Wednesday, February 27, 2013

  Arroyo Toad (Anaxyrus califonicus)

(=Bufo californicus)

Adult male, desert side of San Bernardino Mountains

http://www.californiaherps.com/frogs/pages/b.californicus.htm


This is a small toad, 2 to 3 inches snout-vent length (5), which lives around bodies of fresh water and in adjacent uplands and is native to Southern California and parts of Mexico (1). It is colored to blend into its environment, often with spots, ranging from green or gray to light brown, with a white v-shaped stripe crossing the top of the head between the eyes and a buff-white belly that often does not have spots. It tends to hop instead of walk or take long jumps (5).

 

Habitat

 

Desert side of San Bernardino Mountains
http://www.californiaherps.com/frogs/pages/b.californicus.html
Its breeding habitat is slow moving streams and shallow pools. It deposits its egg masses in shallow sandy pools that are surrounded by sand and gravel flood terraces usually (4). Conditions have to be optimal to breed. This species has been known to naturally skip breeding in years when conditions are not optimal such as during times of drought when slow moving shallow water is not available (6). When it is not the breeding season, Arroyo Toads are mainly terrestrial (4). They forage and need burrowing areas in the upland areas around the streams. Also, male toads may migrate to other populations through the upland areas (8). 

Close up of egg strings
http://www.californiaherps.com/frogs/pages/b.californicus.html
Tadpoles
http://www.californiaherps.com/frogs/pages/b.californicus.html

Population sizes are difficult to measure. Surveys of populations have historically been done using audiation. However, male toads only call during breeding season (8). Because of the tendency for this species to not breed when conditions are not optimal, timing for surveys have to match up to breeding seasons to detect the presence of populations. This problem may be exasperated by less breeding due to loss of habitat for breeding (6). (Video clip is of a male arroyo toad calling during breeding season).