First water vole post of 2010....

The river is still very high (but not on flood watch), as is the ditch running through the centre of the Ock meadow

Which itself is water logged:

Previously, both the river and the ditch have been locations of water voles in 2009, but as the pictures show, it's very unlikely that there are any water voles there now.

However, on Sandford Brook, flowing to the north east of the Ock meadow there are what looks like water vole burrows in the bank of the stream:

This is the site where I saw signs of feeding last year:

http://viewsoftheock.blogspot.com/2009/06/return-to-stream.html

If these are water vole burrows, they may not be inhabited and could be remains of a extinct colony.

But a close up of one of them may show signs of feeding and possibly footprints

Perhaps not enough evidence to yet make a conclusion, but it is somewhere to keep an eye out as spring approaches.

River foam

The high water at the weekend  has resulted in foam being produced on the river along the Ock valley walk:

I've noticed this before on the Ock and other rivers and thought this blog would be an opportunity to try and research it.  The foam seems to be made by surfactants - 'a substance that reduces surface tension' (Oxford English Dictionary).  The resulting reduction in surface tension and the faster flowing water creates bubbles which are moved by the wind and the currents to the calm parts of the river where they accumulate - resulting in the foam, in this case forming by one of the weirs.

There appear to be two possible causes of these surfactants,  natural organic material - decomposing plants and animals, the rate of this could be caused up by an increase in temperature or pollution or man made material - detergents for example.
As there is not a lot of it  and there has been a sudden increase in temperature and water flow, coupled with the lack of industry along the river (especially any which are likely to produce detergents) it is probable this foam is natural - although it doesn't look like it.  I hope to go back at the weekend to see if it had dispersed. 

This article proves a remarkable amount of foam can occur naturally (if a man-made dam is considered natural) without any pollution: http://www.dundeeonline.com/articles/12.1.2003.html

As always, if anyone knows anything more about this, I'd be very interested to hear.

References:
http://www.in.gov/idem/wqsurvey_025surfacefoam.pdf
http://www.duluthstreams.org/understanding/foam.html

After the snow...

As expected, now the snow has almost melted, the river is very high

And it appears to have burst it's banks, causing slight  flooding on the Ock meadow

The ditch running along the Ock meadow is also very high, contributing to the flooding:

On the meadow itself are a series of holes, maybe made by field voles?

And the predators are out, making the most of the first feeding opportunity for nearly two weeks. A heron by the ditch - maybe after a displaced water vole?

A kestrel seeking out small mammals on the meadow

A  flood watch has been issued for the Ock

http://www.environment-agency.gov.uk/homeandleisure/floods/34681.aspx?area=061WAF17Ock&page=1&type=Town&term=abingdon

And 32 other rivers in the 'Thames' area:

http://www.environment-agency.gov.uk/homeandleisure/floods/34678.aspx?type=Region&term=Thames

Update 18/1/2010: The river Ock in no longer on flood watch


http://www.environment-agency.gov.uk/homeandleisure/floods/34681.aspx?area=061WAF17Ock&page=1&type=Town&term=abingdon

 

Garden Birds

With the cold weather continuing, numerous birds have visited the garden. Some regulars, some not
A first for our garden are redwings.  A winter migrant that is normally found in hedgerows and judging by internet postings  they (and fieldfares) are moving into gardens in their droves.

Collard doves have become more frequent visitors over the past few months, especially now they have mastered the bird feeder:

Blackcaps are very rare visitors, so I took the opportunity to try and get a picture - even if it meant I was late for work

Two goldfinches enjoying the same feeder some time later, although the number of goldfinches in our garden has declined.  In previous years we've had up to 10 , now we are lucky if we get a maximum of 4 (maybe they've just found a better source of food).

This is all practice for the RSPB's Big Garden Bird Watch at the end of the month: http://www.rspb.org.uk/birdwatch/
It will be interesting to see if the visiting redwings and fieldfares remain long enough to be counted and to see if anyone else has seen a decline in goldfinch numbers.

Since my previous post, several articles have subsequently been written about this spell of cold weather including this one by Simon Moss: http://news.bbc.co.uk/today/hi/today/newsid_8455000/8455832.stm
It seems I am wrong about the impact on some birds of prey, Simon Moss argues that the cold weather will increase their food supply as more animal succumb to the cold.  Although I haven't seen any red kits or buzzards in recent weeks - perhaps I have not been looking hard  enough.

Colder than Antarctica?

