Wednesday, 18 September 2019

The Bats of Tar Lakes


On the 16th September, a bat walk was held at Tar Lakes, with a great turnout of people keen to see what wildlife the night sky had to offer. 14 of the UK’s 18 bat species can be found in Oxfordshire – the county’s woodland and hedgerow habitats make it a great place to see a range of different species. The group hoped to collect information on what sort of bats are using the lakes and their surrounding habitats, and find out a bit more about these elusive nocturnal creatures. Using bat detectors that lower the bat’s ultrasonic calls to the range of human hearing, the participants listened in on a number of different bat species as they made their way around the lake complex. Here is what we saw;



Common and soprano pipistrelles

Common pipistrelles Pipistrellus pipistrellus were the most frequently heard bat on the walk. This small species can be found in woodland and urban habitats, making use of holes in trees and buildings to roost in. Their calls sound like fast slaps as they pass by, at a frequency around 45kHz.

A soprano pipistrelle Pipistrellus pygmaeus was first bat species spotted on the walk, foraging over a patch of scrub habitat. This species looks and sounds similar to the common pipistrelle, however their calls are pitches higher at 55kHz – as their name would suggest!

Both of these bats were seen flying over scrub and hedgerow habitats, where their insect prey was most abundant – ‘feeding buzzes’ were heard on the detectors as the bats honed in on their prey. Hedgerows are incredibly important for bats, due to their use as navigational tools as they commute from roosting to foraging grounds.


Common Pipistrelle in flight
A common pipistrelle bat © Paul van Hoof


Noctule

Noctules Nyctalus noctula are one of the larger bats we have in Oxfordshire – they are associated with woodland habitat, and can occasionally be heard without detectors by children and adults with good hearing, due to their calls sometimes being just low enough for humans to hear at around 20kHz. Noctules were heard several times on the walk, but despite their large size, the group could not spot them in the air as they few rapidly around!
 
Image result for Noctule
Noctule © Branko Karapandza

Daubenton’s bat

A bat that is commonly associated with water habitats is the Daubenton’s bat Myotis daubentonii – this species is seen trawling across rivers and lake with its large hairy feet, catching the midges that hover above the surface. Using high-powered torches, we were treated to a few sightings of this bat foraging across the lake.

Daubenton's bat © Paul van Hoof


Mystery myotids

Bats that are part of the Myotid genus, such as Natterer's bats and Bechstein's bats, are very hard to tell apart using only a bat detector due to their similar sounding calls – they can even be challenging to identify when in the hand! Their rattling call was heard a few times briefly above the hedgerows bordering the lakes, perhaps commuting between roosting and foraging sites.

Other nightlife

The group also spotted some other wildlife whilst on the walk – several common newts and toads were encountered on the northern path around the lake, which narrowly avoided being trodden on at times! A surprisingly large number of devil's coach horse beetle were also seen, with their long black bodies and scorpion-like poses spotted in the grass.

Many thanks to the Oxford Bat Group for lending us their bat detectors for the evening – for more information on the work they’re doing across the county, visit their website - http://www.oxfordshirebats.org/

Wednesday, 22 May 2019

Thames Water Blitz - Lower Windrush Valley

The 8th Thames Water Blitz took place on 26th - 29th April 2019, involving hundreds of volunteers carrying out quick and easy to use tests for phosphates and nitrates in ponds, lakes, ditches, streams and rivers across the Thames catchment.
The testing can help give a snapshot of water quality across a catchment, raise awareness about nutrient pollution and create data for use by scientists, policy makers, land managers, catchment partnerships and local communities.

LWVP volunteers tested 28 sites across the Lower Windrush, the results are summarised here:
The good news is that these results support the findings of more focused surveys coordinated by LWVP in 2016 and 2017 - lakes and ponds in the Lower Windrush Valley are an important clean water resource. Most are fed by groundwater flowing very slowly through gravel, which helps keep the water clean and free from nutrient pollution, and allow freshwater wildlife to flourish.  The bad news is that, like in most areas of lowland Britain, the majority of streams and rivers suffer serious nutrient pollution.

Full results of the Thames Water Blitz, including those from the Lower Windrush Valley, can be viewed via an interactive map on the Freshwater Watch website: https://freshwaterwatch.thewaterhub.org/totally-thames-water-blitz

Case Studies from the Lower Windrush Valley surveys conducted in 2016 and 2017 can be found on our website here: https://www.oxfordshire.gov.uk/residents/environment-and-planning/countryside/lower-windrush-valley-project/what-we-do






Thursday, 2 May 2019

Protecting Water Voles in the Lower Windrush Valley

Water Voles are Britain’s fastest declining mammal. They have lost a staggering 95% of their range since 1900. 
A Water Vole


Why have Water Vole numbers declined?
Water voles inhabit the edges of ditches, streams and rivers and make their burrows in the soft riverside banks. They feed on the reeds and grasses found nearby. The feeding and burrowing activity of voles creates favourable habitat alongside river edges for other animals and plants such as Kingfishers, who often use Water Vole excavations for nests. The impacts of the loss of this habitat on Water Voles is huge, and it has been exacerbated by predation from North American Mink.
The North American Mink is not native to Britain, but they are now widely established throughout the UK, largely due to escapes and releases from Mink farms in the 1950’s. Mink can have a devastating impact on our native fauna, and the decline in Water Vole populations is directly linked to predation by Mink. Mink are successful predators of Water Vole because they can swim well and are small enough to enter Water Vole’s burrows. 


