By Stephanie Braswell for The Island Connection
Kiawah’s historically healthy and stable bobcat population is declining, due in part to a recent rise in mortality rates. Four of the six bobcats fitted with GPS collars this past winter as part of the town’s Bobcat GPS Study have died, and town biologists have been trying to figure out why. The latest incident occurred on Aug. 1, when Bobcat 300, an adult female, was found dead near Seascape Villas. Biologists sent the bobcat to the University of Georgia’s Wildlife Disease Laboratory for analysis. Laboratory tests revealed that the bobcat died from consuming toxic levels of four different anticoagulant rat poisons.
The four poisons identified in Bobcat 300 at high levels were Bromadiolone, Brodifacoum, Diphacinone and Difethiolone. A fifth poison, Difenacoum, was found at low levels. All of these poisons work by inhibiting the body’s recycling of Vitamin K, which is vital to the blood clotting process. Infected rodents ultimately bleed to death three to seven days after consuming the poison. Bobcats pick up these poisons secondarily by eating infected rodents, not by consuming the actual poison itself.
Secondary poisoning of wildlife from anticoagulant rodenticides is well documented in places such as California’s Santa Monica Mountains, where a recent study found that 92% of bobcats and 94% of mountain lions had been exposed to rat poison. Other studies have shown high levels of rat poison in many different species of raptors. The extent of the problem on Kiawah is currently unknown, and, while future studies may provide additional details, taking action now to curb the use of these toxic chemicals is critical.
Rodenticides, especially the more toxic second-generation anticoagulants, are heavily regulated and can only be used by licensed, commercial pest control agents. Due to their high toxicity to people and pets, baits containing these rodenticides are placed within black plastic bait stations to prevent access. Bait stations are placed around homes and other structures where rodents enter the box, eat the poisoned bait and ultimately die somewhere nearby. Predators, including bobcats, hawks, owls and snakes that provide natural control of Kiawah’s rodent populations, eat the poisoned rodents and over time accumulate a toxic amount of these rodenticides. Town biologists will continue to research this emerging issue.
If you have questions, contact Jim Jordan at 843-768-5106 or firstname.lastname@example.org.