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Species of the month

Every month it is our aim to highlight a species that is “in-season” and, although not necessarily rare or difficult to identify, has been highlighted by our local recording groups as being somewhat under-recorded and for which new records would therefore be welcomed.

If you or your recording group are aware of species such as this then please contact Bob Foreman.

 

August: Silver-spotted Skipper Hesperia comma

Silver-spotted Skipper Map

Heatmap of distribution of all Hesperia comma records - blue dots show 1km squares occupied between 1970 - 1990
Source: SxBRC

Silver-spotted Skipper - Bob Eade

Silver-spotted Skipper, Cradle Valley
Photo: Bob Eade

Silver-spotted Skippers - Bob Eade

Mating Silver-spotted Skippers, Cradle Valley
Photo: Bob Eade

In the 1970s there was a distinct possibility that this heat loving species might become extinct in East Sussex. It was already, at this time completely absent from West Sussex. The only locations it could be seen were a couple of sites on the Downs east of Lewes. However, from this low point the butterfly has spread westwards, occupying most suitable habitat in East Sussex and as far west as Chantry Hill and Cissbury Ring in West Sussex.

Adults will only be active when the temperature is above 20°C and the females require a temperature of at least 25°C before they will lay eggs on the preferred larval foodplant, Sheep's-fescue Festuca ovina. Unsurprisngly, the hot, dry, close-grazed slopes of the downs are the butterfly’s chosen habitat. The decline of the species to its 1970 low-point was undoubtedly as a result of scrub-encroachment and loss of rabbits and their grazing habits to myxomatosis. Its westward resurgence is, no doubt, a result of not only increased conservation grazing across the Downs, expanding the areas of suitable habitat but also climatic heating, which is in all probability the major factor.

One of the latest species to emerge, adults are normally first seen in mid- to late-July with numbers peaking in early August. Where it is present, this distinctively marked skipper can be seen in good numbers at this time of year (if maybe, a little difficult to spot owing to its size, high-speed flight and whirring wings). The best sites to see the species in Sussex are probably High and Over, Malling Down (in East Sussex), Newtimber and Wolstonbury Hills, Cissbury Ring and Chantry Hill in West Sussex but there are plenty of other suitable locations that it might turn up and all records of the species are particularly welcome, particularly via iRecord.

Text borrows heavily from The Butterflies of Sussex by Neil Hulme and Michael Blencowe

 

 

July: Glow-worm Lampyris noctiluca

Glow-worm Neil Fletcher

Glowing female Glow-worm
Photo: Neil Fletcher

Glow-worm Derek Middleton

Male Glow-worm
Photo: Derek Middleton

Glow-worm Charles Roper

Glow-worm larva
Photo: Charles Roper

Glow-worm map

Heatmap of distribution of Glow-worm records in Sussex
Source: SxBRC

Glow-worms Lampyris noctiluca are sexually dimorphic beetles, with a male that resembles a traditional beetle while the females are larviforme.

You can find L. noctiluca in chalk grassland margins, edges of hedgerows and railway embankments, through June and July with lower numbers into August. The wingless females are up to 25mm long and emit a bioluminescent glow from the two bottom sections of the lower abdomen for a few hours each night in order to attract the mostly glow-less male, and can often be found sitting on a stem or leaf to show off their light. They spend the day in the understory. Adults do not feed, conserving their energy for attracting a male and mating.

Males will come to light, so if you have a moth trap or open window, keep an eye out for the mostly brown-black beetle, 15-18mm in length with brown elytra, a clear pronotum with a brown spot in the centre. Males can have a faint glow, but it is the females that will catch your eye on a summer evening.

Larvae can be seen from April to October, similar to ladybird larvae but bigger and flatter, with pale orangey spots at the edge of each segment. They can be seen on paths in daylight when looking for prey of slugs and snails, which they inject with digestive juices through a series of bites that paralyse their prey until it dissolves the soft body into a drinkable fluid.

