Breeding

Not well studied, probably because nests are located in steep and precarious habitats, and the species behaves secretively at the nest.

Pair Formation

Information needed. Reported to initiate territorial behavior in January in Arizona (1 Tramontano, J. P. (1964). Comparative studies of the Rock Wren and the Canyon Wren. M.S. thesis, University of Arizona, Tucson, AZ, USA. Close ), and February in Colorado (16 Jones, S. L., and J. Scott Dieni (1995). Canyon Wren (Catherpes mexicanus). In The Birds of North America, No. 197 (A. Poole and F. Gill, Editors). Academy of Natural Sciences, Philadelphia, PA and American Ornithologists' Union, Washington DC, USA. Close ).

Nest Building

Nest building peaks early May to early June, but starts in southern portions of the range in mid-March. In the lowland Sonoran Desert of Arizona, nest building documented by 18 March (67 Corman, T. E., and C. Wise-Gervais (2005). Arizona Breeding Bird Atlas. University of New Mexico Press, Albuquerque, NM, USA. Close ), and by 5 April in Big Bend Mountains of western Texas (85 Wauer, R. H. (1973). Birds of Big Bend National Park and Vicinity. University of Texas Press, Austin, TX, USA. Close ). In the Front Range of Colorado, nest building documented 20 March to 15 August, including instances of renesting when first nests failed (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ).

First/Later Broods Per Season

Figure 1. In the Sonoran Desert of Arizona, fledglings have been observed as early as 9 April, suggesting that some clutches are laid by mid-March; at higher elevations in Arizona, active nests are commonly noted through June (67 Corman, T. E., and C. Wise-Gervais (2005). Arizona Breeding Bird Atlas. University of New Mexico Press, Albuquerque, NM, USA. Close ). In Colorado, clutches (n = 23) were initiated between 23 April and 15 August (median clutch initiation date 17 May) (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ), though an early nest with young was reported on 13 April during the second breeding bird atlas (48 Wickersham, L. E. (Editor) (2016). The Second Colorado Breeding Bird Atlas. Colorado Bird Atlas Partnership and Colorado Parks and Wildlife, Denver, CO, USA. Close ). First broods typically fledge late May or June, and second broods from July and early August to mid-August (LB).

Selection Process

Information needed.

Site Characteristics

Typically nests on rock walls, cliffs, outcrops, or banks; some nests are attached by a stick and twig base to rock faces in caves (22 Bent, A. C. (1948). Life histories of North American nuthatches, wrens, thrashers, and their allies. United States National Museum Bulletin 195. Close , 1 Tramontano, J. P. (1964). Comparative studies of the Rock Wren and the Canyon Wren. M.S. thesis, University of Arizona, Tucson, AZ, USA. Close , 3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Nests frequently are protected by a projecting ledge or shelf covering the top, and are often in a small crevice, cranny, or hole that keeps them hidden from view (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Often nests in or above intact or partial Cliff Swallow (Petrochelidon pyrrhonota) nests on cliff faces in Colorado (86 Warning, N., and L. Benedict (2013). Atypical Canyon Wren nesting locations. Colorado Birds 47:175–177. Close , 5 Warning, N., N. Covy, A. Rose, X. M. Phan, and L. Benedict (2015). Canyon wren territory occupancy and site attributes in northern Colorado. American Midland Naturalist 174:150–160. Close ), a behavior also reported in Arizona (67 Corman, T. E., and C. Wise-Gervais (2005). Arizona Breeding Bird Atlas. University of New Mexico Press, Albuquerque, NM, USA. Close ) and Sonora, Mexico (66 Russell, S. M., and G. Monson (1998). The Birds of Sonora. University of Arizona Press, Tucson, AZ, USA. Close ). May also build nest in human-made structures, such as mineshafts, fences, porches, barns, and occasionally nest boxes (86 Warning, N., and L. Benedict (2013). Atypical Canyon Wren nesting locations. Colorado Birds 47:175–177. Close ; unpublished data, Nestwatch.org).

