Spring Wood Ant Antics

Wood ant with heather seed

Wood ant (Formica rufa) foraging in early spring

The wood ant mounds among the pine trees were beginning to stir on my visit to the RSPB’s Arne reserve in Dorset recently.

Nests become active in early spring when worker ants begin to forage for food items and building materials to repair damage sustained over the winter months. Badgers, magpies, jays and other animals often raid wood ant nests for food.

Wood ant carrying twig

Wood ants are capable of carrying relatively heavy loads

Wood ant colonies can contain up to half a million individuals. On sunny days worker ants ‘sunbathe’ at the nest entrance to absorb heat and then re-enter the nest to release it – keeping it at a steady temperature. When the nest becomes too warm they open small vents to cool it down.

Wood ants at nest entrance

Sunbathing worker ants at nest entrance

The ants are particularly aggressive in springtime as they re-define their territories. Sometimes ants from weaker neighbouring colonies are recruited by force and carried back to the main colony.

Worker ant carrying another wood ant between nests

This species of wood ant is classified as Near Threatened (NT) in the IUCN Red List and classified in Great Britain as Local. Numbers seem to be increasing in the south of England but it has become locally extinct in parts of its former range in the north and east of England, the Midlands and north Wales.

Photographing ants is always a challenge because they’re small and they move very fast. It’s a good idea to keep your trousers tucked firmly into your socks when lying on the ground this close to a nest full of them! They will bite occasionally but can’t pierce skin. The formic acid they squirt in defence is too weak to harm humans.

Springwatched

Spider hunting wasp with spider

Spider hunting wasp with paralysed arachnid prey

The team at BBC’s ‘Springwatch Unsprung’ programme used a sequence of my photos to illustrate the intriguing behaviour of the spider-hunting wasp, Anoplius viaticus.

This solitary wasp targets spiders, which it paralyses with venom and then hauls back to its subterranean nest burrow. Once wrestled inside the female wasp will lay its eggs on the spider’s body for its larvae to eat when they hatch.

Bug expert Nick Baker explained that this species stores its prey before excavating the burrow and so the unattended spider often becomes the victim of a tug-of-war between Anoplius viaticus and other opportunistic wasps and ants.

BBC Springwatch studio broadcast

Chris, Nick, Michaela, Martin and the Springwatch gang

Natural history superstar Mr. Chris Packham then related the curious fact that one of his first ever TV assignments was to film this invertebrate behaviour on nearby Studland Beach – this being made all the more awkward because it’s also frequented by enthusiastic naturists! Happily this particular site was a safe distance to the north on the peninsula. 🙂

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Dorset Life: Hunters

A selection of my images illustrates an article about predatory animals and plants in the May edition of Dorset Life magazine, out this month.

Dorset Life magazine

Dorset Life: Dorset Hunters. Double spread I

Dorset Life magazine

Dorset Life: Dorset Hunters. Double spread II

Featured flora and fauna include: the kestrel, adder, red fox, otter, sundew, kingfisher and hornet robberfly. Words by Joël Lacey.

Available now at all good newsagents and supermarkets in the Dorset area!

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RSPB Panels

Interpretation panels

Interp panels at RSPB Arne

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.

Raft Spider Life Cycle

Raft spider on pond surface

Raft spider on pond surface

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

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

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.

1. Sex

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

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.

2. Birth

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

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

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

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

Raft spider hatchlings closeup

But soon the young raft spiders are large enough to fend for themselves and disperse around the pond.

3. Death

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:

Not such a pretty sight!

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