HBW 4 - Species accounts: Greater Roadrunner (Geococcyx californianus)

Genus GEOCOCCYX Wagler, 1831

131. Greater Roadrunner
Geococcyx californianus

French: Grand Géocoucou German: Wegekuckuck Spanish: Correcaminos Grande

Taxonomy. Saurothera californiana Lesson, 1829, California.
Population from Texas (USA) S to Nuevo León and Veracruz (Mexico) averages smaller and has been described as race dromicus; but birds from this region overlap in size with those in other parts of range. Monotypic.
Distribution. SW USA and Mexico, from California, Utah and Colorado E inland to Missouri and Louisiana, through coastal Texas and Baja California, S to Michoacan, Puebla and Veracruz.
Descriptive notes. 56 cm; male 320 g, female 290 g. Large and slender, with long tail and long legs; streaked brown above with bronze gloss, shaggy blue-black crest, tail with broad white tips on outer 3 rectrices; whitish below with brown streaks; eye-ring blue, bare skin behind eye usually white (male) and orange, iris brown with yellow ring, bill blackish, feet grey. Female averages smaller, postorbital skin usually blue and orange. Juvenile duller, feather tips more pointed, with white U-shaped patches on tips of primary coverts; white tips of rectrices wedge-shaped, rather than oblong; postorbital skin as in adult female, inner iris develops grey ring around pupil, outer iris brown.
VOICE. Mournful dove-like "coo" notes, slow and descending in pitch; also a bill-rattle.
Habitat. Arid scrub, lowland or montane; widely dispersed in dry open country with scattered brush, mesquite, palo verde, creosote, cholla cactus, prickly-pear cactus, upper oak and pi¤on pine scrub, in yucca and shortgrass plains of N Texas panhandle; also in tall pines and magnolias in E Texas; clearings in farms and dry scrubby woods. Roosts and feeds in shelter of trees and rocks. Mostly in arid and semi-arid regions having at least 140 clear sunny days from sunrise to sunset; N limit to range determined by prolonged deep snow cover. Occurs from lowlands up to 2500 m.
Food and Feeding. Opportunistic carnivore, taking: insects (grasshoppers, crickets, cicadas, caterpillars, beetles), scorpions, centipedes, spiders (including tarantulas), toads, lizards, small snakes (including rattlesnakes), small birds and eggs, mice, young ground squirrels, young rabbits, young bats fallen from cave ceilings, roadside carrion; also, up to 10% of diet made up of fruits and seeds, e.g. prickly-pear (Opuntia) cactus, sumac (Rhus integrifolia). Terrestrial and cursorial, foraging solitarily or in pairs; can fly, but usually runs on bare ground under cover; runs after prey on ground, leaps at flying insects, tosses and batters lizards and snakes against a stone, attacks scorpions by the tail; members of pair sometimes co-operate in attacking a snake.
Breeding. In S California, breeds from late Feb in low elevations of Lower Sonoran Life Zone, a month later in upland deserts of Upper Sonoran Life Zone; in S Arizona from mid-Apr to mid-Jun and late Jul to mid-Sept, with pause in hot dry summer and increased nesting after summer rains (varies with annual rains); in Texas breeds Mar-Oct, in Oklahoma Apr-Jul/Aug. Breeding male feeds mice, small birds, snakes and lizards to his mate. Nest is an open bulky platform of sticks, lined with leaves, snakeskins, dung and mesquite seed-pod debris; often placed in shade, 1-3 m up in bush, low tree, thicket or cactus clump. Eggs 2-6 (clutches larger after summer rains), white, 39 x 30 mm; laying interval often 2 days, but variable; incubation 17-18 days, by male at night and by both sexes in daytime, female having one bout in morning and one in afternoon; hatching asynchronous, age differences of nestlings up to 7 days. Hatchling 14 g, nearly naked, skin black (throat whitish) with short (1-7 mm) whitish hair-like feather