All posts by djmbwr

Dragonflies in spring and summer

Female Emperor egg laying at Great Kneighton

With all the hot weather that we have had this year, the Dragonflies and Damselflies have been spectacular. I started the season watching Large Red Damselflies in late April this year, as they appeared in my garden, which is over 150 yards from Cherry Hinton Brook and lakes. I went on to look at Hobson’s Conduit as it flows across Empty Common and in front of the Botanical Gardens which is the perfect place to watch Damselflies and Dragonflies going about their short adult existence.

Late May and early June is the time when the number of species steadily climbs as more adults emerge from their aquatic larval forms to dance above the waters. Most adult dragons and damsels are relatively short lived and many only live for a few days. The larvae climb up onto a piece of emergent vegetation and then can be seen climbing out of their old skin to emerge in all their adult glory. They leave their old skin still attached to the vegetation and this exuvium can be collected and identified to species.  After emergence they have to disperse and mate, although since many emerge together, mating must often occur quite quickly. In June, there were so many Azure and Blue-tailed Damselflies mating and egg laying on the Conduit, I sometimes had numerous pairs in the frame of my camera.

Brown Hawker on a bulrush in the Science Park

The section of Hobson’s Conduit by the Botanical Gardens really is superb and sometimes Emperor, Four-spot Chaser or Brown Hawker Dragonflies will pass within just a few feet. Emperors are easy to identify, as they are the largest British dragonfly and have a green thorax (the bit between the wings). Brown Hawkers don’t come out until July and are identified by their brown bodies and orangey wing colour.

A Southern Hawker on Cherry Hinton Brook

A little later in July Southern Hawkers emerge, with their blue and yellow abdomen and broad yellow stripes on the thorax. These three are the biggest of our native species and are all magnificent as they hunt up and down the water course.

The Chasers and Skimmers are also present and early in the spring and summer the most common species is the Four-spot Chaser. The striking medium-sized beast has a brown body, much shorter than any of the Hawkers. It also has 4 black spots across the fore wings and another four across the hind wings, So I am not sure why it wasn’t called the eight-spot chaser.

Four-spot Chaser on Hobsons Conduit

The Broad-bodied Chaser seems a more elegant creature altogether with a  pale blue abdomen with little yellow spots down the side. The thorax is essentially brown with paler markings.

Male Broad-bodied Chaser on Hobson’s Conduit

In Grantchester Meadows and also in the ditch around the new bird ponds at Great Kneighton, one can find the Black-tailed Skimmer. The male looks a bit like the Broad-bodied Chaser but with a striking black end to its abdomen and lacking the yellow spots. The female is yellow in colour with two lines of black markings down the abdomen.

Female Black tailed skimmer on Grantchester meadows

In July and August, Southern Hawkers, Migrant Hawkers, Ruddy and Common Darters all make their appearance. So the summer is constantly interesting with new species to observe.

Common Darter: The insert shows the yellow stripe on the foreleg that does not occur in the very similar Ruddy Darter

One of the most spectacular dragonfly events takes place in Cherry Hinton chalk pits in August. Many Migrant Hawkers and Southern Hawkers can be found hunting in the bushes in the pit on sunny days. Then as the sun begins to go down, a shadow sweeps across the bottom of the pit and the dragonflies move to keep in the sun, so slowly the numbers flying just ahead of the shadow can be very great and hundreds of Dragonflies are amassed together following the setting sun.

There are some other really good sites to see Dragons and Damselflies in Cambridge, the list includes: The ditch across Coe Fen, The complex of ditches in Ditton Meadows, Banks of the River Cam just north of Fen Ditton, Logan’s Meadow, Science Park lakes, Barnwell Pit, Botanical Gardens ponds, Skaters Meadow and Sheep’s Green. Some of the smaller Cambridge nature reserves also have ponds which have good potential, but in the 2018 heat,  these have tended to dry up due to lack of water supply.

I will write more about Damselflies in my next blog.

Duncan Mackay

Egrets on Cherry Hinton Brook

Long ago it was a very rare event to see Little Egrets in the UK. But increasingly they are becoming commonplace and their numbers have increased dramatically in recent years. So it was no surprise as I jogged along Cherry Hinton Brook to find several of them hunting for fish near Cherry Hinton Hall. They are remarkably tame as well and will let you photograph them, as long as you don’t get too close.

Their numbers have been steadily increasing in France and they made the leap across the channel to breed in Dorset for the first time in 1996. By the start of the new Millennium they had reached 100 breeding pairs in this country and went on increasing in numbers. Now there are over 1,000 pairs. Initially birds visiting this country returned to France for the winter, but now they have become resident and can be seen throughout the year. The fact that they have colonised the city and are almost urban birds is rather surprising, but an exotic addition to our local fauna.