At Red Rocks Mountain Park near Denver, Colorado, nests had a mean southern orientation of 158 degrees and nest height ranged from 0.8–18.4 m (mean 6.7, n = 16) (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). In Arizona, nest height ranged from 0.4–37.0 m (mean 2.0, n = 18) (67 Corman, T. E., and C. Wise-Gervais (2005). Arizona Breeding Bird Atlas. University of New Mexico Press, Albuquerque, NM, USA. Close ).

Construction Process

Nests built by both male and female (84 Verner, J., and M. F. Willson (1969). Mating systems, sexual dimorphism, and the role of male North American passerine birds in the nesting cycle. Ornithological Monographs 9. Close , SLJ).

Structure and Composition

The nest is a cup with a base of twigs and coarser material (e.g., moss, twigs, grasses, dead leaves), lined with lichens, plant down, wool, cobwebs, feathers, or other soft material. The nest sometimes contains other miscellaneous matter, including metals, threads, and plastic (87 Lofberg, L. M. (1931). “Office Aids” in Nest Building. Condor 33(6):245–246. Close , 22 Bent, A. C. (1948). Life histories of North American nuthatches, wrens, thrashers, and their allies. United States National Museum Bulletin 195. Close , 3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ).

Dimensions

Mean nest size: outer width (at base) 14.2 cm, outer depth 9.5 cm; inner diameter (cup) 5.6 cm, inner depth 3.9 cm (n = 11, Western Foundation of Vertebrate Zoology [WFVZ]; n = 2, SLJ).

Microclimate

Information needed.

Maintenance and Reuse of Nests

Nests are occasionally reused, both for second broods and in subsequent years (88 Bailey, A. A., and R. J. Niedrach (1965). Birds of Colorado. Denver Museum of Natural History, Denver, CO, USA. Close ; unpublished data, Nestwatch.org).

Nonbreeding Nests

Deserves more study. Possible observation of "dummy" nests in one breeding population (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ).

Shape

Ovate to nearly elliptical-ovate.

Size

Mean dimensions of 50 eggs (22 Bent, A. C. (1948). Life histories of North American nuthatches, wrens, thrashers, and their allies. United States National Museum Bulletin 195. Close ): 17.9 × 13.2 mm; the extreme eggs were 19.8 × 13.7 mm, 17.7 × 14.1 mm, 16.8 × 12.7 mm, and 17.5 × 12.6 mm. In C. m. conspersus, 18.15 mm (range 16.35–20.66) × 13.61 mm (range 12.86–14.63). In C. m. albifrons, 18.75 mm (range 17.35–19.43) × 13.90 mm (range 13.46–14.29). Information needed for C. m. mexicanus.

Mass

In C. m. conspersus, empty shell weight: 0.107 g (range 0.07–0.143, n = 20 clutches, 98 eggs; WFVZ). In C. m. albifrons, empty shell weight: 0.103 g (range 0.088–0.122, n = 19 clutches, 93 eggs; WFVZ).

Information needed on mass of whole eggs.

Color and Surface Texture

Ground color is a pure, clear white, usually sparingly marked with fine dots of reddish brown, sometimes so faint in appearance as to appear unmarked. Occasionally, eggs have small spots of dark brown, sometimes concentrated at the larger end (22 Bent, A. C. (1948). Life histories of North American nuthatches, wrens, thrashers, and their allies. United States National Museum Bulletin 195. Close ). Surface texture is smooth and non-glossy or slightly glossy.

Eggshell Thickness

Information needed.

Clutch Size

Usually 5 eggs, rarely fewer than 3 eggs or > 6 eggs (see Measures of Breeding Activity). One study in Colorado found a mean clutch size of 4.5 eggs (range 2–6, n = 22; 3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ).

Egg Laying

One egg laid per day.

Incubation Patch

Only females develops brood patch (10 Pyle, P. (1997). Identification Guide to North American Birds Part I. Slate Creek Press, Bolinas, CA, USA. Close ).

