Wildlife Management in Park Slope

What is living above a Park Slope ceiling, and how did it get up there?

Something that arrived along a canopy and got in at a roof edge — because on this housing stock there is no other realistic route.

Wildlife work in a neighborhood of attached rowhouses is roof work. There is no attic in the suburban sense, no gable end, no soffit vent running round four elevations, and no crawlspace. What there is instead is an apartment or near-flat roof with a parapet, a bulkhead housing the stair head, roof drainage, frequently a deck, and a cornice at the front and sometimes the back. Everything gets in at that level or it does not get in.

Getting to that level is easy here, and that is the local part of the story. Park Slope has the Prospect Park canopy running along its whole eastern boundary, mature street trees on nearly every block, and rear yards with their own established trees forming a continuous planted interior behind the houses. An animal can move from the park into the street trees, from the street trees onto a cornice, and along a roofline that continues unbroken into the neighboring buildings, without ever crossing open ground. The neighborhood has effectively built an elevated corridor and connected it to a large park.

What uses it, in order of how often:

Eastern gray squirrels, which are the overwhelming majority of calls. They travel on branches, on cornices, on parapets and on cables, they gnaw, and they take any void that offers shelter — a cornice box, the space above a top-floor ceiling, a bulkhead, a disused chimney flue.

Raccoons, which are established in and around large city parks and the neighborhoods next to them. They need a bigger opening than a squirrel and they are strong enough to make one, usually by working a roof edge, lifting a section of flashing, or forcing a bulkhead door that no longer closes properly.

Big brown bats, which use gaps well under an inch at parapet junctions, roof-plane changes and around bulkheads, and which carry the hardest seasonal and legal constraints of anything on this list.

Birds, chiefly in cornice voids, behind failed metal panels and in vent terminations that have lost their cowls.

The diagnostic that matters most on a first call is the pattern of the noise. Daytime activity, particularly around dawn and late afternoon, with quick scampering and the sound of something being gnawed, reads as squirrel. Heavier, slower movement after dark, sometimes with vocalisation, reads as something larger and should not be closed up on the strength of a guess. A rapid, light, high-frequency pattern at dusk around a parapet is a reason to look at bats specifically before touching anything.

Why is the cornice the reliable entry on these houses?

Because a pressed metal cornice is a hollow box hanging off the top of the front wall, and boxes have seams.

This is the detail that distinguishes rowhouse wildlife work from suburban wildlife work, and it is worth understanding properly.

A great many of the houses built here during the boom of the 1880s and 1890s carry a projecting cornice at the roof line. On the grander stone-fronted houses it may be carved masonry. On an enormous number of them it is pressed sheet metal — formed panels of galvanised steel or tin, made to look like carved stone or heavy timber molding, fixed to a light timber framework that cantilevers out from the wall.

That construction has four consequences.

It is hollow. Behind the decorative face is a framed void running the width of the building. It is dry, sheltered, warm from the building below and completely enclosed. As habitat it is close to ideal.

It is made of joints. Panels meet at seams. The cornice returns at each end where it meets the neighbors’ buildings. It meets the roof along its back edge, usually behind a parapet or an upstand. Each of those is a joint that was made by a sheet metal worker over a century ago and has been moving, corroding and being patched ever since.

It is exposed and neglected. A cornice exists to throw rain and snowmelt off the face of the building, so it takes weather constantly. Corrosion at fixings and seams is the normal end state. Many have been repaired badly, boxed in, partly removed, or replaced in a lighter modern material that does not match the fixings behind it.

It is at exactly the height a squirrel arrives at. Street trees on these blocks are mature, and the branches routinely reach or overhang the cornice line.

Add those together and the cornice void is the single most productive wildlife entry on the housing stock. Once an animal is in it, it is inside a continuous framed cavity at the top of the front wall, from which the space above the top-floor ceiling is often directly reachable.

The repair is a metalwork and carpentry job rather than a pest job, and that is worth saying because it changes who does it and what it costs. Ends and returns are closed with rigid material cut to fit. Open seams are made good in metal. Where the framing behind has decayed — and water in a cornice void decays framing — the repair has to reach the timber, not just the skin. Anything soft enough to be chewed is not a closure, and on a front elevation it is also visible.

