Estate Living Magazine Connection - Issue 43 July 2019 | Page 42

C O M M U N I T Y
L I V I N G
RAT
POISON
THREAT TO CITY’S
PERI-URBAN WILDLIFE
Pest control is an essential element in estate management, but it needs to be carefully managed – both
to ensure the safety of residents and pets, and also to prevent ‘collateral damage’ to urban and peri-
urban wildlife.
The study was conducted within and around Cape Town’s Table
Mountain National Park, and is believed to be the first of its kind in
South Africa. It measured the presence and concentration of rat
poison compounds in liver and blood samples from 41 animals, with
a special focus on caracal as part of the Urban Caracal Project.
At 92%, exposure to rat poisons was highest for caracal. Overall, they
found 81% exposure across seven species tested. The predators
aren’t eating the poisons directly. Rather, the poisons are designed
to work slowly in their target species, rats, which become sick over a
period of days and end up as easy prey for predators.
‘We detected at least one of the four most toxic rat poison
compounds, all available in over-the-counter products, in six of the
seven species tested,’ said Dr Jacqueline Bishop, lead supervisor on
the project.
Caracals living in or near vineyards had the highest exposure to rat
poisons but the route to exposure is unclear.
Young male caracal.
Urban rat poisons are spilling over into Cape Town’s natural
environment, threatening species such as caracal, mongoose, otter
and owl. Anticoagulant rat poisons are infiltrating Cape Town’s
peri-urban wildlife food chains, according to a team of University
of Cape Town (UCT) researchers in the Institute for Communities
and Wildlife in Africa (iCWild). The team’s recent paper, in the
journal  Science of the Total Environment, identified six predator
species at risk: caracal, Cape clawless otter, Cape Eagle Owl, large
spotted genet, honey badger and water mongoose. Others are
likely to be affected as well.
These animals already face challenges that include increasing
habitat loss, vehicle collisions, poachers and fire, said lead author Dr
Laurel Serieys, a postdoctoral research fellow in iCWild.
‘Vineyards in Cape Town don’t use rat poisons to protect their vines,
but they do host restaurants, spas and hotels and occur adjacent to
dense residential areas where rat poisons are widely used. Caracals
regularly hunt in vineyards and it is here that they are likely to be
exposed to poisoned rats, in and around urban structures,’ she said.
Non-target species conundrum
The researchers focused their poison testing on caracal but were
also able to opportunistically test several other species that had died
after being hit by cars, including Cape clawless otters, large spotted
genets, honey badgers, water mongoose, small grey mongoose
and the Cape Eagle Owl.
The fact that these species use different habitats shows that rat
poisons may profoundly impact many different species.