Landscape connectivity for medium and large mammals in the city of Los Angeles
Mammals with large area requirements and wide-ranging movements are vulnerable to habitat fragmentation. Their populations may persist if animals can move between fragments, but connectivity may be limited in cities where habitat is scarce and busy roads and other intensive development inhibit animal movement. While mule deer and several species of carnivores have been documented in the City of Los Angeles, California, little is known about connectivity for these species across Los Angeles. Thus we initiated a connectivity study for Griffith Park, a large multi-use, recreational area in the middle of Los Angeles with an undeveloped, rugged interior. However, wildlife must cross major freeways to move between Griffith Park and nearby mountains or the Los Angeles River, which runs alongside freeways bordering Griffith Park for 8 km. Starting in 2011, we set motion-activated cameras at locations where wildlife might cross the freeway that separates Griffith Park from the Santa Monica Mountains to the west, placing multiple cameras on roaded bridges over the freeway and in adjacent habitat. In 2012, we placed cameras at the openings of 3 tunnels under freeways between Griffith Park and the Los Angeles River and in Griffith Park’s interior, to examine external and internal connectivity.
Cameras on bridges recorded coyote, deer, and opossum, but only infrequently, and animals appeared to cross during rare periods with little vehicle traffic. Cameras that we placed in open space near the bridges recorded a male mountain lion in 2012, the first verifiable documentation of a mountain lion in the Griffith Park area, although we can only infer his travel route across the freeway. We detected coyotes at all 3 tunnels between Griffith Park and the Los Angeles River, and bobcat or deer at 1 of the 3. These tunnels, which provide safe passage for pedestrians, equestrians, and cyclists between Griffith Park and the River, could allow the wildlife species studied here to use the Los Angeles River as a corridor to other habitat but we do not yet know about wildlife movements within the River itself. At other camera sites in Griffith Park’s interior, we detected gray fox, raccoon, and striped skunk, in addition to bobcat, coyote, deer, and mountain lion. Further monitoring will help us determine if these other species occasionally move in or out of Griffith Park.