This is usually understood as warning behavior by loons. If you see a loon doing this on the lake, it means you are too close and should back off. Many thanks to Jeramy Paxton for sending these pictures.

Protecting Lake Iroquois
Nestled amid the rolling hills of mid-Chittenden County, Lake Iroquois is a 237-acre spring and tributary-fed body of water surrounded by the towns of Williston, Hinesburg, Richmond and St. George. The Lake Iroquois Association is a steward of this haven for recreation, wildlife, and the surrounding ecosystem.
Controlling Invasives

Learn how LIA continues to work to prevent and control the spread of invasive species such as Eurasian milfoil, water chestnut, and zebra mussels.
Water Quality

We maintain and improve the lake's water quality through 40+ years of data, stewardship projects, plant surveys and a detailed manual for lakeshore property owners.
Meet our greeters, spot wildlife, swim in the clean water, learn about boat safely, and have an enjoyable time at the lake.