Country diary: a swan builds a fortress for a nest

River Tern, Shropshire: Despite their size and aggression, swans are very vulnerable to egg thieves such as fox, mink or ravenThe pen is mightier than almost anything on the river, except the flood. The pen here is the female mute swan, Cygnus olor, and her nest is a fortress, a circular thatch of riverbank vegetation laid around the bird like a keep. It looks impregnable but, despite their size and aggression, swans are very vulnerable to egg thieves such as fox, mink or raven, and to the vagaries of the weather that can turn downpours in the river catchments into floods with devastating force. This is probably a second home on the same stretch of water - a couple of weeks ago most swan nests on the rivers Tern and Severn were washed away.With a ferocious whiteness, bright as may blossom and cow parsley, white as the vapour trail of a high jet in a blue sky with long swan-feather clouds, the bird hunkers, wings and paddle-feet folded in the nest. The S-bend of the neck holds a swallowed cat hiss of warning. Continue reading...