Snowberry eaters

What eats snowberries?

Most types of berries are colourful, sweet and juicy, a persuasive combination that prompts birds to eat them and consequently to spread the seeds. In stark contrast, snowberries (waxberries) are white, tasteless and dry. As snowberries are both widespread and common, they have clearly evolved an effective strategy for propagation, but what is it? What eats snowberries and disperses their seeds?

A web search for snowberry eaters produces a list of frugivorous (fruit-eating) birds. There were also suggestions, such as that of Wayne Weber, that snowberries aren’t the preferred food of birds and that most of them probably fall to the ground before they get eaten.

Terry Taylor takes this idea further and argues that: by not being juicy, they avoid the competition of the fall berry season; by not being sweet, they resist mould and so extend seed dispersal into the hungry time of winter; by being white, they are more readily visible on the ground at night where they can be eaten by mammals. He suspects that the seeds are spread primarily by rodents.

Taken together, these nice bits of biological detection suggest that, while birds occasionally eat them, snowberries evolved to appeal primarily to mammals.

In the fall, most berries compete for the attention of birds by being colourful, sweet and juicy. These rowan berries (mountain ash) have attracted Bohemian Waxwings (November 18, 2014).

Snowberries avoid the fall competition by being white, tasteless and dry, but they last into the hungry season when they have the stage to themselves (October 18, 2012). Although occasionally birds eat them, I have yet to see this.

However, I have seen mammals eat them. This is a White-tailed Deer (November 11, 2011).

And, here is yestermorn’s observation of a Red Squirrel.