More than 40 different species of birds and animals utilizes ditches for nest sites, food, and cover.
Wildlife such as cottontail rabbits, meadow voles, mallards, common yellowthroats, western meadowlarks and many more rely on the vegetation in roadside ditches.
For optimum wildlife benefit, it's recommended that landowners, and others responsible for ditch maintenance, manage ditch vegetation in ways that maximizes wildlife use.
In much of northern Minnesota, wildlife habitat is fairly abundant; woodlands and wetlands are widespread. However, in the Red River Valley, and other regions of Minnesota where agriculture is the primary land use, roadside ditches have become increasingly important to wildlife. Ditches not only serve as nesting sites for a host of different kinds of birds and animals, roadside ditches can also serve as corridors to other, more suitable habitat nearby.
Ideally, leaving the ditches undisturbed the year around would be the best management approach. This includes avoiding such activities as mowing, spraying, vehicle encroachment, grazing, and burning. Mowing, if it must be done, should wait until after Aug. 1 in order to give nesting birds plenty of time to successfully raise their young.
If mowed after Sept. 1, the vegetation should be clipped no shorter than 10-12 inches so the following year's early nesting birds have enough residual cover to nest in. As well, leaving a little extra cover provides roosting and escape cover too.
Some ditch mowing may be necessary for improved sight-distance or snowdrift control. Even so, minimal mowing along the shoulders of roads does little to disturb wildlife use of ditches. Wildlife tend to utilize the ditch-bottoms and back-slopes more than near-road habitat.
Aside from the benefits to wildlife, benefits to road authority budgets can also be realized, particularly if suitable roadside ditches are planted to native grasses and forbs. Native, warm season grasses - those grasses that mature late in the summer such as big bluestem - are better adapted to poorer soils and drought conditions.
Whereas the root systems of cool season non-native grasses such as smooth brome and Kentucky bluegrass (not to mention noxious weeds like Canada thistle and spotted knapweed), extend to depths of only 1-2 feet below the surface, the roots of native grasses like side-oats grama and big bluestem can reach to 6 and 10 feet respectively! The superior root masses and depths of native grasses contribute to improved soil erosion control, ability to grow in poorer soil conditions, and capacity to reach deeper water tables.
Moreover, and again because of their extensive root systems, many species of native grasses can actually out-compete noxious weeds and other non-native plants for water and nutrients. According to DNR information, "once established and managed properly, the native grasses effectively keep weeds from ever getting established. The ultimate benefit of managing native vegetation on roadsides, whether remnants or re-established, is that pesticide use will decrease, mowing costs will decrease, and the wildlife habitat value of roadsides will improve."
There really is so much more that can be done to provide additional and better wildlife habitat. For example, many homeowners choose to mow adjacent roadside ditches. And while a mowed ditch might appear ideal, it does little to attract wildlife. The fact is, very few ground-nesting birds, if any, will find such ditches suitable enough for nesting or hiding.
As well, white-tailed deer, as many people know, are attracted to roadside ditches that are mowed or otherwise maintained. And while ditch vegetation that is mowed in late summer and early fall will provide deer with nutritious food (the last green vegetation of the growing season before winter sets in and the first vegetation to green up in the spring) having such forage availability is not necessarily wise. Deer feeding in ditches frequently leads to encounters with vehicles.
Another great way to improve conditions for wildlife along roadways, not to mention benefiting road authorities and motorists, is to plant "living snow fences." Throughout the open landscapes of Minnesota's farm country, shrub and native grass plantings along windswept roadways not only help decrease snow-drift, such vegetation also provides important food and cover for wildlife, including sharp-tailed grouse, gray partridge and ring-necked pheasant.
When roadside ditches are managed with wildlife in mind, wildlife will benefit. Eastern bluebirds readily use nest boxes placed beside ditches when adjacent habitat is favorable. Vegetation that is not clipped too short will harbor plenty of insects for these insectivorous birds to hunt and feed their hungry broods.
The American kestrel, Minnesota's smallest falcon, is another species of bird that's commonly observed hunting above roadside ditches. These tiny raptors hunt for voles, amphibians, and insects while hovering or perched above grassy ditches. Other animals that find roadside ditches as important hunting areas include red fox, striped and spotted skunks, and raccoons.
Indeed, roadside ditches, if left relatively undisturbed, will receive almost continuous use by many different kinds of wildlife throughout the year. Regarding those that nest in ditches, such as grassland nesting birds, one can expect some of these types of birds will be nesting in roadside ditches from April to August.
And for us, another way to appreciate wildlife as we get out and enjoy the great outdoors.
For more information on managing roadside ditches for wildlife, call the DNR Roadsides for Wildlife Program at 507-359-6000.
Blane Klemek is the Bemidji area assistant wildlife manager, DNR Division of Fish & Wildlife. He can be reached at email@example.com