Spring– the best I can remember – has given us a long period of fluctuating warm and cold spells, with enough rain to keep things moving.  This has prolonged the emergence of leaves and spring flowers.  Duncan reports fish are migrating into small streams to spawn and sends a picture of two large Chub in the ditch around Jesus college.

Mammals

Colin was sitting on a bench by Baits Bite Lock (April 1^st) when approached by a weasel which came right up to the toe of his boot: very small with body under six inches long and no black tip to tail. Larger mammals in the city are also reported: the Jesus College Foxes have made it on to national media (https://www.facebook.com/watch/?v=443236599757826) and Nets saw a Roe Deer in her Chesterton back garden. Jill caught a hare in Fulbrooke Wood on a night camera.

Bats have emerged in the last couple of weeks (one dead Pipistrelle on my mat, sadly) and lots over the new lake at Hobson’s Park. Alec noted a brown Rat in the shed, which then declined and a day later was found dead. However, Duncan was witness to the birth of a Muntjac fawn and managed to film the mother as she cleaned it up.  (https://www.youtube.com/watch?v=5U3tC2koL9Q)
 

Birds

 Lots of reports of the arrival of spring migrants: Swallows on 2^nd (Bob) and 14^th (Holly), Cetti’s Warbler singing in scrub by lakes across from St Bedes crescent, Chiffchaffs and Blackcaps singing all along the brook (Holly), Blackcaps in Jesus College (Rhona) and on feeders in Newnham (Jean), Willow Warbler (17^th Holly, mid-April Martin Tenison Ave, 27^th Olwen Grantchester Meadows).

Jays seem to be doing well: Duncan reports the beech woods are full of them and I saw 5 flying together over the playing fields. Judith noted a part-albino Blackbird on 4^th, at Christ’s Pieces and the first baby Moorhen brood was seen on 17^th April. A Tawny Owl chick was spotted at Girton College.

Sue notes. “Our lawn has been dive bombed by Starlings over the past week – up to around two dozen. We haven’t seen a starling for about five years, so I am not sure what has attracted them”.

Mike reports that the Paradise Heronry has 12 “Apparently occupied nests” to date and that numbers are still stable despite some favoured trees blown down in recent years.  This was in contrast with the other large colony in the area (Stapleford), which was down from 10-15 pairs to only one in 2017, then totally abandoned in 2018. He believes that a gang of super aggressive Rooks,that were displaced from their usual site, harassed the herons so much in the early spring of 2017 that they departed.  (In Paradise, the Rooks gather in the winter, but depart as the herons arrive leaving only some Jackdaws from the big winter flock.)

 A couple of unusual sightings: on 18^th Nets was unpacking the moth traps at the Botanic Garden at 08.20am when an Oystercatcher flew over calling loudly. She presumed it had been grounded by the fog. Then on 19^th, I saw a pair of Mandarin Ducks on Pembroke playing fields. But where are all the Nuthatches? They seem to have vanished from all their former city sites, including the Beechwoods reserve. Have you seen any?

Richard reports drama on Hobson’s lake at Great Kneighton. He witnessed a pair of Lesser Black Backed Gulls systematically removing and eating Greylag Goose eggs on the islands in the lake, while Black Headed Gulls mobbed the larger gulls.  Then on 9^th April, four Common Terns visited, disappeared and then reappeared on 24^th April and have stayed since then, catching insects and feeding on fish robbed from the Great Crested Grebes! Their technique is to hover and then swoop on the grebe, forcing it to dive again and abandon the fish. A juvenile Black-Headed Gull appeared to be watching this and when the Grebe emerged from another dive with a fish, it used the same tactics.  However, the grebes seem to be flourishing in spite of all this and at least one pair has, on several occasions, started (but not completed) their wonderfully elaborate courtship display.  Finally, a pair of Canada Geese were seen shepherding six goslings around the perimeter of the lake – the first hatchlings of the year. Evidently more successful than the Greglags in keeping off the predators!

Plants

The ongoing battle against Floating Pennywort continues, this picture showing more in the Cam at Fen Ditton this month. If you see any, please hoick it out!  On 6^th,we spotted a plant which turned out to be Annual Mercury, Mercurialis annua  in Mill Rd Cemetery – a new one for me, but apparently fairly common.  Many flowers now coming out -particularly noticeable is the Bulbous Buttercup, with its turned down sepals, which is turning meadows yellow.

Jean reports the first small plums appearing on the many Cherry Plum trees (Prunus cerasifera) around Cambridge, a legacy of the Edwardian’s use of this species for hedging.  Last year a wide-spread infection by Taphrina pruni affected all these trees, destroying their fruit.  This fungal plant pathogen of Blackthorn(Prunus spinosa) causes the Pocket or Bladder Plum gall, a chemically induced distortion of the fruit,which becomes swollen on one side, resulting in a deformed and flattened fruit gall without a stone. The twigs on infected plants may also be deformed with small strap-shaped leaves. This year, the infection is still present on these trees and signs of the fruit deformation already visible.

Invertebrates

Everything is waking up fast, the first Peacock butterfly of the year on 1^st April (Pam, Olwen) Holly Blues in good numbers from 1^st April (Duncan, Paul, Rhona), Orange Tips (Duncan, Pam), Small Tortoiseshell, Brimstone (Pam) and Comma (Paul).

There are also lots of 7-spot Ladybirds, and Jonathan spotted the rather uncommon Eyed Ladybird in Robinson College.  Sightings of others welcome!

Penny reports “An insect with a very long proboscis on a patch of Aubretia. It was the size of a large bumble-bee with caramel coloured wings, a grey head and black and white back end. The long proboscis went into each individual aubretia flower while the wings were flapping so fast that it reminded me of a hummingbird”. This was confirmed as a Humming-bird Hawk-moth, now probably resident in UK.

The earliest damselflies appeared April 23^rd. Jeff saw 2 female Large Red Damselflies in Newnham and then a male on 26th April. More were seen over the Easter weekend: Banded Damoiselle on the Cam near Baits Bite Lock and a Large Red Damselfly in the pond at Cherry Hinton hall (Duncan). Hoverflies are also appearing –this Nursery Web Spider has just caught one and if you hold your hands up in a sunny glade in a wood it is quite likely you can get a hoverfly to land on your fingertips…

Olwen Williams olwenw@gmail.com

PS I have had the Newnham Riverbank Club sightings for 2018: they include Kingfisher, Heron, Snipe, Common Tern, Red Kite, Little Egret, Green Plover (Lapwing) and Otter footprints.

River Temperatures ranged from 0.5C on Mar 2^nd– 23.0C on June 25^th.T