Bufo punctatus Baird and Girard, 1852(a)
Brian K. Sullivan1
1. Historical versus Current Distribution. The type locality of red-spotted toads (Bufo punctatus) is the Rio San Pedro, a tributary of the Rio Grande, in Val Verde County, Texas (Baird and Girard, 1852a). Their range extends from southwestern Kansas, western and southern Oklahoma, central and western Texas, New Mexico, southwestern Colorado, Arizona, southern Utah, southern Nevada, and southeastern California, south into Mexico. Red-spotted toads are found at elevations from below sea level to almost 2,000 m (Stebbins, 1951). Additional comments on their distribution can be found in Collins (1982), Creusere and Whitford (1976), Dixon (1987), Hammerson (1982a), Lowe (1964), and Turner and Wauer (1963).
2. Historical versus Current Abundance. Historical abundance is unknown. In central Arizona, localized populations can be abundant. For example, in early April 1991, 20 males were observed chorusing in a 30 m stretch of the New River, Maricopa County, Arizona; 65–75 d later (June), hundreds of toadlets metamorphosed at this site. Another population breeding during the summer (August 1992) in a cattle tank in north-central Maricopa County contained a minimum of 50 calling males and 20 amplectant pairs (personal observations).
David Bradford (personal communication) and colleagues surveyed sites in southern Nevada and found red-spotted toads at every (n = 16) historical collecting locality examined; they noted that red-spotted toads appeared to be thriving at many disturbed sites (e.g., sites altered for livestock use). Similarly, central Arizona populations occurring in rocky upland sites often use disturbed sites such as cattle tanks for breeding following summer rainstorms (personal observations).
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Breeding occurs from March–September (Stebbins, 1951; personal observations). In the Sonoran Desert, populations along small streams breed in the spring (March–June), whereas populations occurring in rocky desert uplands breed in rain-formed pools during the summer rainy season (June–September). In the Sonoran Desert of southern California (Palm Springs), stream-dwelling populations breed from April–June, depending on the availability of water (Tevis, 1966). Long-distance migrations of large numbers of individuals have not been reported. Adults in relatively arid regions probably reside throughout the year in the vicinity of streams used for breeding. Breeding periods span 2–4 wk for stream-breeding populations and 1–5 nights for rain-pool breeding populations (personal observations). Males call in shallow water, completely exposed on rocks in or near the water, or on land away from water including from burrows and under rocks (Stebbins, 1951; Turner, 1959; Tevis, 1966; Ferguson and Lowe, 1969; personal observations).
ii. Breeding habitat. Small, rocky streams and springs with shallow pools are used for breeding in the spring; rain-formed pools in rocky desert upland areas are used during the summer (Stebbins, 1951; Turner, 1959; Tevis, 1966; Creusere and Whitford, 1976; Sullivan, 1984; personal observations).
i. Egg deposition sites. Eggs are usually laid singly, rather than in gelatinous strands, in rocky streams, springs, and shallow pools; egg capsules are small, 3–4 mm in diameter.
ii. Clutch size. According to Tevis (1966), the "number of eggs per mass varied from 30–5,000 (average 1,500)." Stebbins (1951, 1985) has also described eggs and larvae.
C. Larvae/Metamorphosis. Larvae are generally black with metallic bronze flecks and are often observed clustered in large aggregations in stream habitats, resting on muddy substrates. In central Arizona, the larval period lasts about 8 wk in stream-breeding populations (31 March–1 June). Altig et al. (1998) provided a key to larvae of red-spotted toads and other sympatric anurans in the Southwest. Tevis (1966) described larval development and behavior in a stream-dwelling population in southern California. Luepschen (1981) described albino larvae.
D. Juvenile Habitat. Unknown; recently metamorphosed young have been observed near breeding habitats in Arizona and California (Stebbins, 1951; personal observations).
E. Adult Habitat. Adults are typically associated with rocky streams in the arid West, although may occur away from drainages in well-drained, rocky soils of the Arizona Upland division of the Sonoran Desert Biotic Community (e.g., south-central Arizona). Bradford et al. (2003) propose that red-spotted toads exist as "patchy populations," implying frequent dispersal among patches and virtually no local extinctions. Aspects of water balance are discussed by Brekke et al. (1991) and Propper et al. (1995).
F. Home Range Size. Along a stream in southern California, males moved ≤ 185 m and females ≤ 460 m over a season (February–June; Tevis, 1966). Additional data on movements for a population in Death Valley, California, are presented in Turner (1959).
