December 11 2015 – Large flocks of small birds swing over the fields then land and nibble on alder catkins. It might be one of those years when members of the finch family come down from the north and spend the winter. Pine Siskins make up most of the flocks, small, cheery energetic birds that fly in a weaving wave as they dip down to feed upside-down on seeds. They swing away again, bright balls of energy in the dead of winter. They are small and striped, whitish underneath and darker above, with yellow wing-bars and yellow tail-streaks. They often nest within a few metres of each other and forage in small flocks.
Pine Siskins are nomadic; that is they move around in response to the availability of seeds. Its why one year there are none on island and the next year the sky is full of them. According to the experts it’s hard to assess their population numbers because they are so nomadic but Breeding Bird Survey and Christmas Bird Count data suggest that there is a long-term decline in their numbers.
Siskins and other finches unfortunate fondness for salt and sand on the highway in winter (to supplement mineral intake and aid digestion) leads to many deaths from automobile collisions and potentially sodium poisoning (Brown 2013, Erlich et al. 1988). We estimated that, in January 2014, tens of thousands of siskins died on Highway 16 between Smithers and Prince Rupert. They flew up from the side of the road when we passed and, although we slowed down and tried to avoid them, we did hit one or two. When we got to Prince Rupert we plucked ten dead birds from the grill of one parked car that had passed us earlier on the highway. It was only one of many that had overtaken us both coming and going on our journey.
Siskins are not only killed from hitting vehicles but are also poisoned by ingesting the salt. It’s an issue for other finches as well including Red Crossbills and Pine Grosbeaks that sometimes winter over on Haida Gwaii. Some parts of the world have stopped using salt on the highway completely and have found other methods to melt ice. A paper “Road Salts and Wildlife – An Assessment of the Risk” written by Brownlee, Mineau and Baril for Environment Canada in 2000” is recommended reading for those who salt the highways.