On
the morning of 6th May on the Caldon
Canal, near Hazelhurst Junction, an unusual event occurred. A
female Mallard plus two males took off from the side of the canal.
The strange thing was that the duck had what appeared to be a whole
egg in her bill. The two drakes followed close behind her. The duck
shortly dropped the “egg” and it entered the canal water and
sank. Initially it appeared as though the drakes
were chasing the duck in order to mate with her, after all this is a
commonly seen behaviour at this time of year – it being the
breeding season. The next day a fox was seen in the same place as the Mallards had been seen the day before. I decided to find out what
might have be going on. There isn't much information about this
phenomenon on the internet but this is what I did find.
In
1978 The Wilson Bulletin (published in the United States) describes
observations of (American) Wood Ducks carrying, what were perhaps,
whole eggs. It seemed that, when a predator - in this case
Red-bellied Woodpeckers, had broken some of the eggs in a duck's nest
she removed at least one of the remaining eggs to a new site. It is
speculated that this is an attempt to save her remaining offspring
from predation. According to this paper (see link below) this
observation, by individuals from this species in particular, has been
recorded several times. In an attempt to test the theory that the
ducks were influenced by the action of predators an experimenter
placed broken eggshells on previously un-predated nests whilst the
ducks were temporarily absent. On their return the ducks removed an
egg or eggs. In another paper written by an American and a British
academic, the second from the Wildfowl and Wetlands Trust in
Slimbridge (Glous.), the authors document reports of parent birds of
various species carrying their young to safety either on their backs
or in their bills. In this paper, egg carrying by Mallards and other
species of Anatidae (swans, geese and ducks), is described (see
second link below) though in this paper they mention only addled eggs
being removed from nests. The authors discuss how unlikely it seems
given that the anatidine bill is poorly adapted for carrying items as
they write that these species do not directly feed their young or
courtship feed, and appear to have difficulty carrying nest material
in their bills.
So,
it seems we can't be sure what was observed, but perhaps the
presence of the fox seen the next day is significant. Maybe the birds
were disturbed by the fox and all three flew up, the female's
instinct impelling her to grab the egg which she subsequently
dropped. Had it been a fresh egg presumably it would have eventually
risen to the water's surface and floated, whereas an addled egg would
stay under water. Next time we see something like this we will watch to see if the egg
sinks or floats! Anyway, whatever is the actual story it certainly
prompted some interesting speculation!
A Mallard and her ducklings.
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