There is a lot of science to how and why they glow which is far better explained by an expert than by me, a casual Glow-worm enthusiast, so the paragraph below is copied from the UK Glow-worm survey:

The light from glow worms is cold, and is a form of bioluminescence. It is far more efficient than most light sources we are familiar with. It is caused when a molecule called luciferin is oxydised to produce oxyluciferin, with the enzyme luciferase acting as a catalyst in the reaction. Adult Lampyris noctiluca do not have the same control over the oxygen supply of many fireflies, which can switch their lights on and off in an instant, and take minutes to switch on or off. Larvae, however, have smaller light-emitting organs and can twinkle briefly. Male glow worms have the same ability, but it is rare to see them glow.

The Lesser Glow-worm Phosphaenus hemipterus can be confused for the larger L. noctiluca, but both male and female of P. hemipterus are flightless, and communicate with hormones rather than light so will only illuminate when disturbed.

Glow-worm populations face a number of environmental challenges that have seen populations fall by 3.5% a year over the last 18 years. Submitting records can help give us a better picture of how populations are doing in Sussex. They are also a fantastic natural spectacle, if you have the time and enthusiasm for a late night summer walk.

More information on Glow worms can be found on the UK Glow-worm survey homepage: https://www.glowworms.org.uk/
You can submit records to iRecord using the custom form: https://irecord.org.uk/enter-glow-worm-record

Lois Mayhew
SxBRC Biodiversity Projects Officer (and resident Glow-worm fan)

 

 

June: Glow-worm Lampyris noctiluca

Glow-worm Neil Fletcher

Glowing female Glow-worm
Photo: Neil Fletcher

Glow-worm Derek Middleton

Male Glow-worm
Photo: Derek Middleton

Glow-worm Charles Roper

Glow-worm larva
Photo: Charles Roper

Glow-worm map

Heatmap of distribution of Glow-worm records in Sussex
Source: SxBRC

Glow-worms Lampyris noctiluca are sexually dimorphic beetles, with a male that resembles a traditional beetle while the females are larviforme.

You can find L. noctiluca in chalk grassland margins, edges of hedgerows and railway embankments, through June and July with lower numbers into August. The wingless females are up to 25mm long and emit a bioluminescent glow from the two bottom sections of the lower abdomen for a few hours each night in order to attract the mostly glow-less male, and can often be found sitting on a stem or leaf to show off their light. They spend the day in the understory. Adults do not feed, conserving their energy for attracting a male and mating.

Males will come to light, so if you have a moth trap or open window, keep an eye out for the mostly brown-black beetle, 15-18mm in length with brown elytra, a clear pronotum with a brown spot in the centre. Males can have a faint glow, but it is the females that will catch your eye on a summer evening.

Larvae can be seen from April to October, similar to ladybird larvae but bigger and flatter, with pale orangey spots at the edge of each segment. They can be seen on paths in daylight when looking for prey of slugs and snails, which they inject with digestive juices through a series of bites that paralyse their prey until it dissolves the soft body into a drinkable fluid.

There is a lot of science to how and why they glow which is far better explained by an expert than by me, a casual Glow-worm enthusiast, so the paragraph below is copied from the UK Glow-worm survey:

The light from glow worms is cold, and is a form of bioluminescence. It is far more efficient than most light sources we are familiar with. It is caused when a molecule called luciferin is oxydised to produce oxyluciferin, with the enzyme luciferase acting as a catalyst in the reaction. Adult Lampyris noctiluca do not have the same control over the oxygen supply of many fireflies, which can switch their lights on and off in an instant, and take minutes to switch on or off. Larvae, however, have smaller light-emitting organs and can twinkle briefly. Male glow worms have the same ability, but it is rare to see them glow.

The Lesser Glow-worm Phosphaenus hemipterus can be confused for the larger L. noctiluca, but both male and female of P. hemipterus are flightless, and communicate with hormones rather than light so will only illuminate when disturbed.

Glow-worm populations face a number of environmental challenges that have seen populations fall by 3.5% a year over the last 18 years. Submitting records can help give us a better picture of how populations are doing in Sussex. They are also a fantastic natural spectacle, if you have the time and enthusiasm for a late night summer walk.

