When St. Mary Reservoir in southern Alberta was filled in the 1950s, no one knew that it submerged an incredible record of life from 13,000 years ago. That record, including footprints of mammoth, camel, and horse, was recently exposed – the internationally significant site is now informing opinions about the role humans played in the extinction of Alberta’s ‘megafauna’.
Shayne Tolman, a teacher from Cardston, is responsible for drawing attention to St. Mary Reservoir and Wally’s Beach, a site complex on an ancient island in St. Mary River that is currently being investigated by Dr. Brian Kooyman and a team from the University of Calgary. Archaeologists have discovered that the menu of some of Alberta’s oldest humans included megafauna like camel, horse, and perhaps mammoth. Over six thousand artifacts indicate that people were hunting big game at a time when these animals were likely struggling to cope with climate change. Did human hunting lead to megafauna extinction or are warming temperatures to blame? Many researchers argue that pre-contact human populations were too small to impact big game while others suggest that targeted hunting patterns among small groups could have big consequences.
Dr. Todd Surovell of the University of Wyoming is a world renowned champion of the ‘overkill’ idea (that human over-hunting led to megafauna extinctions) and he explained his research during a lecture series in Edmonton this year. Dr. Surovell has mapped the global overlap of humans and proboscideans (elephants and elephant-like species), constructed detailed chronologies of megafauna extinction, and run mathematical models to extrapolate the potential impact of early humans in North America. All lines of evidence point to a simple observation: “Outside of Africa, when humans arrive, elephants disappear”.
Mammoth trackways at Wally’s Beach were left by older animals with very few juveniles: perhaps a sign of a stressed population. In this state, Surovell argues that if humans culled 3% of the mammoth population per year, they would’ve been driven to extinction in a few centuries. This could’ve been greatly abbreviated if hunters targeted specific demographics like fat-rich females (which we know First Nations preferred when it came to buffalo hunting).
At the other end of the research spectrum, some argue that climate change at the end of the Ice Age (which peaked around 17,000 years ago) is the culprit that leveled many of Alberta’s big animals. Warming temperatures fostered new plant communities, wreaked havoc on mammal gestation rates, and stressed breeding patterns of big game. Most archaeologists have found a middle ground and suggest that humans delivered the final blow to populations that were already weakened by habitat fragmentation and warming temperatures.
Bighorns and Smaller Horns
What can modern wildlife biology tell us about human impacts on animals? Dr. Marco Festa-Bianchet of the Université de Sherbrooke, Dr. David Coltman of the University of Alberta, and their colleagues have generated data from a continuing 40 year study of bighorns in Alberta’s Rockies. Until 1996, male sheep on Ram Mountain were hunted if their horn curl met a minimum dimension. After that time, regulations tightened, and rams were rarely taken. Hunting stopped in 2011. The regulatory changes offered an intriguing mountain top laboratory to investigate how human selection of specific traits (large horns) influenced animal evolution.
The research team discovered that rams with the biggest horns were hunted before they achieved reproductive success, which drove long-term declines in horn length. Within three to four generations, human hunting had altered the sheep population’s phenotype (physical expression of a gene). The trend towards shorter horns (a decrease in 30% over 20 years) stopped when trophy hunting sharply dropped in 1996 but horn size has been slow to recover. If other traits, like body mass, are genetically linked to horn length, we may be driving the evolution of sheep and other big game in directions that threaten their survival.
Archaeological and palaeontological records, such as those from St. Mary Reservoir, should be indications that hunting patterns on a backdrop of climate change can be a powerful one-two punch for some species. Not all of the dynamic changes that occur in the natural world can be controlled by humans, but it is clear from both prehistoric and modern evidence that people in Alberta can have both direct and indirect impacts on the ecosystems around us.
Heritage Art Series
The Heritage Art Series is a collaboration of the Historic Resources Management Branch, the University of Alberta, and the Royal Alberta Museum. Each artwork shares an important story about the people of our province: we hope it fosters a greater awareness of our past and instils a deeper respect for it. The artwork below is by Edmonton artist Kelsey Stephenson and is a layered look at landscape change in Alberta. Overlapping shapes represent sheets of ice and huge ‘proglacial’ lakes that once covered what are now Edmonton and Calgary, the urban networks of which are depicted as cut-out layers. Interspersed are the footprints of animals like camels and mammoth from Wally’s Beach.
Want to learn more about the Heritage Art Series? Check out other colourful stories and scenes from Alberta’s past here.
A full version of this article will appear in an upcoming issue of Nature Alberta.
Written By: Todd Kristensen (Archaeological Survey) and Chris Jass (Royal Alberta Museum)