Projects and Research

Listed and Sensitive Species

To better understand the Refuge’s biological resources, the Refuge staff conducts periodic surveys to assess the distribution and status of its plants and animals, with a focus on the species that are endangered, threatened, or otherwise considered sensitive or rare. The Refuge has the presence of or habitat for nearly 50 such species! Surveys may include mapping the breeding territories of endangered least Bell’s vireos (Vireo bellii pusillus), a migrant songbird, along the Sweetwater River and its tributaries, or assessing the condition of dot-seed plantain (Plantago erecta), a low growing plant within openings in the coastal sage scrub that is the host for larvae of the endangered Quino checkerspot butterfly (Euphydryas editha quino). The information gathered from such surveys allows the Refuge to understand whether populations are increasing, decreasing or stable and may trigger management actions such as controlling invasive weeds that reduce habitat quality, or limiting public access to nesting areas to remove disturbance during the breeding season. Sharing survey results with other agencies and researchers enhances work to recover populations of these species across their range, with the ultimate goal of having robust populations that are no longer endangered or threatened with extinction.    

Habitat Restoration and Enhancement 

Habitat restoration and enhancement projects support the conservation and recovery of listed and sensitive species by improving habitat quality in the many habitat types found on San Diego NWR. These projects include controlling invasive plants in recent burn areas or those disturbed by past development or agriculture; removing non-native shrubs and trees from riparian riparian
Definition of riparian habitat or riparian areas.

Learn more about riparian
areas that crowd out the native plants; planting cactus in previously burned areas to jumpstart habitat recovery for the cactus wren; planting and maintaining oak seedlings to replace those lost to disease, pests, and past human use; installing nest boxes for burrowing owls and western bluebirds; and restoring vernal pools for the suite of sensitive species associated with this rare clay soils habitat. 

Habitat and Wildlife Protection

Various management strategies minimize the potential for disturbance to wildlife, and reduce adverse effects to water quality from erosion, illegal encampments, and dumping. The Refuge staff install and maintain fencing, gates, and signs; look for homeless camps, vehicle trespass, dumping, and other unauthorized activities including unauthorized off-trail activities or unleashed dogs; when necessary, Refuge law enforcement officers issue citations for violations. Abandoned mine shafts are closed to human access using wildlife-friendly gates that allow bats and smaller wildlife to continue to use the shafts as habitat. Trails may be rerouted to reduce erosion and impacts to sensitive habitats and wildlife. 


Biologist John Martin measures weather conditions.

The Refuge supports a variety of research and resource survey work conducted in association with graduate work at various universities and/or implemented by other public (e.g., USGS, CDFG), private, and non-profit researchers (e.g., California Native Plant Society, Center for Natural Lands Management, San Diego Natural History Museum).  All research conducted on the Refuge is evaluated to ensure that the work being conducted is compatible with Refuge purposes and is likely to result in benefits to Refuge management and/or Refuge resources.  Work conducted on the Refuge by outside parties that are not directly related to Refuge management may only be conducted after a Special Use Permit (SUP) has been issued by the Refuge Manager. 

Southern Border Fuels Project

Learn more about the project to remove non-native invasive plants along the Sweetwater River.

SoCal Urban Wildlife Refuge Project

Learn how by working together with program partners we are helping city-dwelling communities re-connect with nature and building stewards for the environment.