What does a flat roof with a parapet and a bulkhead actually offer?

A level, sheltered platform with several purpose-built openings in it, connected to every roof on the row.

Once an animal is on a Park Slope roof it is on a walkable surface. The parapet gives cover from the street. The roofline continues over the party walls into the buildings either side, so the whole row is one terrace. From there, the openings are these.

The bulkhead. The structure housing the stair head, with a door onto the roof. Bulkhead doors are exposed to weather on all sides, they are frequently old, and their thresholds, jambs and bottom rails are the first things to fail. A bulkhead with a gap at the bottom of the door is an open route into the top of the stair enclosure.

The parapet junction. Where the roof membrane turns up the inside face of the parapet, and where the parapet meets the neighbors’ at the party wall. Both are changes of plane, both are flashed, and both are where a membrane lifts.

Roof drainage. Internal drains, scuppers through a parapet, and downpipes. A scupper is a hole through a wall by design. Where its grille or cover has gone, it is an opening into whatever the drainage passes through.

Vent terminations and disused flues. Waste stack vents, boiler flues, extract terminations, and — very commonly on converted houses — chimney flues abandoned when the house went over to gas and never capped. An open flue is a vertical shaft from the roof to a fireplace opening in somebody’s bedroom, and it is a classic route for a bird or a squirrel that then cannot get back out.

The deck. Where a roof deck has been built, it sits on sleepers or pedestals with a void underneath, and it hides the membrane, the parapet base and the drainage from view. Planters on a deck hold wet soil directly over a top-floor ceiling. A deck is not a defect, but it is a large area of roof that nobody has looked under for years.

The extension roof. Where a rear extension has a roof at a lower level, it creates a step, a change of plane and an upstand against the original rear wall — another junction, at a height easily reached from the yard trees.

The survey therefore walks the whole roof including under any deck that lifts, looks at the parapet on all sides including the party junctions, opens what covers the drainage, and checks every termination. On an attached row it also looks along the neighbors’ roofs, because an entry two doors down is your problem if the void behind the cornice is continuous.

What happens at ground level and in the rear yard?

Less than people expect for wildlife, but not nothing — and the yard’s real contribution is as a ladder.

The rear yards on a Park Slope block form a continuous interior, on a hillside, with mature trees, retaining walls, decking, sheds, raised beds and compost. Most of what lives in that interior is a rodent question rather than a wildlife one, and it is dealt with under rodent control in Park Slope.

For wildlife specifically, the yard matters in three ways.

It is the route up. A yard tree with limbs over a rear extension roof is the most direct path from the block interior to the building. So is a boundary fence running to a wall, a downpipe, a trellis, a fire escape and a cable. Squirrels climb rough surfaces readily and can jump a short gap, so a clear zone around the roof edge does more than any single closure.

It is where the food is. Bird feeders in particular. A feeder is a reliable food supply that trains an animal to visit a specific property daily, and squirrels take them regardless of design. Compost that is not in a rodent-resistant enclosure does the same job. Neither creates the entry point, but both raise how many animals are working your building rather than the one three doors down.

Structures at ground level hold their own occupants. A shed on a paved pad, decking on sleepers, a void under a raised patio. These are usually a rodent finding, occasionally a wildlife one, and they are worth opening during the same survey rather than in a separate visit.

The one honest caveat is about tree work. Cutting back limbs that overhang a roof is genuinely effective and it is also somebody else’s decision much of the time — street trees are the city’s, and garden trees may be the neighbors’. What can be done unilaterally is closing the openings, which works regardless of how the animal arrives.

Why can the calendar stop this work outright?

Because closing an occupied void with dependent young inside it is not a scheduling error, it is an outcome nobody wants and one that cannot be reversed.

The rule underneath all of this work is simple: an exclusion is a one-way door out of a structure, and it only works if every animal that needs to leave is capable of leaving. Young that cannot yet move are not capable of leaving. Sealing a void that contains them leaves them inside a structure somebody lives under, with everything that follows from that — the odor, the flies, the eventual need to open a ceiling or a cornice to reach what is behind it, and the fact that it was avoidable.

So the sequence is always the same. Establish what is present. Establish whether young are present. Have a licensed operator get the animals out. Then close, which is our part.

