It has always intrigued me that two geographic spots of earth and water can be so vastly different in their respective biotic components when just a few hundred yards separate the two locations.
Microcosms, those small scale versions of communities or places compressed into a larger whole are everywhere we look and travel, be it the ant mound teeming with scores of ants going about their daily routine, ever-working and building higher their home; to a somewhat larger scale of microcosm that, for example, I see everyday surrounding woodlands and body of water where I live.
Assawa Lake, the small 40-acre basin that my property nestles up against, has provided me with endless enjoyment for the past 18 years and counting. The spring-fed wetland with no natural inlet or outlet is replete with native plants that typify clean water—water shield, bulrush, white water lily, arrowhead, and sago pondweed among them.
Wildlife, too, of course. Ring-necked ducks, blue-winged teal, mallards, wood ducks, and hooded mergansers are the more common waterfowl species, as are Canada geese, pied-billed grebe and trumpeter swans. Yet, these species of birds can be observed nearly everywhere on the lake from one side to the other and everywhere in between.
Not so much so with other species of plants and animals. Truly, to experience these subtle floral and faunal differences takes either a short hike around the lake or a quiet paddle inside a canoe to discover and observe.
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My neighbor, Agnes, owns the property bordering the west side of the basin. This side of Assawa is adjacent to a 30-acre grassy hay field that isn’t cut and baled until July most years. What’s interesting to me is the difference in birdlife on that side of the wetland, compared to my side.
On a recent canoe paddle to Agnes’ side of the lake, the tinkling and delightful songs of singing male bobolinks wafted from the upland to my ears, instantly taking me back to a time when I was a boy on the farm. This species of bird, related to red-winged blackbirds that nest within the periphery of the lake’s ring of cattails and are frequent visitors at my bird feeders, is a grassland nesting species of the blackbird family. Nesting and singing bobolinks are found nowhere else near Assawa Lake except for on Agnes’ hay field.
Nearby and on the same field, the song of the Savannah sparrow can be heard. Again, though my home is only a few hundred yards to the east, I never hear or observe this open landscape/grassland nesting sparrow anywhere nearby but only on the west side of the basin. What I do observe where I live, however, are relatives of the Savannah sparrow such as song sparrows and chipping sparrows. These two latter species of sparrows are common sparrows of brushy, more wooded areas that are often adjacent to wetlands.
Located on the south side of the Assawa Lake is a large sedge meadow. This area of the wetland is often flooded in the springtime, but generally becomes dry as the season progresses into the summer and autumn months. This is also the home of another bird that I don’t see or hear where I live near the lake—sedge wrens.
As its namesake aptly applies, sedge wrens inhabit short grass and sedge meadows. Singing as incessantly as its cousin the house wren, sedge wrens are secretive species that are often only observed flitting quickly from one blade of grass or sedge-stalk to another.
Meanwhile, house wrens, as mentioned, are a species of wren that occupies its preferred woodland and edge habitats on my side of the lake, are not found where sedge wrens reside only a few hundred yards away. Indeed, tireless, singing male house wrens annually fill my birdhouses with sticks in their hopes of attracting mates on one side of the basin while sedge wrens breed and nest on the other side. Both species of wrens, similar in body type, size and song, establish their breeding and nesting territories in vastly different niches.
As we travel and explore Minnesota’s bountiful bottom-lands, lake and river country, and forests and prairie grasslands, pay attention to who’s singing what and where and who’s occupying what niche in relation to another niche. Surprises and discoveries are sure to be yours as we get out and enjoy the great outdoors.
Blane Klemek is a Minnesota DNR wildlife manager. He can be reached at bklemek@yahoo.com.
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