Heron Colony

One of the largest inland heron colonies currently in Maine is located just off the Outback Trail at Libby Hill.

In 2010, two dozen or more herons began nesting on the edge of Libby Hill trails.  Beaver activity on the section of Thayer brook has created a beaver pond that is over four feet deep in sections and hundreds of dead trees (snags) that act as excellent nesting locations for herons.  The department of Inland Fisheries is actively monitoring this colony and one of the herons has been GPS tracked for several years.  Named Cornelia, she migrates to the Bahamas every winter with many stops along the way. In the summer of 2021, Cornelia migrated to the bog at the outlet of Sabbath Day Lake and in September her transmitter stopped working.

Herons usually nest on offshore islands in Maine, so having an inland colony is a real gem for our wildlife lovers!

Finding the colony and when to visit

The colony is actively occupied from early May until early July.  To see chicks’ heads above the nest, usually the June is the best month to go.

Park at the trail head across from the GNG Middle School.  Take the Lynx (Blue) to Harold Libbey (Red) then Outback (Yellow) trails.  After crossing the brook at about 200 feet you come to a trail junction, go left for one-half mile until you see the open marsh and nests.  Work your way round the marsh off trail.  Total distance is about three miles, allow 2 hours or more for your trip.

Link to Google Map

How to behave when visiting active nests

Please be aware that this is a delicate nesting site and disturbing herons can threaten their return. Please minimize taking dogs to this area and if you do, please leash them (this is true for all trails). Also stay within twenty-five feet of the Outback trail when viewing. You will benefit from having binoculars or a spotting scope since nests are several hundred feet away. Here is some additional info provided by staff at the Maine Inland Fisheries Department regarding heron nest visits.

“When nesting herons perceive a threat, they defend their nest with a steady escalation in alarm. At first, herons become alert and silent, but as a perceived threat continues to increase, they vocalize, first with repetitive “chortle” or “cluck” calls, followed by loud prolonged squawks (depending on the level of perceived threat), or hopping off their nests or flushing from the nest site. They will often circle above the nest trees until the threat has ended. An unusual, loud, or rapid disturbance may cause herons to immediately flee rather than show a progression in alarm.

If the volunteer believes his/her presence is causing birds to leave their nests, alarm call, or flush from the site, they must leave and choose an alternative location for subsequent observations. Some colonies may be impossible to observe without causing disturbance; in such cases, volunteers will not monitor these colonies. It is not worth the risk of causing abandonment of a colony.”

Note to Birders

eBird has a hotspot location for the Heron Colony to help document both heron and other bird activity at Thayer Marsh. Please restrict your bird watching to within twenty-five feet of marked trails around the marsh. The Outback Trail is the best observation area. Please refrain from bushwhacking toward the east side of the Marsh which is closer to the nests where you may disturb nesting birds. Nesting begins in late April and continues through early July.

Trails are groomed! Winter Rules are in effect! Skiers only on groomed trails.