The Saturday volunteer group worked very hard installing a ‘Brushwood mattress’ at The Rush stream on Sheep’s Green. The idea is that the brushwood collects passing silt and by doing so creates a narrowing of the channel. This narrowing increases the flow of water which in turn creates a faster more dynamic section of the stream, keeping the bottom gravel clear and oxygenating the water. Vegetation soon grows through the mattress helping to hold it all in place and offering an added habitat and shelter for fish and invertebrates.

If you are interested in joining the volunteers email: parks@cambridge.gov.uk for further information.

Take a walk to Sheep’s Green and listen out for the unfamiliar sound of rushing water. This is due to the completion of a very exciting new project which has transformed a heavily silted water course in to something very special. Previously the slow-moving watercourse met the river at a seized sluice gate which provided no upward access to the river for fish species. Barriers to fish within a stream or river have a very negative impact on that ecosystem. The Rush project will turn this a round. The change in level between the upper river and the mill pool will be gradually lost in a series of ramps and pools that allow the fish to travel upstream but also to shelter and feed. The increased flow will expose gravel for spawning and create a suitable habitat for many aquatic invertebrates.
As aquatic and marginal vegetation grows the look of the stream will soften and naturalize. Species such as Minnows, Chubb, Dace and hopefully Brown trout along with a multitude of other native species will find a healthy oxygenated watercourse to thrive in.
To have this interesting and varied habitat in such close proximity to the city is wonderful. It is valuable to people as well as nature. It is something which everyone can enjoy and watch develop

As spring slowly brings our nature reserves to life you may spot these tiny mounds of earth in the grass or on patches of  bare earth. They are the nests of the Tawny Mining bee which build their nests at this time of year. The nest consists of a vertical shaft 8-12 inches long with several brood cells branching off. The female fills each cell with a mixture of nectar and pollen on which she lays one egg. The larvae quickly develops and begins pupating, to emerge as an adult the following spring.

This all sounds like a good plan however we are not the only ones who notice these nests! Bee flies are notorious for flying over the nests and flicking their own eggs in to the entrance. These eggs then develop into maggot like larvae which wriggle in to the prepared cells to continue developing in comfort. Cuckoo bees, Nomad bees and many solitary wasps have also developed strategies to exploit the Tawny mining bees nest sites. The picture was taken Barnwell West nature reserve.

Spring is definitely on the way, you can hear it!

Not just the sound track of the birds establishing territories but also the friendly hum of Bumblebees.

This time of year it is the queens that you will hear as they emerge from hibernation to start a new colony.  They wake up hungry and thirsty and therefore it is vital that they find early flowers to feed on. The newly emerged queens eat both nectar and pollen. It is actually the pollen that helps her ovaries develop in preparation for all the worker bees she will give birth to. She continues feeding and sheltering at night near the food plants until her body signals her that it is time to find a nest site.

Nests can be underground in disused rodent holes, under sheds or compost heaps. The Tree Bumblebee(Bombus hypnorum)shown in the picture prefers to nest higher up in hollow trees, bird boxes or maybe a house loft. This species is relatively new to the UK, it has been steadily spreading from the European continent and parts of Asia since the start of the 21st century. These Bumblebees prefer habitats that others do not, allowing them to pollinate flowers in areas that many other species do not get to. This has helped with their growing establishment and success.

The city’s waterways seem an unlikely habitat for finding otters in but as always nature can surprise you. Working with the Wildlife Trust the city’s nature reserves were surveyed for otter activity with very pleasing results. Spraint was found at 9 Wells, Logan’s Meadow, Stourbridge Common and Coldhams Common.

According to the Wildlife Trust just 15 years ago the otter population had almost disappeared around Cambridge. But since then the numbers have been steadily rising. Survey statistics gathered from Wildlife Trust staff and volunteers, the Cambridgeshire Mammal Group and the Cambridgeshire and Peterborough Water for Wildlife project have found evidence of a significant increase in Otter numbers.

The Otter survey carried out on the city’s nature reserves was part of a larger initiative which was surveying the whole of the county’s waterways and tributaries. The results are being gathered and will hopefully reveal a similar trend. It is certainly an optimistic picture for Cambridge city.

If you are interested in this project more information can be found at the Cambridgeshire and Peterborough Water for Wildlife Project- 01954 713555.