Monday, 18 June 2012

Northern snippets

Choughs, The Oa and a fat, juicy tipulid larva.

A welcome change of scenery last week looking at reserve issues on Islay, with The Oa and Loch Gruinart being the main sites visited.  An Otter in the bay below the campsite at Port Charlotte was a good start.  Management for Chough was one focus of the visit.  They prefer places with short, grazed pasture, less than 5 cm in height, and soft soils where they can probe to find food.  A specialist feeder on invertebrates, they will take beetles and their larvae, fly larvae (especially tipulid (Cranefly) larvae), ants, their grubs and pupae, and spiders.  Dung invertebrates are an important source of food.   Such food resources can be patchily distributed, as we found by sampling various areas of turf but we did turn up some particularly juicy tipulids in a key feeding area.

Marsh Fritillary butterflies are locally frequent on Islay. Attack by parasitoid wasps appears to have an important effect on the population dynamics of the butterfly and may help to explain its requirement for large habitat patches. Two parasitiod wasp species, Cotesia bignellii and C. melitaearum, are present in the UK  and are of conservation importance in their own right, one being specific to the Marsh Fritillary. Studies suggest that the parasitoid and its host may have a shifting metapopulation distribution, with the butterfly 'escaping' parasitism in some areas by dispersal and colonisation, with local extinctions occurring in other areas.
A Marsh Frit caterpillar with cocoons of emerged parasitiod wasp larvae.

Highlights of the trip included 30+ Chough, 6 crekking Corncrakes, 4 Golden Eagles, Hen Harrier, Tystie and Great Northern Diver.  Loch Grunart produced Corncrake and Quail calling together in front of a pair of Whooper Swans.  As well as an approachable flock of 20+ Chough, Ardnave Point also produced a typically tame migrant Dotterel.  And all this sandwiched between a daily menu of various local delicacies; from full Scottish breakfast with ‘square’ sausage and tattie scone through to sampling the local whiskies.

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