen 17-18.5 mm (mean 17.7 mm); tarsus 22-25 mm (mean 23.8 mm); middle toe 13.5-14.5 mm (mean 14.2 mm) (n = 9; 5 Ridgway, R. (1904). The birds of North and Middle America. Part III. Bulletin of the United States National Museum 50. U.S. Government Printing Office, Washington, DC, USA. Close )

Females

wing 55-58 mm (mean 56.2 mm); tail 44.6-45.5 mm (mean 45 mm); exposed culmen 15.5-16.5 mm (mean 16 mm); tarsus 23-24 mm (mean 23.5 mm); middle toe 13.5-14.5 mm (mean 14 mm) (n = 3; 5 Ridgway, R. (1904). The birds of North and Middle America. Part III. Bulletin of the United States National Museum 50. U.S. Government Printing Office, Washington, DC, USA. Close )

Frequently, and until recently, treated as conspecific with C. modestus (5 Ridgway, R. (1904). The birds of North and Middle America. Part III. Bulletin of the United States National Museum 50. U.S. Government Printing Office, Washington, DC, USA. Close , 6 Hellmayr, C. E. (1934). Catalogue of Birds of the Americas and the Adjacent Islands in Field Museum of Natural History. Part 7. Corvidae, Paridae, Sittidae, Certhiiidae, Chamaeidae, Cinclidae, Troglodytidae, Prunellidae, Mimidae, Turdidae, Zeledoniidae, Sylviidae. Field Museum of Natural History Publication 330. Zoological Series 13. Field Museum of Natural History, Chicago, USA. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close , 2 Kroodsma, D. and D. Brewer (2019). Plain Wren (Cantorchilus modestus). In Handbook of the Birds of the World Alive (del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie and E. de Juana), Lynx Edicions, Barcelona, Spain. pp. Available from https://www.hbw.com/node/58143. Close ), and sometimes also with C. zeledoni (6 Hellmayr, C. E. (1934). Catalogue of Birds of the Americas and the Adjacent Islands in Field Museum of Natural History. Part 7. Corvidae, Paridae, Sittidae, Certhiiidae, Chamaeidae, Cinclidae, Troglodytidae, Prunellidae, Mimidae, Turdidae, Zeledoniidae, Sylviidae. Field Museum of Natural History Publication 330. Zoological Series 13. Field Museum of Natural History, Chicago, USA. Close , 7 Ridgely, R. S., and J. Gwynne (1989). A Guide to the Birds of Panama, with Costa Rica, Nicaragua, and Honduras. 2nd Edition. Princeton University Press, Princeton, NJ, USA. Close , 8 Angher, G. R., and R. Dean (2010). The Birds of Panama. Cornell University Press, Ithaca, New York and London. Close , 9 Garrigues, R., and R. Dean (2014). Birds of Costa Rica. Christopher Helm, London, UK. Close ). A recent study involving mtDNA, morphometrics and colorimetrics has proposed the separation of elutus and modestus into distinct species (10 Saucier, J.R., Sánchez, C. and Carling, M.D. (2015). Patterns of genetic and morphological divergence reveal a species complex in the Plain Wren (Cantorchilus modestus). Auk 132(4): 795–807. Close ) and, despite some disagreement (11 Boesman, P. (2016). Notes on the vocalizations of Plain Wren (Thryothorus modestus) and Canebrake Wren (Thryothorus zeledoni). HBW Alive Ornithological Note 294. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Close , 2 Kroodsma, D. and D. Brewer (2019). Plain Wren (Cantorchilus modestus). In Handbook of the Birds of the World Alive (del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie and E. de Juana), Lynx Edicions, Barcelona, Spain. pp. Available from https://www.hbw.com/node/58143. Close ), this treatment has been followed by some authors (12 Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood (2019). The eBird/Clements Checklist of Birds of the World: v2019. Cornell Laboratory of Ornithology, Ithaca, New York, USA. Close ).

