The time of year that the Humane Society of America compares to a “natural disaster” is almost upon us. It’s kitten season.
Ann Dunn, the director of Oakland Animal Services, a city-run shelter in the San Francisco Bay Area, shares that the emotional toll during these months is incredibly draining. She knows that with each year, the challenge only grows.
In the United States, the summer marks the peak of kitten season. This is the period from spring to fall when cats are most fertile. For more than a decade, animal shelters nationwide have observed that kitten season is starting earlier and lasting longer. Experts believe that climate change, leading to milder winters and an earlier spring, could be contributing to the increase in feline birth rates.
This past February, Dunn’s shelter organized a clinic for spaying and neutering outdoor cats. They discovered that over half of the female cats were already pregnant, even though kitten season in Northern California typically doesn’t start until May. Dunn finds this trend both terrifying and relentless.
Cats reproduce when females enter estrus, signaling they are ready to mate. This can happen several times a year, with each cycle lasting up to two weeks. However, births usually increase between April and October. While it’s known that longer daylight hours trigger a cat’s estrus, the impact of rising temperatures on kitten season is still being explored.
One theory suggests that milder winters could allow cats to start mating sooner. Christopher Lepczyk, an ecologist at Auburn University, notes that no animal will breed unless it can survive. He points out that outdoor cats might find more food available, such as small rodents, which thrive in warmer weather. Additionally, kittens are more likely to survive in less harsh winters.
Peter J. Wolf, a senior strategist at the Best Friends Animal Society, believes the perceived increase in kitten season may be due to people spending more time outdoors in warmer weather, noticing kittens earlier, and bringing them to shelters.
Regardless of the cause, the presence of a large number of feral cats poses a significant threat to local biodiversity. Cats are apex predators and can severely impact local wildlife populations. On islands, outdoor cats have contributed to the extinction of an estimated 33 species. They pose a significant threat to birds, which constitute half of their diet.
Scientists, conservationists, and cat advocates agree that unchecked outdoor cat populations are problematic. However, there is deep division over the solutions. Some conservationists suggest culling, but cat populations tend to recover quickly. A single female cat and her offspring can produce hundreds, if not thousands, of descendants in just seven years.
Although many cat rescue organizations favor sterilization methods like “trap, neuter, and release,” Lepczyk argues that it’s nearly impossible to do effectively. Without controlling the influx of new cats into the environment, these efforts may not be sufficient.
Rescue shelters are doing their best to manage the situation, despite facing resource and veterinary shortages. Some provide materials to help the community identify when outdoor kittens need help, while others focus on recruiting foster volunteers for the essential round-the-clock care of kittens.
Dunn emphasizes the importance of addressing the needs of these young lives. Her shelter is committed to giving everything they have to help.
This article was originally featured in Grist, a nonprofit, independent media organization focused on climate solutions and a just future. Learn more at Grist.org.