"This is critical to how many animals we can save - we can't help animals if we have no where to put them."
Veterinarian nurse Adrianne Cossey, who oversees the cats and kittens brought into the SPCA, said that on any day up to 20 animals were brought in, and on a busy day up to 75.
"I've got 47 cages which are filled most days, we try and rotate them as quickly as possible."
Ms Cossey said people would be caring for kittens which needed to gain weight or were sick.
Mrs Laird said up to 20 families a day were needed to foster the new cats and kittens brought in.
One of the foster managers, Karyn Sage, said there was a constant turnover of animals needing foster homes.
"It never quietens until May."
Another foster manager, Lorna Crouth, said people had asked if they could take foster animals with them over holidays.
"Some do it when they get back from holiday, it doesn't matter as long as it helps the animal."
People willing to foster need to have a spare room for the cat or kitten, and must keep it away from other household pets to prevent infection.
The SPCA would restock pet food supplies to foster homes.
Can you help?
To inquire about fostering a cat, call the SPCA on (09) 256 7300.