What's for Dinner? The Diet of the Snowy Owl and Canada Lynx
A look into the similar rodent-based diets of the Snowy Owl (Bubo scandiacus) and the Canada Lynx (Lynx canadensis)
What Do I Eat?
Snowy Owls primarily eat Lemmings (Lemmus trimuconatus), and voles (Microbus arvalis). During a winter in Wisconsin, it was determined that 73% of a Snowy Owl's diet was voles, 30% was muskrat, 24% was duck, 3% was rats and 3% was other birds (10). However, this can vary depending on the birds habitat and availability of food sources, for example, in British Columbia it was found that 80% of a Snowy Owl's diet was duck (17), and on the Aggatu Island where there is an absence of small mammals, Snowy Owls primarily ate Acient Murrelets (Synthliboramphus antiquus) (27).
Here you can see a captive bred Snowy Owlet being hand-fed ground chicken, yum!
Video courtesy of Chris Ketola and the Ontario Specialized Species Centre (6).
Energy Values of Common Foods
Snowy Owl Hunting Vole, Jim Zipp, www.Arkive.org
Voles (Microbus arvalis) provide on average 1.5 kcal/ g. body weight. So, for an average adult weighing 50 g, this provides 75 kcal.
DM= 35%, CP= 57.3%, EE= 11%.
An adult male Snowy Owl will consume about 1/3 of their body weight in voles a night, which is roughly 6 voles a day, providing 450 kcal of energy, satisfying the average energy expenditure of 3.9x BMR per day (13).
Lemmings (Lemmus trimuconatus) provide on average about 1.7 kcal/g. body weight. So, for an average adult weighing 78 g., this provides 133 kcal.
DM= 35.4%, CP= 58%, EE= 24.9%.
An adult male Snowy Owl will consume about 3-5 lemmings each day, which provides 532 kcal of energy, satisfying the average energy expenditure of 3.9x BMR per day (12).
In the winter months, prey species have a higher percentage of body fat, and in the summer months they have a higher percentage of body water and protein. This affects their energy densities, since fat has more energy per gram than protein (13). Lemming populations fluctuate in roughly 5 year cycles, affecting Snowy Owl populations as well, which follow the same trend (11). Lemmings are more available when there is thick snow cover in Winter, allowing them to burrow more effectively (17). Owls excrete 50 kcal/ day through their vents and by pellet ejection (7).