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Feral Cats Threaten the Health of our Watershed

A feral cat has the capacity to decimate large sections of a breeding colony, arriving suddenly and, in a single event, wiping out multiple adult birds, as well as chicks and eggs, before fleeing the scene without a trace.

Without predator control, a cat could take a whole seabird colony. In recent years, new cat tracking and trapping techniques have yielded promising signs that fewer seabirds are succumbing to the teeth of feral cats.

In one prime nesting area for endangered Kauai seabirds, the number of seabirds killed by cats and observed by researchers has dropped from 31 birds in 2016 to 11 birds in 2017, according to data cited in a press release by the state Department of Land and Natural Resources. Last year there were five recorded deaths in the same region.

What is toxoplasmosis and why should we care?

Toxoplasmosis is a disease caused by a microscopic parasite, T. gondii. The parasite can only sexually reproduce in the digestive system of a cat. And unlike all other groups of animals that can get infected with this parasite, “toxo” is shed into the environment exclusively in the fecal matter of cats.

Long after the cat feces decomposes, the eggs remain in the environment and are very resistant to degradation. They are capable of surviving in the soil or in water (fresh or salt), and withstanding a wide range of temperatures for months to about 2 years. When it rains, the eggs wash into the ocean, exposing animals like monk seals that ingest the parasite through contaminated water and infected prey.

Once it gets into a monk seal, the parasite is almost always lethal. The disease has now killed at least 12 monk seals, making it a leading threat to the main Hawaiian Islands population.

Latest Kauai Research on Toxoplasma:


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