More information on Glow worms can be found on the UK Glow-worm survey homepage: https://www.glowworms.org.uk/
You can submit records to iRecord using the custom form: https://irecord.org.uk/enter-glow-worm-record

Lois Mayhew
SxBRC Biodiversity Projects Officer (and resident Glow-worm fan)

 

 

May: White-spotted Sable Anania funebris

Anania funebris - Bob Eade

White-spotted Sable Anania funebris
Woodland near Ringmer, 2014
Photo:Bob Eade

Anania funebris distribution

Map showing distribution of records for Anania funebris
Source: Sussex Moth Group/SxBRC

Distribution map for Solidago virgaurea

Distribution map for Solidago virgaurea
Generated from SBRS data by SxBRC

Anania funebris Bob Eade

White-spotted Sable Anania funebris
Denge Wood, Kent
Photo: Bob Eade

A member of the family Crambidae, the White-spotted Sable Anania funebris is an extremely distinctive and attractive day-flying micro moth that can be found, usually in woodland rides and glades, during the latter half of May and most of June, it is single brooded. Extremely local and favouring limestone areas, its distribution in the British Isles includes Sussex and Kent but it appears to be more frequently recorded in parts of west Wales, western England, Scotland and Ireland.

The adult moth has a wingspan of approximately 20mm and it flies, in sunshine, with a fast, spinning motion making it very difficult to follow, only being straightforward to identify when it has settled. In flight it could possibly be mistaken for a Grizzled Skipper Pyrgus malvae which, although it doesn’t ‘spin’ in flight is similarly difficult to see. Another possible confusion species is the closely related Spotted Magpie (or Elder Pearl) Anania coronata, also dark with white blotches on the wings these are less clearly defined, the latter species also lacks the distinctive yellow flanks on the thorax of A. funebris, A. coronata is also much less likely to be encountered during the daytime.

The larvae of Anania funebris feed exclusively on Goldenrod Solidago virgaurea (although some sources suggest that Dyer’s Greenweed Genista tinctoria is also used) which, as can be seen from the distribution map above is not uncommon and is widely distributed. However, the moth itself is very scarce in Sussex and we have very few records in the database from either of the two Vice Counties. The only records we have from the 20th Century are from woodlands to the northeast of Lewes, the most recent being from 2014. In the 1990s it was recorded at Chailey Common on a few occasions but not since. Sadly, it is possible that the moth is extinct in Sussex but it would be very good news if it were proved otherwise.

Please keep an eye out when you’re walking in the woods in May or June (especially if Goldenrod is present) and report any sightings, with photos to iRecord.

 

 

April: Lords and Ladies or Cuckoo-pint Arum maculatum

Arum italicum subsp neglectum

Distribution map for Arum italicum subsp neglectum
Generated from SBRS data by SxBRC

Arum italicum subsp italicum

Distribution maps for Arum italicum subsp italicum
Generated from SBRS data by SxBRC

If there were a prize for the UK wild flower with the largest number of English names I’m pretty sure this one would win it... and many of its names are rather rude. It is the fault of the unapologetically upright member which wobbles within a sort of open cloak, together making up the most obvious part of the flower. The function of this arrangement is to help attract small insects so that they drop into the small chamber below where the business of pollen transfer takes place. Of course, all this happens in spring when love is in the air, with birds dating and mating, and green shoots bursting out everywhere. The ‘pint’ in Cuckoo-pint, I cannot avoid mentioning, is derived from ‘pintle’, an old nickname for the appendage of the male. But let’s try not to think about all that.

The common Lords and Ladies with pale spadix and spathe

The common Lords and Ladies with pale spadix and spathe.
Photo: Nick Sturt

Form with dark spadix within an unusually dark spathe

Form with dark spadix within an unusually dark spathe.
Photo: Nevil Hutchinson

Many plants of the common Lords and Ladies have speckled leaves

Many plants of the common Lords and Ladies have speckled leaves.
Photo: Nevil Hutchinson

