Only two adult Great Blue Herons should be expected to be around one nest according to what has been written about that species. However, this month, around a solitary nest off Tigertown Road in Norwich, VT, three adults have been present at the same time, as occurred again this morning (June 13) while I was watching that nest.

In my initial viewing of today, there were only two adults, one on the nest and another on a side limb below the nest but still high up. Later, a third adult flew in, landing at the top of the tall pine, then descending to the nest. Soon thereafter both of the previously present adults flew away separately. The newly arrived adult fed at least one nestling. By the time I left the area this morning, only that one adult was present and standing on the nest.

This morning, at least one nestling was in the nest and perhaps two, but I could not see two nestlings at the same time. Viewing of the nest is from a long distance while looking up from ground level, and views of activity in the nest itself are partially blocked by limbs and pine needles so it is difficult to discern much about nest contents or exactly what is going on inside the nest.

Today is the sixth day since Cynthia Crawford first found and photographed three adult herons around that nest on June 7. Her still photographs and video leave no doubt that three adults were present, and my observations of June 9 and today indicate continuing presence of three adults around that nest. However, not all three adults are continually present as exemplified by observations today and also yesterday morning (June 12) 'when I found only two adults.

A question remains as to why there are three adults around that Norwich nest. One possibility is that the third bird is helping the parents, but such behavior has apparently never been reported for that well studied species. Because the three adults at the Norwich nest look alike it would seem difficult to confirm whether the third bird is actually helping the other two.

Great Blues are reported to be monogamous within a single nesting cycle so polygamy seems unlikely.

A suggestion that the third bird might hanging around with the intent to devour the young can probably be ruled out in view of a lack of observed hostility among the three adults and the duration of their continued association together around the nest.

So far, there does not appear to be a satisfying explanation as to why a third adult would remain with the nesting pair in Norwich.

George Clark
Norwich, VT

 


To post messages, send e-mail to:  [log in to unmask]
Set your e-mail application to PLAIN TEXT ONLY to post messages.
To contact the list owner:  [log in to unmask]
To unsubscribe:  E-mail this command to [log in to unmask]  UNSUBSCRIBE UV-Birders
To change your e-mail address:  E-mail this command from your old address to: [log in to unmask]  CHANGE UV-Birders [new e-mail address]

Web based archives and subscription management are available at:
http://listserv.dartmouth.edu/Archives/uv-birders.html