sheaths, gape flange pink, mouth red with white upper palate, raised area of white papillae on each side of palate and at base of throat, feet black; cared for by both parents; half adult weight at 14 days; when disturbed, nestlings give loud vocal "churr", also bill-rattle, and will also excrete a blackish foul-smelling liquid; fledging 17-19 days; young fed by adults for further 2 weeks; follow parents to feeding areas and catch their own food within 2-3 weeks. Pair can nest again a month after first nesting, male taking over care of fledglings while female lays second clutch; single-brooded, double-brooded or even triple-brooded, depending on weather. In Texas 73% of nests were robbed by predator, 22% of eggs survived to fledge, and a pair that nested twice could produce on average 3·5 chicks in a season; in another study, in New Mexico and Oklahoma, 66% of eggs laid hatched, 87% of nestlings fledged, and overall nest success was 72%.
Movements. Resident. Pair remains on territory all year and in successive years; one remained 5 years in the same site. A pair may sometimes move together to a new territory and renest 1·6 km from an earlier nest, while other birds move independently of their mate, in both cases after failure of earlier nest. No evidence of seasonal movements. Juveniles thought to disperse from their natal territories.
Status and Conservation. Not globally threatened. Common to fairly common; population numbers over most of range have shown no significant change in period 1966-1993. Most numerous in SE California, S Arizona (Chihuahuan Desert) and Texas W of Pecos R and S of Edwards Plateau. Density on rocky slopes in S California 0·65 birds/km2, lower in other desert habitats; in coastal S Texas 3 birds/km2; territories average 0·5 km2. Adult annual survival at least 60% (few ringing recoveries). During 20th century, range has expanded N and E in California, E Kansas and Oklahoma, and across Ozarks into basin of Mississippi R; land clearance, overgrazing, and a later reinvasion of scrub may be involved in the eastern range expansions. On a more local scale, range is decreasing in urban areas (see page 522), where habitat is developed for agricultural and residential development, and the species has been extirpated in Central Valley and S counties of California. Has bred in captivity.
Bibliography. Baumgartner & Baumgartner (1992), Beal (1978, 1981), Beal & Gillam (1979), Bent (1940), Berger (1952, 1954), Binford (1971), Bleich (1975), Browning (1978), Bryant (1916), Calder (1967, 1968a, 1968b, 1968c), Calder & Bentley (1967), Calder & Schmidt-Nielsen (1967), Coues (1900), Dobie (1939), Dunson et al. (1976), Eltaher (1980), Emlen (1974), Engels (1938), Finley & Finley (1915), Folse (1974), Folse & Arnold (1976, 1978), Garland (1989), Garrett & Dunn (1981), Geluso (1969, 1970a, 1970b), Gorsuch (1932), Grinnell & Miller (1944), Harris & Crews (1983), Harrison (1978), Herreid (1960), Howell & Webb (1995), Hughes (1996b), James & Neal (1986), Johnsgard (1979), Kavanaugh & Ramos (1970), Kimsey (1953), Lasiewski et al. (1971), Lowe & Minde (1969), Mayhew (1971), McCaskie et al. (1988), Meinzer (1993), Miller & Stebbins (1964), Muller (1971), Oberholser (1974), Ohmart (1972, 1973, 1989), Ohmart & Lasiewski (1971), Ohmart, Chapman & McFarland (1970), Ohmart, McFarland & Morgan (1970), Pemberton (1916, 1925), Peterson (1980), Price et al. (1995), Pridgeon (1995), Rand (1941b), Root (1988), Rutgers & Norris (1972), Schaafsma (1989), Sherbrooke (1990), Shetlar (1971), Shufeldt (1885, 1886a, 1886b, 1886c), Small (1994), Smith (1981), Stotz et al. (1996), Sutton (1913, 1915, 1922, 1967, 1972), Tweit & Tweit (1986), Van Tyne & Sutton (1937), Vehrencamp (1982), Vehrencamp & Halpenny (1981), Weathers (1983), Whitson (1971, 1975, 1983), Wilbur (1987), Woods (1960), Zimmerman (1970).