[CT Birds] Station 43 Least Bittern

Paul Cianfaglione pgcianfaglione at gmail.com
Sun Jul 2 20:41:42 EDT 2017

*Russ Smiley’s July 1st sighting of two Least Bitterns at Station 43 in
South Windsor was very interesting to me. The species was not present
during the entire spring season, as well as on the Hartford Summer Bird
Count. *

*Could this pair be on its second brood from another location? Possibly. If
not, Birds of North America (online edition) mentions that since Least
Bitterns are highly insectivorous, delayed breeding cycle may be a response
to increased availability of food later in the season. *

*I might also suggest that it is likely that Least Bitterns are delaying
their nesting until the Marsh Wrens lay their own eggs.*

*House Wren nesting behavior may well provide support for this type of
delay;  *

*After mating, the female will choose a nest and lay her eggs. This is when
something incredible happens. As soon as eggs become part of the male House
Wrens life, the aggressive behavior will magically disappear, as if a light
switch had been shut off in its mind. Interestingly, this change in
aggression may have evolved as a safety mechanism to keep wrens from
inadvertently destroying their own eggs (Di Silvestro, R. House (Wrecking)
Wrens, 2010).  *

*This behavioral change (and a well-timed delay) may prevent bittern egg
loss from equally aggressive male Marsh Wrens. *

*Paul Cianfaglione*


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