Pest regulation: Exclude grazers

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

Pest regulation (0 studies)

Pest damage (1 study): One site comparison in grassland in the USA found no relationship between plant numbers and gopher numbers in ungrazed sites, but found fewer plant species in grazed sites with more gophers.

Ratio of natural enemies to pests (0 studies)

Pest numbers (1 study): One site comparison in grassland in the USA found more signs of gopher activity in ungrazed sites, compared to grazed sites.

Natural enemy numbers (0 studies)

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A site comparison in 1991 in annual grassland on the Central Coast, California, USA, found more signs of pocket gophers Thomomys bottae in ungrazed sites, compared to grazed sites. There was a correlation between gophers and plant species in grazed sites, but not in ungrazed sites. Pest damage: In grazed sites, fewer plant species were found where there were more gophers. However, in ungrazed sites, no relationship was found between gopher numbers and plant numbers (data reported as statistical results). Pest numbers: More signs of gopher activity were found in ungrazed sites, compared to grazed sites (5% vs 2% cover of soil that had been dug up). Methods: European domestic cattle were introduced to Monterey County in 1770. In 1937, grazers were excluded from one landscape (the Hastings Natural History Reservation), but not from a nearby landscape. In 1991, 43 sites in the ungrazed landscape and 37 sites in the grazed landscape were sampled (methods not clearly reported, but the cover of gopher tailings was measured in 20 x 50 cm quadrats in a different part of this study).

    Study and other actions tested
Please cite as:

Shackelford, G. E., Kelsey, R., Robertson, R. J., Williams, D. R. & Dicks, L. V. (2017) Sustainable Agriculture in California and Mediterranean Climates: Evidence for the effects of selected interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Mediterranean Farmland

This Action forms part of the Action Synopsis:

Mediterranean Farmland
Mediterranean Farmland

Mediterranean Farmland - Published 2017

Mediterranean Farmland synopsis

What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust