The RSPB’s reserve at Arne in Dorset recently requested the use of my wetland wildlife photos for their new seasonal interpretation panels. They also commissioned a stitched panoramic landscape image to highlight landmarks visible from their stunning observation point overlooking Poole Harbour.
Featured above are the Southern Hawker dragonfly, Osprey, Wasp Spider, Raft Spider and Marsh Harrier, all of which can be found on the Arne reserve at different times of the year. Well worth a visit!
You’d think that arachnids and water was an unhappy combination, but one species of European spider has made boggy ponds their home.
The raft spider (Dolomedes fimbriatus) is the UK’s largest native spider – its body growing up to 2cm long.
It uses the water’s surface like other spiders use their webs – feeling for the vibrations of potential prey with front legs extended. Using this technique it hunts tadpoles, insects and occasionally small fish:
Raft spider eating damselfly
When alarmed, the water repellent hairs on the raft spider’s legs enable it to dive beneath the water, trapping a bubble of air to keep it alive until the coast is clear and it cautiously re-emerges:
The wetland pools favoured by raft spiders are increasingly rare in this country. On the RSPB’s Arne reserve in Dorset their habitat is lovingly preserved, and offers wildlife watchers easy access from the nearby heathland trail:
Boggy pond habitat
On a good day dozens of raft spiders at various stages in their life cycle can be witnessed at the pond’s edge.
The female raft spider is often considerably larger than the male and mating is a dangerous business. He approaches her cautiously, waving his front legs tentatively to judge her receptiveness:
Male raft spider approaches female at her den
She may rush out to scare him off on numerous occasions, after which she retreats and the process begins again, the male edging closer all the while. It’s a nerve jangling thing to watch, let alone participate in.
The female spins a silk bag to contain the fertilised eggs, which she carries about beneath her body, keeping it just warm and moist enough to ensure their survival:
Raft spider carrying egg sac
Then, when the baby spiders are ready to hatch, she lashes the egg sac to vegetation at the edge of the pond and the tiny hatchlings emerge:
Baby raft spiders in nursery web
Mum typically lies in wait nearby to ensure that her young ones don’t come to any harm:
Raft spider guards her hatchlings
This phenomenon of hundreds of spiderlings crowded together for their own mutual safety is only really appreciated up close:
Raft spider hatchlings closeup
But soon the young raft spiders are large enough to fend for themselves and disperse around the pond.
Raft spiders are not fussy eaters. When times are tough and food is scarce, or when too many raft spiders compete for the same local resources, they may even turn to cannibalism:
What kind of crazy folk go out at night and gather round bright lights in the expectation of winged visitors? Stoned party-goers after a particularly heavy session? Die-hard pagan worshippers perhaps? And moth trappers obviously.
It was my delight both to participate in and bear witness to this strange spectacle on an evening with the Surrey Wildlife Trust and assembled experts on Chatley Heath in Surrey last month. It began innocuously enough with a barbecue meal and mildly alcoholic beverage, but then the great orb in the sky descended, the darkness gathered, and things began to get weird.
Moth trappers at Chatley Tower
A white sheet stapled to the side of Chatley Semaphore Tower and illuminated with fluorescent light set the stage for our distinguished guests to arrive, and it wasn’t long before the lure of this burning beacon drew them in.
Moth trapper with net
At which point all pretence of ceremony evaporated and a man with net in hand, a wild gleam in his eye, pounced with the irresistible speed of a coiled spring released!
Once netted, the moth in question was transferred to an improvised lab bench nearby for inspection, ID and recording.
Identifying and recording moths
Steadily a queue of nocturnal visitors grew, each enclosed in a cylindrical plastic cell, and each requiring identification. A few of the larger, more striking moths, were familiar to the interested observer, but – to all except the most dedicated experts present – the majority remained strange and new.
Moth trap jars with inmates, including the yellow brimstone moth
There are roughly 800 species of ‘macro moth’ in the UK. These are the species you will find illustrated in standard field guides on the subject. But there have been 2,400 species of moth recorded in the UK when ‘micro moths’ are accounted for, and only the high priests of this cult can read the runes of their colouring and patternation with any degree of certainty.
On this particular night 73 separate species of moth were recorded – the list of outlandish guests including:
Mother of Pearl
Dark Sword Grass
True Lovers’ Knot
Setaceous Hebrew Character
Elsewhere on the heath nearby an even brighter beacon was being kindled: a Skinner Trap, fitted with a blinding electric bulb powered by its own noisy generator.
Skinner moth trap and trappers
Not only is this contraption very effective at attracting moths, it’s also remarkably photogenic! A portal to another world appears to have opened up on the heath at night. And for all those present at this special event, it undoubtedly had.
Light rays illuminate the heath
Nobody knows precisely why these creatures of the night are attracted to bright lights amidst the darkness, but it’s fortunate for us that they are.
Post-industrial landscape reclaimed for wetland wildlife at RSPB Arne
The Arne peninsula in Dorset juts out into Poole Harbour, separating the Wareham channel from the main body of water. Right out at the tip, concealed by the remains of ancient oak woodland, lies a former ball clay pit.
The extraction company, Imerys, finished mining the deposit in 2008. Since 2010 they have been restoring the area as part of their mitigation agreement, before transferring ownership of the site to the RSPB, who manage the surrounding nature reserve at Arne.
I was asked to document this reclamation process on behalf of the RSPB, in particular the flooding of the claypit basin with water from the harbour to create a saline lagoon habitat for wading birds and other species.
With mining activities ended the pit was re-profiled with heavy earth-moving equipment, and a layer of topsoil deposited above the expected final water level in the summer of 2011.
Next, a channel was cut through the embankment to join the claypit with the harbour at the south end of the site. On especially high tides the water from the harbour would flood this channel to gradually fill the lagoon.
This process was expected to take many months and it was decided to document the process with a timelapse camera.
View to a spill
We surveyed the best location for the camera – somewhere with a wide view of the pit, a glimpse of the harbour in the background, a small island in the middle ground and some vegetation in the foreground to provide varied visual interest.
Unfortunately this necessitated pointing the camera due south, so we also calculated the position and angle of the sun in future months to try to minimise its dazzling effect on the camera’s lens and sensor.
The pit itself is off-limits, but there is public access to the surrounding area and it is too remote to monitor. Exposure to the elements over such a long period was also a consideration, so an expensive DSLR setup was not a practical option, and a relatively cheap-and-cheerful alternative was sourced.
The pit filled much more rapidly than the engineers had predicted and in April of the following year, after only 7 months, the rising water had achieved its final level.
The following video sequence shows events over that period, compressed to just 1 minute, using stills taken at 3 hour intervals:
The island habitat is already frequented by shelducks and sika deer regularly visit its shores. It will take longer for the waters to settle and for other species to establish themselves.
It’s hoped that the regular interchange of water with the harbour will prevent the process of eutrophication, which would otherwise make the lagoon inhospitable. The suspension of clay particles in the water can be a serious problem in this respect.
Whether this industrially exploited area becomes the wildlife oasis hoped for only time will tell.
With thanks to Mark, Rob, Damon, James and Em at RSPB Arne.