Cassin's Sparrow

Peucaea cassinii



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Cassin's Sparrow skylarking.

When giving Flight Song (“skylarking”), male flies directly upward, giving introductory notes as the male rises with trembling wing strokes at an angle of 30°–60°. Male then floats downward on set wings while singing trill, final two descending notes given just before landing.

© Bill Maynard , Colorado , United States , 14 June 2016
Cassin's Sparrow skylarking.

Flight posture has head up, tail fanned, legs stretched downward.

© Bill Maynard , Colorado , United States , 10 May 2017
Cassin's Sparrow skylarking.
© Lyndie Mason Warner , Arizona , United States , 30 May 2018


Walking, Hopping

Ground movement consists of walking and short hops. Runs rather than flies initially when pursued, but will fly > 100 m when harassed (JBD).


Capable flier, but often moves by skulking through ground vegetation rather than flying. In winter, flies short distances (> 10 m) presumably because of extremely small defended areas (RKB).

When giving Flight Song (“skylarking”), male flies upward using trembling wing strokes at an angle of 30–60° (8) to a height of 2–6 m (mean 4.6 m, n = 42) (3) and floats downward on set wings while singing. Skylarking flight often extends 5–15 m (78), and apex may occasionally reach 12–15 m during intense boundary disputes (3). Flight posture has head up, tail fanned, and legs stretched downward. See also Sounds and Vocal Behavior: Vocalizations.


Preening, Head-Scratching, Stretching, Bathing, Anting, etc.

Never seen dust-bathing. The only report of water bathing was an immature bathing briefly in a puddle created by lawn sprinklers (78). No reports of anting or stretching behavior.

Sleeping, Roosting, Sunbathing

No information.

Daily Time Budget

Based on a summary of 150 h of observation on 6 males and 3 females from March–late September 1982–1983, in San Angelo, Tom Green County, Texas (see Table 2) (7): Unmated males spent most of their time in ground activity (feeding and walking) and perched, only 1% of time was spent skylarking (see Sounds and Vocal Behavior: Vocalizations). Skylarking behavior increased dramatically after females arrived, but decreased as females began incubation, and remained low until the end of breeding attempt. Perched singing of Primary Song by males was high before females arrived and during fledgling care. Time spent feeding by males varied from 64% prior to arrival of females to 19–20% during the later part of the breeding cycle. Schnase et al. (7) used these time measures to estimate potential energetic costs using energetic estimates developed for Savannah Sparrow; there are no direct estimates of energy costs for Cassin's Sparrow.

Agonistic Behavior

Intraspecific interactions in Cassin's Sparrow are mostly limited to song duels by territorial males. There are few observations of direct fighting or chasing during territorial disputes.

Cassin's Sparrow and the closely related Botteri's Sparrow have overlapping territories in arid grasslands near Santa Rita Mountains, Arizona (RKB, JBD). Male Cassin's Sparrow has been observed chasing Botteri's Sparrow (RKB), but individuals of both species can be seen perched on the same branch of small shrub after extensive singing bouts with no agonistic interaction noted (JBD, RKB). See also Social and Interspecific Behavior.



Territory boundaries are usually defined by the distribution of male song perches, since visual displays or physical contact between males is difficult to observe (7, RKB, JBD). Territorial defense is mostly accomplished by song duels between males. Occasional pursuits of intruding males were observed by Schnase (29), but only early in the breeding period. Male sings from perches until other males appear, then shifts to Flight Songs (78). First songs of the season are quiet, getting progressively louder as more males appear. Williams and LeSarrier (78) did not observe physical contact between singing males.

Territorial males increased aggressive behavior (such as Flight Song) when exposed to song playback, but this was not due to increases in plasma testosterone levels. Plasma testosterone and luteinizing hormone levels not at maximum levels prior to playback experiments. Studies therefore do not support the Challenge Hypothesis, which states that breeding males respond to social challenge by quickly increasing plasma androgens (112).

Territory size in west-central Texas was reported as 2.6 ha ± 2.6 SD (range 1.7–3.3, n = 21 observations of 14 males over 2 years) based on observations of males throughout day (29). Territory sizes of 2 males in southeastern Arizona were 0.35 ha and 0.26 ha, based on plots of song posts (RKB). Territory size as estimated from distribution of song posts underestimates true home range (as measured using birds marked with radio telemetry) in Bachman's Sparrow (108, 113). However, mean territory size was 0.55 ha (SE = 0.55, range 0.17–1.23, n = 52) in Oklahoma sagebrush grassland, similar to Arizona territory size, although based on territory mapping and song playback (114). Authors of the Oklahoma study suggested differences in Oklahoma and Texas territory sizes were likely due to differences in quantification methods.

In Oklahoma, territories clustered in space with shared boundaries, occupying only 11% of suitable habitat in study area (114). Territories were more frequent on north aspects and had 3 times more shrub cover than random points in the greater landscape, but no more shrub cover than random points within study plots. Territories and random points were similar within study plots and the greater landscape in grass and forb cover and the percentage of bare area (114).

In Arizona, highly territorial in winter on small (< 0.25 ha) grassy patches or continuous grassland (RKB, JBD). Very responsive to broadcast of recorded song, usually responding with Psit Call and occasionally Chitter Call, and close approach of the speaker. Only one of 32 color-marked birds captured on winter territory changed location within season (RKB). Sex of individuals defending areas was unknown, but it was assumed that both males and females were involved (RKB). Color-banded birds remain on winter territories until late April–early May, then are replaced by different population that breeds in July–September (see Distribution, Migration, and Habitat: Migration).

Individual Distance

No information.

Dominance Hierarchies

None reported.

