Kerguelen Island cats, the albatrosses’ bête noire

Mammals introduced to islands benefit from the “surprise effect” on an evolutionary scale, causing the disappearance of many seabirds. On Kerguelen, hyperspecialized cats threaten the chicks of the great albatross.

At the other end of France’s overseas territories, the cats of the Kerguelen Islands are a source of blood and ink. On February 18, the scientific journal Ecosphère published a study showing that the survival of albatross chicks in colonies on the Courbet Peninsula does not depend on cat density, but rather on the presence of individuals specialized in hunting chicks. Let’s look back at the history of this animal.

The little feline, companion of explorers, hunters and then farmers, has been introduced on several occasions. The last one (between 1951 and 1956) led to a biological invasion of the archipelago. The number of cats was estimated at 7,000 in 1990, leaving many seabird corpses in their wake. In 2014 and 2017, what was true for small birds became true for larger ones.

Among albatross-eating cats, there are large specimens weighing almost five kilograms. Studies on the evolution of these beasts show that their skeletons have been strengthened in the skull and jaws. These “little panthers” are black and white, and when they’re not taking refuge in the underground, they’re sheltering in small rocky caves, littered with skeletons, feathers and sometimes other congeners.

Living night and day, they patrol a territory of around 50 hectares, catching mice in the grassy beds and waiting for rabbits to emerge from their burrows. The plumper, fluffier albatross chicks are of interest just before winter, when the adults are at sea.

According to the study, around a third of cats identified near nests take action. Unlike other cats, they are hyperspecialized, adding albatross chicks to their menu. This represents a challenge for this uninhabited archipelago the size of Corsica. By organizing their hunting, the French Southern Territories National Nature Reserve limits the presence of felines around the Courbet peninsula, where 348 pairs of great albatross breed. Other chicks could also be affected, such as those of gentoo penguins.

Camille Lin, PolarJournal

Link to the study : Blanchard, P., Delord, K., Bodin, A., Guille, K., Getti, T., Barbraud, C., 2024. Impact and control of feral cats preying on wandering albatrosses: Insights from a field experiment. Ecosphere 15, e4792. https://doi.org/10.1002/ecs2.4792.

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