North Park is one of San Diego's older neighborhoods, and its housing shows it. Streets east of Balboa Park are lined with Craftsman bungalows from the 1910s and 1920s, many on raised wood foundations with crawl spaces. Over a century, those homes picked up add-on rooms, new plumbing, rewiring and patched siding. Each change can leave a gap.
Roof rats are the main problem. They nest in palms, bird of paradise clumps and overgrown vines, run along the alley fences and climb into attics and wall voids. House mice use the gaps at the sill and around old pipes under the house. In a bungalow with a crawl space, the walls are open at both the top and bottom, so rodents can travel from the floor to the attic inside the walls.
Alleys run behind most blocks, with detached garages, trash and green bins and storage sheds. Many of those garages are as old as the houses, with gaps at the slab and wood siding that has shrunk. Rats often nest in the garage and visit the house at night.
Switzer Canyon and the smaller canyons that cut north and east through the neighborhood bring brush and open space right up to backyards. Homes on the canyon rims see more activity than those in the middle of the grid. Balboa Park on the west edge adds its own population of rodents in the trees and gardens.
University Avenue, 30th Street and Ray Street are packed with restaurants, bars and breweries, and their shared alleys see a lot of food waste. A number of the older apartment buildings and courtyard complexes in North Park share attics and trash areas, so a problem in one unit spreads.
If you call from North Park, mention whether the house has a crawl space and a detached garage. Ask the technician to check under the house and in the garage, not just the attic. See mice in walls if the sounds are inside the walls.