Loon Nesting Program

A loon swimming in calm water with a blurred background of water and trees.

Big Mantrap:
Sanctuary for Common Loons

Big Mantrap Lake is a favorite hangout for loons—and it’s not just because of all the cozy bays and quiet points. If you’ve ever heard that haunting, echoing call across the lake at dusk—that’s a loon. These iconic birds are known for their eerie, beautiful vocalizations, which they use to communicate with mates and defend their territory. Loons are exceptional divers, capable of plunging over 200 feet in search of fish, and they need clear, healthy lakes like Big Mantrap to hunt and thrive.

While they’re graceful in the water, they’re a bit awkward on land due to their rear-set legs—so they rely heavily on water access for nesting and takeoff. That’s why protected shorelines and nesting rafts make such a difference.

About 25% of the loon pairs on the lake build their nests naturally, but the majority–around 75%–choose to use our floating nesting rafts. These platforms act as a safe backup, especially during years with high water levels or when predators are lurking.

Big Mantrap Lake is ~1,600 acres in size, with more than 26 miles of irregular shoreline, including five islands and many bays and coves.  

25-30 potential loon nesting territories have been identified and at this time we average 24 nesting pairs use the lake between natural and man made sites.  

Loon nesting rafts are set immediately the day the ice goes out and removed three weeks after the chicks hatch. The rafts are removed so that the natural beauty of the lake is not impaired.  Refurbishing the nests, setting them out, and removing them, requires the efforts of a number of volunteers.

The Big Mantrap Lake Loon Nesting Program began in 1990 with rafts based on the a Minnesota DNR model. Our raft fabrication materials have shifted from wood to plastic and now aluminum. Light weight aluminum nesting rafts best suit the needs of our lake, because of the number of rafts needed and the seven mile length of the lake. Two rafts with anchors and buoys can be hauled in and out of a 16 foot boat. 

A fenced trap floating on a body of water with reeds and a tree line in the background.
A metal dog crate with a sliding tray, two gray mats, and a camera mounted on a pole at the front.
A duck resting on a nest made of reeds and grass at the edge of a lake with water and trees in the background.

The heart of the Loon program: The Looners

  • Three men standing on a dock beside a boat with two trap cages and a float underwater, surrounded by a forested lake.

    The Looners

    The healthy population of loons on Big Mantrap has a lot to do with the volunteer ”Looners” who run the Loon Nesting Program. This dedicated crew deploys special loon nests each spring to ensure the Loons have safe places to nest.

    Nesting Platform Details
  • A spotted bird with a long black beak sits on a nest made of twigs, near a body of water with trees in the background.

    Loon Cam

    Researchers have discovered that territorial male and female loons are replaced every 6–7 years. Male loons normally select the nest site. Loons may nest successfully on a raft for years, but the new male may select a natural nest site within the area.

    Loon Image Gallery
  • A man sitting in a small aluminum fishing boat on a lake with lily pads, near a fallen tree and boats in the distance.

    Barry & The Boat

    The Looner Leader — Barry Guptill and his Loon Boat.

    For questions regarding the Loon efforts on Big Mantrap Lake, you can contact Barry @ (218) 732-9039 or email below.

    Email Barry