Closely related to C. modestus and C. zeledoni (5 Ridgway, R. (1904). The birds of North and Middle America. Part III. Bulletin of the United States National Museum 50. U.S. Government Printing Office, Washington, DC, USA. Close , 6 Hellmayr, C. E. (1934). Catalogue of Birds of the Americas and the Adjacent Islands in Field Museum of Natural History. Part 7. Corvidae, Paridae, Sittidae, Certhiiidae, Chamaeidae, Cinclidae, Troglodytidae, Prunellidae, Mimidae, Turdidae, Zeledoniidae, Sylviidae. Field Museum of Natural History Publication 330. Zoological Series 13. Field Museum of Natural History, Chicago, USA. Close , 10 Saucier, J.R., Sánchez, C. and Carling, M.D. (2015). Patterns of genetic and morphological divergence reveal a species complex in the Plain Wren (Cantorchilus modestus). Auk 132(4): 795–807. Close , 2 Kroodsma, D. and D. Brewer (2019). Plain Wren (Cantorchilus modestus). In Handbook of the Birds of the World Alive (del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie and E. de Juana), Lynx Edicions, Barcelona, Spain. pp. Available from https://www.hbw.com/node/58143. Close ).

Isthmian Wren is found in the southern half of the Pacific Slope of Costa Rica, from the vicinity of San Isidro de El General, San Jose, south and east to just east of the Canal Zone in Panama (7 Ridgely, R. S., and J. Gwynne (1989). A Guide to the Birds of Panama, with Costa Rica, Nicaragua, and Honduras. 2nd Edition. Princeton University Press, Princeton, NJ, USA. Close , 13 Stiles, F. G., and A. F. Skutch (1989). A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, NY, USA. Close , 4 Kroodsma, D. and D. Brewer (2005). Plain Wren (Thryothorus modestus). In Handbook of the Birds of the World Volume 10: Cuckoo-shrikes to Thrushes (del Hoyo, J., A. Elliott and D. A. Christie), Lynx Edicions, Barcelona, Spain. pp. 428. Close , 10 Saucier, J.R., Sánchez, C. and Carling, M.D. (2015). Patterns of genetic and morphological divergence reveal a species complex in the Plain Wren (Cantorchilus modestus). Auk 132(4): 795–807. Close ).

Forest edge, second growth, well-vegetated gardens, overgrown citrus plantations with epiphytes, and similar habitats. Mostly in humid forest, but avoids dense wet forest (14 Blake, E. R. (1958). Birds of Volcán de Chiriquí, Panamá. Fieldiana Zoology 36(5):499–577. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close , 16 Slud, P. (1964) The birds of Costa Rica: distribution and ecology. Bulletin of the American Museum of Natural History 128. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close ). Sea-level to c. 2000 m (13 Stiles, F. G., and A. F. Skutch (1989). A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, NY, USA. Close , 8 Angher, G. R., and R. Dean (2010). The Birds of Panama. Cornell University Press, Ithaca, New York and London. Close , 9 Garrigues, R., and R. Dean (2014). Birds of Costa Rica. Christopher Helm, London, UK. Close ).

None reported, presumably a sedentary resident.

The diet of Isthmian Wren has not been reported in detail, but is presumably similar to that of Cabanis's Wren (T. modestus), and consists largely of arthropods and small invertebrates. Nevertheless, adult seen to feed a berry to fledgling (15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close ). Has been seen to attack eggs of other species, but more probably as a means of reducing competition than for actual food (17 Fleischer, R.C. and Tarr, C.L. (1995). Plain Wren destroys egg of Dusky Antbird. J. Field Orn.. 66(3): 404-405. Close ). Usually found in pairs, foraging low down in dense vegetation, occasionally higher up in trees (15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close , 16 Slud, P. (1964) The birds of Costa Rica: distribution and ecology. Bulletin of the American Museum of Natural History 128. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close ).

Song a loud motif of 3–4 clear whistles, “chin-cheer-gwee” or “chin-cheery-gwee,” sometimes given entirely by male, but frequently as a perfectly timed antiphonal performance, male giving first 2 or 3 notes and female the final one; unmated male has softer, less strident song; recently fledged juvenile sings quite differently, a low diffuse rambling song reminiscent of that of Grey Catbird (Dumetella carolinensis). Calls include harsh “chur” and tinkling “chi-chi-chi” (10 Saucier, J.R., Sánchez, C. and Carling, M.D. (2015). Patterns of genetic and morphological divergence reveal a species complex in the Plain Wren (Cantorchilus modestus). Auk 132(4): 795–807. Close , 11 Boesman, P. (2016). Notes on the vocalizations of Plain Wren (Thryothorus modestus) and Canebrake Wren (Thryothorus zeledoni). HBW Alive Ornithological Note 294. In: Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Close , 2 Kroodsma, D. and D. Brewer (2019). Plain Wren (Cantorchilus modestus). In Handbook of the Birds of the World Alive (del Hoyo, J., A. Elliott, J. Sargatal, D. A. Christie and E. de Juana), Lynx Edicions, Barcelona, Spain. pp. Available from https://www.hbw.com/node/58143. Close )

The nesting of Isthmian Wren is, on the whole surprisingly poorly known. Despite the description of a fair number of nests, little is known of its breeding ecology and behavior, and the nestling period remains poorly defined.

