At daybreak today, pleated clouds and the first frost. Autumn is when the Rooks and Jackdaws return to the tall trees by the river in Newnham and duly on Sept 8^th the first of the rooks arrived – a fantastic noise.  Curiously, this is neither rookery nor overnight roost. The main roost is over at Madingley, but in autumn and winter, they gather here at dusk and again at dawn.  So far only about 30-40 rooks and 20-30 jackdaws, but at peak the mixed flock is several hundreds. Autumn has arrived!

David Brown, gardening at St John’s College, has kept a bird list since May 2016.  He sends a fantastic list of sightings: 17 species by the river, another 5 flying over including Red Kite and Cormorant and 30 in the Gardens and Wilderness area.  Most notable are the Nuthatch (which we thought we had lost from the City), Treecreeper, Red Legged Partridge (once in 2017) and a Tawny Owl.  Perhaps his sharp eyes will find more of the once common birds such as Little Owl or Lesser Spotted Woodpecker. He also reports 2 Whinchat at Hobsons park (and a Great White Egret at Fen Drayton, sadly out of our study area).

A couple of reports of late Swifts – 3 in Chesterton on 12^th (Nets) and 6 over Granta pond on 13^th (Guy). No reports of incoming migrants yet, though. Lesley spotted Jays in Histon Road Cemetery and near Jesus College. Autumn is their time for collecting nuts and acorns for the winter. For a few days there was a Buzzard resting in the trees by the river in Chesterton (June). In Mowbray Road, a couple of Red Legged Partridges (Ann) and in the Botanic Garden, a Kingfisher against the autumn colouring of Acer cissifolium (Vicky) attracted attention. In Jesus, Rhona  heard some birds ‘kicking off’ and found a Tawny Owl in the woods.

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For several weeks, Bronwyn’s garden was home to a Pigeon.  Probably feral, not apparently ringed, quite aggressive with pigeons and collared doves in a neighbouring garden. “It had a strange sort of bouncing motion when perched on the fence.” A lost racer, perhaps? Very distinctive but finally moved on (or became dinner for a peregrine?)

You can’t keep a good naturalist down, even when eating lunch.  Chris reports an Ant which emerged from a Cambridge-bought nectarine. It was identified (by Rhian Guillem) as a queen Crematogaster scutellaris, a Mediterranean species. A good example of how impossible it is to control the introduction of species in a globalised world (see below)!  I am looking forward to hearing what emerges from the next batch.  Meanwhile, Duncan reports an interesting coupling between two different species of Damselfly.  The male is an Emerald Damselfly with dark brown wing patches (pterostigma) and the female is a Willow Emerald with light coloured pterostigma. The Willow Emeralds are newcomers to the UK, but (he says) they should be used to the Common Emeralds, as they occur in France as well.   He asks, “Are they just confused, did the male make a big mistake, will we get some sort of hybrid, or is it just the French getting up to their old tricks again?”

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Badgers continue to expand their range in the city.  In Harvey Goodwin Ave, Chesterton, Ben reports sightings on two consecutive nights in July of a badger harrying a Hedgehog (rescued). I gather male urine sprayed around is a good deterrent to badgers…..  The City has a good number of Local Nature Reserves: Guy reports a Fox at West Pit and a Weasel at Nine Wells.  We also had a visit to Nine Wells and found a wonderful orb-web Spider, Araneus quadratus busy parcelling up a crane fly.

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Rhona’s Jesus Ditch has juvenile Water Voles (about half the size of an adult). Lesley notes the local north Cambridge Grey Squirrels have increasing numbers of black individuals.

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Not much news on the plant front, except for Floating Pennywort again, growing in a private pond at Regatta Court after escaping some time ago from the river. Mike says it is possibly spread by Moorhens and “This will be promptly removed!” In general, clearance has been very successful from the main river.

On Sept 5^th, there were swarms small black Caddis Flies over the river. Paul found a Red Admiral sipping on over-ripe blackberries at Coldhams Common and also the Four-banded Bee-grabber Conops quadrifasciatus, a handsome but rather nasty fly if you happen to be a bumblebee, as they are parasitic, laying their eggs inside the bee.  https://www.flickr.com/photos/63075200@N07/collections/72157658279506405/

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In his moth trap, Paul found a Twin-spot Centurion Sargus bipunctatus. “Such an attractive fly to emerge from dung.” The two white spots make this an easily identifiable species.

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In the systematic beds at the Botanic Garden, I found numerous ground nesting bees, identified as Ivy Bees, Colletes hederae. They are recent colonists, first seen in Cambridgeshire in 2016 but now widespread and often feasting on flowering ivy. Rhona reports Hummingbird Hawkmoths, usually on the Ceratostigma plants. 

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Liza found a Box Tree Moth Cydalima perspectalis, the introduced destroyer of topiary.  So far her variegated box has no signs of infestation ….  However, Martin reports more from Grantchester, they have turned up in Paul’s moth trap and there is a plague in Trumpington where 259 turned up in a trap on one night.  Box has been used extensively on the new estates in this area, so this almost certainly is related to the big increase in numbers. Have they increased because of the abundance of new food sources, or because the newly planted Box plants were already infested?

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Originating from south-east Asia, they were first recorded in Kent in 2007 and have been extending their UK range since then. The moths are iridescent white with a purplish brown border  and there is also a less common melanic variation, the wings being purplish brown with a white spot near the centre of the forewing.

Autumn is the season for fungi and Guy found a group of Shaggy Inkcap on a Shelford Rd Lawn. He also reports 4 Brown Trout, an Eel and Spined Loach during the final monitoring of the Rush.

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And finally, Val was surprised to find a large Frog leaping frantically into the downstairs shower, desperate to escape the hoover.  “It must have snuck in through the open back door at some point. Reader, I caught the frog with my bare hands and returned it to the part of the garden where it had previously been observed to lurk meditatively.”

Olwen Williams olwenw@gmail.com