Vantage Point

Missouri Ozarks a Magnet for Migrants

The indigo bunting seemed out of place. We had just visited one of Missouri's natural wonders - Blue Spring in Shannon County. The bunting resembled a piece of the spring crystallized in space. Its startling blue shape swooped and darted ahead of us on the trail.

We were in the Missouri Ozarks, one of the most productive breeding areas for migratory birds in the hemisphere. And though the indigo bunting looked healthy enough, as a population they are on the decline. The reasons for their decline are not fully understood, but recent research points to some answers and clears up common misconceptions.

Indigo buntings are "neotropical migrants." These birds, like the ruby-throated hummingbird, northern oriole, wood thrush and over 100 other species of songbirds, nest in the Midwest during summer then migrate to Central and South America for the winter. The heavily forested Ozarks is an ideal area for nesting. The Ozarks helps songbird populations compensate for nesting areas in other regions where hatches of young birds are too low to replace the natural mortality of older birds.

A recent five-state study published in Science shows that forest fragmentation in their breeding areas is responsible for the decline of many species of neotropical migrants. What causes forest fragmentation?

"Forest fragmentation is caused by land conversion - previously forested areas that are developed or converted to other use," explained Brad Jacobs, Conservation Department ornithologist. "While birds are doing very, very well in the Ozarks, you can look at a fragmented forest in southern Illinois or north Missouri, for example, and find just the opposite. The difference seems to be cowbirds and nest predators like bluejays, snakes and small mammals."

Cowbirds are a species that evolved in association with buffalo. They traveled miles with roaming herds and consequently could not build their own nests. They adapted by laying their eggs in the nests of other birds, removing the other birds' eggs to make room for the cowbirds'. Now that the buffalo have passed from the scene, cowbirds are active in agricultural and suburban areas. Wherever a forest is surrounded by suburbs, farm or grazing lands, cowbirds can have an adverse impact on songbird populations.

Forest fragmentation does not occur because of sustainable forest harvest practices, Jacobs said. "Even when all the trees are cut, as in evenaged management, that land is still forest. Tree sprouts and young trees provide insects and nesting cover. Blue-winged warblers, yellow-breasted chats, prairie warblers and lots of other songbirds are drawn to the abundance of insects in the young forest. They nest nearby and bring their young to feed in the new forest."

The five-state study showed, for example, that about 50 percent of nests in the Ozarks fledge at least one nestling, and about 4 percent are affected by cowbirds; in fragmented north Missouri forests, only about 10 percent fledge young and 50 percent fall victim to cowbirds.

On Conservation Department lands, the average size of an evenaged area is just 12 acres; they are seldom more than 20 acres in size. "Harvesting trees does not eliminate, or fragment, the forest," said State Forester Marvin Brown. "It creates a forest of different ages that will always be there. Depending on the species, trees can live 60, 100 or even 300 years. If we want our offspring 100 years from now to be able to see a 100-year-old tree, then that tree has to start growing today. A well-regulated harvest using both even- and uneven-aged harvest techniques can support both the forest product needs and the needs of migratory birds in the Ozarks."

Cowbirds aren't the only cause of neotropical migrant declines. Forests that are destroyed for development are no longer available as nesting areas. Even though the Ozarks is currently one of the most productive songbird areas of the world, awareness of its importance is essential.

"It's important to identify the source of problems affecting songbirds now instead of when they're on the endangered species list," said Jacobs.

The buntings and warblers, thrushes and hummingbirds depend on abundant forests - and sustainable forest management practices.

AGENTS NOTEBOOK

The giant Canada geese visiting many Missouri lakes are highly prized game birds and are also enjoyed by many residents, who feed and pamper them as pets. However, some state residents view these beautiful geese as pests.

Goose droppings on docks, decks, boats, lawns and beaches upset some lakeside residents, swimmers and sunbathers.

Geese also trample grass and overgraze, especially during their flightless period during the latter part of the brood-rearing season.

The first step to minimizing goose damage is to stop feeding them. Handouts result in unnatural concentrations of geese.

You can keep geese from yards with woven wire fencing or closely spaced shrubs or trees. Allowing the shoreline vegetation to grow will also discourage geese from walking to lawns or decks.

Once geese are accustomed to visiting a location, it may take several consecutive days of harassment, such as fireworks, gas exploders, dogs, helium balloons, flags or spotlights, to break their patterns. To be effective, scare devices must be moved often.

Fall hunting, where legal, can alleviate goose problems. Birds that have been hunted are also more likely to react to scare devices during the rest of the year.

Whether geese are prizes, pets or pests depends on your perspective, and on the amount of effort you put into controlling the damage they cause. Bryant Ward, Table Rock Lake