Clues to the cause of the Tsushima leopard cat (Prionailurus bengalensis euptilura) decline from isotopic measurements in three species of Carnivora

The estimated population of the Tsushima leopard cat Prionailurus bengalensis euptilura is only 80-110 individuals. However, the cause of the population decline is not clear. We investigated temporal changes in the food habits of the cat and two other species of Carnivora (marten and weasel) inhabiting the Tsushima Islands by measuring delta(13)C and delta(15)N values in hair samples. Hair samples of the cat were collected not only from specimens and furs, but also from feces. The gathering of hair from cat feces was most efficient when the feces were collected in the spring. The food habit of male cats seemed to be more diverse and tended to comprise prey of higher trophic levels than the food habits of the females. The delta(13)C and delta(15)N measurements suggested that the trophic level of the food sources has been decreasing over the last several decades for the cat and weasel, but not for the marten. Increased consumption of prey from lower trophic levels in the food habit of the cat seems to be related to the decline of the cat population because these phenomena occurred simultaneously.