New research this spring on B.C.'s at-risk ungulates is advising caribou maternity pens to closely monitor how the food they prescribe to these animals impacts their natural diet, health and survival in the wild.
A team of B.C.- and Alberta-based biologists, veterinarians and experts on southern mountain caribou's favourite food, lichen, emphasized last May in a study published in the academic journal Molecular Ecology that diets of penned caribou should be regularly monitored for conservation work.
Among the research team is Helen Schwantje, who served as a wildlife veterinarian for B.C.'s caribou and bighorn sheep over the course of nearly 30 years.
The researchers say that because caribou largely eat nutrient-rich lichen and have bacteria in their gut (known as their microbiome) highly specialized for it, even different types of lichen can have different impacts on their health. For example, lichen from trees provides different kinds of carbohydrates than lichen that grows on the forest floor, influencing caribou's microbiome differently.
The Arrow Lakes Caribou Society, for example, relies on hundreds of hours from volunteers each year to collect 300 kilograms of lichen for its maternity pen near Nakusp, to ensure a dozen caribou are adequately nourished during calving season.
But because caribou can't enjoy the same, 100 per cent natural diet in maternity pens, humans transition their diets away from hand-picked lichen and onto commercial feed pellets. Before they're released back into the wild, their feeding regime in the maternity pen switches back to lichen.
Wild southern mountain caribou from the Columbia North herd near Revelstoke and the Central Selkirks herd around the Arrow Lakes were among those sampled in May 2017 for the study, along with central mountain caribou from the maternity pen run by Revelstoke Caribou Rearing in the Wild near Lake Revelstoke.
The researchers found "strong differences" between the microbiomes of naturally fed deep-snow caribou and human-fed penned caribou.
This change in caribou's microbiome "is important because the lack of a robust native microbial community in penned animals may compromise animal health and reintroduction success," the researchers write.
"Because (maternity pen) management is a recognized method of recovery of endangered species and has gained support for caribou recovery efforts, exploring the mountain caribou microbiome could contribute essential information for future conservation actions."
Southern mountain caribou remain a federally threatened species, with subgroups such as the Columbia North herd left with only a couple hundred caribou.
The three maternity pens that have operated in B.C., including near Revelstoke and Nakusp, have played a critical role reducing caribou predation during calving season, when calves and mature females are most vulnerable to wolves, grizzlies, cougars and wolverines.
As part of this important work, the researchers encourage B.C.'s maternity pens to regularly monitor samples of their caribou's feces, focus on gathering types of lichen preferred by local caribou, and change the composition of their feed pellets to more closely mimic caribou's natural diet.
The study says monitoring changes to the diets of caribou in these pens could prove valuable, as they continue to be brought in and out every spring and summer, and as their diets are already highly limited by logging and human-caused global warming changing forests and food availability.
As the researchers conclude, "the narrow range of lichens preferred by deep-snow caribou reinforces the broader message that maintaining free-ranging (wild) caribou populations will require greater protection of the old-growth forest habitat that supports high quantities of the specific lichen species that these endangered animals consume."
The full study is available at .
