Canyon Wren Catherpes mexicanus Scientific name definitions

Stephanie L. Jones, Joseph Scott Dieni, Nathanial B. Warning, David Leatherman, Lorraine Dargis, and Lauryn Benedict
Version: 2.0 — Published January 6, 2023



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), and February in Colorado (16).

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), and by 5 April in Big Bend Mountains of western Texas (85). In the Front Range of Colorado, nest building documented 20 March to 15 August, including instances of renesting when first nests failed (3).

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). In Colorado, clutches (n = 23) were initiated between 23 April and 15 August (median clutch initiation date 17 May) (3), though an early nest with young was reported on 13 April during the second breeding bird atlas (48). First broods typically fledge late May or June, and second broods from July and early August to mid-August (LB).

Nest Site

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, 1, 3). 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). Often nests in or above intact or partial Cliff Swallow (Petrochelidon pyrrhonota) nests on cliff faces in Colorado (86, 5), a behavior also reported in Arizona (67) and Sonora, Mexico (66). May also build nest in human-made structures, such as mineshafts, fences, porches, barns, and occasionally nest boxes (86; unpublished data, Nestwatch.org).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). In Arizona, nest height ranged from 0.4–37.0 m (mean 2.0, n = 18) (67).


Construction Process

Nests built by both male and female (84, 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, 22, 3).


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).


Information needed.

Maintenance and Reuse of Nests

Nests are occasionally reused, both for second broods and in subsequent years (88; unpublished data, Nestwatch.org).

Nonbreeding Nests

Deserves more study. Possible observation of "dummy" nests in one breeding population (3).



Ovate to nearly elliptical-ovate.


Mean dimensions of 50 eggs (22): 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.


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). 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).

Egg Laying

One egg laid per day.


Incubation Patch

Only females develops brood patch (10).

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). 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, 88, 84, SLJ).

Hardiness of Eggs

Information needed.


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

Young Birds

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). Natal down described as gray and in sparse tufts on crown (3) and "dull tilleul buff, pale vinaceous buff, or drab" (8).

Growth and Development

In the Colorado Front Range, the nestling period averages 16.9 d (range 12–19, n = 17) (3). 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.

Parental Care


Only the female broods; male has been observed feeding the brooding female (1, 88, 84, SLJ).


Both parents feed and care for the nestlings and fledglings (1, 84).

Nest Sanitation

In northern Colorado, both parents removed fecal sacs from nests and dropped them in flight within a few seconds of departing (72).

Cooperative Breeding

Not known to occur.

Brood Parasitism by Other Species

Not known to occur.

Fledgling Stage

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). 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, SLJ).

Immature Stage

Information needed.

Recommended Citation

Jones, S. L., J. S. Dieni, N. B. Warning, D. Leatherman, L. Dargis, and L. Benedict (2023). Canyon Wren (Catherpes mexicanus), version 2.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.canwre.02