Name: Jim S.
We visit a lake near the Kalamazoo river every
year. Every year we see at least one pair of swans, every year they
start off with six to ten young, and every year they lose several or all
of their young.
This year we had one pair with seven cygnets, soon to be six. One
night two disappeared, one of which we found washed up on a sand
bar. The next day the parents were obviously driving away or trying to
kill one of the cygnets. It was very dark and difficult to observe the
exact behavior but they had obviously separated the one from the other
three, he (she) was screaming either in pain or bewilderment, and the
adults appeared to be trying to drown it. The next morning the cygnet
was alone on the shore and as I understand from my in-laws it dead. They
found it with a severed foot and broken wing.
Do you have any idea what is behind this behavior?
As a former field biologist, the first thing you need to think about is exactly what
did you see? Predators are the number one problem with geese and swan success in
rearing young. What you may have witnessed is the parents attempting to protect a
cygnet. Of course, I do not know for I was not there. Snapping turtles, owls, hawks,
snakes, raccoons, etc. are always looking at young birds as meals. The missing foot
may have been the work of a snapping turtle. Common! It is a hard life out there on
the pond and you may not have seen the entire picture. As for parent behavior toward
their young, usually the adults gradually abandon their broods, but only after a point
that they can survive on their own. At this point in time, chasing away offspring may
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Update: June 2012