Bats, Squirrels and Raccoons in Connecticut Roofs
Connecticut Department of Energy and Environmental Protection names June to mid-August as the maternity period. Below is the sentence it publishes, the link to it, the federal layer that sits on top, and the squirrel and raccoon calendar that runs alongside.
CT DEEP names June to mid-August as the maternity periodThe Connecticut bat exclusion calendar
Quoted, not computedThe dates above are Connecticut Department of Energy and Environmental Protection’s, and the link to the page they came from is in the next section. Ask CT DEEP before you close anything up.
What Connecticut publishes
Bat exclusion is restricted during the maternity season in a large number of states, and the reason is mechanical rather than sentimental. The humane method is a one way door. Fitted while pups are still flightless it lets the mothers out and shuts the pups in, and they starve in the wall. That is why agencies publish dates, and it is why those dates are worth reading before anybody gets on a ladder.
Here is the Connecticut text, exactly as published.
“Exclusion should NOT be done from June through mid-August as flightless young may be trapped and die in the roost. In addition to resulting in the suffering of bats, this would likely cause odor problems.”
On permits
“If the bats need to be trapped or handled, the specialist must be licensed by the DEEP Wildlife Division.”
Listed species in Connecticut
“There are over 1,400 species of bats in the world – 9 species of bats may be found in Connecticut, and all but one of them (the Big Brown Bat) are on Connecticut's List of Endangered, Threatened, and Special Concern Species.”
One caution on that sentence. State pages are not always current with federal listings, which change on their own schedule: the northern long eared bat moved from threatened to endangered in a final rule published in November 2022, and state pages around the country still describe it the old way. Where a state page and the U.S. Fish and Wildlife Service disagree about federal status, USFWS is the one that sets it. The federal section below quotes USFWS directly.
Federal protection sits on top, not instead
Some bats that roost in American buildings are protected under the federal Endangered Species Act as well as by state law. Federal status is set by the U.S. Fish and Wildlife Service, it has changed more than once in the last few years, and it changes independently of anything a state does.
Northern long-eared bat (Myotis septentrionalis): Endangered
“on November 29, 2022, the U.S. Fish and Wildlife Service found that the species now meets the definition of an endangered species and published a final rule to reclassify the northern long-eared bat as endangered under the Endangered Species Act.”
USFWS describes maternity colonies giving birth over this period. USFWS gives the period as “from late May or early June to late July, depending on where the colony is located within the species’ range”.
Indiana bat (Myotis sodalis): Endangered
“The species was originally listed as in danger of extinction under the Endangered Species Preservation Act of 1966 and is currently listed as endangered under the Endangered Species Act of 1973, as amended.”
The same profile describes maternity colonies forming under loose bark of living or dead trees, and only less often in artificial roost structures, so this is a species you are far more likely to affect by felling a tree than by sealing a soffit.
Tricolored bat (Perimyotis subflavus): Proposed for listing, not listed
“On September 13, 2022 the U.S. Fish and Wildlife Service announced a proposal to list the tricolored bat as endangered under the Endangered Species Act.”
As of the date read, the USFWS profile still described a proposal and still framed its guidance documents as prepared in the event that the species is listed. That status can change without warning, so the USFWS profile is the place to confirm it.
One way doors, and why the timing is the whole thing
The humane method that wildlife agencies describe is not a trap and not a poison. It is a one-way door: a sleeve or a sheet fitted over the gap the animals already use, which lets an animal out and does not let it back in. Once the roost is empty the gap is sealed. That is why the calendar matters so much. A one-way door fitted over a maternity roost lets the mothers out and shuts the flightless pups in.
“Bats can be safely evicted from homes via the use of one-way doors that allow bats to leave but not return.”
“Loosely hang plastic sheeting or bird netting over the exit hole(s) to prevent bats from returning and allow the remaining bats to exit.”
What happens when the timing is wrong
“Exclusions occurring during this period will separate mothers from their flightless pups, leaving the pups to die of starvation and potentially exacerbating the homeowners’ bat problem as frantic bat mothers search for an opening to reach their pups.”
Two things follow from that sentence, and only one of them is about the bats. The other is about the building: a colony sealed in does not disappear, and the mothers outside do not give up. That is the mechanism by which a badly timed job becomes a worse problem than the one it was meant to fix.
Fitting one is a job for a permitted nuisance wildlife operator or a state wildlife biologist, which is who the agency pages linked above name.
Which of the three is it?
This matters more than it sounds, because the three animals have completely different legal positions and completely different calendars. The single most diagnostic thing is not the noise itself but the time of day it happens at, and it costs nothing to notice.
Bats dusk and dawn
ChiropteraSound. Faint scratching and high chittering at dusk and again before dawn, from a wall cavity or the gable end rather than from the middle of the ceiling. Almost nothing during the day.
Sign. Small dark droppings that crumble to a glitter of insect wing scales, piled directly below one entry point, and a greasy dark stain where fur has rubbed the gap for years.
Way in. A gap around a quarter of an inch across. That figure is CDC’s, on its Preventing Rabies from Bats page.
Why your roof. A hot attic in June is a very good place to raise a pup, which is the entire reason the calendar on this page exists.
