What Will Happen to Wildlife at Stilson?

What Will Happen to Wildlife at Stilson?

Keeping Wildlife on the Move: Safe Passages at Stilson Park

The extreme seasonality of climate and distribution of habitat in Jackson Hole require most wildlife to move both seasonally and as a part of their daily lives.  Oftentimes, the movement patterns and migration routes of the Valley’s iconic wildlife intersect with our sprawling road system. This is where wildlife crossings come in – innovative structures designed to keep both wildlife and motorists safe.

Teton County has been a leader in wildlife crossings both in Wyoming and nationally. In 2019, The Jackson Hole Conservation Alliance helped our community approve a $10 million Special Purpose Excise Tax (SPET) specifically for wildlife crossing projects. This funding, along with collaboration between Teton County, the Wyoming Department of Transportation (WYDOT), and federal agencies, has led to significant progress for our wild neighbors who must navigate our sprawling road system.

Below is a snapshot of the local crossing projects from our 2022-23 Coexistence Report.

One particularly exciting development is the installation of wildlife underpasses on Highway 390 and Highway 22 at Stilson Park in Wilson, Wyoming (#1 in the image above, being completed currently).  This high-traffic area has been a known wildlife-vehicle collision hotspot. By constructing underpasses, wildlife will have a safe passage beneath the roads, reducing the risk of wildlife vehicle collisions.

The underpasses at Stilson Park are intended to reduce the number of wildlife collisions on both Highways 390 and 22, as the Greater Stilson area has been a hotspot for wildlife vehicle collisions, especially moose, shown below (Jackson Hole Wildlife Foundation data from 2011-2021).

A schematic of the concrete box crossing structures and locations (#3 and #4 on road map)

In this time of rapid change and activity at Stilson, it’s important for us to anticipate wildlife behavior change and to do all that we can to help them navigate safely to and from the new highway underpasses.  Critically, both of the underpasses empty into Stilson Park, so what we decide to do, or not do, there is now more critical then ever!  A major north-south travel corridor in the Snake River riparian complex for moose, elk, mule deer, and other wildlife is at stake!

What are the anticipated changes in wildlife activity patterns?

Research has shown that the presence of roads and human activity can significantly alter the activity patterns of wildlife. Animals may change the location and timing of activities to avoid human development and activity, with some species becoming more nocturnal to evade daytime disturbances. The installation of wildlife crossings at Stilson is expected to have an impact on the wildlife that is known to use that area – namely moose and elk.

Nocturnality and Crossing Behavior

One of the most significant changes anticipated with the new crossings is an adjustment in nocturnal behaviors. Studies have indicated that animals like elk and moose modify their crossing behavior to avoid peak human activity times, with elk crossing earlier in the morning and later in the evening, and moose opting for later at night (see figures below). This shift towards increased nocturnality is a direct response to the need to navigate human disturbances safely.  What we do at Stilson at night really matters – that is when wildlife are going to be traveling through.

Data from Banff National Park front-country crossing structures vs. backcountry crossings (Baruetto et al. 2014).  The difference between the orange line (backcountry) and blue line (wildlife crossing structure) indicates how each species changed their road crossing behavior at a wildlife crossing. Both elk and moose showed increased nocturnality when using the wildlife crossings.

A Worldwide Increase in Nocturnality

A recent meta-study of 163 species across 103 projects all around the world found that as human activity increased, generally mammals showed increased nocturnality.  There were differences between different types of animals (see figure below from Burton et al. 2024), bur generally, animals moved their activities to night time to avoid human encounters.

The Role of Human Management

An essential factor in the success of wildlife crossings is the management of human development and activity around these structures. Poorly planned and inconsiderate development at Stilson would render the publicly funded multi-million dollar underpasses defunct. Limited and intelligent development that includes appropriately wide travel corridors, and properly managed human activity. These considerations will allow wildlife to trust the safety of these underpass crossings. Considerate planning enhances the safety and connectivity of animal and human populations in the Valley.

Below is how the Jackson Hole Conservation Alliance envisions the future of Stilson: A transit center and a wildlife corridor – nothing else!

The Future of Stilson

The installation of new wildlife crossings at Stilson in Wilson, Wyoming, represents a significant step forward in conservation efforts to maintain our iconic wildlife in Jackson Hole. By providing safe passage for animals across highways 22 and 390, these crossings are expected to reduce habitat fragmentation and the impact of roadways on wildlife. 

To maximize the success of the new underpasses, we should remove barriers to animal movement, keeping an open 600 foot wildlife corridor, closing Beckely Parkway at night, and keeping other development out of this important wildlife area. 

As we move forward, the continued study and responsible management of these crossing structures and Stilson Park will be vital in ensuring safe passage for our wildlife. 


Phone: (307) 733-9417
685 S. Cache St. PO Box 2728
Jackson, Wyoming 83001