A bill to make Maine’s animal trespass law apply to cats swiftly ran up against opposition from cat lovers on Monday.

Herding cats, it turns out, may be simpler than getting people to agree on how to keep them from roaming and killing birds.

Rep. Vicki Doudera took great pains to point out that she likes cats — her most recent were named Tom and Jerry — but she said cats are getting a "free and unfettered" pass for the harm they do to bird populations.

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The bill she sponsored would add cats to the state's animal trespass law, which now expressly excludes them. Under the law, people can be fined $50 to $500 for letting pets or animals wander onto others' property.

Doubts quickly emerged during a public hearing held by the Committee On Agriculture, Conservation and Forestry.

One lawmaker was a former police officer who was skeptical of enforcement, and another was a farmer who had 10 barn cats and raised questions about feral cats. Shelter officials fear they'd be swamped by cats and a veterinarian feared euthanizing cats if the change was made.

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But even some opponents of the bill acknowledged cat owners need to be educated about the danger their pets pose to birds if allowed outside.

Francesca Gundrum, from the Maine Audubon, said the harsh reality is that cats that roam outside — including family pets — represent the No. 1 "direct, human-caused threat to birds" in North America. Those include endangered birds like piping plovers, and she recounted one being pulled alive from a cat's mouth this year in Scarborough.

Doudera, a Democrat from Camden, said she hopes her bill brings about change. "I think we can start a conversation," she said.