Sexual Behavior

Mating System and Sex Ratio

Presumed monogamous, although Rising (27) stated “virtually nothing known” about this species' mating system. Rising (27) found that testes size was smallest relative to body size, compared to 19 other sparrow species. Large testes: body ratio in other species was assumed to be evidence for polygyny.

No information on sex ratio.

Pair Bond

Courtship and copulation poorly described; much activity takes place on ground in dense grassy habitat. Pair bonds form mid-April to mid-May in Texas (7). Male pursues females across territory before pair bond establishment, but does not pursue outside territory (29). In Arizona, males are already mated when singing commences with monsoon rains in July (RKB, JBD), but not known if birds arrive paired. From 78: pairs initiate courtship flights by circling territory together just above tops of trees or shrubs. Both members of pair give rapid Tzee-tzee-tzee Call as they chase each other. Male may fly to song perch and give Tzee-tzee-tzee Call as he floats down from perch. During pause in chases, male perches in bush or on ground and assumes display posture: tail fanned and elevated, head down, wings outward and fluttering. During display, female perches low in same bush or nearby.

One variation in above display (78): Male was present on territory giving Primary Song from perches and in flight for about 30 min. Second bird flew up from ground, sat in top of mesquite, and assumed display posture described above while giving Tzee-tzee-tzee Calls. Male was performing a Flight Song, and sailed down to branch 1 m from displaying bird. Both then flew up to height twice that of typical Flight Songs, floated silently down to grass and were lost to view.

Copulation is usually done hidden in vegetation or on ground. Observed once by Williams and LeSarrier (78): male singing, female perched in nearby shrub without calling or display. Male flew from perch to female and copulated. Copulation was observed on 3 occasions by Schnase (29): one in low mesquite and two on the ground, each proceeded by courtship display.

Extra-Pair Copulation

No information.

Social and Interspecific Behavior

Degree of Sociality

Cassin's Sparrow is not particularly social. It often reaches high density in good habitat, but there is no evidence of true coloniality. Young may form independent flocks of juveniles with 10–20 individuals (29). Such flocks move through territories without provoking response from adults. The species is also reported in small, loose foraging flocks of “several adults and independent juveniles” that occasionally include other sparrow species (90). See Nonpredatory Interspecific Interactions, below.


None described.

Nonpredatory Interspecific Interactions

Dorn and Dorn (90) observed “several adults and independent juveniles” in small, loose foraging flocks with Lark Bunting (Calamospiza melanocorys), Brewer's Sparrow, Chipping Sparrow (Spizella passerina), Clay-colored Sparrow (S. pallida), and Vesper Sparrow (Pooecetes gramineus) in late summer on the breeding grounds (90). In September 1998, 12–15 juvenile Cassin's, Rufous-crowned, and Grasshopper sparrows were in a compact foraging flock in Cimarron County, Oklahoma (J. Grzybowski, personal communication).

Cassin's Sparrow and Botteri's Sparrow have overlapping territories in arid grasslands near Santa Rita Mountains, Arizona (RKB, JBD). Male Cassin's Sparrow has been observed chasing Botteri's Sparrow (RKB), but individuals of both species can be seen perched on the same branch of small shrub after extensive singing bouts with no agonistic interaction noted (JBD, RKB). More work is needed on interspecific relationships between these 2 species. Grasshopper Sparrow (Ammodramus savannarum) have been seen chasing Cassin's Sparrow (RKB).

Eight observations of attacks on Cassin's Sparrow by Ash-throated Flycatcher (Myiarchus cinerascens) during sparrow Flight Songs at Santa Rita Experimental Range in southeastern Arizona (115). Ash-throated Flycatcher usually knocked Cassin's Sparrow to the ground. Austin and Russell (115) speculate that Cassin's Sparrow flight display is similar to flycatcher hawking maneuver, and attacks are misplaced aggression to a presumed competitor. Ash-throated Flycatcher has also been observed attacking Cactus Wren (Campylorhynchus brunneicapillus) making similar flying motions.


From Williams and LeSarrier (78): one bird impaled on yucca spine by Loggerhead Shrike (Lanius ludovicianus). Young in one nest near Midland, Texas, were almost completely consumed by large red ants. Not known if ants killed young birds or were scavenging.

Snakes are common in arid habitats that constitute breeding grounds, and presumably are responsible for loss of eggs and young. Of 13 nests followed in Arizona in 1983, four failed due to predation: one in egg stage, three in nestling stage (RKB).

One extensive study of avian depredation in Mexico (116) looked at the diet of Aplomado Falcon (Falco femoralis) in central Chihuahua. The most common species on line transects (meadowlarks, Sturnella spp.) was also the most common prey item. Cassin's Sparrow was third most common species detected on transects, but was not found in falcon pellets or prey remains at falcon nests. Cassin's Sparrow might not have been preyed upon because of their small size. Similar-sized and common Black-throated Sparrow (Amphispiza bilineata) and Horned Lark (Eremophila alpestris) were likewise missing from diet, although larger but rarer Northern Mockingbird (Mimus polyglottos) and Mourning Dove (Zenaida macroura) were found in prey samples.

Response to Predators

None recorded directly. An individual injured during banding ran along ground and dove into a kangaroo rat burrow to escape (117). RKB and JBD dug up the burrow to retrieve the sparrow, and found the bird about 0.6 m into the burrow, which was paralleling the ground surface. When released, the sparrow immediately re-entered the burrow (now a trench) until it was stopped at the same point as before (presumably too narrow for further movement). Behavior suggests that Cassin's Sparrow may use underground burrows to escape predators, a behavior also reported for Black-throated Sparrow and Canyon Towhee (Melozone fusca; 118, 117).

Recommended Citation

Dunning, J. B., Jr., R. K. Bowers Jr., S. J. Suter, and C. E. Bock (2018). Cassin's Sparrow (Peucaea cassinii), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.