The only running water in southern Arizona!
Our exploration of oak savannas in southeastern Arizona has taken us along a lot of gravel roads that cross dry creek beds. Although these creek beds might be full of water after a heavy thunderstorm, they are otherwise dry. (Just ignore the signs that warn about the dangers of entering these creek beds.)
Thus, it was really refreshing to visit the Patagonia-Sonoita Creek Preserve of the Nature Conservancy, about 60 miles from Tucson. Sonoita Creek flows year around, and although this was an unusually dry year (Tucson had only 5.67" of rain for the whole year!), this creek just keeps flowing (see the photo). There is some interesting hydrology going on here!
Understandably enough, Sonoita Creek has some interesting ecology. It is one of the rare habitats of the Gila topminnow (Poecilopsis occidentalis), an endangered species. It also provides the support for a rare streambank Fremont cottonwood forest. This is one of the few remaining sites in Arizona where this once-common forest type still persists. Arizona black walnut, velvet mesquite, velvet ash, netleaf hackberry, and various willows are found in slightly different habitats throughout the preserve. This vegetation itself provides support for an interesting avifauna. Among others, we greatly enjoyed watching the antics of the acorn woodpecker.
In part of the Sonoita system are cienegas (marshes), where the rare Huachuca water umbel, Santa Cruz striped agave, and Santa Cruz beehive cactus thrive.
The Sonoita Creek site was the Nature Conservancy's first preserve in Arizona, and it is managed very well. A small but fine visitor center is near the entrance, and a full-time manager lives on the grounds. (The preserve is just a few miles from Patagonia, Arizona. Follow the signs from the center of town.)
The green vegetation in the creek bed in the photos is watercress, a nonnative but nevertheless pleasant to see in this otherwise dry environment. The frequent deer love to eat it!