Spotlight on the Amargosa toad

“Are you a native?” It’s one of those things Nevadans ask. There’s great pride in having a family history in the Silver State, and pride too, for those who’ve chosen to move here among all the American alternatives.

But one of our neighbors has a more legitimate claim to being a native than most Nevadans.  The Amargosa toad (Bufo nelsoni) is found only in Oasis Valley in Nye County, Nevada. Historically, the tiny toad only ranged within a 10-mile reach of the Amargosa River, tributaries, and nearby springs and wetlands.

The little amphibian fits in your palm, and pretty cute, as toads go.  Perhaps that’s why so many people have taken steps to preserve their habitat, which occurs mostly on private lands in Oasis Valley.

Even though they are quite rare, Amargosa toads can be found in a variety of habitats in Oasis Valley. Most important are wet areas near springs, along the Amargosa River, and yard and garden areas. These moist areas provide places to find food and stay hydrated in this desert environment.

Fortunately, wet areas are common in Oasis Valley early in the spring, after winter rains have created small pools and puddles. As early as January or February, temperatures rise and Amargosa toads converge on these pools to lay eggs. Egg laying continues into June and can go on as long as late as July or August if there is rain. In most years, breeding activity ends in April or the beginning of May.

Amargosa Toad breeding habitat

Toads prefer to lay eggs in still water that is between half an inch to 9 inches deep. Frogs seek calm for egg-laying because eggs will not be swept downstream to habitat that may put the developing embryos at risk of being eaten by predators.  In addition, placid water often collects has fine- grained materials like silt and/or sand, in which tadpoles can find the food and nutrients they need to develop. In addition, still, shallow puddles heat up in the sun – warmer temperatures help the eggs and tadpoles develop more quickly.  It’s great to know the value of puddles, and it might make us think twice before we jump in one to make a splash!

Outside the breeding season, Amargosa toads do not need much water. Interestingly, toads don’t “drink” water; instead, they absorb it through their behind! A thirsty toad will absorb the necessary water through their “seat patch” located on their lower belly.

In fact, water can harbor species that could eat the tadpoles. Shallow ponds that dry up quickly make for inhospitable conditions for introduced predators like crayfish and bullfrogs that prey upon the toads.

These two recently introduced predators pose a larger threat than native predators because the Amargosa toads have not had time to evolve and adapt new defensive behaviors, making the toads more susceptible predation.

Native wildlife, as well as dogs and cats, avoid adult toads because they taste horrible! The bad flavor comes from a toxin excreted from the toad’s skin. Crayfish and bullfrogs, on the other hand, don’t seem to notice.  Toads have been found with missing feet, broken legs, and in the stomachs of bullfrogs.

Once the toads move out of the water, they take up residence in the uplands. This dry habitat occurs near the wetlands (usually within 50 yards) and often has small animal burrows that the toads use as shelter throughout the year.  These subterranean dwellings protect them from extreme heat and cold.

Though dispersal is infrequent, some toads do move to other wetland habitats. Obviously toads aren’t built for long distance migrations, but when they do move to a new area, they must travel across these dry upland areas. Toads have been observed as far as a quarter mile from surface water – a long distance for those little legs! In order to maintain their populations, it’s important for there to be habitat that allows them to move between sites and mantain populations throughout the valley.

Credit / Source: NDOW


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