Lords-and-ladies (aka Bulls and Cows, Wake Robin, Dog’s Dibble - sorry!) is a widespread and common species in England and Ireland but north of the border in Scotland, where it does occur sparingly, it is not considered a true native. In Sussex it has been recorded in more than 94% of the 1,000 or so 2x2 km squares. Its favoured habitats include woodlands, hedge banks and other shaded areas on moist, well-drained and reasonably fertile soils; and it frequently crops up in gardens. In January and February underground tubers send up leaves which emerge rolled up and in clusters; they then unfold into a more or less arrowhead shape, often shiny green and looking as if they have had a fresh coat of gloss paint. Some plants have dark blotches on the leaves due to the pigment anthocyanin, in others the leaves are plain. The flowers appear typically in April - a tall, pale green hood-like sheath (the spathe) loosely enfolding the suggestive little ‘pestle’ or ‘clapper’ (the spadix) which may be purplish-brown or pale yellow-cream. In some individuals there is a smart dark border to the spathe and occasionally even spots. Although research has been carried out into these variations in appearance no firm conclusions have been reached as to any advantage conferred by some forms over others.

The ingenious mechanism whereby small insects are detained and presented with first the stigmas and then the stamens before being released is described in detail in Cecil Prime’s New Naturalist monograph Lords and Ladies (1960). What follows is an abbreviated account and it will help to look carefully at the excellent photograph of the flowers in cross-section kindly provided by my assistant Nevil. It has been observed that the spadix itself heats up and emits an odour attractive to flies. The scent is detectable to some humans at least, descriptions varying but united by a general theme of the bodily and the unpleasant. The surrounding spathe helps to funnel the insects into the lower chamber: they slip through a weft of one-way hairs and reach the base of the spadix where the rings of stigmas and stamens are located. Firstly they have the chance of depositing any pollen they may have gained from another Arum maculatum plant on the stigmas, which are receptive. Later, the host’s stamens present their own pollen for the insect to blunder into. After that they are free to go because by now the hairs guarding the way back up and out of the chamber have relaxed. So the escapee is free and will almost certainly fall for the same trap in another Lords and Ladies flower. Note that this mechanism is designed, through the different timing of the development of stigmas and stamens, to avoid self-pollination.

Cross-section of flowers

Cross-section of flowers. Arranged around the base of the spadix you can see the yellowish one-way hairs, the dark band of stamens and below them the stigmas.
Photo: Nevil Hutchinson

Ripe fruit

This is actually the ripe fruit of the Scarce species but the common one is very similar.
Photo: Nick Sturt

Emerging leaves of Scarce Lords and Ladies

Emerging leaves of Scarce Lords and Ladies.
Photo: Nick Sturt

All sorts of different insects turn up for no good reason in the Arum flower but it seems that the chief pollinator, the one which falls into the trap time and time again, is the Moth- or Drain-fly Psychoda phalaenoides. After pollination the weeks pass and then in June, by which time the spathe has withered away, there is a knobbly cluster of green berries. These turn orange and are taken by birds, which in due course void the seeds away from the parent plant, so achieving the desired dispersal.

In Britain the first mention of Lords and Ladies occurs in Turner’s Herbal of 1538 as ‘Cockowpyntell’. The herbalist repeats the story found in the Greek and Roman writers that bears seek it out after waking from hibernation as it prepares their gut for the intake of food again; but he does not make any recommendations regarding its medicinal use for humans. Sussex’s own Culpeper, on the other hand, provides a long and occasionally gruesome list of its applications for just about anything from plague to freckles; but he then refuses to vouch personally for any of the cures with the wonderful disclaimer ‘Authors have left large commendations of this herb, but for my part I have neither spoken to Dr Reason nor Dr Experience about it.’