During the week in Oxfordshire it reached -17⁰C which is apparently colder than the current average temperature in Antarctica and it has presented other opportunities for a healthy walk to work and to take more pictures.

The very low temperatures have also created some impressive icicles

It's been a great time for pictures, snowball fights and snowmen, it has started me thinking what the effect would be on the wildlife I've been following for the past few months.

The small birds in the vicinity should be OK as lots of people feed the birds in their garden - the number of chaffinches has increased over the past few days and for the first time ever, we've had fieldfares visit the garden. This is as well as the usual collection of blackbirds, sparrows, great tits, goldfinches and  house sparrows.
Unfortunately, it is has probably been harder for birds of prey - red kites and buzzards often feed on earthworms at this time of year as well as carrion, both of which would be hard to find in this weather.  This excellent post from Spot (already a candidate for next years blog roll) shows the problems with low flying raptors: http://tamar-valley-life.blogspot.com/2010/01/buzzard-rescue.html who are weak and trying to find sources of food.
It is possible to feed red kites and buzzards - as some in the Chilterns do  - but there are strict guidelines and there is the risk of regular feeding causing dietary problems. For more information: http://www.zsl.org/conservation/regions/uk-europe/native-birds/helping-red-kites,566,AR.html. And probably shouldn't be encouraged in urban areas due to the risk of attracting vermin.

The garden pond has been covered with snow and when broken each day for the birds to drink from it has been 5cm thick, in fact the pond weed is frozen into the ice and breaks when the pond is broken

Dr Jeremy Briggs has answered some of my pond questions and concerns in this blog post http://thegardenpondblog.org.uk/2010/01/07/questions-from-richard. It seems the oxygen producing pond weed will recover, but the pond snails and the rat tailed maggots (http://viewsoftheock.blogspot.com/2009/11/rat-tailed-maggots.html) may not fend so well.
The pond conservation trust has issued a press release on managing ponds in the cold weather: http://www.pondconservation.org.uk/aboutus/News/latestnews/PressRelease9Jan201.htm in summary, clear the snow (if safe), but don't worry about breaking the ice.


The Ock itself is still flowing but the water voles will have had a hard time of it - they don't hibernate, but instead shelter in their burrows where they can have a store of food and occasionally venture out for feeding. The harsh weather and recent high waters may have affected their ability to forage and caused possible drownings - unless they've moved location...
Any badgers in the locality would be tucked into their setts, having stocked up on food during autumn so unless they need to find food should not be impacted unless they need to forage.
The rabbits are probably in a similar situation, although this may impact on their predators - foxes and any stoats or weasels.

Unlike water voles, queen bumblebees do hibernate and I've been in touch with the Bumblebee Conservation Trust (http://www.bumblebeeconservation.org.uk/) who have told me there isn't any detailed research on the effect of severe cold weather on British bumblebees. Although there is an Arctic bumblebee (bombus polaris) - so bumblebees can survive in severe weather. A British queen will store enough reserves to make it through the winter, but in this extra cold weather she might shiver her flight muscles to create warmth, but the risk is if the cold snap continues she may run out of energy and die. Especially if her hibernating site isn't deep enough.
More information can be found at http://www.birdguides.com/webzine/article.asp?a=1896

Since I started writing this blog post the BBC have announced a special to their Autumnwatch / Springwatch series called 'Snow watch'; it will be on BBC2 on Wednesday 13th January on BBC2 (http://www.bbc.co.uk/blogs/autumnwatch/2010/01/snow_watch_we_need_your_help.html) 

But it won't be till spring till we see what the affect this cold spell has had on the local wildlife.

#UKSnow

16cm of snow fell in Oxfordshire last night (well in our back garden anyway), so a normal 45 minute walk to work increased to 1.5 hours, the fact that I took 107 photographs probably explains why it took so long.  But opportunities like this must be taken and once again it's also an excuse to play with the panorama software.
Four landscape pictures of the Ladygrove meadow shows a blanket of fresh snow:

The Ock Valley Walk was as picturesque as ever, but interestingly after last weeks flood watch it's not high (http://www.abingdonblog.co.uk/2009/12/mill-stream.html), as the lower Ock shows here:

The Abbey Meadows is always a good opportunity for a picture:

And another panorama of the Thames from the meadow:

Other pictures of Abingdon in the snow can be seen at: http://www.abingdonblog.co.uk/ and http://martingulliver.blogspot.com/

The progress of the snow can be seen on the twitter #uksnow map: http://uksnow.benmarsh.co.uk/