Monday 29 August 2011

Last of the summer water voles?

As summer gradually becomes autumn, the water vole mating season slowly grinds to halt and as they are no longer seeking mates or guarding territories they can be harder to see, especially as the days are now starting to get shorter.
So it is always a pleasure to see them, like this one, making the most of the arrowhead whilst it still grows.
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Wednesday 24 August 2011

Yet more dead crayfish

Regular readers of this blog would be aware of the occasional post featuring dead and half eaten signal crayfish (identified by the red claws). 
Certainly I seem to be building an interesting collection of photographs of these mutilated crustaceans (I wonder if there is a name for this?). The most recent being found during August along the Ock Valley walk:
This one was found earlier in the month, have only lost the end of the tail.
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The other was found on Saturday and suffered a very violent and frenzied death - having a claw torn off, it's lower half removed (probably eaten) and lost part of it's head.
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Whilst the death of the first could have several explanations, this one almost certainly is the result of an otter kill.
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The non native signal crayfish has committed a lot of damage on UK wildlife - eating fish eggs in the thousand, climbing up river banks to eat young kingfishers in their borrow and driving the native crayfish to the brink of extinction.
But maybe  the return of otters to UK rivers (http://www.bbc.co.uk/news/uk-england-14557381) has been assisted by this alien (and obviously tasty) invader.

Wednesday 17 August 2011

Signs of Autumn?

Although  meteorological calendar has autumn starting in September, there is a definite feeling that the seasons are already changing.  Not only are the days getting shorter, it seems to get dark at 8pm now and there is a definite chill in the morning.
There are more obvious signs that summer has come to an end.  The lavenders in the garden have lost their flowers and as a result there are no more bumblebeees on them.  Having existed for for only the spring and summer, most bumblebee nests will now be collapsing and will no longer be  requiring them.
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The blackthorn along the old canal, once in bloom in spring has now produced it's fruit:
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The barley growing in the fields is south Abingdon has now been harvested, leaving just stubble:
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This impressive caterpillar may appear to be a symbol of spring, but it is  actually looking to borrow into the leaf litter. Where it will pupate and see out winter, before hatching into an adult hawkmoth next summer.
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Still with autumn commencing there are other things to look forward to, the appearance of impressive fungus, the starlings forming their murmation and the return of Doctor Who.

Friday 12 August 2011

Rabbits

Introduced by the Normans when they invaded back in 1066, rabbits are now a ubiquitous sight in the meadows and fields throughout Britain:
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By  the 1950's rabbits reached an estimate population of nearly 100,000,000 and were considered a severe pest for farmers, so myxomatosis was released. Having the desired affect of reducing the rabbit population by 99%.
This massive reduction in the rabbit population had various side affects on other species.
Perhaps not surprising, there was an initial increase in plant variety, but this was eventually replaced by scrub. Some invertebrates - snails, marbled white butterflies and burnet moths benefited from the increased grass, yet others - adonis and large blue butterflies suffered, as well as sand lizards and ground nesting birds through the loss of habitat.
Surprisingly, foxes were not drastically affected, as they changed to catching voles, but this had the side affect of decreasing owl populations who now had less voles to catch. 
Other predators of rabbits- stoats and polecats - suffered the largest decline in numbers as did red kites and buzzards
Eventually rabbit populations built up an immunity to myxomatosis (although there are still small outbreaks) and the population has returned to an estimated several million and can be seen dashing into the undergrowth near the Ock:
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Not all rabbits are as quick and as rabbit numbers have increased, so have their predators:
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References:
Collins complete guide to British animals
Mammals of the British isles (Mammal Society)

Wednesday 3 August 2011

In search of sundew.

Whilst most plants gain their nutrients from the soil via their roots, others have have evolved to obtain theirs from other sources -  consuming insects.
Such insectivorous plants are the staple of wildlife documentaries,  so it somewhat of a surprise to find they can be found only of couple of miles from Abingdon. 
Growing in the fen at Parsonage Moor nature reserve is sundew.  A fascinating plant that secretes a glue from tentacles on it's leaves, which intices insects (which are fooled into thinking it is nectar) but instead of feeding, the unfortunate insect is stuck to the leaves, which slowly fold in as the insect is digested.
Parsonage Moor is part of the Cothill Fens network of nature reserves which are fed by  a series of springs, these feed into the Ock via Sandford Brook.  And trying to locate such a small, scarce inconspicuous plant  in such an environment is somewhat of a challenge - the fen is covered with tall reeds in which there are small pools where the sundew grow:
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Although there are paths running through the fen, there is a risk of damaging the rare plants and insects which also inhabit the fen, as well as accidentally stumbling into some deep water or scaring the ponies which are used to graze the fen to control the scrub:
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Fortunately another site exists in Oxfordshire where finding and photographing these remarkable plants is a lot more straightforward - the  Oxford Universitry Botanic Gardens, where there is an entire greenhouse devoted to insectivorous plants, including Sundew:
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