Written by Jess Wenick, Malheur NWR Project Leader
Photo of reed canarygrass dominted wet meadow on Malheur NWR

As shared in previous CCP public meetings, Malheur National Wildlife Refuge and partners are preparing an experimental, pilot-scale effort that uses targeted cattle grazing guided by GPS virtual fencing to reduce tall, invasive reed canarygrass and evaluate habitat response. Project specifics will continue to be refined based on site conditions and monitoring.

What we are trying to learn, and why.

Reed canarygrass can form dense monocultures in wet meadows. The pilot’s goal is to reduce those impacts by strategically targeting reed canarygrass at its most vulnerable physiological stage (tiller elongation/early boot).

This approach aligns with the idea that short-duration, targeted grazing can reduce reed canarygrass height and thatch and create space for native plants, then allow us to evaluate vegetation and wildlife response.

This project also reflects practical constraints of this landscape. In areas with a naturally high water table and flood irrigation, reed canarygrass can express strongly, and treatment access can be limited during key windows. The pilot focuses first on structural management (vegetation height and thatch), with the longer-term question being how, when, and whether additional methods should be added to help desirable species reestablish.

Where the pilot will occur.

The pilot will occur within a defined treatment area in the Lava Beds Field (Unit 9). See image to the right with Unit 9 highlighted in neon green.  

Why cattle are the preferred herbivore tool here.

Herbivory is a common vegetation treatment tool, and different livestock species behave differently:

• • Goats are typically browsers and often prefer shrubs and many broadleaf plants, which can make them less targeted on dense grass monocultures.
  • Sheep can be effective grazers, but refuge experience in the late 2000s using sheep for perennial pepperweed control was challenging due to herding needs and mosquitoes and included sheep mortality events associated with blue-green algae in feeder ditches.
  • Cattle are well-suited to grazing large acreages of grass-dominated vegetation with repeatable pressure, and they pair well with virtual fencing for the type of targeted grazing this pilot requires.

The pilot documents reflect that the strategy is to use cattle fitted with virtual fence collars to target-graze the Lava Beds Field.

What has been done so far (baseline work).

In summer 2025, the team completed pre-treatment monitoring in the Lava Beds Field, including vegetation composition and average height by plot, plus bird monitoring using Autonomous Recording Units (ARUs) and on-the-ground landbird point surveys.

What the pilot is designed to do.

The pilot’s core objectives include managing cattle within a designated treatment area using virtual fencing, reducing average herbaceous height from about 4 ft to 1.5 ft or less, and evaluating bird response, along with longer-term plant community diversity response.

This is a pilot rather than a fully controlled academic study. The intent is to pair real-world implementation constraints with structured monitoring, then let the data inform future management direction over time.

What to expect this season (timing, herd size, and duration).

Turnout timing will be based on plant growth stage and site conditions.

Current planning assumptions are mid-May (dependent on conditions), with cattle trained on collars on private land for about two weeks prior to turnout into the study area.

Herd size is still being finalized. The pilot anticipates between 200-300 cattle.

Depending on reed canarygrass conditions and monitoring feedback, grazing may be on the order of about 90 days, with flexibility to adjust if objectives are met early, safeguards are triggered or an extension is required.

The treated portion of the field will be broken into 2 to 3 units and rotated based on vegetation cues, allowing targeted grazing pressure where it is most needed.

How virtual fencing works in the field.

Cattle wear GPS-enabled collars. The system uses audio cues and mild stimuli to guide animals away from the boundary, and the boundary can be adjusted to focus grazing where it is needed. This also allows us to set avoidance zones for areas of concern and update those zones as conditions change. Areas of concern may include sensitive habitat of native grasses, riparian habitat, or identified nesting sites. 

Safeguards, oversight, and protection of wildlife and wetlands.

Technology is not the only safeguard. Oversight will be led by a dedicated position assigned to the pilot project, supported by refuge staff, partners, and the livestock owner. The pilot occurs within a larger management unit where rake-bunch grazing normally occurs, and the perimeter is fully fenced.

For wildlife, including nesting birds, monitoring informs timing and boundary placement and can include buffers or no-graze zones.

Within the Lava Beds Field, some habitats are suitable for nesting; those areas will be avoided and do not fall within the designated treatment area.

To protect wetlands, water, and soils, sensitive areas will be excluded or buffered, and staff and partners will watch for trampling and water quality concerns, adjusting or stopping if thresholds are exceeded.

ARS is also conducting a soil compaction survey comparing compaction on idle ground, normal haying and grazing (fall and winter), and summer grazing impacts.

Measuring success and sharing results.

Success measures include changes in reed canarygrass height and structure and longer-term changes in plant diversity and habitat conditions, with a commitment to share a public summary of methods, monitoring results, and any adaptive changes.

In addition, we will share bird response to both treatment and livestock presence, consistent with the pilot objectives.

Looking ahead.

This pilot is planned as a three-year effort focused on warm-season grazing impacts to reed canarygrass. A potential fourth year could include late-season grazing or a return to traditional rakebunch grazing, depending on what monitoring shows. Grazing is not the only tool for shifting plant species composition; this initial phase focuses on structural change, with future decisions considering how to transition toward more desirable plant communities through adjustments in grazing strategy and, if warranted, additional methods.

Core partners.

Core partners for this pilot include Malheur NWR (Travis Miller), OSU Extension (Dustin Johnson), Bird Alliance of Oregon (Teresa Wicks), and USDA-ARS (Rory O’Connor), alongside the livestock owner/permittee and additional refuge staff and collaborators.