US Fish & Wildlife Service

Three moose in Anchorage, Alaska are dead after eating buds, branches or berries from European bird cherry trees (Prunus padus). In one case a moose ate branches that had been pruned in the fall and stored under a deck. One of the moose also ate a toxic amount of Japanese yew branches.

European bird cherry, also known as mayday tree, May Day tree, or hagberry, is considered invasive along streams in both Anchorage and Fairbanks, Alaska. The tree is native to northern Europe and closely resembles native chokecherry trees. In the two Alaskan cities, European bird cherry is changing the mix of plant species in riverside ecosystems. Typically, moose do not browse the tree, allowing the non-native tree to dominate the native species that the moose do eat. The tree has also naturalized in Illinois, New York, New Jersey, Pennsylvania, Delaware, Ontario, and New Brunswick

No one is sure why the moose ate the trees now, when they usually don’t, or why the trees proved so toxic, since the level of toxins in the tree can vary. The only unusual event noted was a mid-winter thaw.

For the full story in the Anchorage Daily News, click here.

For a PDF backgrounder on Prunus padus from the National Park Service, including lots of photos of flowers and fruits, click here, and get ready to download the file.