Grave problem: Banff struggling to manage Columbian ground squirrels in cemeteries
Digging isn't a foreign concept in a graveyard, but some industrious rodents are damaging historic burials in the Town of Banff, and officials are trying to find ways to keep the unwanted visitors out.
Graves settle over time, but with an underground network of tunnels and annual freeze and thaw cycles, the Columbian ground squirrel's handiwork is resulting in sunken graves and toppled monuments in both the Old Banff Cemetery and Mountain View Cemetery.
"They have been creating significant damage," said Agustina Rocha-Jaje, municipal parks manager.
The Columbia ground squirrel, often mistaken for a gopher, resides in mountainous terrain and high plains in Canada.
The Old Banff Cemetery was designated a historic resource in 2016. There are more than 2,000 people buried there, one of the first graves is said to date back to 1890.
Plot owners are typically responsible for maintaining the graves and monuments, but spotty record-keeping in many instances means the town has to take on levelling graves and fixing some of the immediate hazards in the cemeteries because the owners can't be found or confirmed.
"Regarding sunken monuments and graves … there is damage from Columbian ground squirrels," Rocha-Jaje said. "Some of the issues we think are related to having monuments and graves sinking."
Because both graveyards are in a national park, the ground squirrels are fortunate that Parks Canada won't allow poisons or lethal trapping.
Headstones emulate boulders
Alberta naturalist Chris Fisher says cemeteries are a great place for ground squirrels. They look for open areas with plenty of things to forage and good cover.
"They really like to dig their burrows in rocky areas, typically near natural boulders. The headstones and tombstones are really emulating those features," Fisher said.
Banff municipal parks workers are allowed to live trap the ground squirrels. Parks Canada dictates this should be done only during the periods that the rodents emerge from their burrows.
According to a relocation guideline document for the area, the ground squirrels hibernate nearly 70 per cent of the year.
Small trapping window for the town
The Town of Banff finds an opportunity to catch the diggers in mid-July. Two employees create a serene environment outside, so the squirrels aren't afraid to peek out from burrows. This means shutting off any power tools they may typically use for maintenance on the grounds. Once the traps are tripped, the two workers follow Parks Canada guidelines for relocation.
Work to trap and relocate the ground squirrels started in 2018 at the Old Banff Cemetery. The following year, the town started setting traps at the Mountain View Cemetery as well.
Throughout the trapping and relocation project, the town has captured 160 squirrels. Up until 2021, the critters were being released near 40 Mile Creek. This year, Parks Canada switched up the approved release site to a location near Tunnel Mountain Road.
Burrows covered, graveyards have perimeter fencing
The town is also able to cover up burrow entrances. These squirrels are visually orientated and like to keep their burrow entrances in sight.
"Unfortunately, we can only cover the burrow entrances and we are not able to cover the entire tunnel systems that they may or may not have underground," Rocha-Jaje said.
The town has added a perimeter screen to further block the animals' view of those burrows, another attempt to keep them out of the cemeteries.
It's not something just a few years of a trapping program will solve, Fisher said. All of the mitigations the parks managers are trying need to be kept up, every year, to win this battle.
"Columbian ground squirrels have a reproductive rate that would make a rabbit envious," he said. "Any establishment of animals in the cemetery is likely to lead to a population explosion and set the program back to ground zero."