Multi-species Benefits

The State Highway System currently offers some opportunities for species migration in providing access to habitat for common and listed species. However, there are many opportunities to improve the use of existing under-crossings and to determine where additional multi-species connectivity opportunities are needed. The multi-species connectivity story map below demonstrates where species are currently crossing, attempting to cross but not actually crossing, or where there may be needs to further consider science and data in determining where to provide new crossing opportunities.

The following photos are recent 2021 photos from the recently completed Salsipuedes Creek location (PAD 700085, Santa Barbara County, Rt 1, PM 15.61). Click on the photos to enlarge.

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Literature on Crossing Structures

Arch-Style road Crossing Structure from Relative Movement Rates of Large Mammals
by A.Z. Andis, M.P. Huijser, and L. Broberg. 2017. Frontiers in Ecology and Evolution. (5):1-13

ABSTRACT - In recent decades, an increasing number of highway construction and reconstruction projects have included mitigation measures aimed at reducing wildlife-vehicle collisions and maintaining habitat connectivity for wildlife. The most effective and robust measures include wildlife fences combined with wildlife underpasses and overpasses. The 39 wildlife crossing structures included along a 90 km stretch of US Highway 93 on the Flathead Indian Reservation in western Montana represent one of the most extensive of such projects. We measured movements of large mammal species at 15 elliptical arch-style wildlife underpasses and adjacent habitat between April and November 2015. We investigated if the movements of large mammals through the underpasses were similar to large mammal movements in the adjacent habitat. Across all structures, large mammals (all species combined) were more likely to move through the structures than pass at a random location in the surrounding habitat. At the species level, white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) used the underpasses significantly more than could be expected based on their movement through the surrounding habitat. However, carnivorous species such as, black bear (Ursus americanus) and coyote (Canis latrans) moved through the underpasses in similar numbers compared to the surrounding habitat.

For a copy of the complete article, click here.

Improving Habitat Quality in Western Big-Game Winter Range and Migration Corridors (Department of the Interior 2019)

Two focus areas in this report are within the geographic scope of FishPACs, respective of potential anadromy:

Del Norte (pages 25-28) - Roosevelt elk

San Luis Reservoir Elk Area (pages 29-30) - Tule elk

The following areas in this report may overlap with listed resident fish, threatened and endangered species range, or hot spot information:

Lake Crowley (District 9, Bishop)  – mule deer

Doyle Herd (District 3) – mule deer

Loyalton-Truckee (District 3) – mule deer (note: This location might overlap with known Lahonton Cutthroat Trout and current PAD locations)


Best Management Practices are a menu of options available to avoid and minimize impacts to California's threatened and endangered native fish and wildlife species. The following illustrations document best management practices that can be used during construction to ensure the health and well-being of species that may be found in and adjacent to highway construction projects. Click on the front and back of the cards to view a large version.