Great Blue Heron

The Great Blue Heron by Polly Kolstad

     It started as nature’s quiet distraction high in the cottonwood trees along the Sun River in late March, and soon became a Great Blue Heron rookery, a rare sight, not previously observed in the area.

      A lonely bend in the river protects these water waders from disturbance and predators. They are diligent about their privacy.  From the periphery of the colony they want to encounter no human activity to take place during their courtship and nesting season.  It is likely that the males may have showed up first to compete for the females.  They like to breed in protected areas between their nests where they can forage for food.   

     Daily, the skies brought forth more and more high flying birds.

     Now, this heron haven provides essential breeding and nesting habitat for approximately thirty Great Blue Herons that shimmer as lone sentinels guarding their colony. It seems to be a sound and safe neighborhood.  Studies recommend a minimum of 300 meters buffer zone in which no human activity should take place. 

     “In the twelve years we have been here, we have never seen heron nests in this area,” said a nearby landowner, adding, “maybe a solitary perch, or just a lone figure.”

     Why have they taken up residence in an area where before an occasional heron would  fly by?

     “It is possible that the previous colony received wind damage, or human activity could cause them to take flight,” said Bryce Maxell, Senior Zoologist, Montana Natural Heritage Program.

      “They are sensitive to disturbances and they depend on cottonwood trees to establish their rookeries.”

     The name Ardea Herodios , (Greek) is the largest heron in North America.  An abundant wading bird, they typically live along riverbanks, marshes, and swamps.  The tall bluish-gray bird has a black strip over its eye with a white fore-neck and a yellowish bill.  It has long rounded wings, a long and tapered bill, and a short tail.  It also has reddish thighs.  In flight, the heron folds its neck in an “S” shape and extends its legs along the body axis.  The wing beats are deep and slow moving.  The adults have long occipital plumes.   No other heron in Montana is the size or color of the Great Blue Heron nor are other herons likely to be encountered in Montana in the winter.

     Migration is fairly common, yet, some herons are permanent residents with more than 100 nesting colonies scattered across the state according to the Montana Field Guide.  Those that migrate come from Central America with their six foot wing span carrying them at speeds from 19 – 29 miles per hour.  Referring to the Birds of North America Guide, “herons can migrate alone or in groups of three to one-hundred.”  Once here, they stay until September or October.

     These elegant birds choose new mates each year and immediately begin building bulky stick nests.  The clutch size is 2 – 6 eggs.  The egg laying occurs from early April to early May with hatching from early  May to early June, and fledging from early July to early August.  Both parents raise the young taking turns to incubate the eggs.    

     The Great Blue Heron’s song is a harsh loud “rok-rok” or a prolonged croaked “frohnk” which one may hear when they are taking flight, or involved in aggressive action.  It has also been described “like a cough followed by a screech.”  They have been known to dive bomb humans and other animals when protecting their habitat.

     Primarily fish eaters, herons also will eat amphibians, invertebrates, reptiles, mammals and other birds.

     As I quietly exited the rookery area, I turned around to observe eight Great Blue Herons in a nearby field standing tall like stilts ever wary of sounds around them.   They are the “wild and the wayward” as Henry Wadsworth Longfellow described in his Song of Hiawatha, “the haunts of nature, like voices from far off.”

     The  Montana  Field Guide is a good resource for the study of varieties of species: plants, animals, aquatic and terrestrial.  Also, an excellent reference is the Montana Natural Heritage Program which is easily accessed online.( http://mtnhp.org).