Establishing whether young are present is not guesswork. It is a matter of what species it is, what time of year it is, what the activity pattern looks like, and where possible direct observation of the void. Squirrels and raccoons both have periods in the year when this is the governing question, and bats have the strictest constraint of all, because sealing a roost while flightless pups are inside is both an animal welfare failure and a regulatory one.

Bats also bring the legal layer, and it is more concrete than the phrase “protected species” usually implies. The northern long-eared bat is federally endangered, which under New York’s Endangered Species Law makes it endangered in this state as well. And the New York State Department of Health, in written guidance for children’s camps, tells operators not to batproof buildings “during the period from late May to mid-August, to avoid trapping baby bats inside the building” — a state agency naming the window in plain language. Anyone who offers to clear a protected species on a convenient date is describing what they would like to be true. Where a species or a situation carries a legal constraint we say so and the schedule moves, and if that means six weeks then it means six weeks.

Who does the removal, and who closes the cornice?

Two firms, because the two halves of a Park Slope wildlife job need two different sets of skills and two different credentials.

Taking a nuisance animal for a fee is separately licensed in New York — a nuisance wildlife control operator credential issued by the Department of Environmental Conservation, with its own examination behind it, and further permits stacked on top for endangered and threatened species, for migratory birds under federal jurisdiction, and for a schedule of protected mammals and native reptiles. Graduate coordinates that half with licensed nuisance wildlife partner firms. They set the device, they read the animal, they do the visit; we schedule the job around it and we are there for what follows.

What follows is the reason to call us, and on this block it is a metalwork job. The entry is a seam in a pressed sheet metal cornice a hundred and thirty years old, or a parapet upstand where the membrane has lifted, or the bottom rail of a bulkhead door that has been weathering on four sides since the house went over to gas. Closing those means fabricated 26-gauge galvanised sheet metal cut to the profile, mortar where the parapet is masonry, copper or stainless mesh at a scupper or a flue that has to keep breathing, Xcluder fill fabric at a door threshold, and mechanical fasteners into sound framing rather than into the rotten timber the water already found. Where the framing behind the cornice face has gone soft, the repair reaches the timber. Anything less is decoration.

The gap between those two halves is where this market’s wildlife work generally sits. The animal comes out, the invoice is issued, and the seam is closed with expanding foam or a bead of sealant — which a squirrel takes apart in an afternoon, and which is now a photograph of finished work. Foam does not appear in Graduate’s specification in any role, on any job, because a barrier a squirrel can chew is not a barrier. Exclusion is what this company does; the removal in front of it is a visit by somebody licensed for it.

There is one further seasonal point specific to this stock. Autumn is when animals look for winter shelter, and a roofline closed in late summer never acquires the occupant it would otherwise carry through the winter. Winter is when a building shows its openings, because a cold still morning reveals where warm air escapes and those points are frequently the same ones an animal has found. Spring is the masonry and metalwork season, after freeze-thaw has done its work on parapets, cornices and flashings.

How is an entry actually found on an attached roofline?

By working from the inside out and then confirming from the outside, because the opening is rarely where the noise is.

The method, in order:

Locate the void from inside. Where is the noise, at what time, and against which surface? A top-floor ceiling, a party wall at high level, a chimney breast, the front two feet of a room under a cornice. Noise carries through structure, so the audible location is a starting point rather than an answer.

Look for the physical evidence indoors. Staining on a ceiling. Gnawed timber where anything is accessible. Insulation displaced in a roof space where one is reachable. Droppings, and a note of where they are concentrated. A smell, which on an occupied void of any duration is unmistakable.

Then go up. Walk the whole roof. Look at the cornice ends and returns, the parapet on all sides including the party junctions, the bulkhead and its door, every vent and flue termination, the drainage, and under any lifting deck boards.

Read the surfaces. An entry in regular use is worn. Fur catches on a rough edge. The surrounding surface is rubbed clean or discoloured. On metal, there is bright material where a gnawed or forced edge has exposed fresh steel; on timber, fresh gnawing is pale against weathered wood and darkens over weeks, which dates activity.

