Integrated Pest Management Strategies

for

Round-Tailed Ground Squirrels

Shaku Nair1, Dominic Henry2, Dawn H. Gouge1

1University of Arizona, Department of Entomology

2US National Park Service, Coolidge, AZ




Image Credit: Ryan Kaldari, Wikimedia Commons

Round-tailed ground squirrel (RTGS)

(Spermophilus tereticaudus, Sciuridae: Rodentia)

  • Common residents of natural areas throughout the desert southwest region of North America.

  • Live in colonies of several adults and young.

  • Diurnal during the active season (March to September).

  • Reside in burrows excavated in the ground.

  • May modify and occupy vacant burrows of other animals.

Damage by RTGS

  • Can cause extensive burrowing, which is often NOT a significant cause of damage to humans and property.

  • Burrowing can disfigure landscapes and pose trip hazards.

Concerns associated with RTGS

  • Can lead to human-wildlife interactions that may include RTGS themselves, but also their predators such as rattlesnakes, coyote, foxes and feral dogs.

  • RTGS and their predators can host for fleas, ticks and other parasites, and could vector plague or other diseases during human interactions. RTGS predators may increase potential rabies risk.

Coyote, Canis latrans

Image credit: Jitze Couperus, Wikimedia Commons

Feral dog, Canis famiiaris

Image credit: USGS, Wikimedia Commons

Gray fox, Urocyon cinereoargenteus

Image credit:Tom Benson, Wikimedia Commons

Kit fox, Vulpes macrotis

Image credit: Magnus Manske, Wikimedia Commons

Concerns associated with RTGS

  • Burrowing by larger predators can damage sensitive sites of cultural and archaeological significance.

Concerns associated with RTGS

  • Use of rodenticides for managing RTGS can lead to inadvertent ingestion by non-target species including humans. Even appropriate use can lead to secondary poisonings of non-targets, so careful rodenticide selection is important.

  • Using snap traps is challenging; traps pose risks to humans and are not considered a humane option.

Image credit: Stan Keiser/Audubon
Image credit: National Park Service

Managing RTGS through Integrated Pest Management (IPM)

  • Systematic monitoring of property, especially spots adjoining wild or natural areas helps to determine population, activity levels, damage risk to preserved sites, and pest related human risks.

  • Trapping in strategic spots using snap traps early in the active season (starting March) helps to identify active spots and inform decisions regarding further, focused management measures.

  • Filling of burrows with soil or other suitable material is helpful.

  • Filled burrows pose less risks of tripping or slipping into burrows, and also help to detect new activity.

  • Make sure to fill burrows completely and compact it to level it with the ground.

  • Overgrown landscape trees and shrubs make attractive habitats for RTGS and other wildlife.

  • Irrigation should be monitored regularly to avoid leaks and water pooling in tree basins. Filling tree basins with mulch or gravel will help to conserve soil moisture and prevent wildlife from accessing water in these spots.

Feeding of wildlife should be prohibited.

  • Repellents such as predator (coyote and fox) urine and plant-based products showed some effect in high activity areas in studies conducted during 2017-2019. Further testing is needed for more conclusive results.

Conclusions

  • RTGS are prominent components of the desert ecosystem. Complete eradication may be impossible and unnecessary.

  • IPM has been successful! (Squirrels trapped in study area in 2019 = 130 vs. >1000 in 2013).

  • Base actions on monitoring.

  • Making habitat unfavorable in multiple ways is the best option.

Acknowledgements

  • Mike Garcia, Park Volunteer

  • Katherine Shaum, Former NPS Tech

  • United States National Park Service

  • UA College of Architecture, Planning and Landscape Architecture (CAPLA)

  • Casa Grande Ruins National Monument

  • UA Arizona Pest Management Center

Contact

Shaku Nair, Ph.D. Entomologist, Associate in Extension, Community IPM

Arizona Pest Management Center

University of Arizona - Maricopa Ag. Center, 37860 W. Smith-Enke Road

Maricopa, AZ 85138-3010

Office: (520) 374-6299 / nairs@email.arizona.edu