Riverlands Migratory Bird Sanctuary (RMBS) is about 2 miles upstream of the confluence of the Missouri and Mississippi Rivers. The sanctuary, just 40 minutes north of St. Louis, is a U.S. Army Corps of Engineers property located at Lock and Dam #26. Most of the wetland habitat of RMBS is in Missouri (West Alton) though birds use adjacent habitat on the other side of the Mississippi River in Illinois (Alton). There is a warm-water outlet upstream at a power plant that enables the birds to overnight in extreme weather. Most years at least a small pool stays open in Ellis Bay for the birds.
Trumpeter Swans arrive at the end of October in small family groups of three to six. Upon arrival, Trumpeters fly low over the marshes, calling back and forth, before settling. Through mid-December, groups continue to arrive, some to stay the winter, others to rest before moving farther and farther south.
In 1999, the RMBS winter population was about 30 birds. A decade later, in the winter of 2008-2009, the mid-December high count, when winter residents and migrants are present, was 560. This past winter (2009-2010), the RMBS wintering flock was estimated at 440.
Staff and volunteers of RMBS record the band numbers, tally daily counts, and record mortality, which occurs mainly from power line collisions, high lead levels, and illegal shooting. Between 2002 and 2008, an impressive total of 72 collared birds was noted. Most of the birds are from the Wisconsin population with collared birds from Iowa and Ohio recorded as well. Hatch-year birds comprise 20 percent of the total.
RMBS is internationally recognized as part of the Great Rivers Confluence Important Bird Area. There are local bird walks on most weekends, and organized Bald Eagle watches are conducted during the peak numbers in January and February. The large size of the Trumpeters, and their relative tameness, make them a subject of many photographers. An astute observer will find 10 to 20 Tundra Swans among the birds, and the occasional Mute Swan.
Riverland’s bird list is 300+, including several state firsts: Ross’ Gull, Slaty-back Gull, Black Skimmer, Smew. 18 species of gulls are on the area list. During the winter the sonorous bass of the Trumpeters provides a counterpoint to the raucous calls of the gulls. Each day, and every movement, begins with head bobbing and calling. When the area is frozen, the birds will sleep until well after sunrise, but, as the days warm, they are up and about at daybreak. By mid-February, the swans begin to move north and the marshes again go silent.
Article contributed by David Rogles, President, St. Louis Audubon Society
and State Compiler, North American Migration Count.