Monsoon rains pull the Sonoran Desert Toad out of hiding

The monsoon has flipped a switch for the Sonoran Desert Toad (Incilius alvarius). Across the Tucson basin and washes from Cactus Forest Drive to Madera Canyon, Box Canyon Road, and Sonoita, observers have logged 49 sightings of this heavy-bodied toad in the past 30 days, following eight months of near total absence, with only two stray records between last October and this May.¹

A similar pattern, near-silence followed by a sharp midsummer cluster, appears in last year's iNaturalist records too, though these are community-science observations shaped by observer effort as much as by the toad's actual movements, so it's worth treating as a suggestive signal rather than a confirmed recurring trend. What is well established is the biology behind it: this is North America's largest native toad, a stocky, warty animal that can reach over seven inches long, and it spends most of the year buried underground in a state of dormancy, waiting out the dry heat. It surfaces almost entirely in response to soil saturation from monsoon rains, emerging to breed in temporary rain pools that may hold water for only a few weeks. Eggs and tadpoles have to develop fast in that narrow window; miss it, and there is no second chance until the following summer.

The species is also listed as threatened on iNaturalist, which makes this brief, rain-triggered burst of activity worth watching closely while it lasts, rather than something to assume will repeat on the same schedule every year.¹ A poor monsoon, or pools that dry too quickly, can mean a season with no successful breeding at all for a toad that already spends the other eleven months of the year out of sight.