Sunday 04 June – RSPB Arne
Forty-seven members of the BOC, Bristol Naturalists and Bath RSPB joined the coach trip to Arne RSPB reserve. The weather was overcast with sunny spells and a bit windy, the rain holding off until the journey back. RSPB staff, Rob and George met us at Arne. We split into two groups for a guided tour of some of the reserve, including parts not normally open to the public.
My group walked up the West Trail passing remains of a WWII gun emplacement. Arne was a decoy for the cordite factory at Holton Heath and was heavily bombed. Some of the bomb craters are now wildlife-friendly ponds. A Neolithic barrow is close by. The barrow is on the highest point of the reserve and was once covered in bright flint nodules visible for miles in a treeless landscape. The barrow and the gun emplacement mark the beginning and end of lowland heath in Arne. The natural state of the land is oak woodland. Our Neolithic ancestors felled and burnt the trees. The thin, acid soils turned to heathland (which once stretched from Sussex to Devon). In the 1940s the heath converted to conifers for timber production. The RSPB is restoring the heathland landscape. A thick mulch of needles is left once the pines are gone. This prevents natural regeneration and is difficult and expensive to remove. The RSPB is experimenting with Mangalitza (woolly) pigs who root about exposing the soil. Heather seeds can remain dormant for 100 years and will germinate once exposed to light and air. The pigs also supply the bacon for the café which is harsh, but tastes delicious. The pigs are confined by an ineffective electric fence. They escaped and followed us like a pack of dogs as we walked down the hill.Arne is a stronghold for Dartford Warblers. In the 1960s only ten Dartfords survived in the whole country with just two in Arne. With careful management, Arne now has up to 70 pairs. The birds don’t migrate and are very vulnerable to cold winters. They have up to three broods a year so recover from population crashes quite quickly but they are slow to recolonise if they become locally extinct. The gorse is coppiced in rotation to create low, dense bushes that shelter the birds, and the spiders they prey on, from winter snow. We had a good view of a family of four Dartfords, in spite of the wind.
The heath is also home to Smooth Snake, Adder, Grass Snake, Common and Sand Lizards. We were shown a number of shallow, oval holes created by Sand Lizards excavating burrows for their eggs. We saw one female lizard in the act. Rare Ladybird Spiders (as seen on Autumnwatch) are captive bred and released onto the reserve, so far going well with an expanding population.
After the tour, we were free to explore the rest of the reserve. Coombe Heath is to the south. This looks out over Middlebere Lake (part of Poole Harbour). This area is good for Dartford Warbler, Stonechat, Linnet, Meadow Pipit. We were unlucky not to see Osprey. A young male has adopted one of the artificial nest sites but on Sunday he was elsewhere.
To the north, the reserve consists of mixed woodland (oak, birch and pine), farmland pasture and patches of heath. A colony of Black-headed and Mediterranean Gulls nest on Long Island. An evildoer stole all the eggs last year (apparently gulls’ eggs are a thing in posh restaurants). Increased vigilance this year has led to a successful breeding season, although the only Mediterranean gull seen was in Middlebere Lake. Common and Sandwich terns nest on Brownsea Island but we saw not one! However, one member saw a group of Avocet in the distance. Plus a couple of Common Seal.
A very enjoyable and interesting day out. As is normal with birding ‘we should have been there yesterday’ but we saw 59 species including a Red Kite from the coach (near Shaftesbury). (thanks Alastair for the organisation and leading) Alastair Fraser