Friday, November 25, 2016

Otters as sentinels for environmental health

On Wednesday 23 November 2016, Dr Elizabeth Chadwick talked to the Society about the work of the Cardiff University Otter Project, which she has managed for twelve years. The talk emphasised the otter’s importance as an indicator species for the general health of river ecosystems, and as a charismatic umbrella species that provides a focus for education and freshwater habitat conservation.

The Eurasian otter (Lutra lutra), one of 13 otter species worldwide, has an extensive range extending across continental Europe, Russia, China, and parts of north Africa; though in modern times its populations have become fragmented. In the UK, populations dramatically declined between the 1950 and 1970s, with chemicals in the environment (e.g. PCBs and organochlorine pesticides) mainly to blame. However, this protected species has recovered in the UK, and its once-isolated UK populations are again interacting. Nevertheless, by nature it is non-sociable and lives at low densities, so it can be hard to spot in the countryside.

Dr Chadwick explained the different methods used to monitor otters. The main methods used by the Cardiff University Otter Project are the monitoring of spraint (faeces and scent gland secretions) and the post-mortem of dead otters (mainly roadkill reported by the public).

A study of the spraint otters deposit at prominent locations around their territories is revealing interesting information. The spraint contains 432 volatile chemicals, and its smell is unique to an individual. The components of the spraint marking also change with age, enabling adults and juveniles to be identified.

The Cardiff University Otter Project started collecting samples from dead otters in the 1990s, when it would process around 10 otters/year (this figure is now around 200/year due to the otter’s recovery). This large sample bank now amounts to 3,000 specimens that can be used retrospectively for a wide range of interdisciplinary studies. Dr Chadwick described some of the studies that Cardiff University and its collaborators have done with these samples. These include studies on the presence of chemical contaminants over time and the effectiveness of legislation (e.g. bans on pesticides and lead), parasites infecting otters, dietary studies from stomach contents (83% fish), and genetic studies over time as a more contiguous UK population re-established. New areas of study include looking for the presence of micro-plastics and a new wave of emerging pollutants (e.g. pharmaceuticals).

For further information, visit the project’s website:

Report by Stephen Nottingham

Monday, November 14, 2016

The Tremendous Oak


Possibly the biggest or oldest oak in Wales? Whilst out walking near Cwmdu in the Brecons recently my walking colleague, Ian Moody, and I came across a large oak. Whilst the object of our outting was walking we always keep an eye open for any wildlife of interest and have regularly recorded veteran  trees which go on to the Ancient Tree Register managed by the Woodland Trust. Amazingly there may be little or no protection for some of our oldest living things but there are calls for a specific National Tree Register for Wales. As the Woodland Trust comments:
'A national register will help to classify, celebrate, and protect each of Wales’ Trees of Special Interest for the rest of their days. It will also help landowners properly care for these incredible trees by allowing them to access more support through grants and specialist advice.
But the most important reason for a register is to celebrate these incredible and much-loved natural treasures!'

We have recorded 20 trees so far but these have all been veterans. A veteran tree is one which is in its second or mature stage of its life, an ancient tree in its final stage. As a general guide any oak with a girth of more than 6 metres is a possible candidate for ancient. Our oak, immediately adjacent to a public footpath came in at 10.36 metres and exhibited many of the other characteristics of an ancient tree such as hollowed-out trunk and  fallen branches. It was originally pollarded, often the case with many of our oldest oaks.

When we first reported it we did not know if it had been recorded previously so the response from the Ancient Tree Register staff was encouraging:
'This is a most remarkable ancient oak you have recorded in the Brecon Beacons. What a great find and thanks for adding it to the Woodland Trust’s Ancient Tree Inventory... Although the girth could be exaggerated by the trees condition, falling open, it still suggests this is one of the biggest and possibly oldest oaks in Wales.'

Interestingly whilst we were the first to record this tree we later came across an article in Broadleaf, the Woodland Trust magazine, which was about writer Horatio Clare ('Running for the Hills') where he said:
'... a slightly famous oak... It is the most extraordinary tree, partly for its position, high above the Cwmdu valley, with a view across the Brecon Beacons. My brother Alexander, my mother and I moved there after London, and the oak stands at the top of our lowest field so it was the first of our allies, the gatekeeper we passed on our way up the mountain. We used to speculate on whether it had seen the Romans build their camp, or the battles of Own Glyndwr's rising, one of which took place in the valley. The great poet of Tretower, Henry Vaughan, would certainly have seen it when he lifted his eyes to the hills'.

So, if you know of any venerable trees it is worth checking if they are on the Register and, if not, making sure they are added so they will get the attention and protection they deserve.

Text by Bruce McDonald
Photos by Bruce McDonald and Roy Carr

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