Confirm before closing. Where it matters — and it usually does — the opening is monitored to establish whether it is in use and by how many animals, rather than closed on the strength of appearances. On an attached row it is worth also establishing whether the void behind the cornice is continuous into the neighboring building, because closing an opening on your house that leads into a shared void achieves considerably less than it looks like it does.

That last point is the one that most distinguishes this from detached work. On a free-standing house, closing the entry ends the access. On an attached row, the void may continue, and the honest answer is sometimes that the roofline needs doing across more than one building.

Who authorises the work when the noise is over a tenant’s bedroom?

The owner, and in this housing band that is often somebody who has never commissioned roof work in their life.

Roughly a third of the neighborhood’s units sit in buildings of two to four units, and a great many of those are owner-occupied houses with the upper flats let. The top-floor tenant is the one who hears the animal. The owner, who lives lower down, may hear nothing at all and is being asked to authorise work at roof level on the strength of somebody else’s description.

That produces a set of practical frictions worth anticipating.

Belief. A report of noise from a tenant is evidence, and it should be treated as such rather than as an inconvenience. In a house with no super there is nobody else who is going to notice.

Access. Reaching the roof usually means going through the top-floor apartment or its stair, and the void may need opening from inside a room somebody rents. That is a notice-and-arrangement question, planned in advance.

Cost and scope. Cornice, parapet and bulkhead repairs are building fabric work. They are more expensive than the removal visit in front of them, and they are the actual answer. An owner who buys the animal out and stops there has bought a vacancy, not a result.

The party line. A parapet junction or a cornice return belongs to two buildings. Work at that point is a conversation with a neighbor, and where several houses on a row have the same problem, doing the roofline collectively is materially cheaper and more effective than doing it one house at a time.

Where responsibilities between owner and resident are unclear, landlord and tenant pest responsibilities sets out how they usually divide, and the general duty on an owner of a multiple dwelling is at the NYC Housing Maintenance Code and pests. Where the roof is on a landmarked block — and the historic district covers roughly 2,575 buildings across about forty blocks — a cornice repair on the visible front may attract review, which changes the timetable rather than the specification. Concealed work, and everything at the rear and on the roof plane itself, proceeds meanwhile.

What has to happen after the animal is out?

Three things, and skipping any of them produces the same call next year.

Close and repair in materials that hold. Rigid closure cut to fit at cornice ends and returns. Metal where a metal element has failed. Sound timber where framing has decayed, because closing a hole in a rotten fascia achieves nothing. Mesh where a vent or a drain has to stay open, which is the distinction most often got wrong: a scupper, a flue that must breathe, a vent termination and an areaway drain are screened rather than sealed. Nothing an animal can bite through counts as a closure, however tidy it looks the day it goes in.

Clear and treat the site. An occupied void holds nesting material, droppings, urine and scent. The scent is the operative part: it is a signal to the next animal that this is a used and successful site, and it is why a removal without a clean-out reliably produces a re-entry at the same point. There is also a secondary consequence, because nesting material and droppings support their own insect populations — cluster flies and carrion-associated species turn up in exactly these voids and are frequently the reason somebody calls in February about a completely different problem.

Check the rest of the roofline. The opening that has just been closed was the best one. The second best is still there. On an attached house that means the whole roof, the cornice across its full width, both party junctions, the bulkhead and every termination — and, where the void is continuous, a conversation with the buildings either side.

The verification step comes later and is worth booking rather than intending. A season later, after weather, somebody looks again: at the closures, at the parapet, at the cornice fixings, and at any new limb growth that has reached the roof edge since. On a hundred-and-forty-year-old building with a metal cornice and a flat roof, that check is part of the work rather than an extra.

For the discipline in general, see wildlife management. The closure specification overlaps almost entirely with structural exclusion in Park Slope, and voids that have held an animal frequently produce insect work afterwards — see ant control in Park Slope where wet cornice framing is involved. For what this housing stock produces across every service, pest control in Park Slope, with the New York City hub. Brooklyn Heights has the same roofline problem in older fabric, and the Upper East Side runs it at the scale of pre-war apartment houses.

If something is moving above a ceiling, tell us what you hear and when you hear it before anything gets blocked up.

Related

• Wildlife Management — how we approach it
• All pest control in Park Slope
• Rodent Control in Park Slope
• Cockroach Control in Park Slope
• Bed Bug Treatment in Park Slope