Are Roof Rats Legal in Massachusetts? Keeping, Breeding & Selling

• Massachusetts Division of Fisheries & Wildlife (MassWildlife), written reply June 2026: confirmed that roof rats (Rattus rattus) are not a legal pet in Massachusetts, and directed us to the state’s published ‘Wildlife as pets’ guidance. This confirms there is no general pet-keeping pathway for R. rattus in Massachusetts, even though its near-twin the fancy rat (Rattus norvegicus) is exempt and fully legal. The barrier is that the species is simply absent from the state’s exemption list, not a finding that domesticated roof rats are dangerous.
• Massachusetts Division of Fisheries & Wildlife (MassWildlife), follow-up reply June 2026: confirmed that an educator may apply for a permit to possess roof rats, and provided the possession/importation application form. So while roof rats are not a general legal pet in Massachusetts, a documented educational or scientific keeper can apply to MassWildlife for a possession permit.

Keeping / owning   Restricted

Confidence: High · Last verified 2026-06-10

R. rattus is not on the 321 CMR 9.01 exemption list nor the 321 CMR 9.02 domestic-animals list (both name only the Norway rat / laboratory rat derived from R. norvegicus). As a non-listed undomesticated mammal it may not be possessed without a MassWildlife license under M.G.L. c.131 §23, and MassWildlife’s own guidance states no permit is issued for keeping a wild animal as a pet, so there is no lawful pet pathway. Refined (assume-a-pathway re-audit): R. rattus isn’t on the 321 CMR 9.01(12) exempt list (only R. norvegicus is), so possession needs a MassWildlife license under MGL c.131 §23 / 321 CMR 2.12, BUT 2.12 requires DENIAL of applications to keep a wild animal ‘as a pet’ (MassWildlife: ‘you will not be issued a permit for keeping a wild animal as a pet’). No private pet pathway; only a scientific/educational/commercial-propagator license (institutional). = restricted, not flat-prohibited. The operative trigger confirmed by Gemini DR (2026-06-10) is 321 CMR 9.02(2)(c): any vertebrate taxon not listed ‘shall be presumed to be wild and shall be subject to the provisions of M.G.L. c. 131,’ which is what subjects an unlisted R. rattus to the §23 licensing regime.

Sources: MA Division of Fisheries & Wildlife (via Cornell LII), MA Division of Fisheries & Wildlife (via Cornell LII), Massachusetts General Court, MA Division of Fisheries & Wildlife, MA Division of Fisheries & Wildlife (via Cornell LII)

Breeding   Restricted

Confidence: High · Last verified 2026-06-10

Breeding an unlisted wild mammal requires a Class 4 Propagator’s License under M.G.L. c.131 §23 / 321 CMR 2.12, which authorizes a holder to possess, maintain, propagate, buy, sell, or dispose of specified mammals, but acquisition is gated by an exhaustive application (scale diagrams/photos of enclosures, a written disposition plan and justification, documentary proof of professional husbandry qualifications, and a liability/inspection agreement). Critically, 321 CMR 2.12(9) MANDATES denial of any application to ‘possess, maintain, propagate, or cultivate animals as pets,’ or where the intent is ‘purely on curiosity, impulse, novelty, or to provide personal amusement or entertainment.’ There is therefore no hobby/small-breeder threshold: a Class 4 license for R. rattus is only structurally available for a certified non-pet purpose, scientific (recognized institution), educational (recognized institution), or commercial propagation for the agricultural/laboratory supply chain divorced from the pet trade. R. norvegicus needs none of this because it is exempt/domestic. Hobby/pet breeding is barred.

Sources: Massachusetts General Court, MA Division of Fisheries & Wildlife (via Cornell LII), MA Division of Fisheries & Wildlife (via Cornell LII), MA Division of Fisheries & Wildlife (via Cornell LII)

Selling or giving away   Restricted

Confidence: High · Last verified 2026-06-10

Commercial sale, offer for sale, barter, or transfer of a presumed-wild mammal requires a Class 6 Dealer’s License or a Class 4 Propagator’s License under 321 CMR 2.12(3) / M.G.L. c.131 §23. Because R. rattus is unlisted, the ‘without a permit’ privilege in 321 CMR 9.01 does not reach it. A second, independent barrier blocks the retail pet channel: under 330 CMR 12.00 (Licensing and Operation of Pet Shops), a licensed pet shop may sell only an ‘Animal,’ defined as a species that may be kept without a MassWildlife permit per 321 CMR 9.01/9.02, so the roof rat falls outside what any pet shop may lawfully sell. The result is a closed regulatory loop: a Class 4/Class 6 holder may transfer R. rattus only to another permitted person or institution, permanently sequestering the species from public pet ownership. Private give-away/sale of a pet roof rat is not authorized; only a licensed non-pet dealer/propagator transfer is structurally possible.

