Bright red elderberries ripe for bears to harvest. (Photo courtesy of Caroline Cheung/United States Fish and Wildlife Service)
Climate change may be throwing off the Kodiak bears eating equilibrium.
On years with warmer spring temperatures, research says that elderberries ripen several weeks earlier than normal.
Oregon State Universitypostdoctoral researcher William Deacy just published findings from a multi-year study of bears on the southwest side of Kodiak Island.
The paper looks at how climate change affects the relationships between two species that have evolved to rely on one another.
Elderberries are the Kodiak bears favorite snack, Deacy said, even more than salmon.
The salmon is essentially the super Aktins diet for the bears, he said. Its just lean protein, almost no fat, and they end up gaining very little weight eating that, and the elderberries have a really perfect amount of protein for bears, and that allows them to gain weight really rapidly.
Bears normally feed on salmon,Deacy said, and then switch over to elderberries.
This new pattern means that the elderberries are available at the same time as salmon spawn in tributary streams.
Deacy said the bears sense that, and once they switch over from one food source to the next, they stick with the berries.
Its probably because theyre very, very good at detecting what foods are valuable to them, and they have instincts that tell them that these berries are the best food, and so they go and just eat those berries instead of having a mixed diet.
Deacy said the warming temperatures force bears to choose between salmon and elderberries.
Meanwhile, the salmon spawn out and die.
He says that leaves a gap where bears dont have access to either elderberries or salmon.
The bears usually stick to one area with its own resources and salmon run patterns,partly due to how much energy they expend while moving from point A to point B,
Bears dont appear to be suffering from these changes so far, Deacy said, and reproductive rates are about the same, if not better.
He said one possible effect of the timing change is that during early elderberry years, salmon may spawn more successfully.
Just cause the bears arent there and the salmon can kind of do their thing without being killed, so thats pretty intuitive, but we dont know whether that would show up four, five, six years later as increase in returning salmon because theres just so many other things that could happen to salmon in their life cycle before they come back.
This study is one example of how climate change can scramble the timing of two closely tied species and disrupt a food web, he said.
Originally posted here:
Warmer temperatures may disrupt the Kodiak bear's diet - KTOO
