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Clearing my asparagus beds I came across a half-buried, white, chicken-sized egg. How did it get there?

Sent in by Sharman Flindall

Sharman asks: 'Clearing the dead folliage of my asparagus bed I came across a white egg, about the size of a chicken egg. It was half buried. What could have laid it and how did it get there?'

The size and colour of this egg suggests that it was laid by a duck, most likely a mallard. Though mallard eggs are usually pale blue-green, this can vary and an almost white one would not be unheard of.

Though pigeons can also breed this time of year, their eggs (though white) are much smaller than a chicken egg. The breeding season for mallards is usually around March onwards. It can, however, potentially occur any time from February to late Autumn and maybe even earlier if the weather is mild. Because of the recent mild weather many birds have begun to breed earlier than usual.

Mallard nests are usually built by the female and form a hollow lined with grass, leaves, down and feathers into which she will lay around 10-12 eggs. These eggs are then incubated for around 28 days.

Hidden by cover, mallards regularly nest on the ground, making their contents easy prey for an opportunistic predators, such as foxes. I suspect this egg has been removed from the nest by a fox which has subsequently buried it for later retrieval. Such caching is not unusual amongst mammals, grey squirrels, for example, are notorious in burying nuts for when food is less readily available. Fox caches are, for the most part, temporary and may last a night or two at most, with eggs being a common cached foodstuff. Fox caches are rarely dug very deep and in urban areas can be found in flowerbeds or plant pots!

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