Their white plumage is not exactly what one would consider good camouflage for a hunting bird. But when you realise that the fish they are hiding from are looking up at the bright sky, white plumage is the perfect disguise. Their black legs are curiously ended with bright yellow feet. Does this give them some sort of advantage? Perhaps its handy to be able to see your feet in the murky water when wading.

Eventually they got fed up with me stalking them along the stream and took to their wings and flew away majestically.

Duncan Mackay 13/2/2018

The Water Vole and the Folk Festival

I was cycling along  Cherryhinton brook one afternoon last week and heard the music from the Folk Festival drifting over the alotments, a nice lilting melody mixing with the sounds of nature all around. As I rounded one of the bends in the footpath I noticed a little water vole sitting mesmerised on a patch of Greater pond sedge (Carex riparia) .  I am sure it was feeling just as mellow as I was. It knew I was watching but went about its nibbling for some moments. Then plunged into the water and dived down to the bottom of the stream. A great cloud of mud billowed up as the vole started an excavation process. It was digging at the base of the sedge plant and eventually resurfaced with a length of white succulent rhizome in its mouth. It then resumed its meal and had soon consumed this prized moursel. I imagine the rhizomes must contain lots of stored starch, so the vole was getting a much better meal than it gets from endless nibbling of the leaves.  It was a very young vole and quite small, so I wonder how it learnt to expertly dive and excavate in this way so early in its life. Presumably by watching its parents.
I have discovered that if you want to see a water vole, the easiest way of spotting them is to look out for unusual ripples on the water surface. The voles sit under the bank and nibble food. The frequency of their nibbling is much faster than other animals, so the ripples they produce are a shorter wave length than say a moorhen or a mallard, which are also found along the brook. I think the ripples come from the vibration of their tummies as they nibble. They are very enthusiastic nibblers and they are always eating. I can often find the hidden voles right in the middle of a sedge bed in this way. You just hang around a while and the vole is sure to appear.

Mistletoe Survey – Radio interview

Today I did an interview with David Webster of BBC Radio Cambridgeshire about the Mistletoe survey. We are hoping to get lots of records of Mistletoe growing wild in the city and by publicising it on radio, we will hopefully encourage people to report their sightings. It will be broadcast tomorrow (22/12/2016) at just after 7am


The Mistletoe hotspot seems to be at the junction of Madingley Road and Queens Road.  There are quite a few good bunches  mostly growing in lime trees.  As you go up Madingley road there are some trees that are heavily covered and must be suffering from the burden.


This one is a Hawthorn tree outside Churchill College which has a huge Mistletoe growing in the centre of the main branches. This is obviously a female Mistletoe, as the male doesnt have berries.


Here is a rather more diminutive male plant, showing the haustorium, where the stem of the Mistletoe fuses with the branch of the tree and the modified roots penetrate the host tissue to obtain water and minerals.

We would like to collect any sightings of Mistletoe so please use the  sightings link on this webpage to let us know where the Mistletoe plants are growing. if you prefer to use email, then send your messages to . please include exactly where the plant is growing, which host tree species is involved and roughtly how big is the Mistletoe. if you can give us a 6 figure grid reference or a post code that will be very helpful.

Please let us know where you see Mistletoe growing in Cambridge. See our Mistletoe survey for more information.

Duncan Mackay


Intro to the project by Olwen Williams

Cambridge City Natural History


The city of Cambridge includes grand buildings, new and old houses, streams, lakes, cemeteries, water meadows, gardens and recreation areas. The river Cam runs through the centre, forming a focal point for residents and visitors alike.  It is a small city, roughly eight kilometres square, densely populated but full of green spaces. Nowhere are you far from the countryside and even within the city, wildlife abounds.


This project, planned to last for 3-4 years, aims to increase public awareness of the diversity of plants, animals and fungi within the city and to involve everyone in documenting Cambridge’s natural history heritage. As part of the programme, a garden will be chosen in each square kilometre across the city and surveyed intensively.  Initial studies show that as many as 70 native plants may be present in an average garden and moth trapping in north Cambridge turned up a beautiful privet hawkmoth.


Just now, the season is turning from summer to autumn.  Tawny owls – two males and a female – were calling last night from the tall trees.  Other birds are quiet, in autumn eclipse.  There is no longer the noisy racket from the heronry by the river, suggesting that this year’s young have at last fledged.  The horse chestnut trees, whose leaves are attacked by the larvae of a moth, have turned brown and prematurely shrivelled. Although this moth only arrived in the UK in 2002, it has spread rapidly northwards.  Spiders abound – the webs of the garden spider lace the bushes. Butterflies, bumble bees and dragonflies persist, but in smaller numbers than before. A mating pair of Willow Emerald Damselflies were seen in the Botanic Garden on Sept 4th. This species was first recorded breeding in the UK in 2007 and seems to be expanding its range