Archive for the ‘Wildlife’ Category

Return of the grazers – cattle are coming back to the downs!

Wednesday, November 8th, 2017

In mid-November, a group of Gloucester cattle will be taking up residence on the downland of Westonbirt Arboretum. They will be helping us to create and maintain diverse habitat for wildflowers and insects that make their home on the Downs.

 

Photo credit: Rare Breeds’ Survival Trust

 

The steep parts of the Downs here at Westonbirt are a particularly good example of  wildflower rich limestone grassland, and surveys over recent years have shown that they are home to at least 236 different plant species –  around 8.1% of the UK flora! In recent decades, this type of limestone grassland has been in rapid decline across the country; in the 1930’s 40% of the Cotswolds was covered in wildflower rich limestone grassland; today that figure has fallen to 1.5%, a decline which is reflected across the rest of Great Britain.

 
So why is this grassland disappearing? Well, a large factor is that many herbaceous plant  species found in these habitats , are susceptible to being outcompeted by more aggressive, tall rank species such as cocksfoot grass, docks and thistles.

 

 
Historically, these more competitive species have been kept in check and managed in Cotswolds grasslands by a combination of grazing, mowing, and burning. Burning is not an option at Westonbirt, and mowing is both labour intensive and does not produce as diverse a sward as grazing does. Grazing by livestock reduces the dominance of coarse, aggressive species (such as tall oat-grass and dock), which in turn allows less competitive species to establish and thrive. Through the action of their hooves, the animals open up the sward and soil to provide niches where seeds can germinate.

 

 

However, not all grazers are suitable for the Westonbirt downland. Sheep, for example, are highly selective grazers, preferring to eat flower-heads and buds of herbaceous plants rather than grass. Horses are also selective, and mainly eat finer species of grass, producing extensive ‘lawns’. Cattle are less selective than sheep or horses; they will eat grass and herbaceous plants equally, and are especially good at removing coarse grasses. The way cattle eat is important too: rather than nibbling with their teeth (as horses and sheep do), they pull clumps of vegetation from the ground with their tongues; this creates a more tussocky sward, and provides small areas of bare soil in which seeds can germinate.

 

Photo credit: Cotswold Farm Park

There are two other important factors to consider; the number of animals used, and the timing and duration of grazing. Too few cattle, and any beneficial effects will be negligible; too many, and the area will soon become too poached up with large areas of bare soil, which are too disturbed to allow seedlings to establish. In order to ensure that we are getting the number just right, we’ll be closely monitoring the effects of the grazing via vegetation surveys. If needed, we can adjust the numbers and frequency of grazing. Timing-wise, it’s important to stop the grazing when the vegetation starts to flower, then get them back on the ground once most of the species have shed their seeds. Grazers should also be removed if there are signs of excessive ground disturbance during periods of prolonged wet weather.
As long as the cattle are with us, it is important for our visitors to remember that, whilst Gloucester cattle are mostly docile, you should not try to touch or pet them. Whilst dogs do not have to be on the lead near the area where the cattle will be grazing, please ensure that all dogs are kept well under control and to heel when near them.

 

Watch this space as we share updates on the benefits that the cattle bring to the nationally important habitat of the Westonbirt Downs!

 

A walk into the unknown, by Ben Oliver, Learning and Participation Manager

Wednesday, May 23rd, 2012

We’ve always known that we have bats at Westonbirt – but we’ve never really gone out looking for them.

Gloucestershire Bat Group - Miranda Winram
Previous bat walks have recorded pipistrelles and the odd Daubentons over the dewpond. Staff have found long-eared and horseshoe bats hanging in the tree team toilet. And a harp trap project last year recorded the rare Bechstein and also a whiskered bat. But this was really the sum total of our knowledge.

Was this all the species we had? Where did they fly in the arboretum? We didn’t really have answers to these questions… but then looking for small quick flying mammals at night in woodland is a bit like needles in haystacks.

However, thanks to the combined efforts of Gloucestershire Bat Group (GBG) and Forestry Commission staff (who ensured GBG members didn’t get lost) we now have a much better picture.

Assembling around 8.30pm last night seems a bit odd when you’ve only just left work – but all of us were quite excited as to what we might find (and truth be told a little nervous that we might not find much!)

The plan was to combine essential training for GBG trainees with the first bat survey transect of the arboretum using Anabat detectors. These remarkable gizmos record bats echo locating as they navigate in flight. Because different bat species echolocate at different frequencies and at different speeds it is possible for those in the know to identify the different species present by looking at their sonograms.

As dusk fell on a lovely warm day we split into three groups and headed out to our agreed survey areas – two covering Silk Wood and one in the Old Arboretum.

Armed with our detectors we were all soon hearing a variety of bat echo locating sounds including ‘smacks’, ‘ticks’ ,’clicks’ and ‘tocks’ – and of course the occasional raspberry; indicating a feeding burst as the bat closed in on its prey.

My group were given a particularly fine show in Sand Earth where we were able to watch bats spinning round Douglas fir lined amphitheatres.

Meeting back at Keeper’s Cottage, the GBG carefully reviewed the recorded sounds to identify the full list – and this was quite a revelation; as well as recording common pipistrelle, soprano pipistrelle and possibly a long-eared, the Anabats also detected serotine, noctule and two species of Myotis (the sonogram characteristics suggested Brandt’s and whiskered, but as Sandi, our bat trainer explained, she couldn’t be sure without a body). Finally another exciting possibility – a Leisler’s bat; although again this couldn’t be 100% certain from the sonogram – giving us possibly 4 new species on the night and taking the total bat species at Westonbirt to a possible 11 (out of a UK total of 18).

Whether or not it was or wasn’t a Leisler’s (or a Brandt’s for that matter) really wasn’t that important though – it was just exciting to get a glimpse of the nocturnal activities taking place on site that we had previously never really known about. And as David from the GBG said not knowing precisely provides the perfect excuse for some mist netting surveys.

Many thanks must go to the Gloucestershire Bat Group for coming out – we very much hope to continue our work together in future.

Photo: Members of the Gloucestershire Bat Group, by Miranda Winram

Useful links
Find out more about the Gloucestershire Bat Group
Become a member of the Friends of Westonbirt Arboretum
More about wildlife and bio-diversity at Westonbirt