April has been colder than normal and very dry – almost no rain for about six weeks. The last reported winter visitors were 3 Fieldfare seen on 4th (Jeff), while the first Swift arrived extremely early on 24th (Dick, Clarke, Jeff). Other notable arrivals were a Willow Warbler in Paradise on 25th (Olwen), several reports of calling Cuckoos from 23rd (Becky, Jenny), 4 Swallows on 6th, 2 Terns at Fulbrook allotments (Jill), a Lesser Whitethroat at Eddington 28th April and a Cetti’s Warbler at Fen Ditton 29th (Bob). There have been an abundance of Chiffchaffs and Blackcaps (Lesley, Becky, Jo, Rhona).
A second-hand report of a Ring-necked Parakeet in Grantchester St has not been confirmed. However, I gather they have reached Northhampton and also are around St Ives/Hemingfords, so are getting nearer. I am not sure how welcome they are, as they are noisy and occupy other species’ nest holes. Other less usual sightings included a pair of Mistle Thrushes in Newnham, a pair of Mandarin Duck at Grantchester Meadows, a Wheatear and a Ring Ouzel (Jeff), a Green Sandpiper, a Black-tailed Godwit and a pair of Little Ringed Plovers at Eddington (Bob). The Science Park turned up a Firecrest (Pat) and there was a Goldcrest in Paradise.
A Nuthatch was singing at Girton College and a displaying male Yellow Wagtail at the farm site in north Cambridge (Bob). Fifteen Golden Plover were seen near the M11 (Jeff) and a Lapwing at Eddington (David). Ionathan spotted two Common Cranes flying over about 10.30 at night – these too are getting nearer.
Nine Heron’s nests are ‘occupied’ at Paradise Island : Mike reports lots of “clacking” of hungry juveniles on 29th. In Ionathan’s garden, out of 3 eggs laid, two “extremely cute” juvenile Robins have fledged. His mealworm feeders are very popular with Starlings who queue up, each bird spending up to 30 seconds on the feeder before moving to the back of the queue. Eve says a male Wren checked out a nest site in the shed but went off again. I think they commonly make 2-3 nests and invite the female to choose! And they still find time to sing constantly.
Butterflies have been slow to appear, but towards the end of the month, Speckled Woods (Lesley, Jeff, Rhona), Green-Veined Whites and Orange-Tips have all been reported (Becky, Jeff). Rhona was particularly pleased to find Orange-Tips laying orange eggs.
Rhona saw the first Large Red Damselfly of the season on 23rd April in the Botanic Garden. She also reported various bees: Ashy Mining Bee, Grey-patched Mining Bee, Mourning Bee and Paul added Gooden’s Nomad Bee (a nest parasite of other bees), Buffish Mining Bee and Lathbury’s Nomad Bee. The last is uncommon here, being more associated with gorse-clad hillsides, sandy heathland paths and vertical faces of sandpits – it turned up in the Trumpington Community Orchard. From a Churchill College student came a query of an unknown insect, which was identified as yet another bee, a member of the Coelioxzys Sharp-Tailed Bees.
Rhona found masses of Hairy Shieldbugs and also 5 Crucifer Shieldbugs, 1 red form and 4 white form – uncommon in Cambridge. Paul sent a picture of my favourite fly, the Yellow Dung Fly –the male golden yellow and the female greenish. Any decent fresh dung pat will host up to 100 males, waiting in hope of the female arriving to lay her eggs. However, Paul’s April special were 2 nymphs of the Planthopper Issus coleoptratus in some ivy. Like all planthopper nymphs, they have a small, gear-like structure on the base of each of their hind legs. These have teeth which intermesh, keeping the legs synchronized when the insect jumps, thus preventing it from spiralling. The insects shed this gear before moulting into adults. He comments, “It also has strange fibres projecting out of its bottom which are a waxy excretion, but no one seems to know what function they serve.” I would suggest that like all gears, some lubrication is required and wax might do very nicely.
Purple Toothwort is a non-native parasitic plant which grows on the roots of various other plants and has spread from the Botanic Garden along Hobson’s Conduit in both directions. This patch was growing at head height on a willow branch (or perhaps on the roots of the ivy there) on Coe Fen (Ben, Paul).
Magog Down has been a wonderful place to visit this spring. Richard and Vanessa found a coppiced Willow which had a large number of Crown Galls on its many branches. The bacterium which causes these galls is Agrobacterium tumefaciens. It apparently has an important role in genetic modification of certain crops, in order to improve resistance to diseases or improve yields – especially useful and important in countries in Africa.
The interconnected Newnham Nature Reserves (Paradise, Sheep’s Green and Coe Fen) have become home to Water Voles, working their way up from Snob’s Brook and along the main River Cam. Water voles are a priority species under the UK Post-2010 Biodiversity Framework, and one of the key reasons for their decline was the non-native North American Mink. In East Anglia, a mink eradication programme which started on the Bourn Brook in the winter of 2010/11 has largely cleared the Cam catchment area, so the remnant population had chance to breed safely in the absence of the predator. Since then, there have been eight breeding seasons when the brook has been free of mink, and being prodigious breeders like most rodents, they have rapidly spread along the entire length of the brook and are now colonising elsewhere.
Susanne witnessed a Heron which had just caught a Water Vole at Logan’s Meadow. David reported a Swan and a Coot incubating eggs on the Lake at Eddington, watched closely by a nearby Heron. I was happily watching a vole, when my eye was caught by movement on the opposite bank: a Stoat and a Moorhen were in fierce argument over the contents of the Moorhen’s nest by the bank. The stoat even swam in the river briefly and eventually departed with dinner. Nature, red in tooth and claw maybe, but predators must provide for their youngsters too.
Olwen Williams firstname.lastname@example.org