Desert bighorn have not been residents in Saguaro National Park since the 1950's, but they are sometimes seen passing through the park and hopefully will someday become re-established.
Photo: John Clark and Pamela Grant-Clark, Nov. 23, 2020.
Removing Barriers for Wildlife
Saguaro National Park is working to remove barriers to wildlife in and around both the Tucson Mountain (west) and Rincon Mountain (east) districts of our park. We are making boundary fences more wildlife-friendly, removing old fences that are no longer needed, and working with our neighbors to improve connectivity throughout the Tucson area.
The Importance of Wildlife Connectivity
Wildlife "corridors" are areas that animals can pass through safely between protected habitats where they can live, eat, drink and reproduce. At Saguaro National Park, this connectivity is crucial for large animals such as bears, mountain lions and bighorn that need areas that are larger than the park to survive.
Habitat connectivity is also important for smaller animals such as kit foxes, badgers and reptiles that tend to need specialized habitats within a protected area. Their populations are too small to be sustained over long periods of time because they need an influx of immigrants, and their young need to be able to leave to find mates.
Wildlife Barriers
Structures such as fences, roads, and urban and agricultural developments can inhibit habitat connectivity and create major barriers to all kinds of wildlife. These landscape modifications decrease habitat area and reduce diversity simply by shrinking areas in which animals using the habitat can live (MacAuthur and Wilson 1967). Without proper planning, these barriers can contstrain wildlife movement and lead to fragmented habitats.
Habitat fragmentation occurs when animal migration is limited, which disrupts their ability to find food, shelter, and mates. Over time, populations get isolated from one another and are more vulnerable to diseases, inbreeding and reproductive problems, reducing their resilience to stress and lowering their chance of survival (Wilcox 1985). Some species may even go locally extinct, and event called extirpation.
Extirpation occurs when an animal ceases to exist in a particular area but continues to exist elsewhere. For instance, we can no longer find grizzly bears, porcupines, jaguars, Mexican gray wolves or bighorn sheep at Saguaro National Park due to their local extinction. The loss of species is not only bad for the animals themselves and the people who enjoy seeing them, but it can have huge detrimental effects on the entire desert ecosystem.
By removing wildlife barriers, we can improve habitat connectivity, which is a key aspect for sustaining biodiversity inside the park because many species require resources that extend beyond park boundaries. For more information on connecting Saguaro National Park to its surrounding landscapes, check our our resource brief on connectivity.
Aerial view of the Tucson Mitigation Corridor, showing crossing structures over the Central Arizona Project canal.
Photo: Bureau of Reclamation
Wildlife Conservation in Action
Tucson Mitigation Corridor
The 2,514-acre Tucson Mitigation Corridor (TMC) is one of the best kept wildlife conservation secrets in Tucson. The Bureau of Reclamation acquired and officially established the TMC in 1990 as mitigation for the construction of the 336-mile Central Arizona Project Canal (CAP), which delivers water for municipal and agricultural use to central and southern Arizona from the lower Colorado River at Lake Havasu. The Tucson B aqueduct of the CAP canal borders the Tucson Mountains to the west, which restricts the free movement of plants and animals to other nearby federal and tribal lands. Part of the importance of the TMC is the strategic placement of a series of seven siphons, which are concrete pipe sections that travel underneath desert washes to allow the natural movement of wildlife and other biological processes. When its contruction was planned, research showed that the canal would interrupt the primary wildlife movement corridor between the Tucson Mountains and across Avra Valley to the Roskruge Mountains and Ironwood Forest National Monument.
Because the CAP would affect wildlife movement and their habitats outside of Saguaro National Park, the Tucson Mitigation Corridor was established, and a number of crossing structures were built over the canal. Wildlife studies have shown that mule deer, bighorn, and many other animals use these crossings. The Tucson Mitigation Corridor continues to serve as an important linkage, helping to conserve wildlife in the region.
Get Involved
Saguaro National Park hosts volunteer fence removal opportunities throughout the cooler months to aid wildlife connectivity. The park is seeking out individuals and groups willing to hike out into the desert and work hard to help wildlife. For more information on these volunteer opportunities, please email Kara_O'Brien@nps.gov.
There are also ways you can help to preserve wildlife by making changes right in your yard at home. Check out the links below to learn more about how to improve your yard, or even your whole neighborhood, for wildlife.
