The river runs low

The river is at her seasonal low, the run of dry weeks restricting the amount of water reaching her. The sluggish water sits well below the level of the bank and, in places, larger stones breach the surface. The sluice that guards a looping arm of the river, normally a roar of noise dropping into a turbulent pool, has been reduced to a trickle and the water below is dark and silent. With less water now passing through this arm of the river, the shallows have been reduced to a slither of silver that glints and chuckles through pebbles and stones. The otters that passed this way earlier in the year would now have to walk rather than swim.

A little upstream the river has more depth but even here the riverbed can be seen, a paler floor between the rippling weed that has grown dense with the season. A family party of mute swans has held court on this stretch for several weeks now, the adults displaying aggressively at any goose or duck that ventures too close to the swans’ fluffy grey chicks. This level of parental care bodes well and, despite losing one of their seven chicks very early on, the six remaining youngsters are doing well.

Here and there the yellow globes of water lily break the surface, their buttercup yellow flowers standing bright against the dark shadows cast by the riverside willows. Other gems, in the form of banded demoiselle damselflies, glint in the shafts of light that pierce the shade. The metallic emerald green of the females is particularly striking. Clouds of small flies can be seen hanging in the air above the water’s surface. In places these are picked off by the grey wagtails which, nesting nearby, use the floating vegetation as a platform from which to feed.

The summer river provides an idyllic scene, albeit one that is perhaps a little tatty around the edges. There is a sense that the river is bursting with life, crowded as it is with plant growth and supporting a wide community of creatures. I like the seasonality of the river and its changing moods. Right now it is drowsy but its character will soon change with the arrival of the rains.

The swollen river

The river is a powerful force, especially now that it is swollen with last week’s rain. For much of its length the river gives the illusion of being inert; a soft-brown gently flowing mass that moves down an imperceptible gradient on a course that will, eventually, bring it to the sea. It is only where the river is divided, with part of its volume squeezed through a narrow weir, that its true power is revealed in a roar of spray and noise.

This winter river is very different from that of late summer and it is difficult to picture how it looked just a few short months ago. It is brown, rather than clear and the lush growth of aquatic vegetation has long since gone, rotted down and now part of the detritus held in suspension like some full-bodied broth. The bank-side willows are bare, their slim fish-shaped leaves cover the banks like a mass of sardines, once silver but now brown with the stain that decomposition brings.

While there is an air of decay about the river, the riverside creatures bring a sense that spring will soon be upon us and the river will once again return to life. On bright days, early Mistle Thrush and Great Tit can be heard singing, while three Great Spotted Woodpeckers indulge in ‘chase-me’ games high among the bare branches. The Grey Wagtails are often heard calling, their bouncy flight catching the eye as they move up and down the stretch of water near the weir. They have bred here in the past but in recent years have favoured a different nest site further downstream. It seems that there are still sufficient insects along the river to sustain them through this difficult season. A pair of Goosander hints that these sawbills might breed on the river again this year, a new and recent pattern that adds an exciting dimension.

The other week I heard of an Otter sighting a mile upstream; a cub just a few weeks old and the first confirmed breeding record for some years. It is another encouraging sign but, with the river rising by over a foot in recent days, I worry for its safety and hope that its mother will have found a secure holt. There is something remarkable about the river. Perhaps it is its changing moods, matching the seasons but also, in some small way, independent of them. The fact that on a bright summer day one part of the river can be shallow and babbling like the proverbial brook, while another, shaded by the willows, can be dark and sullen. Even in the depths of winter the river can be many things, always changing and ever my companion.

Climate and the elegant wagtail

The lengthening days and spring sunshine make my riverside walk to work all the more pleasurable.  The background chorus of singing birds lifts the spirit, something that is further enhanced by the sight and sound of grey wagtails, newly returned to this stretch of the river. At first glance the name ‘grey wagtail’ seems a confusing one; for, although this elegant bird sports a slate-grey back, it has a striking yellow breast and sulphur yellow undertail coverts. However, once you have seen a yellow wagtail, ­the choice of name seems a fair one. A sometimes-used local name for the grey wagtail is ‘water wagtail’ and this provides an accurate distinction between the two species. While the yellow wagtail is associated with lowland wet grassland, the grey wagtail is strongly tied to fast-flowing streams and rivers.

Although widely distributed across Britain, the grey wagtail has its stronghold as a breeding bird in the uplands, traditionally only moving into the lowlands in winter. Over the last hundred or so years the species has been noted increasingly as a breeding species across lowland Britain, nesting among tree roots or under bridges above water on faster stretches of river. The grey wagtail remains scarce in the east of England, with the first successful breeding attempt in Norfolk not recorded until 1923 (at Taverham Mill). Today some 20 or 30 breeding pairs are reported annually from within the county. One of the main reasons for this change in breeding range is thought to be climate change. As a year-round invertebrate feeder, the grey wagtail is susceptible to extended periods of cold winter weather, during which food is hard to find and mortality rates increase. The two severe winters of 1961/62 and 1962/63 are known to have had a big impact on the grey wagtail population. Since then, the run of mild winters has enabled the population within lowland England to increase.

Breeding starts very early in the year, with eggs laid from late March or early April, and this certainly ties in with the activity I have been seeing over recent days. The presence of the birds close to where they nested last year is revealed by the distinctive flight call, a metallic sounding ‘tzitzi’. The birds themselves can often be seen in flight, bouncing and undulating their way up- or down-river.  However, it is when seen on the ground that they are at their most elegant. The long tail is proportionally longer than that of our other wagtails and seems in constant motion as a bird walks about picking up small spiders or flies. On occasion one will fly up to catch an insect in flight, just like a flycatcher only with more balletic poise.