Habitat connectivity provides important ecological functions relating to biodiversity, gene flow, population dynamics and species movement and dispersal25. Given its east-west orientation, gentle topography, and position between large tracts of protected land, the Cuyama Valley seems well-suited facilitate to wildlife movement. Additionally, wildlife species may migrate from the coast inland along the river valley36. This habitat connectivity may prove crucial for species dispersal and adaptation to climate change. Highway 166 is the biggest impediment to species movement within the valley. Further land development and diminished water resources may degrade the existing connected habitat and threaten the viability of conservation targets.  Informed foresight of potential land transformations will allow for strategic conservation efforts to mitigate threats to existing habitat connectivity.

Connectivity Results

The output from Circuitscape displays species movement in terms of electrical current. High current (bright yellow) indicates “pinch points” where species are funneled through a narrow area. These areas could be interpreted as critical pathways. Where current is less concentrated (green to blue), many options exist for species movement. Highway 166 and 33 pose the greatest restrictions to species movement. Critical connections across the highway can be seen, most commonly indicating the location of a bridge. Additionally, oil fields contain many roads fragmenting the landscape leading to low connectivity values for all species

Despite these barriers, there is so much natural vegetation surrounding agriculture and developed lands that overall connectivity in the valley is strong. Resistance values were not obtained for the entire valley due to the segmented input maps. A more detailed discussion of resistance values for each species will be presented in the Scenario Planning section of this website.

Blunt-nosed leopard lizard and Two-striped gartersnake cannot move through agricultural or developed areas. The footprint of agriculture is most apparent in these species’ maps.  The snake’s use of the river bed to move in a linear path through agriculture is indicated by the strong yellow line in the central valley surrounded by dark blue. The Pronghorn antelope map clearly shows the difference between various types of agriculture. Antelope will move through grain, alfalfa and vegetable fields, while orchards and vineyards pose more of a barrier.  

The Two-striped gartersnake is a unique species found along the California coast from the Monterey Peninsula through Baja. The species population is in decline from conversion of natural habitat, excessive livestock grazing, and flood control28. The snake requires water year-round, a sparse resource in the Cuyama Valley. It is often found in riparian vegetation such as willows, near livestock watering sites, or in rocky stream beds28. This species was chosen to model genetic connectivity east-west along the valley. It is assumed the species only moves long distances in the valley during the wet winter season.

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The Blunt-nosed leopard lizard is an endangered species that likes flat arid environments with sparse vegetation and sandy soil, allowing plenty of room to run28. They will not use lands that have been tilled for agriculture. It may take up to ten years for the lizard to re-inhabit previously tilled land. Lands surrounding agricultural areas may seem like suitable habitat, but in fact may not support populations of the leopard lizard due to pesticide spraying28. Each male can have a home range of up to 22 acres, but there may be some overlap between home ranges28. Three habitat types found in the valley are a particularly suitable for the leopard lizard including, grasslands, desert washes, and alkali flats. The species was chosen to represent east-west genetic connectivity along the valley bottom.

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The San Joaquin kit fox is a charismatic species with light rusty-brown fur and big ears. They are nocturnal animals that feed on small mammals and rodents. The fox was added to the federal endangered species list in 1967. The Cuyama Valley and Carrizo Plain represent the extreme southern end of the species range28. The fox was chosen as a generalist species for the valley as it uses many of the habitats found in the area including grasslands, pinyon-juniper shrublands, oak and pine woodlands, and desert chaparral. No habitat was given a suitability rating of 100, but many habitats were assigned mid-range values (33-66).  The fox uses underground dens often previously inhabited by other animals. At times they have also been observed using culverts and other large pipes as dens28.

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Pronghorn antelope were reintroduced along with Tule elk to the Carrizo Plain National Monument41. Forbs and shrubs make up the majority of their diet with sagebrush being the most preferred shrub species. Grass is used as spring forage and may include the use of alfalfa18. Verbal accounts note that the species will travel through agricultural fields, but no literature has been found describing their use of the Cuyama Valley. Pronghorn may migrate between summer and winter ranges and move up to 90 miles between ranges18. Although this has not been documented for the population in the Carrizo Plain, the distance across our study area is only 22 miles. Given their large size, roaming grazing behavior and migrations in other areas, they were chosen to represent cross-valley movement connecting the Carrizo Plain and Los Padres National Forest.

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Currently 300-400 vehicles travel on the road per day4. The roads are assumed to be a complete barrier for Blunt-nosed leopard lizard and Two-striped gartersnake. Neither species will cross a road of this size, regardless of traffic patterns. One the other hand, the San Joaquin kit fox and Pronghorn antelope will cross roads, but with significant risk of stress, injury, or mortality. As observed during field visits, most the bridges in the lower part of the valley are open-span bridges. These types of bridges have been proven effective for large mammals including elk and deer29. Thsee images highlight places important to connectivity are directly related to the bridge underpasses.