By Dave DeGroot, Cohort 2
Creosote bushes are so common in Pima County that we hardly give them a second thought. Many desert animals, however, give the creosote a second and third thought – some depend on the bush for their existence. Animals with a very close relationship to the plant include the desert iguana and the leafcutter ant. Other animals that have an interest in the creosote bush include mice, pack rats, kangaroo rats, jackrabbits, chuckwallas, many species of bees, beetles and millipedes.
The big desert iguana can be seen rummaging around in creosote bushes, eating yellow flowers and munching on the waxy leaves when the blooms fade – even duringsome of the hottest days of the summer. Not only does the big lizard feed in the bush, but it digs burrows under it to escape predators and find relief from extreme heat. In fact, the desert iguana’s range corresponds to the territory where creosotes are found, in the Sonoran and Mojave Deserts.
At the other end of the size-spectrum is another creosote connoisseur, the little leafcutter ant – not to be confused with its larger tropical cousin with the same name. In our area, leafcutter colonies can be found scattered throughout creosote flats. The ants often parade in single file, carrying pieces of creosote leaves back to their holes. They don’t eat the leaves they work so hard to collect, though – they cultivate a fungus that grows on theirstockpiled leaves, and it is the fungus they use for food.
Interestingly, another very close animal-creosote relationship probably flourished in our area eons ago, totally disappeared for 15,000 years, and then started up again (briefly) in 1856. This odd footnote to history was written when Arabian camels were imported by the U.S. Army Camel Corps before the Civil War. Camel wranglers noticed that their transplanted dromedaries happily munched on creosote leaves, and this led to speculation that little extinct North American camels dined on creosote cuisine until they disappeared around 15,000 years ago.