Harvest Mouse Survey

Harvest mouse at night

Harvest mouse (Micromys minutus) captured on survey after dark

Last week I joined Surrey Wildlife Trust on a harvest mouse survey in wetland habitat beside the River Wey.

Harvest mice are tiny rodents 5cm in length. Their remarkable prehensile tails add an extra 6cm. They live in long tussocky grassland, reedbeds, hedgerows and around woodland edges, building a spherical nest of tightly woven grass, high up amongst the stems. We found several examples at this site:

Harvest mouse nest

Harvest mouse nests are woven from a mixture of living and cut grasses which provides excellent camouflage

Nests are the most obvious sign of harvest mouse activity since the animals are especially active around dawn and dusk and rarely spotted in the thick vegetation.

Dozens of rodent-friendly traps of different designs were set in the thick wetland reeds and grasses. Surrey Wildlife Trust staff and volunteers returned three times each day over the course of a week – at dawn, midday and dusk – to ensure that no trapped animals were left for any longer than necessary.

Rodent trap

Rodent trap baited with peanut butter, bird seed and dried blowfly larvae

After retrieval from the trap harvest mice are transferred to a transparent bag for weighing and sexing:

Harvest mouse in bag

Harvest mouse recovered from trap

Weighing harvest mouse

Harvest mice weigh only 5g on average

Once the details of each rodent have been recorded a small patch of fur is trimmed to identify any animals which are subsequently re-captured.

Harvest mouse being marked

Marking harvest mouse – a delicate operation!

The highest number of individuals captured was 12 one morning, making this the most abundant site for harvest mice in the county at present.

Harvest mouse in the hand

Harvest mice require very careful handling by trained experts

With thanks to Surrey Wildlife Trust staff and volunteers.

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Dartford Warbler Winter

Dartford Warbler Snow Drift

Dartford warbler (Sylvia undata) foraging on snow covered heathland

In the severe winter of 1962/63 the Dartford warbler (Sylvia undata) was almost wiped out in Britain. The national population dropped to just 10 pairs.

But in good breeding seasons, and with suitable habitat, its numbers are capable of bouncing back, thanks to repeated nesting and high survival rates among its offspring.

On the Surrey lowland heaths Dartfords have been doing well, re-colonising Thursley Common last year for the first time since a devastating fire in 2006.

During the recent freezing winter weather I photographed this Dartford warbler foraging in the snow on Chobham Common:

Dartford Snow Flurry

Dartford Snow Dipper

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The Cult of Moth Trapping

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

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 trap and man with net

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

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

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:

  • Water Veneer
  • Mother of Pearl
  • Maiden’s Blush
  • The Mocha
  • Lime-speck Pug
  • Coxcomb Prominent
  • Dark Sword Grass
  • Shuttle-shaped Dart
  • True Lovers’ Knot
  • Setaceous Hebrew Character
  • Neglected Rustic

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

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 from moth trap on heath

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.

With thanks to SWT Ranger Gemma.

Hobby Hawking

A former boating lake beside the A3 dual-carriageway in Surrey around rush-hour is not the first place you’d go looking for hobbies in the UK. But a pair of these young raptors fledged in the area this summer on land managed by the Surrey Wildlife Trust.

I’ve had good views of hobbies in Dorset before as they pursue their favoured dragonfly food, and whilst it’s reasonably easy to capture them eating their prey mid-flight, snapping the fleeting moment in which they close in and grasp their nimble prey is another matter.

On this particular gloriously warm and sunny September afternoon I sat by the lake shore and waited as a pair of birds arrived from the neighbouring heathland and began one of many bombing runs up and down the lake in front of me.

A handful of shots managed to freeze this aerial ballet between predator and would-be prey for a moment:

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When one of the hobbies paused from the fray in the branches of a pine overlooking the lake it was even joined by a sparrowhawk, which must have been studying its technique with some envy:

Hobby and sparrowhawk

Hobby and female sparrowhawk

To the victor, the spoils:

Hobby with dragonfly prey

Hobby with dragonfly prey