Squirrels From the Park, Rats From the Open Lots: Pest Help in Washington Park

An 1871 park plan and the railroad blocks west of it

Frederick Law Olmsted and Calvert Vaux published their plan for the South Park system in 1871, months before the Great Fire. It paired a lakefront tract that became Jackson Park with an inland rectangle of prairie that became Washington Park, joined by the Midway Plaisance. The inland park took George Washington's name in 1880. Its 372 acres hold a hundred-acre meadow, broad belts of open woods and a lagoon that now circles Bynum Island, and the park was added to the National Register in 2004. Daniel Burnham designed several of its early buildings, and the DuSable Museum and the Fountain of Time sit within or at the edge of the grounds.

West of the park, Irish and German railroad workers and meatpackers settled the blocks in the late 1800s. By the 1920s the community was predominantly African American and part of the wider Black Metropolis centered on 47th and King Drive. Population peaked at nearly 57,000 in 1950, then fell to about 12,700 by 2020 as public housing along State Street, including the southern end of the Robert Taylor Homes, was built and later demolished, and as older buildings were lost. The result for pests is unusual: a mature park, a century-old masonry district and wide stretches of open land, all within a dozen blocks.

Gray and fox squirrels in greystone cornices facing King Drive

The park's open woods hold one of the largest squirrel populations on the South Side, and the greystones that face it along King Drive and the Garfield Boulevard parkway are the closest warm, sheltered structures. Both eastern gray and fox squirrels live here. They run power lines and parkway trees to the roof, then work on the weakest wood they can find: cornice joints, the backs of parapets, rotted soffits behind box gutters and the vents of the cockloft, the shallow void between the top-floor ceiling and the flat roof.

Once inside a cockloft, a squirrel has a long, insulated tunnel running the width of the building. Top-floor residents hear scratching and rolling sounds at dawn and late afternoon, sometimes nuts dropped into wall cavities in fall. Litters arrive in March and April and again in late summer, and nesting females chew insulation and occasionally the sheathing of wiring. Gaps the size of a fist at the cornice, chewed edges on fascia boards and shredded material in gutters are the outside signs.

Wildlife specialists usually fit a one-way door over the active hole, confirm through a few days of observation that the animals are out, then close the opening with metal flashing or heavy hardware cloth worked into the cornice. Checking for a litter before sealing is essential in spring. Limb trimming is the part owners can control: branches within eight feet of a roof are a ramp, and on blocks facing the park that applies to parkway trees as well as yard trees.

Raccoons crossing King Drive at dusk

Raccoons spend daylight in the park's wooded margins and around the lagoon, then cross King Drive and Cottage Grove after dark to work the alleys. Garbage carts with broken lids, pet food on rear porches and birdseed under feeders are the draw. Greystone rear walls give them an easy climb, with stacked wooden porches three stories high, downspouts and porch roofs that connect to the main roof. Uncapped chimneys and loose cockloft vents near the rear are the usual den entries.

Females hunt for den sites from February through April and raise kits through spring, which is why removal at that time is a careful job. A specialist confirms whether young are present, then uses an exclusion door or a live trap under Illinois rules, retrieves any kits, and seals the entry. Raccoon latrines on flat roofs and in attics can carry roundworm eggs that stay infectious for years, so cleanup of a heavy latrine belongs to someone with protective gear. Opossums use the same routes but tend to settle lower, under porch stairs and in garages with gaps at the slab. Striped skunks turn up near the park's edges too, digging small holes in parkway grass for grubs in late summer and occasionally denning beneath a rear stoop.

Norway rats on the open land toward State Street

The western half of the community area, between the Green Line and the expressway corridor, holds most of the vacant land. Overgrown lots, slabs where garages once stood, weedy rail embankments and dumped debris are ideal ground for Norway rats, which dig burrow networks with several openings along fence lines and under concrete. From those colonies they forage nightly into the alleys of occupied blocks, where shared carts and old garages with gaps at the slab edge give them food and cover.

A rat problem on these blocks rarely belongs to one property. The most reliable results come when owners on the same alley treat together: locked bait stations along garage walls and fences, burrows treated and collapsed, garage door bottoms sealed, and cart lids kept shut. Requesting city rodent baiting through 311 for the alley and any city-owned lot adds crews the private work cannot replace. New construction on a long-empty lot can push rats into neighboring yards for several weeks, so sealing the garage and foundation before excavation starts is cheap insurance. Snowmelt in March is the best time to walk the fence line and count burrow openings, because bare ground shows every hole before spring growth hides them.