Season in Costa Rica very protracted, with active nests found from January to September (15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close , 13 Stiles, F. G., and A. F. Skutch (1989). A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, NY, USA. Close ). Season presumably similar in Panama, but breeding activity reported only during May (18 Blake, E.R. (1956). A collection of Panamanian nests and eggs. Condor. 58(5): 386–388. Close ).

Nests are built in second-growth habitat, at forest edges, and in vine tangles, usually situated 0.5–3 m up in dense vegetation (19 Skutch, A. F. (1940). Social and sleeping habits of Central American wrens. Auk 57:293-312. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close , 18 Blake, E.R. (1956). A collection of Panamanian nests and eggs. Condor. 58(5): 386–388. Close ).

Nest elliptical, the short axis being horizontal, circular entrance hole facing slightly downwards and sometimes protected by short lintel, made from grasses and vegetable fibres, lined with plant down or feathers (19 Skutch, A. F. (1940). Social and sleeping habits of Central American wrens. Auk 57:293-312. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close , 18 Blake, E.R. (1956). A collection of Panamanian nests and eggs. Condor. 58(5): 386–388. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close ). Dormitory nests are similar to breeding nests, but much more flimsy and usually unlined (19 Skutch, A. F. (1940). Social and sleeping habits of Central American wrens. Auk 57:293-312. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close ).

Eggs 2, unmarked white (18 Blake, E.R. (1956). A collection of Panamanian nests and eggs. Condor. 58(5): 386–388. Close , 3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close , 20 Skutch, A. F. (1945). Incubation and nesting periods of Central American birds. Auk 62(1):8–37. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close ).

Incubation by female alone, period 18 days (20 Skutch, A. F. (1945). Incubation and nesting periods of Central American birds. Auk 62(1):8–37. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close ).

Parental care of nestlings, and the details of the nestling period not well documented. Fledging period c. 13–14 days or more (20 Skutch, A. F. (1945). Incubation and nesting periods of Central American birds. Auk 62(1):8–37. Close , 15 Skutch, A. F. (1960). Life Histories of Central American Birds. Part 2. Families Vireonidae, Sylviidae, Turdidae, Troglodytidae, Paridae, Corvidae, Hirundinidae and Tyrannidae. Pacific Coast Avifauna 34. Cooper Ornithological Society, Berkeley, CA, USA. Close ).

There is a single record of a nest parasitized by Striped Cuckoo (Tapera naevia) (21 Kiff, L.F. and Williams, A. (1978). Host records for the Striped Cuckoo from Costa Rica. Wilson Bull.. 90(1): 138-139. Close ,3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close ).

Not well studied, but this species is a reported host for several species of blood parasites (22 Huff, C. G. and A. Wetmore. (1967). Blood parasites of birds collected in four successive years in Panama. Bulletin of the Wildlife Disease Association 3:178-181. Close , 23 Sousa, O. E., and C. M. Herman (1982). Blood parasites of birds from Chiriqui and Panama provinces in the Republic of Panama. Journal of Wildlife Diseases 18(2):205–221. Close ).

Not evaluated (as separate from T. modestus). Despite small range, is unlikely to be considered globally threatened. Common or abundant in much of its range. Adapts well to modified and regenerating habitat (3 Wetmore, A., R. F. Pasquier, and S. L. Olson (1984). The Birds of the Republic of Panama. Volume 4. Passeriformes: Hirundinidae (swallows) to Fringillidae (finches). Smithsonian Miscellaneous Collections 150, Smithsonian Institution, Washington, DC, USA. Close , 13 Stiles, F. G., and A. F. Skutch (1989). A Guide to the Birds of Costa Rica. Cornell University Press, Ithaca, NY, USA. Close , 24 Redondo-Brenes, A. (2010). Effects of land-use change on the conservation of bird species in the path of the Tapir Biological Corridor, Costa Rica. Ph.D. thesis, Yale University, New Haven, CT, USA. Close ).