Sources: Massachusetts General Court, MA Division of Fisheries & Wildlife (via Cornell LII), MA Division of Fisheries & Wildlife (via Cornell LII), MA Dept of Agricultural Resources (via Animal Legal & Historical Center)

Transport & import   Restricted

Confidence: High · Last verified 2026-06-10

Cross-border movement of R. rattus is treated as importation of ‘wildlife’ under 321 CMR 2.15 regardless of captive-bred origin. No person may import a live mammal without an Importation Permit from the Director (321 CMR 2.15(2)); the application must be filed at least ten days in advance with the originating/destination facility details and a signed certification that the export is lawful in the origin jurisdiction, and the Director may deny under 321 CMR 2.15(10) where importation is ‘detrimental to the fish and wildlife resources of Massachusetts … and is not in the public interest’ (a real risk given the roof rat’s invasive-pest reputation), and may require zoonotic-disease/parasite health certificates; illegal or diseased imports may be seized and humanely destroyed (321 CMR 2.15(22)). Once lawfully in-state under permit, transport is allowed only with the permit accompanying the animal and subject to Director-imposed caging/safety conditions. Liberation is ABSOLUTELY barred, never release; release of a non-native presumed-wild rodent is a serious violation. So transport is permit-gated and restricted, not unregulated. (The MDAR animal-health/CVI layer is secondary to the wildlife-import permit.)

Sources: Massachusetts General Court, MA Division of Fisheries & Wildlife (via Cornell LII), MA Division of Fisheries & Wildlife (via Cornell LII), MA Dept of Agricultural Resources (via Cornell LII)

• Do not bring a roof rat into Massachusetts
• If advocating: petition MassWildlife to add captive-bred R. rattus to the 321 CMR 9.02 / 9.01 lists

Where: Massachusetts Division of Fisheries & Wildlife (MassWildlife)

Source: MA Division of Fisheries & Wildlife, MA Division of Fisheries & Wildlife (via Cornell LII)

Massachusetts uses a “prohibited-unless-listed” system for keeping animals. The state’s exemption list (321 CMR 9.01) and its domestic-animals list (321 CMR 9.02) name only the Norway rat (Rattus norvegicus) and the laboratory/fancy rat strains derived from it. The roof rat (Rattus rattus, also called the black rat) is not named on either list. The operative trigger is 321 CMR 9.02(2)(c): ‘Any vertebrate taxa not listed in 321 CMR 9.02 shall be presumed to be wild and shall be subject to the provisions of M.G.L. c. 131.’ The state therefore treats a roof rat as a non-listed wild mammal that cannot be kept without a MassWildlife license, and MassWildlife’s guidance says it will not issue a permit to keep a wild animal as a pet. The practical result is that a tame, captive-bred roof rat is off-limits in Massachusetts because the species name is missing from a list, while its near-identical cousin the fancy rat is fully legal. This is a species-not-domestication gap, not a judgment that domesticated roof rats are dangerous or different to care for.

The ask: Ask MassWildlife to add captive-bred Rattus rattus to the 321 CMR 9.01 exemption list (subsection (12), List of Mammals) and/or the 321 CMR 9.02 domestic-animals list, the same regulatory route already used for the Norway rat / fancy rat. The controlling statute, M.G.L. c. 131 §23, lets the Director amend the list after a public hearing using four criteria. A domesticated, indoor-kept, captive-bred roof rat line appears to satisfy all four, and the Director is asked to weigh it against them: the roof rat is already established in the region, so an escaped tame animal adds little new ecological risk; it is no more dangerous or demanding to keep than the fancy rat the list already allows; and trade in a captive-bred line has little bearing on wild populations. The fancy rat is itself the wild brown rat (R. norvegicus), domesticated only in the 19th century (see https://blonderoofrat.com/how-the-sewer-rat-became-the-fancy-rat/), so a captive-bred R. rattus is the same case one species over. Whether the four criteria are met is the Director’s judgment after a public hearing; the request is only that the question be evaluated. This can be raised informally by email, or formally as a petition for rulemaking under G.L. c. 30A §4 directed to the Director of the Division of Fisheries & Wildlife and the Fisheries and Wildlife Board (Permit Section, 100 Cambridge Street, 6th Floor, Boston, MA 02114).

