Motorists traveling US-127 near Houghton Lake on a summer evening may be annoyed by the frequent tap, tap, tap of insects hitting their windshields, but they may not notice the adjacent wetland where most of these flying creatures are coming from.

Stretching three and one-half miles between M-55 and the Muskegon River, the Houghton Lake Flats marsh lies on the east side of the interstate.

This productive marshland
grows an abundant variety of invertebrate life that goes unnoticed by most, except for the birds, reptiles and amphibians that consume them by the thousands.

This land, which originally was part of a varied wetland complex connected to Houghton Lake, was significantly changed by the construction of US-27 in the early 1960s. The Michigan Highway Department funded development of the Houghton Lake Flats marsh as part of a plan to mitigate the impact of building a new expressway on such marsh functions as pike spawning habitat.

In 1964 and 1966, a series of internal dikes, ditches and two pumping stations were developed between the new highway and Old US-27 to create a marsh and shrub complex intended to provide pike spawning habitat and habitat for waterfowl and aquatic mammals such as mink, muskrat, otter and beaver.

Water levels are managed with pumps and control structures, but even with these improvements, the area has never been a cost-effective pike marsh, so wildlife production has been the primary objective since 1979.

Department of Natural Resources Wildlife Technician Doug Pavlovich, who has been tending the Houghton Lake Flats since 1980, knows every square foot of its 670 acres, miles of ditches, and its pumps and culverts.

"After 27 years, some of the maintenance tasks are becoming a challenge, but it's still very rewarding," Pavlovich said. "Many people from all over recognize the flats and enjoy observing the wildlife. When we did the draw-down in 2005, lots of people contacted us wondering what was happening to the marsh."

Pavlovich said water level manipulation within the marsh is performed periodically to permit ditch cleaning, dredging and other maintenance, and rejuvenate marsh plants.

"The water is pumped into Houghton Lake," he said.

Houghton Lake Flats is best known by bird-watching enthusiasts as the site of one of the most visible heron rookeries in the state. The 30-plus, treetop nests are only a few hundred feet off the US-127 roadway. Thousands of individuals stop to observe this amazing site each season. After leaf-out, the nests are more difficult to see, but the herons make quite a racket that is easily heard.

The DNR Wildlife Division also maintains eight platforms scattered throughout the flats that are regularly used by nesting osprey.

"This has been a very productive area for this state-threatened species," said Glen Matthews, Wildlife Division Northeast Management Unit supervisor. "Osprey chicks from this area have been used to expand their range into southern Michigan."

Matthews said a good place to observe ospreys during the nesting season is from the elevated wildlife observation deck located off Old US-27.

This deck was built in 1998, and a connected barrier-free fishing deck was built in 2000 with financial support from the Michigan Conservation Foundation. Anglers fish for a variety of panfish, such as perch or bluegills, and even have the chance to hook a smallmouth bass, bullhead, bowfin or carp.

One of the current management concerns at the Houghton Lake Flats is the growing presence of exotic plant species, such as Eurasian water milfoil, purple loosestrife and phragmites, that DNR biologists fear may displace native vegetation important to wildlife.

"These invasive, nonnative plants are one of the biggest threats to maintaining good habitat for wildlife," said Mark Boersen, a DNR wildlife biologist who, with Pavlovich, oversees the area.

In the near future, Boersen said systematic botanical surveys are planned to list and map the presence of the invasive plant species so appropriate management actions can be taken.

Over the past few years, for example, screens have been installed in discharge ditches to help ensure undesirable plant species are not transported to Houghton Lake.

"We're just beginning to understand how much work it will take in the future to protect such important areas," Boersen said.

In 2000, approximately 5,000 Galerucella beetles were gathered from Crow Island State Game Area near Zilwaukee and released at the south end of the Houghton Lake Flats flooding in an experimental effort to control purple loosestrife.

Since their release, sampling surveys have shown these beetles, which feed exclusively on loosestrife, have slowly spread to greatly reduce the number of plants in that area.

"Although they are not spreading as fast as we had hoped, progress is steady and we believe that over the next decade the initial release will spread to help other problem areas within the county," Boersen said.

Houghton Lake Flats is one of 121 locations for watching wildlife listed in The Michigan Wildlife Viewing Guide which can be accessed online under the "Wildlife and Habitat" section of the DNR Web site at www.michigan.gov/dnr. A paperback copy of this guide can be purchased through the state of Michigan eStore at www.michigan.gov/estore.