Squirrels daytime
Sciurus spp.Sound. Heavy, confident daytime running, usually just after first light and again in the late afternoon. Rolling and gnawing. Silent at night, which is the single most useful thing to notice.
Sign. A chewed hole with bright torn edges, often at a corner where two roof planes meet, and shredded insulation or leaf litter drawn into a heap.
Way in. A hole they made themselves. They are rodents and they will enlarge a gap that was already there.
Why your roof. A dry, defensible cavity that nothing can climb into, in the two seasons of the year when they have young. It is a better tree hollow than any tree hollow.
Raccoons after dark
Procyon lotorSound. Loud. Thumping and dragging at night, and in spring a chirring, churring, almost bird-like noise from the young that people frequently mistake for birds.
Sign. A torn soffit or a lifted shingle rather than a neat hole, and a latrine: a single place used repeatedly, which is the reason the health section on this page exists.
Way in. Nebraska Extension puts the size of opening a raccoon needs at four to six inches across, and notes that smaller ones get enlarged.
Why your roof. A chimney or an attic is a hollow tree that does not blow down, and it is where a spring litter gets raised.
Squirrels: two litters, two seasons, one roof
Gray and fox squirrels raise two litters a year in most of their range, one in late winter and one in late summer. That is why a squirrel problem in a roof has two seasons rather than one, and why the quiet months between them are the ones people actually get the work done in.
“Most litters are born in February or March, and July or August.”
Penn State Extension gives the gray squirrel breeding periods as mid December or early January and again in June, and puts weaning at about two months of age. Fox squirrels are described as following a similar pattern. Its terms ask for written permission before text is reused commercially, so the page is linked rather than quoted. Penn State Extension
| Litter | Born | Moving under their own steam |
|---|---|---|
| Late winter litter | February to March | April to May |
| Late summer litter | July to August | September to October |
The middle column is quoted from the sources above. The right hand column is this site’s arithmetic from the weaning interval those same sources give, a rough guide rather than a published figure.
Raccoons: one litter, in spring, and it is always in spring
Raccoons raise one litter a year. Breeding is in late winter, the kits arrive in spring, and they are not moving under their own steam for a long time afterwards. A raccoon in a roof in May is a mother with young in the roof until proven otherwise.
“Most breeding occurs in February, and most litters are born in April or early May, though some litters are born as late as August.”
“The young are usually weaned by August but stay with their mothers until the next spring.”
Nebraska Extension puts raccoon breeding at January through March, with females giving birth about nine weeks later to litters of two to five, and notes that a raccoon usually needs only a four to six inch opening to get into a building. Nebraska Extension, publication G1688
The attic latrine
Raccoons use one spot repeatedly, and CDC documents what can be in it. On the parasite: “Baylisascaris procyonis is thought to pose the greatest risk to people because of the often-close association of raccoons to human dwellings.”
On where it is found: “Raccoon feces can also be found on woodpiles, decks, rooftops, and in attics, garages, and haylofts.”
On who is most affected: “People become infected by consuming infectious eggs. Most infections are in children and others who are more likely to put dirt or animal waste in their mouth by mistake.”
Whether a particular attic is a problem, and how to deal with it, is a question for animal control and the health department. Read Preventing Raccoon Roundworm in full, from Centers for Disease Control and Prevention, page dated November 5, 2024. CDC also says: “Contact your local animal control office for additional assistance.” In Connecticut, the Connecticut Department of Public Health is the body to ask.
Rabies: what CDC says, and who to call in Connecticut
Bats and raccoons are the two rabies reservoirs most likely to be in an American roof. Exposure is assessed by the health department and a clinician; what follows is what CDC publishes, and who to phone in Connecticut.
“In the United States, bats are the most reported animals with rabies.”
“Avoid touching bats. Bat bites can be tiny, and you may not even know if you were bitten.”
“If people wake up with a bat in the room, CDC recommends that they assume they may have been exposed to rabies and see a healthcare provider right away”
Who to contact in Connecticut
The Connecticut Department of Public Health is the body to contact.
In its own words: “In the United States, where rabies in dogs has been largely eliminated, rabies is still widespread in wildlife. Bats, raccoons, skunks, and fox are the major reservoirs and serve as a source of potential infection for other animals and people.”
CDC: “If you think you have been in contact with a bat, talk to your health department.” And on a bat found indoors: “If you find a bat in your home, contact animal control or your health department to safely capture it for rabies testing. Do not release the bat until you talk with a public health expert.”
If there has been contact, or possible contact, the people above are the ones to call, and a healthcare provider is the one to see.
Connecticut attic wildlife FAQ
The rest of the Connecticut calendar
More Northeast attic wildlife timing
Every date and every restriction on this page is quoted from the body named beside it and linked to the page it was read on, on 28 August 2026. Where Connecticut publishes no timing, this page names the agency to ask. Wildlife rules change, some are municipal rather than state, and several bat species carry federal protection on top of state protection, so confirm with CT DEEP before any work starts. Federal listing status is from the U.S. Fish and Wildlife Service species profiles. Rabies and raccoon roundworm material is from the Centers for Disease Control and Prevention pages named above. Squirrel and raccoon breeding timing is from state conservation department field guides and land grant extension publications. National picture: bat exclusion windows in every state →
Hero image: “Bat in Eave” — Bearerofthecup — Public domain