Climate Change and Birds in Northwestern Michigan
By William C Scharf
Climate effects were evident in the local avifauna (bird populations) even before I arrived here in the 1960s. We now take for granted local year-around bird species such as Cardinals, Mourning Doves, Tufted Titmice, and House Finches. They are all recent arrivals here, coming from more southerly regions. More than purely temperature change has been involved in this story. Great increases in the human population have also brought about more winter feeding of birds. Recently, urbanized habitats have decreased migrant birds in Traverse City. Tall buildings lining the Boardman River on both sides make a narrow corridor for bird flight between walls of glass and brick. A local proliferation of woody plants which are alien to the region make a hostile environment. Trees such as Norway Maple, Colorado Blue Spruce, Siberian Elm, and Tree of Heaven have been planted and invaded widely on their own. Additionally, invasive shrubs such as Japanese Honeysuckle, Autumn Olive, and Eurasian Burning Bush have spread through incentives from federal agencies and local nurseries. These species do not support insect life for food or provide nesting habitat necessary for our native bird species.
We have captured and banded over 7,000 migrating birds at a preserve near Empire over the past 11 years. Our sample totals 102 species. Many were sparsely known from our area previously. Some of the 102 species are already bird species in peril. One recently captured bird, the Rusty Blackbird, has already decreased 89% in the last ten years by international census estimates. Continuation of our project will show the increase and decrease in migratory species moving through this location. It is already apparent that long-distance migrant birds are suffering declines on their way to and from the tropics where they spend most of their lives. Habitat destruction, pesticides, building collisions, deforestation, and cats are only a partial list of the perils they face on their journey.
The local high-water levels flooding their nesting sites have negatively affected waterfowl, Gulls, Terns, and Herons. This is attributed to extra precipitation from warming waters due to climate change. The water levels were so high last year in early May that waves swept over Bellow Island near Northport washing the nests of Herring and Ring-billed Gulls away. Fortunately, those birds were able to re-nest last year, but repeated losses will take a negative toll. Meanwhile, we have been testing eggs from Herring Gulls and they show a decrease in the bio-magnification of toxicity that was extremely high in the past. This can only mean greater survival for the birds, and less toxic materials in the food chain which all aquatic life depends on. Formerly endangered American Bald Eagles show modest gains in nesting success, as well as do hawks and owls. But, as habitat dwindles due to urbanization and as their prey decreases in numbers, they too may become species of concern.
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