Water Voles in the Lower Windrush
The Lower Windrush is designated as a Local Key Area for Water Voles, and Water Vole presence has slowly extended along both arms of the Lower Windrush Valley since a population were reintroduced in 2005. In fact, the results of the most recent survey, in 2016, found that Water Vole activity was only absent in areas with unsuitable habitat. Of particular good news is that Water Vole activity has been detected in the area immediately above the confluence with the River Thames, linking the Lower Windrush Valley to other Local Key Areas nearby, effectively creating one extensive Local Key Area for Water Voles.


A Water Vole in the Lower Windrush
Mink monitoring and control in the Lower Windrush
Monitoring for the presence and control of Mink is carried out in the Lower Windrush Valley using Mink rafts provided by The Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT). The rafts have a tray of soft clay, positioned in areas where Mink are likely to be present. The Mink pass across the clay and leave footprints, indicating their presence. Possible Mink prints were recorded in ten different areas of the Lower Windrush Valley during a 2016 survey.


Mink prints on clay from a raft near Standlake

There are currently Mink rafts in the Ducklington area but controlling populations in the lower end of the Windrush is particularly important to reduce the number of Mink travelling upstream from the River Thames.  


New Mink rafts in place!
As of May 2019, a further three Mink rafts are now in place and a new team of volunteers have begun to monitor the rafts on a weekly basis. If Mink prints are identified during monitoring visits, then a trap will be deployed. Once a Mink has been captured, it will be humanely killed following best practise guidelines.

One of the new rafts in position


Volunteers helping to put a new raft in position

Further information
Lower Windrush 2016 Survey Report: https://www2.oxfordshire.gov.uk/cms/sites/default/files/folders/documents/environmentandplanning/countryside/protectedspecies/WaterVoleUpdate-LowerRiverWindrush2016Report.pdf
Lower Windrush 2016 Survey Map: https://www2.oxfordshire.gov.uk/cms/sites/default/files/folders/documents/environmentandplanning/countryside/protectedspecies/WaterVoleUpdate-LowerRiverWindrush2016Map.pdf
BBOWT Water Vole Recovery Project webpage: https://www.bbowt.org.uk/wildlife/wildlife-conservation/water-vole-recovery-project

Monday, 4 March 2019

2019 Rushy Common Birdwatch

On the 27th of January we opened up the doors of the Rushy Common bird hide once more to take part in the RSPB's Big Garden Birdwatch for the second year running.



We had an amazing 28 visitors this year who came and took part in the count. Some were regulars to the hide but many had never visited the site before and it was great to see all of the new faces.
During the hour we counted a total of 25 bird species and 194 individual birds. For comparison, in 2018 we counted 19 species and 167 individual birds.
We also spotted a Roe Deer, making the total species count 26!




The full results from Rushy Common are here:
Species 2018 Count 2019 Count Difference
Black-headed Gull   4 4
Black Swan   1 1
Blue tit 3 3 0
Buzzard   1 1
Canada goose 2 6 4
Carrion crow 2 1 -1
Chaffinch   1 1
Coal tit 1   -1
Coot 38 85 47
Cormorant 14 31 17
Dunnock 1   -1
Gadwall 4 8 4
Goldeneye 2   -2
Great crested grebe 4 4 0
Great tit 4 5 1
Herring Gull   1 1
Greylag goose 2   -2
Lesser black-backed gull 8   -8
Long-tailed tit 4   -4
Magpie 3 1 -2
Mallard  10 1 -9
Moorhen   1 1
Red-crested Pochard   5 5
Redwing   1 1
Roe Deer   1 1
Robin 2 2 0
Shoveler   19 19
Stock Dove   2 2
Teal   1 1
Tufted duck 13 5 -8
Wigeon 50 4 -46
Wren   1 1
Total 167 195  


Results have been submitted to the RSPB and they will publish a summary of the 2019 results here in due course: https://www.rspb.org.uk/get-involved/activities/birdwatch/

Tuesday, 19 February 2019

Improvements to the Windrush Path at Standlake - Part 2

In December we shared some photographs of the surface improvements made to a section of the Windrush Path between Standlake and Newbridge. Today, the project was completed with the installation of two new interpretation panels at either end of the path.
One of the old panels, now out of date and beginning to fall apart!
The new panel in Standlake
The new panel at Newbridge

Thank you to our funders: Trust For Oxfordshire's Environment (TOE) with funding from Grundon Waste Management Ltd through the Landfill Communities Fund, West Oxfordshire District Council, Newland Angling Club, Standlake Parish Council and the Standlake Mosaic Trail fund.