Mice, roaches and pigeons in a shared greystone

Most greystones and walk-ups here are multi-unit buildings with one basement, one set of plumbing stacks and one rear stairwell. House mice enter through gaps in limestone and brick foundations, around abandoned coal chutes and under rear doors, then climb pipe chases into kitchens. German cockroaches follow the same routes, and frequent unit turnover brings in more with boxes and used furniture. Treating one apartment buys a few weeks at most. Effective work covers the building, including the basement, laundry area and trash enclosure, with every unit along an affected stack treated on the same visit.

Older buildings also hide pests in forgotten spaces: former coal rooms, boxed-in dumbwaiter shafts, voids around steam risers and gaps behind original baseboards. Renovations that open these spaces and close them again without sealing pipe penetrations can turn a small mouse problem into a building-wide one. The fix costs little when it happens at the right moment. Ask any rehab crew to pack pipe and conduit holes with copper mesh and sealant before walls are closed, and to leave an access panel where a stack runs through a former dumbwaiter shaft.

Overhead, pigeons roost on the steel of the Green Line structure and on the ledges and cornices of older buildings near the tracks, and house sparrows and starlings nest in vents and eave gaps. Dried droppings build up on sills and porch roofs, and heavy accumulations can carry fungal spores when disturbed. Ledge spikes, netting and vent screens installed by a bird specialist keep roosting from restarting.

Greystone, walk-up, two-flat or infill: where to look first

The building type tells a technician where the trouble usually starts, and the same block can hold all four. A greystone's weak points are at the top and back: cornice, parapet and cockloft vents for squirrels, and the rear porch and chimney for raccoons. Brick walk-ups have long shared stairwells and basement storage rooms where mice nest undisturbed. Two-flats concentrate both problems in a smaller building. Newer townhomes and single-family infill are tighter, but those beside open lots see rats at the garage and foundation and mice at dryer vents and door sweeps.

• Greystone: cornice joints, parapet caps, box gutters, cockloft vents and the top landing of the rear porch
• Brick walk-up: basement storage rooms, laundry areas, trash enclosures and stairwell doors
• Two-flat: shared basement, pipe chases between units and the back stairs
• Infill house or townhome: garage door seals, slab edges, dryer vents and the fence line facing any open lot

From lagoon thaw to first frost

February and March bring the first attic noises along King Drive, as raccoons and squirrels hunt for den sites before the snow is gone. April and May are birthing months for both, and late spring is when rats become more active on vacant land and pigeons nest under the elevated structure. Summer adds wasps under porch roofs, mosquitoes near the lagoon, ants on sidewalks and heavy storms that push water into old basements, pulling house centipedes and millipedes indoors behind it.

In late August and September, squirrels cache nuts from the park's oaks and look for winter quarters, and second litters appear in cocklofts. October and November bring the main wave of mice into buildings. December and January are the best months for sealing cornices and vents, because most wildlife has no young in the nest and bare trees make gaps easier to see from the street and alley.

Checklist for a greystone between the park and an open lot

A building that faces the park and backs onto an alley near vacant land gets pressure from two directions, so prevention has to cover the roofline and the ground. Work through these items once in late winter, before nesting, and again in early fall, before mice move in. Several are common-element decisions in a condo association, so bring the list to the board.

• Trim tree limbs at least eight feet back from roofs, cornices and porch roofs
• Cap chimneys and screen cockloft and attic vents with heavy metal mesh
• Repair loose cornice joints, parapet caps and gutter seams before spring
• Keep carts lidded and off the rear porch, and request a replacement cart if a lid is broken
• Keep birdseed and pet food off porches that face the park
• Seal old coal chutes, window wells and foundation gaps with masonry or metal
• Treat the basement, laundry and trash areas building-wide rather than unit by unit
• Report rodents on city-owned lots and in alleys through 311

Associations, landlords and how a service visit runs

Many greystones here have been converted to condominiums, so the roof, cornices, basement and rear porches are usually common elements that the board must approve and pay to repair. Renters should go to the landlord, who is responsible for treating the building under Chicago's residential landlord rules. Either way, ask for a written inspection with photos of entry points and a note of what was sealed, since that record helps when the board compares bids or a problem returns.

A typical visit starts outside, with a walk of the alley and a look at the roofline from both street and alley. Squirrel and raccoon work is handled by wildlife specialists following Illinois rules on trapping and release, while rodent and cockroach work is done by licensed exterminators. For rats, expect exterior bait stations along the alley and foundation and several follow-up visits. When an animal is loose in a living space, same-day help is often available.