Waterfowl hunters take watch: European frog-bit and invasive phragmites

As hunters pursue waterfowl across Michigan’s Upper Peninsula, they should be watching for a couple of invasive species that can negatively impact marsh habitats.

The first species is European frog-bit, a small floating plant with leaves that resemble miniature lily pads. This plant has recently been identified in several locations across the UP, including Menominee, St. Mary’s River, Les Cheneaux Islands, and marshlands around the Mackinac Bridge, and is rapidly spreading. Frog-bit is a free-floating aquatic plant, which allows it to be easily distributed by currents, boats, and recreational activities. It usually congregates in areas of low wave action including but not limited to bays, floodings, and coastal wetlands. Frog-bit leaves are small and are usually the size of a quarter and can range from round to heart-shaped. When in bloom (June to August) frog-bit produces a single flower with three white petals and a yellow center. It is often introduced to new water bodies when living plant material is transported via gear, dogs, boats, and trailers. Once established, drifting mats of frog-bit can spread to connected waters.

Why should waterfowl hunters care about

European frog-bit?

European frog-bit forms dense mats on the surface of slow-moving waters like backwaters and wetlands. These dense mats on the water’s surface can:

• Negatively affect the movement of puddle and diving ducks and hunting dogs

• Become tangled in boat motors, decoys, and other gear

• Limit food sources for waterfowl and fish

Alongside frog-bit, you may also find an invasive species that is anything but small: invasive phragmites. Also known as common reed, this tall wetland grass regularly grows to heights of 15 feet and can form dense monocultures.

Phragmites has taken a variable but limited foothold across the UP. Much of the region remains “phragmites Free”, while other locations have seen dense localized infestations. The leaves are often a blueish-green color and the tassels, or seed heads, that form in late summer are very dense and bushy.

Invasive phragmites is very disruptive to aquatic habitats. This aggressive species quickly outcompetes native plants to take over shorelines and reduce habitat and resources for wildlife, including fish and waterfowl. While tall, dense patches of phragmites can be a hazard along roadways and in ditches, it can also impede access to the water and make waterfowl retrieval difficult for hunters or dogs.

Phragmites spreads effectively through seed dispersal but also by fragmentation, which means any small portion of the plant that breaks or is cut off can re-root and create a new infestation. Therefore, it’s important that waterfowl hunters avoid using invasive phragmites as camouflage for their blinds and boats, as this can lead to the unintentional distribution of the invasive.

Why should waterfowl hunters care about

invasive phragmites?

• Eliminates waterfowl nesting habitat

• Negatively affect the movement of waterfowl

• Impedes access to the water

• Broken stem fragments can be hazardous for dogs while retrieving down birds

How to Help

Hunters can help prevent the spread of these aggressive invasive species by taking a few simple steps:

• CLEAN: Remove all vegetation and debris from boats, trailers, and gear (including dogs!) before leaving a launch site. Avoid using invasive plants as natural camouflage.

• DRAIN: Remove all plugs and drain water from bilges, ballast tanks, and live wells.

• DRY: Allow boats, trailers, and gear to dry thoroughly before launching at a new site.

If you suspect you’ve found either European frog-bit or invasive Phragmites, be sure to report to your local Cooperative Invasive Species Management Area (CISMA).

Keweenaw Invasive Species Management Area (KISMA) works in Baraga, Houghton, and Keweenaw counties. To learn more about European frog-bit or invasive Phragmites visit Michigan.gov/invasives. To report an invasive species sighting contact kisma.up@gmail.com or visit our website at https://www.mtu.edu/kisma/.


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