Moab Happenings Archive
Return to home

NATURE HAPPENINGS - June 2006


Red Spotted Toads
by Damian Fagan


It is late at night as I walk across the sandy dunes to a desert pool. My headlamp illuminates the way, highlighting obstacles like prickly pear cacti and marauding scorpions.

I am pleased to find this desert pool full from the recent rains. As I scout the edge of the pond for aquatic life, I observe numerous tracks of coyote, kangaroo rat, lizard, mule deer, and especially amphibians in the moist sand.

Red-spotted toadsBut it is the unmistakable, high-pitched trill of red-spotted toads that is overwhelming evidence as to their presence. These are the males, these desert singers, who are calling for the females to join them at this particular breeding site. Perhaps triggered by the recent rains, these toads realize that their window of opportunity is narrow; it won’t take long for this ephemeral pool to become a dry, dusty pothole.

When I reach the sandstone edge of the pool, I see many of these small, warty toads with pointed snouts. The chorusing stops, but only for a few moments. Soon one starts, then another, then another, until the blackness seems pierced by trilling.

I unload my camera gear and set up the tripod. I use a macro lens and have to watch where I place my camera. I carefully move about the pool and sandstone edge, avoiding the toads that seem reluctant to move. Not that I can blame them.

A red-spotted toad (Bufo punctatus) is a small, compact toad, 1½- 3” long. Their squat bodies are grayish to olive to brownish in color and are covered with small reddish or orangish warts called tubercles. Often their coloration matches the surrounding substrate. Behind their eyes are two small, rounded glandular structures called parotoid glands. On some toads these may emit a potent toxin, although these red-spotted toads produce little or no toxins.

The common name and species name, punctatus (which means “spotted”) are derived from the reddish warts that cover the body. Bufo is Latin for “toad” and in Spanish these toads are called sapo.

The red-spotted may be found from sea level up to 7,200’ in elevation. Though the breeding season is from April to September, elevation and rainfall influence that period. Spring or summer rainstorms that are of sufficient duration awaken these slumbering amphibians, and the males leave their underground chambers and start to chorus.

The advertisement call is a high pitched trill that lasts from 6-10 seconds and the male’s dusky vocal sac expands with the call. If the males clasp another male or an unreceptive female, they emit a release call that sounds like a chirp followed by a short trill. A female carries developed eggs that need external fertilization.

When the pair joins together, the embrace is called amplexus. She releases her eggs one at a time, not in long strings, and is the only North American toad to do so. The male fertilizes the eggs, which are enveloped in a gelatinous coating to protect the embryo. The eggs sink to the bottom of the pool and will hatch in only a few hours.

Time and predators are the enemies of the red-spotted toads. Although coyotes, foxes, raccoons, salamander larvae, and some aquatic invertebrate larvae predate on the tadpoles, it is shortness of time that rushes these tadpoles through their developmental stages. The tadpoles take between 40 and 60 days to transform into adults. Sometimes their natal pool will dry out, stranding the tadpoles like whales on a beach.

The red-spotteds ability to lose 40% of its body water and still survive is an adaptation that allows the toad to stray from water or to seek new habitats. Small amounts of water, even dew, may be absorbed through a thin, translucent pelvic patch located behind the legs and extending up onto the abdomen. This allows them to absorb moisture and exchange electrolytes through their underside while in contact with damp ground.

When I am done photographing these toads, I pack my gear and head back to the car. Above me the star-studded night sky lacks an amphibious constellation, but the chorusing toads remind me that this night belongs to them.

Return to Archive Index
 
Return to home

info@moabhappenings.com