Storm clouds in Arizona

Spotty rain and lonely toads

Thunderstorms are the ultimate in chaotic systems, and this years monsoon has been a good example of that.   Some parts of southern Arizona have received plenty of rain and are green and lush.  Others have received too much rain too fast, resulting in flash floods.  And other places, like my neighborhood, have been watching these other areas with envy, as storm after storm dump rain “over there” but not “here.”

Every few years, an interesting variation of the thunderstorm takes place, with a massive storm developing over the Mogollon Rim (a basaltic escarpment that divides the Sonoran Desert in southern Arizona from the Colorado Plateau of northern Arizona), that pushes south into the deserts.  These storms can be two hundred or more miles wide and carry a huge amount of moisture.  The first one I experience dumped 5 inches of rain in 45 minutes.  It was preceded by a huge dust cloud, so it coated everything with a layer of mud.

We experienced such a storm on Sunday night (August 17).  I noticed it on radar in the middle of the afternoon, and watched its steady progress to the southwest.  It arrived in the Tucson area just as it got dark.

It was accompanied by lots of lightning – flash after flash illuminated the sky.  I thought I’d have a go at photographing the lightning, but before I could get the settings on my camera correct, the rain arrived.  Sheets of rain, coming in horizontally.  I had to quickly shut all of the windows on the east side of the house.  My dog hid in the bathroom, while rain pelted the house and the ground rumbled with thunder.  It was a very impressive storm.

Storm over the Rincons

The storm rolls in at sunset

The rain and wind were too wild during the storm to attempt recording.  But two hours after it started, it began to slowly move off to the west.  The wind died down, the rain became soft and vertical.  I set up my recorder in my bedroom, with the window wide open, and recorded the storm as it moved on.

After about 10 minutes of recording, I began to notice an odd, repetitious sound.  Toads!  Southern Arizona has several species of toads that appear during the monsoons, and I had been eager to record them for years, but had never been in the right place at the right time.  But now I had a toad calling not far from my back door.

This is a Couch’s Spadefoot, a fairly common toad in southern Arizona and New Mexico.  Technically, its not a toad, it’s a spadefoot, a distinction that I’m sure only matters to amphibiologists.  They are a true desert critter, spending most of their lives underground.  They respond to the ground-shaking vibrations of thunder, quickly emerging, calling for mates, laying eggs in ephemeral pools and going back underground.  Eggs can become tadpoles in less than a day, and tadpoles can become froglets (spadefootlets?) in as little as two weeks.   Not exactly an exciting lifestyle, but a pleasing component of the desert soundscape.

Couch's spadefoot

Couch’s spadefoot (Scaphiopus couchii)

The storm caused no damage at my house, but several of the dirt roads in my neighborhood were washed out.  Maybe things will finally start to green up around here.


Photo of Couch’s spadefoot by squamatologist (Flickr) under Creative Commons license.

Recorded using a Sony PCM-M10 and Audio Technica AT2022 mic with Felmicamps pre-amp.

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