05 June 2011

Counting Moths

Last night I ran the same two 125w MV traps in the Nitten Field (above Mewslade Valley) as those run the previous night at Llanrhidian. Given that conditions were similar both nights it was quite interesting to compare results:
Skinner trap set at Llanrhidian
Over the two nights combined 140 species were recorded with only 64 of these being recorded at both sites. There were 101 species in Nitten, a mainly arable situation, but with cliffs not far away, and 102 species at Llanrhidian, a site at a woodland / marsh interface. Although near identical in the number of species recorded, numerically Nitten did much better with 1380 individuals compared with 447 at Llanrhidian. However, there were 17 Local species and 1 Nb at Llanrhidian with only 10 Local species at Nitten, indicating that Llanrhidian may have greater importance for localised species.
Red-necked Footman  is a Local species nationally
favours woodland where the larvae feed on lichens
As with my garden, Heart and Darts were the most numerous species at both sites at this time of year, with 452 at Nitten and 40 at Llanrhidian. Other numerous species in Nitten were Marbled Minor agg (210), Dark Arches (85), Setaceous Hebrew Character (80) and White Ermine (60). In addition to Heart and Dart, also in the top five at Llanrhidian were White Ermine (25), Buff Ermine (22), Flame Shoulder (20) and Dog's-tooth (20).
The ubiquitous Heart and Dart is our most
abundant moth at this time of year
This snapshot suggests that where arable land is managed sensitively, as is the case at the Nitten Field, these rather mundane looking habitats can be incredibly productive for invertebrates. This superabundance of prey must be a key factor in determining population levels of predatory bird and mammal species, yet without a moth trap we would not have clue about this incredible bounty.

For more photographs of moths trapped over the last two nights visit http://gmrg-vc41moths.blogspot.com/

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