Science for Decision Making on Uranium Mining in Arizona

Mine Utilization by Bats and Amphibians

At Pinyon Plain (formerly Canyon) Mine


In arid habitat, limited water resources are used by a variety of taxa. Bats represent one group of animals that rely on open surfaces of water for drinking. Containment ponds in mining areas of the Grand Canyon region serve as a possible drinking habitat when other water resources are limited or not available. The containment ponds located at breccia pipe mines serve as locations that could be used by a great number of bat species for drinking but also as an area for feeding on aquatic insects (e.g., midges) that inhabit and emerge from these water sources. Insects feeding on vegetation surrounding these water sources also serve as possible food for bats.

Bat Sampling Objectives

  • Collect and identify insectivorous bats, their guano, and aerial invertebrates that represent the aquatic food chain at the mine1.
  • Characterize exposure of aerial invertebrates and bats to metals and radionuclides potentially related to mining activities2.
  • Use acoustic monitors to determine seasonal activity of bats and help identify which bat species utilize the containment pond at the mine.

Key Bat Findings

  • Mist-netting to capture bats occurred at Arizona 1 and Pinenut mines, as well as two nearby sites that served as proxy sites 4,5.
  • Bats captured directly at Arizona 1 Mine included one pregnant Antrozous pallidus (Pallid bat) and one adult male Parastrellus hesperus (Canyon bat) 4,5.
  • A total of 45 bats, belonging to nine species, were captured at two proxy sites 4,5.
  • Nightly and seasonal presence of bats, as shown through acoustic recordings at each mine, coincided with the seasonal migratory and hibernation behaviors of the bat species 4,5.
  • Statistical comparisons of acoustic recordings with precipitation data show that seasonal monsoon rains generally had a negative effect on the nightly activity and presence of bats 4,5.
  • Diets of P. hesperus from both mines were comprised mostly of coleopterans (beetles) 4,5.
  • The diet of A. pallidus was comprised solely of Coleoptera (beetles) 4,5.
  • Diets of bat species from the proxy sites were characteristic of their respectively known feeding ecology, ranging from the consumption of soft-bodied insects (e.g., moths) to hard-bodied insects (e.g., beetles) 4,5.


Amphibians occupy a range of trophic levels, from plant-feeders to carnivores, and utilize water for foraging and reproduction.

Amphibian Sampling Objectives

  • Use acoustic monitors to identify amphibian species present at the mine during the 2016 breeding season.

Pinyon Plain (formerly Canyon) Mine Activities


Metals and radionuclides were characterized in aerial invertebrates and a limited number of bats prior to uranium ore extraction. Species included big brown bat (Eptesicus fuscus), western small-footed bat (Myotis cilioabrum), and long-legged bat (Myotis volans). Additional collections are planned once the mine is operational to characterize exposure potentially related to mining activities in the Grand Canyon Region.


  • Only Mexican spadefoot (Spea multiplicata) vocalizations were identified3, which is consistent with previous findings at Pinyon Plain (formerly Canyon) Mine1.
  • Metal and radionuclides were characterized in amphibians utilizing the mine containment pond2.
  • Bioaccumulation of arsenic, lead, selenium, thallium, and uranium was evident in Mexican spadefoot (Spea multiplicata) tadpoles from the mine containment pond. Concentrations of arsenic and selenium exceeded toxicity values and were significantly greater than in tadpoles from a nearby water source (Owl Tank). Additional collections are planned once the mine is operational to characterize exposure potentially related to mining activities in the Grand Canyon Region.



Specific Tasks

Task 5a: Compile/evaluate existing and newly collected monitoring data from various agencies/sources
Task 7a: Conduct species surveys


1 Hinck, J.E., Linder, G., Darrah, A.J., Drost, C.A., Duniway, M.C., Johnson, M.J., Mendez-Harclerode, F.M., Nowak, E.M., Valdez, E.W., Wolff, S., and van Riper III, C., 2014, Exposure pathways and biological receptors--Baseline data for the Canyon Uranium Mine, Coconino County, Arizona: Journal of Fish and Wildlife Management, v. 5, no. 2, p. 422-440

2 Hinck, J.E., Cleveland, D., Brumbaugh, W.G., Linder, G., and Lankton, J., 2017, Pre-mining trace element and radiation exposure to biota from a breccia pipe uranium mine in the Grand Canyon (Arizona, USA) watershed: Environmental Monitoring and Assessment, February 2017

4 Valdez, E.W., Hanttula, M.K., and Hinck, J.E. 2021. Seasonal activity and diets of bats at uranium mines and adjacent areas near the Grand Canyon. Western North American Naturalist: Vol. 81 :1-18,

Pinyon Plain (formerly Canyon) Mine Sources:

3 Hinck, J.E., Hossack, B.R., and Honeycutt, R.K., 2017, Amphibian acoustic data from the Arizona 1, Pinenut, and Canyon breccia pipe uranium mines in Arizona: U. S. Geological Survey data release,

Principal Investigators


Jo Ellen Hinck
Columbia Environmental Research Center

Christopher Fuller
Hydrologist (Emeritus)
Earth System Processes Division, Water Mission Area

Marie-Noele Croteau
Research Biologist
Earth System Processes Division, Water Mission Area


Ernest Valdez
Research Wildlife Biologist
Fort Collins Science Center


BLM logo Bureau of Land Management (BLM)
USFS logo U.S. Forest Service (USFS)

Photo Gallery

Checking coverboard

Pinyon Plain (formerly Canyon) Mine Gallery

Sites with Related Activities

Arizona 1 || Pinenut