Incubation Period

Incubation begins when the final egg is laid. In the Front Range of Colorado, the incubation period ranges from 12–19 d and averages 16.9 d (n = 17) (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Incubation can begin as early as mid-April, continuing through May or early June for first nests.

Parental Behavior

Only the female has been observed to incubate; the male regularly feeds the female while she is incubating (1 Tramontano, J. P. (1964). Comparative studies of the Rock Wren and the Canyon Wren. M.S. thesis, University of Arizona, Tucson, AZ, USA. Close , 88 Bailey, A. A., and R. J. Niedrach (1965). Birds of Colorado. Denver Museum of Natural History, Denver, CO, USA. Close , 84 Verner, J., and M. F. Willson (1969). Mating systems, sexual dimorphism, and the role of male North American passerine birds in the nesting cycle. Ornithological Monographs 9. Close , SLJ).

Hardiness of Eggs

Information needed.

Information needed. Eggshells removed from the nest by adults (SLJ).

Condition at Hatching

At hatching (n = 2 nests, 6 nestlings), young are altricial and weak with skin gray-pink, eyes closed, bill and feet pink, mouth lining bright yellow (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Natal down described as gray and in sparse tufts on crown (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ) and "dull tilleul buff, pale vinaceous buff, or drab" (8 Oberholser, H. C. (1974). The Bird Life of Texas. University of Texas Press, Austin, TX, USA. Close ).

Growth and Development

In the Colorado Front Range, the nestling period averages 16.9 d (range 12–19, n = 17) (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Chicks typically hatch on the same day, but nestlings differ in size and/or growth rates. On day 10, five chicks in one nest in north-central (Larimer County) Colorado varied in size, weighing between 7.5 and 10g.

Sex Ratios

Information needed.

Brooding

Only the female broods; male has been observed feeding the brooding female (1 Tramontano, J. P. (1964). Comparative studies of the Rock Wren and the Canyon Wren. M.S. thesis, University of Arizona, Tucson, AZ, USA. Close , 88 Bailey, A. A., and R. J. Niedrach (1965). Birds of Colorado. Denver Museum of Natural History, Denver, CO, USA. Close , 84 Verner, J., and M. F. Willson (1969). Mating systems, sexual dimorphism, and the role of male North American passerine birds in the nesting cycle. Ornithological Monographs 9. Close , SLJ).

Feeding

Both parents feed and care for the nestlings and fledglings (1 Tramontano, J. P. (1964). Comparative studies of the Rock Wren and the Canyon Wren. M.S. thesis, University of Arizona, Tucson, AZ, USA. Close , 84 Verner, J., and M. F. Willson (1969). Mating systems, sexual dimorphism, and the role of male North American passerine birds in the nesting cycle. Ornithological Monographs 9. Close ).

Nest Sanitation

In northern Colorado, both parents removed fecal sacs from nests and dropped them in flight within a few seconds of departing (72 Warning, N., and D. Leatherman (2016). Observations of Canyon Wren nestling diet during prey delivery. Natural Areas Journal 36:181–186. Close ).

Not known to occur.

Not known to occur.

Departure from the Nest

Young typically first fledge early in the morning, but may return to the nest at night for several days after fledging (3 Jones, S. L., J. S. Dieni, and A. C. Araya (2002). Reproductive biology of canyon wrens in the Front Range of Colorado. Wilson Journal of Ornithology 114(4):446–449. Close ). Young are not fully flighted upon fledging.

Association with Parents or Other Young

Fledglings receive adult care for at least 5–10 d after leaving the nest (n = 3; SLJ, JSD). Juveniles continue to forage with their parents after they are able to feed themselves. Family groups may stay together for several weeks to several months (2 Mirsky, E. N. (1976). Ecology of coexistence in a wren-wrentit-warbler guild. Ph.D. dissertation, University of California, Los Angeles, CA, USA. Close , SLJ).

Information needed.