We left Cincinnati this morning and headed west under low, gray clouds. The overcast cleared as we crossed the Wabash River, in western Indiana, and, as we approached the broad floodplain of the Kaskaskia River, in west-cental Illinois, several flocks of snow geese shimmered in the bright blue sky.
Snow geese generally pass through the American Heartland from mid November through mid December but may linger if open water and plentiful food are available. Those that move south through the Missouri and Mississippi Valleys used to winter only in coastal marshes, from western Louisiana to eastern Texas; in recent decades, however, they have begun to utilize croplands of the lower Mississippi Valley as well, expanding their winter range, improving their winter survival and increasing the number of geese that return to Arctic breeding grounds the following spring. As a consequence, despite loosened hunting restrictions, their population has steadily increased and wildlife biologists are concerned that the abundant geese may threaten the health of the Arctic tundra ecosystem.
In addition to the effects of winter cropland utilization, global warming may affect the population and distribution of these vocal migrants; how it will impact their Arctic breeding habitat, the welfare of their predators, the rate of gosling survival, the timing and pattern of their migration and the extent of their winter range all remain uncertain. For now, those of us who live in the Heartland will anticipate the sound and sight of these hardy travelers as they move across the sky in late autumn and early spring.
