The busy Christmas period has only just begun for the Auckland SPCA but already more than 400 cats are available for adoption.

The society has 70 adult cats and 40 kittens in its shelter but soon another 356 felines being looked after by foster families will be looking for new homes.

Operations manager Tracy Dunn said the shelter was almost at crisis point after the start of the kitten season and the SPCA was concerned it might reach capacity before the society's busiest week, between Christmas Eve and New Year's Eve.

"The numbers are really stacking up," Mrs Dunn said. "I hope people will think of us if they are wanting to adopt a pet in time for Christmas."

She said the mild winter and record November temperatures might have prompted cats to reproduce earlier.

"If it had been a cold, miserable winter, we wouldn't be expecting them for another couple of weeks or even a month."

Mrs Dunn said that two years ago, 150 animals were dropped off on Christmas Eve, so it was important the shelter had plans to home as many cats as possible. "The adult cats are our biggest concern. It's easy to overlook them when there are adorable fluffy kittens on display."

Mrs Dunn said she hoped the SPCA's message that all pets should be de-sexed was making a difference, but cat numbers were difficult to control because of stray-cat populations.

"Basically our message is de-sexing saves lives."

The SPCA has halved its adoption prices - kittens are $75 and adult cats $50.

All are de-sexed, microchipped and have had at least one vaccination.