G. Territories. Unknown. Males defend calling territories at breeding sites; interindividual distances typically range from 1–3 m (Sullivan, 1984; personal observations). Males engage in amplexus-like wrestling bouts during territorial disputes (Sullivan, 1984).
H. Aestivation/Avoiding Dessication. Unknown. Adults presumably aestivate in areas lacking summer rainfall.
I. Seasonal Migrations. Unknown. Tevis (1966) considered relatively large (between 450–850 m) movements of a small number of individuals as migrations (see "Home Range" above).
J. Torpor (Hibernation). Unknown, although adults presumably hibernate during cooler and/or drier months (October–February; see Johnson et al., 1948) over most of the range.
K. Interspecific Associations/Exclusions. Hybridization documented between red-spotted toads and western toads (B. boreas) in California (Feder, 1979), Great Plains toads in central Arizona (Sullivan, 1990), Sonoran green toads (B. retiformis) in southern Arizona (Bowker and Sullivan, 1991), and Woodhouse's toads (B. woodhousii) in northern Arizona and southern Colorado (Malmos et al., 1995). Hybrids are generally easily identified by their morphology (intermediate to parentals) and aberrant calls.
Red-spotted toads breed in association with Arizona toads (B. microscaphus), Woodhouse's toads, canyon treefrogs (Hyla arenicolor), and Great Basin spadefoot toads (Spea intermontana) in southern Utah. In south-central Arizona, red-spotted toads breed in association with Arizona toads, Woodhouse's toads, canyon treefrogs, and lowland leopard frogs (Rana yavapaiensis) in the spring, and with Colorado River toads (B. alvarius), Great Plains toads (B. cognatus), Sonoran green toads, and Couch's spadefoot toads (Scaphiopus couchii) in the summer (personal observations). In southern Nevada, red-spotted toads breed with Woodhouse's toads, Pacific treefrogs (Pseudacris regilla), and relict leopard frogs (Rana onca; D. Bradford, personal communication). Creusere and Whitford (1976) suggested that red-spotted toad larvae could not develop to metamorphosis in the presence of larvae of Spea spp. or Couch's spadefoot toads due to heavy predation by their carnivorous larvae.
L. Age/Size at Reproductive Maturity. In central Arizona, calling males at breeding aggregations of five populations (n = 71 males sampled) ranged in size from 47–63 mm SVL. Females in amplexus (n = 8) in a single population in central Arizona ranged from 52–66 mm SVL. For a population in central Arizona, skeletochronology indicated that males matured in their first or second full season following metamorphosis (Sullivan and Fernandez, 1999).
M. Longevity. In a population from central Arizona, average age was 2 yr for both males (n = 22) and females (n = 8); no individuals were > 6 yr of age (Sullivan and Fernandez, 1999). Individually marked males have been captured over four seasons in a population in southern California (Tevis, 1966). Additional mark-recapture data are presented by Turner (1959) for a population from Death Valley, California.
N. Feeding Behavior. Red-spotted toads feed on a variety of invertebrates (Stebbins, 1951); reports on diet include Little and Keller (1937), Smith (1950), and Tanner (1931).
O. Predators. Blazquez (1996) reported predation by a watersnake (Nerodia valida) in Baja California, Mexico; red-spotted toads may be preyed upon by a variety of snakes, birds, and small mammals.
P. Anti-Predatory Mechanisms. Cei et al. (1968) report the presence of presumably toxic indolealklamines from the skin and paratoid glands of red-spotted toads.
Q. Diseases. Unknown.
R. Parasites. Goldberg and Bursey (1991b) reported on the helminth fauna (cestodes, nematodes) for populations in southern Arizona.
4. Conservation. Widespread declines have not been noted for red-spotted toads, but they are listed by the State of Kansas (in the extreme northeastern portion of their range) as a species in need of conservation (Levell, 1997). David Bradford and his colleagues (personal communication; see also Bradford et al., 2003) documented the continued presence of red-spotted toads at all historical localities they surveyed in southern Nevada. One local decline is suspected and requires continued monitoring: red-spotted toads appear absent from the vicinity of Austin, Texas (D. Hillis, personal communication).
Acknowledgments. David Bradford and Jef Jaeger shared their observations and provided helpful comments on the account. Rob Bowker, Mike Demlong, Matt Kwiatkowski, Erik Gergus, and Keith Malmos assisted with some observations. Funding was provided in part by the Heritage Fund, Arizona Game and Fish Department.
1Brian K. Sullivan
Department of Life Sciences
Arizona State University West
P.O. Box 37100
Phoenix, Arizona 85069
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 13 Jul 2020.
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