Moose make distinct food choices when they are foraging in the forest. Willows are a popular winter food but if they are only scarcely available, moose appear to combine pine with bilberry and lingon shrubs to reach a similar nutritional target shows a new study from the Swedish University of Agricultural Sciences, SLU.
In an earlier study, researchers from SLU conducted a feeding experiment at a zoo in Skåne to investigate how moose balance different macronutrients during winter. The results showed that moose chose a stable balance between protein and carbohydrates, which was very similar to the ratio naturally occurring in willow twigs. But how do wild moose know which plants to eat?
– How the nutritional makeup of plants drives moose foraging choices is still not well-understood so we were very curious about whether wild moose would behave similarly to their captive counterparts; that is, chose a diet that is nutritionally similar to willows, says Robert Spitzer, a postdoc at SLU.
To answer this question, the researchers collected moose dung pellets and vegetation samples from different sites across Sweden, spanning an area from Södermanland in the south to Norrbotten in the north. The dung pellets revealed what moose had been eating whereas the vegetation samples provided the nutritional composition of the forage plants.
The results showed that at study sites where snow depth was low and food choices less restricted, moose combined pine and Vaccinium-shrubs (bilberry and lingon) to reach a nutritional balance of protein-to-carbohydrates that closely resembled that willow twigs – just like the moose at the zoo.
– This suggests that pine and Vaccinium-shrubs are nutritionally complementary foods for moose in winter. In other words, their combination seems to be a better diet than each food item separately. However, if willow was abundantly available, moose would probably directly eat more of that, says Robert Spitzer.
If moose can choose, willow appears to be a favorite with the combination of pine and Vaccinium shrubs being a good alternative. Moose do the best with what is available to them; if food choices are restricted, so are the diets.
– To provide a good food base for moose, increasing access to willow and Vaccinium shrubs in the forest could be suitable measures. Moose seem to prefer varied diets, says Robert Spitzer.
The study was financially supported by the Swedish Environmental Protection Agency and Swedish Association for Hunting and Wildlife Management.
Robert Spitzer, Eric Coissac, Joris P. G. M. Cromsigt, Annika M. Felton, Christian Fohringer, Marietjie Landman, Wiebke Neumann, David Raubenheimer, Navinder J. Singh, Pierre Taberlet, Fredrik Widemo, Macro-nutritional balancing in a circumpolar boreal ruminant under winter conditions, Functional Ecology, Volume 37, 2023.
https://doi.org/10.1111/1365-2435.14296