Where the lever really is: This is an agency lever, not a legislative one. The barrier is a regulation the agency itself writes and controls: the exemption list lives in 321 CMR 9.01, a MassWildlife regulation, and the enabling statute M.G.L. c. 131 §23 authorizes the Director of the Division of Fisheries & Wildlife to alter that list after a public hearing, applying four statutory criteria (no ecological harm from escape, no danger to people, care no harder than a common domestic animal, no impact on wild populations). The roof rat’s absence is a gap: the species was never added. The agency has both the power and a built-in mechanism to fix it. The Norway rat / fancy rat got onto the list the same way, and sugar gliders, the four-toed hedgehog, and several chameleons and skinks were all later added to 321 CMR 9.01 through this process. The right move is to ask MassWildlife to add captive-bred R. rattus, either informally by writing to the Division or formally by filing a petition for rulemaking under the Massachusetts Administrative Procedure Act (G.L. c. 30A §4), which gives any interested person the right to ask an agency to amend a regulation and obliges the agency to consider it. The procedural path after a meritorious petition is: agency scientific review, then a public hearing noticed at least 21 days in advance in the Massachusetts Register, then a written comment period, then a Small Business Impact Statement, then a Fisheries and Wildlife Board vote, then final promulgation with the Secretary of the Commonwealth. A legislative bill is not the primary path here, because no statute names or bans the roof rat; the gap is administrative. If the species had been written into a statute by name, appealing to the agency would be pointless and the legislature would be needed, but that is not the situation in Massachusetts.

Where to send it (more than one channel helps):

• Massachusetts Division of Fisheries & Wildlife (MassWildlife) (executive / agency), Mass.Wildlife@mass.gov
  MassWildlife writes and maintains the 321 CMR 9.01 exemption list and the 9.02 domestic-animals list, and under M.G.L. c. 131 §23 its Director can add a species to that list after a public hearing. This is the office with the actual power to fix the gap. Mass.Wildlife@mass.gov is the agency’s official general inbox (verified on mass.gov); start here to ask for clarification and to request that captive-bred Rattus rattus be added, the same way Rattus norvegicus already is.
• MassWildlife, formal Petition for Rulemaking under G.L. c. 30A §4 (public comment), Mass.Wildlife@mass.gov
  If an informal request stalls, the Massachusetts Administrative Procedure Act (G.L. c. 30A §4) gives any interested person the right to file a written petition asking an agency to amend a regulation, and the agency must consider it. A petition to add captive-bred R. rattus to 321 CMR 9.01(12) forces the Division to formally consider the request and respond, and any list change triggers the public hearing required by M.G.L. c. 131 §23, your chance to make the case on the record. Route the written petition to the Director of the Division of Fisheries & Wildlife and the Fisheries and Wildlife Board via the Permit Section, MassWildlife, 100 Cambridge Street, 6th Floor, Boston, MA 02114 (and copy the official Mass.Wildlife@mass.gov inbox). Board communications can also be addressed to the Chairman, Fisheries and Wildlife Board, 1 Rabbit Hill Road, Westborough, MA 01581.

A starting-point message, please put it in your own words; a short personal note carries far more weight than an identical form letter:

To the Massachusetts Division of Fisheries & Wildlife (Director and Permit Section),

I am writing about a gap in the exemption list at 321 CMR 9.01. That list, and the domestic-animals list at 321 CMR 9.02, name the Norway rat (Rattus norvegicus) and its laboratory and fancy strains, but they do not name the roof rat (Rattus rattus, the black rat). Under 321 CMR 9.02(2)(c) any taxon not listed 'shall be presumed to be wild,' so because of that omission a tame, captive-bred roof rat cannot be kept in Massachusetts, even though its near-identical cousin the fancy rat is fully legal.

These are domesticated, captive-bred animals: selectively bred for tameness, kept entirely indoors as pets, and never released. They are not wild-caught and are no more demanding to care for than any common pet rodent.

I respectfully ask the Division to add captive-bred Rattus rattus to the 321 CMR 9.01 exemption list (subsection (12), List of Mammals) and/or the 9.02 domestic-animals list, the same route already used for the Norway rat and, more recently, for sugar gliders, the four-toed hedgehog, and several chameleons and skinks. Under M.G.L. c. 131 §23, a captive-bred domestic line appears to meet all four statutory criteria: (1) accidental release is unlikely to adversely affect the ecology of the Commonwealth, because the roof rat is already established in the region and a tame, captive-bred animal is poorly suited to surviving unaided; (2) the animal in captivity or escaped poses little danger to people by injury or disease; (3) its care is no more demanding in any major respect than common domestic animals; and (4) trade in a captive-bred line is unlikely to significantly affect wild populations. Whether these criteria are met is the Director's determination after a public hearing. I am asking that the question be evaluated, not assuming its outcome.

Please tell me the administrative procedure, designated recipient, and expected timeline for docketing such a request, and whether I should submit it as a formal petition for rulemaking under G.L. c. 30A §4 for a Fisheries and Wildlife Board hearing. I would also welcome the Division's view on whether the presumption of wildness under 321 CMR 9.02(2)(c) is rebuttable on a showing of domestication, or whether a full rulemaking is the only remedy. Thank you for your time.

Sincerely,
[Your name]
[Your town]
[Your email]

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