Friends of Cherry Hinton Brook

This presentation, supported by the generous help of professional and amateur photographers, attempts to show the often surprising variety and animals and plants along the Brook. All the photos were taken along the Brook. To find out more, please visit our website: https://www.friendsofcherryhintonbrook.org.uk, and please consider joining us as a Friend!

Cherry Hinton Brook is a chalk stream which rises at Giant’s Grave, Cherry Hinton (near the nature reserves on Lime Kiln Hill) and flows north-west through Coldhams Common, where it becomes Coldhams Brook, to the River Cam.

Perhaps our most popular resident is the European water vole, ‘Ratty’ in Kenneth Grahame’s The Wind in the Willows. This delightful species has been in decline throughout the UK since the beginning of the twentieth century, and numbers continue to go down, largely because of loss of habitat, particularly the drying up and pollution of streams. It is now a protected species. We are very pleased to have a healthy population on the Brook, of which the numbers are surveyed every spring by Peter Pilbeam of the Cambridge Mammal Group. You can see a short video, created by Nicola Fawcett and Darren Gillings, using a camera lent by Rivercare, here: https://www.youtube.com/watch?v=92YDU-WMlnQ

Astonishingly, in August 2021, there were several sightings of an otter in the Brook over a few days. It was probably just passing through, but it shows that our efforts to keep the Brook clean and the water flowing are paying off. Geoff Oliver got this shot just as the otter had caught a small fish.

Probably the most popular bird to be spotted along the Brook is the kingfisher. Although normally elusive, it can be seen fairly regularly along the brook, flashing blue from tree to tree as it looks for fish. It nests in the lakes, and there have been at least two pairs some years.

There can’t be many places in the UK where you can spot a water rail within the city boundary! But we have recently had regular sightings of one on the Brook, although they are very shy and require patience to spot.

The little egret is a regular visitor to the Brook in winter; there is usually a pair of them and we think they might be overwintering now …. Some of us are old enough to remember when this bird was an exotic immigrant, but there are now about 700 breeding pairs in the south and east of the UK, and many more overwinter here.

In spring, the hedges and trees along the Brook are filled with the songs and calls of migrant warblers, blackcaps, chiffchaffs, Cetti’s warbler, and reed warblers. This reed warbler was photographed near Blacklands allotments and we think it has nested in this location two years running.

We have had two pairs of swans on the Brook this year, one nesting in the Lakes and one at Cherry Hinton Hall. The Lakes pair raised two cygnets this year (six last year), but the Hall pair sadly did not succeed, and it may be that their nest being so close to the path was part of the problem – not all dogs are kept on leads, alas.

Grey herons are often seen; these one is in the newly restored part of the Brook near Blackland allotments.

This year a pair of sparrow hawks raised two chicks in the trees between the Brook and the Lakes. The resident house sparrow population was depleted and evidence of pigeon feathers around the lakes indicated the chicks were being well fed. Other birds of prey over the lakes include kestrels, buzzards and red kites. We don’t have any locally taken photos of these species, so here is a challenge to all photographers!

Of course, there is a huge diversity of other birds – robins, blackbirds, all sorts of tits working through the hedges in groups (along with the occasional goldcrest). Summer visitors include swallows, martins and swifts (we hope the latter will begin to use the nesting boxes we installed along Burnside). Crows, magpies, jackdaws and jays lead their noisy and quarrelsome lives up in the trees, or feeding on the ground, and wood pigeons and collared doves, and moorhens and mallards with their offspring are abundant.

Although not originally native to the UK, two introduced species can give great pleasure to those passing by on Snakey Path. Grey squirrels abound – even though they are classified as vermin, have decimated red squirrel numbers and can be a terrible nuisance in gardens, they none the less have a certain charm.

Muntjacs are also common in the area – another imported species that can cause damage in gardens but none the less delightful.

This year especially, we have had many reports of grass snakes both in the Brook and in nearby gardens and allotments. (It seems to have been a good summer for them everywhere, with multiple sightings in the Cam and in the lake at the Botanic Gardens.)

Frogs, toads and newts can be seen along the Brook, though their numbers have declined dramatically over the past decade.

Bullhead fish are found in the Brook and are good indicators of healthy chalk streams – they provide food for the herons and egrets. And few people will realise that eels, another protected species, are occasionally seen swimming up the Brook – see this short video: https://www.youtube.com/watch?v=ND7DzIf27qs

Some even make it to the lakes in Cherry Hinton Hall (where the fishing is private), where this vast specimen (sadly no longer alive) was discovered by Guy Belcher, City Biodiversity Officer.

The vegetation along the banks and in the Brook itself is as rich as the animal life, with fine old alders, the beautiful willows along Burnside, protected through Tree Preservation Orders (TPOs), and numerous shrubs and wild flowers. Cambridge Natural History Society has inventoried these. The long list includes bindweed, bramble, celandine, coltsfoot, cow parsley (don’t eat it; it’s not garden parsley), daisy, dandelion, dogwood, elder, garlic mustard, goosegrass, hawthorn, herb Robert, hogweed (the sap causes skin irritation), hollyhock, stinking iris, ivy, lords-and-ladies, stinging nettle, redcurrant, violet, wild rose and white dead-nettle. The flowers of many of these plants are attractive to bees, butterflies and moths.

Friends of Cherry Hinton Brook was founded in 2009 by mostly local residents, initially motivated by the need to clear the rubbish from the Brook and its environs, particularly between Cherry Hinton Hall and Sainsbury’s.

Since then, as well as organising regular litter-picks with volunteers, the Friends have become the ‘eyes and ears’ of the Brook and its surrounding footpaths, reporting dumping and trespass problems to the Council, looking after the wildlife and plants of the area, providing information on our notice boards to let passers-by know what to look out for, and volunteering for restoration projects, especially to improve the flow of the water.

We hope you have enjoyed this short presentation of some of the features of Cherry Hinton Brook. Chalk streams are one of the most threatened habitats in the UK – increasingly damaged by drought, pollution and development. The Friends, with our wonderful allies (particularly the Wildlife Trust, RiverCare, and Cambridge City Council), are trying our best to maintain this unique part of Cambridge in the best possible health.

We are also very keen to improve our own knowledge, and so would love to hear of any sightings or identifications that are new to us. You can report any of your own observations to us on: wildlife@friendsofcherryhintonbrook.org. uk