pests Alberta’s rat-free status doesn’t mean infestations won’t happen, just that they will be dealt with
Despite national media coverage, last month’s discovery of a colony of Norway rats at the Medicine Hat landfill is not that big a deal, says an official with Alberta Agriculture’s Inspection and Investigation Branch.
“We’ve found infestations every few years,” said Vaughn Christensen. “This is the first time we’ve had a nest in a landfill, but our control methods are the same.”
Christensen said the province’s claim to be rat free means continual vigilance on the part of landowners, farmers and the general public.
“Anybody who thinks rat free means no rats isn’t thinking straight,” he said. “Rats cross the border from Saskatchewan and we work to control them in the control zone — the three ranges (18 miles) closest to the eastern edge of the province and anywhere else we find them.
“The critical thing to stop rats becoming a problem is by killing individuals before they establish a nest site and by eliminating all the animals in any nest site that does establish.”
One infestation in the control zone led to the collection of 169 dead rats. Specialists never really know how many rats they kill because some may be eaten by predators and others die underground and aren’t found.
The infestation at Medicine Hat became national news after four dead rats were discovered near its landfill on Aug. 8.
“When a rat colony is stressed by running out of feed, water or space, or being disturbed, scouts and strays leave the colony,” said Ed Jollymore, manager of the city’s solid waste utility.
“Those animals are often killed on the road or a dog will bring them in. That’s what led us to the colony in an area of the landfill where there was very little activity.”
It took some effort to find the colony. Neighbouring farms were checked, but after two nights of searching with flashlights, rats were spotted in the landfill. City and county staff immediately began an aggressive baiting program across the landfill and surrounding areas. They were also careful to keep the rats well fed and watered to contain them in their nest. The baiting program worked well, with tens of dead rats found some days. By the end of August, rat patrols had found 111 dead rats at the landfill, 17 in the surrounding county and 18 in the city, but things had slowed down. For over two days, no rats had been found at the landfill or in the county and four cameras linked to motion sensors hadn’t picked up any rat activity in the landfill.
Jollymore’s crew will keep baiting and inspecting the whole landfill twice daily until the rat control experts are convinced the entire colony has been exterminated, probably after 10 to 14 days without any sign of rat activity. Then, they’ll excavate the nest area, destroy any remaining rats and learn what they can about the colony — what waste they choose to nest in, how deep they burrow, perhaps even discover something about the source of the infestation.
“We need to find out all we can about this colony in case there’s another landfill infestation,” said Jollymore. “We will win this fight. If you’re going to have a rat infestation, a landfill is a pretty good place for it. There’s no risk to infrastructure or to public health.”
Both Jollymore and Christensen stressed Alberta’s rat-free status depends on everybody reporting any rat-like animal they see. Rats can hitchhike on trucks, trains, in RVs, or in any sort of shipped material, then hop off anywhere in the province. Ag fieldmen are usually the pest control specialists for rural municipalities and bylaw officers in cities, but staff at 310-FARM are always ready to help control rats. They advise taking a picture if possible. False alarms don’t bother them at all, if you’re not sure it’s a rat you’ve seen.
Modern baits for rats have worked well, said Jollymore. They don’t cause undue suffering in the animals, but take two to five days to kill them. The time lapse prevents even highly intelligent animals like rats from linking the baited foodstuff or water to sickness and death in their nest mates. Also, the amount of poison contained in a carcass is well below the level that would affect non-target species, such as snakes, ferrets, birds or domestic pets.
Alberta’s rat-free status costs the province around $350,000 a year — a bargain, compared to the damage rats can do to stored crops and buildings, as well as the threat of spreading disease, according to Christensen.
“I sometimes ask longtime farmers if they’ve ever seen a rat,” he said. “They almost always say no. Most people have never seen a rat — and that’s the success of the rat control program.”