Fish Eating Northern Harriers
As I’ve mentioned before in this blog, the winter of 2008 was a particularly brutal one in northern Utah. During January and February there was much more snow than usual and it was bitterly cold. During most winters our Northern Harriers rely primarily on voles as a food supply but in 2008 with the voles under the deep crusty snow our harriers were desperate for food. Birds of North America Online provides extensive information on the dietary habits of harriers. It lists small to medium-sized mammals (primarily rodents), birds, reptiles and frogs as harrier food sources, stating further that the diet of harriers during winter in their northern range (which includes northern Utah) consists of voles “almost exclusively”. I can find no mention of harriers eating fish, ever! Each year in early February some of our wetlands managers treat some of our ponds with rotenone (a chemical that prevents oxygen from being absorbed across fish gill membranes) in an effort to control the invasive and damaging carp that do so much damage to the emergent vegetation which is so vital for waterfowl. So, in 2008 for a few weeks, our desperate and starving harriers began to eat fish! In the three winters since then I have never seen harriers eating fish even though the dead carp are always plentiful after the rotenone kill. 1/1250, 1/1000, ISO 500 Many of the carp are brought to the shores or ice surface by Bald Eagles which makes them available to the harriers who generally cannot retrieve them from the water. 1/1250, f/8, ISO…