The changing river

No-one steps in the same river twice, so Heraclitus said. And in similar fashion no walk by the river is the same twice, its shifting water only part of a constant flux of activity.

Some of that flux is more apparent than real, especially where resident birds are concerned. Two days back no wrens were recorded on the walk, whereas there had been three the previous day and three today. They were almost certainly there, but sheltering from the fierce wind.

Then again, today is breezy but the wrens and most other birds aren’t in hiding. Each day is different, especially where non-resident birds are concerned. Reed Warblers are still present, though numbers are down with many of the breeding birds now gone. Meanwhile Willow Warblers and Whitethroats are moving through in numbers, today conspicuous at the tops of bushes where insects congregate. Tomorrow there may be more, or less, or a different mix of species, as they move through as part of a vast and weather-dependent front.

It isn’t just warblers that are in flux. The first Stonechat of the autumn has arrived, as has a juvenile Marsh Harrier. Today has seen a jump in Common Sandpiper numbers – at 15, three times more than two days back. Two Greenshanks fly through as well, revealed only by their peremptory call. There is a clear sense of movement.

And in that movement there are at times patterns. A Hobby flies almost exactly the same route over the riverside hedgerows in pursuit of the same flock of Linnets as it did a couple of days back. The imperative of food is also the reason why a Kingfisher regularly streaks over the same stretch of river to perch by the same knot of reeds. Common Sandpipers gravitate to the same preferred areas of the river edge to forage, or move to the same areas below the overhanging banks for shelter as high tide approaches. As every year, parties of Swallows feed over the water without halting their ineluctable progress southwards. Little of the flux is random or illogical.

Indifferent to these ceaseless patterns of activity the river flows imperturbably, a constant presence in spite of the constant flux of water. But even that constant presence is not changeless, the river’s course shifting slowly over time as the land and climate changes, just as the rivers of Heraclitus’ Ephesus silted after his death, and the city died.