AUGUSTA — The Kennebec Valley Humane Society is waiving pet adoption fees for the remaining three weeks of summer to help clear out its shelter after its busiest time of the year.

The animal shelter off Western Avenue has more than 125 cats and more than 30 dogs, about twice what it typically has during the winter, said Hillary Roberts, the organization’s executive director. Summer is always the busiest time for new animals coming to the shelter, because it’s the mating season for cats, people often make lifestyle changes and some pets are left outside and separated from their owners, Roberts said.

“It’s not just us. It’s all across the country and Maine,” she said. “This is a real tough time for shelters because we see an increase in the number of animals we’re serving.”

Until Sept. 22, the last day of summer, the Kennebec Valley Humane Society will waive adoption fees for cats that are at least 7 months old and for dogs that have been in the shelter for more than a month, Roberts said. The nonprofit organization still is suggesting donations of $25 for cats and $50 for dogs, she said. The fees are typically $75 for cats and $125 for dogs.

All animals at the shelter are spayed or neutered and up-to-date on routine vaccinations, services that can cost pet owners well over $100, Roberts said.

She said one of the concerns of having more animals in the shelter is they can spread illnesses to each other more easily.

“We want to make sure we don’t have a ton of animals inside the building because we don’t want them to become stressed, and we definitely don’t want them to become ill,” Roberts said.

The shelter has done other adoption fee-waiving events this summer and has been doing them every summer for the last five or six years, she said.

The shelter has found them to be effective, and research has shown that people who adopt pets without paying fees don’t connect any less with their animals, Roberts said, citing research by the American Society for the Prevention of Cruelty to Animals. A 2006 study by a researcher with the animal welfare organization showed that there wasn’t a statistical difference in future retention of cats between those that were adopted for a fee and those that had their fees waived.

If the shelter gives an animal to an individual or family who didn’t pay a fee, the owner or owners won’t love the animal any less, Roberts said.

The shelter finds homes for 92 percent of its animals, and a goal of the fee-waiving promotion is to try to maintain that rate even with the additional animals, she said.

Paul Koenig — 621-5663

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Twitter: @pdkoenig