A domestic use has more authority: the boiling of the tubers to create a starch which was employed for several centuries and, apparently, much in demand in Elizabethan times for laundering ruffs. On the Isle of Portland there was a local manufactory of this product which was known as ‘Portland Sago’. Actually this industry, which died out towards the end of the 18th century, processed the tubers of a related, species, Scarce Lords and Ladies (Arum italicum subsp. neglectum). The Scarce plant is slightly larger and restricted in its distribution to the extreme south of England and Wales. In Sussex it was first recognised in 1859 by William Borrer of Henfield growing in Offington near Worthing. Its leaves emerge in November, significantly earlier than those of A. maculatum, and it can be found in West Sussex scattered over the coastal plain and also on the other side of the Downs towards the base of the scarp slope: the distribution map, based on 2x2km squares, shows this very well - the small dots indicate records from 1966 to 1999, the rings 2000 to 2015, and the amalgamation of the two into large dots records from both those periods. Should you wish to see the Scarce Lords and Ladies it is particularly plentiful along Mill Road Arundel in drifts near the Box bushes on the way to the Wildlife and Wetlands Trust reserve; Mouse Lane in Steyning is another good site. The earlier appearance of the leaves is one of the best distinguishing features: they tend to come up in scattered patches without the same rolled-up shape on emergence as the common species; the mature leaves have a more leathery texture and the veins are pale, sometimes an almost creamy colour. The Scarce Lords and Ladies also flowers later, typically in July, and the spadix - marginally chunkier - is always a pale yellow. Because of the different flowering times hybrids between A. maculatum and italicum subsp. neglectum are unusual - but not unknown and possibly overlooked.

Cross-section of flowers

Mature leaves of Scarce Lords and Ladies showing creamy venation.
Photo: Nick Sturt

Ripe fruit

Scarce Lords and Ladies has a chunkier spadix which is always pale.
Photo: Nick Sturt

Emerging leaves of Scarce Lords and Ladies

The spectacularly veined leaves of a garden variety of Arum italicum subsp. italicum.
Photo: Nick Sturt

Finally, mention should be made of Arum italicum subsp. italicum which will be familiar to many a gardener. Over the years this native of the Mediterranean has been selected for its white leaf venation and varietal names such as pictum (‘painted’) and marmoratum (‘marbled’) have been applied. The garden plant does ‘escape’, usually as a throw-out by roadsides, and the accompanying distribution map with its random scatter of dots makes a good contrast with the concentration of dots displayed by its native relative.

Flora of Sussex

Records of the common Lords and Ladies would be especially welcome when accompanied by photographs and/or notes on the degree of anthrocyanin pigmentation on leaves and spathe, and also the spadix colour. Sightings of A. italicum subsp. italicum outside of cultivation will also be appreciated and added to the dot map compiled by the Sussex Botanical Recording Society. The native subspecies neglectum does not extend into East Sussex as a native plant, though it has been found just occasionally as a presumed introduction with imported soil; otherwise its eastward distribution seems to stop abruptly at the Ordnance Survey TQ20 line.

If you want to learn more about the 2,500 or so vascular plant species which occur or have ever occurred in Sussex you are recommended to acquire a copy of the 2018 Flora of Sussex published by Pisces which is available from good bookshops or by contacting the Sussex Botanical Recording Society. The next step would be to consider joining the society itself and so enjoy recording and studying the fascinating wild flowers of our county in the company of enthusiastic and knowledgeable field botanists. We don’t often use the rude English names of plants although I can’t speak for Nevil.

Nick Sturt
Chairman Sussex Botanical Recording Society

 

 

March: Lesser Spotted Woodpecker Dryobates minor

Lesser Spotted Woodpecker - Phil Wallace

Lesser Spotted Woodpecker Dryobates minor
Photo: Phil Wallace ( www.birdmad.co.uk)

The Lesser Spotted Woodpecker Dryobates minor is one of a small set of extremely elusive and rather scarce woodland species which is challenging yet addictive to study. At 14-16.5cm in length, it the same size as a House Sparrow, making it diminutive compared to our two other resident woodpeckers, Great Spotted Dendrocopos major and Green Picus viridis.

This bird is not a long-distance migrant but has suffered similar population declines to species which take long and risky migrations, like Turtle Dove and Nightingale, with an 83% decline since 1970. Since 2010, records have been gathered by the Rare Breeding Birds Panel (RBBP), a dubious honour which applies to birds with a UK population of no more than 2,000 pairs.

Although a sedentary species, it is unusual in that it is only likely to be encountered at a specific time of year, late winter and early spring. The rest of the year, it really does melt away into the woodland and becomes all but impossible to detect. However, when the days are a little warmer and the first butterflies are emerging, until the leaves appear on the trees, it becomes rather easy to find in the right places.

At this time of year, both males and females drum regularly near the site they will excavate their nest, something they do anew each year. It is subtly different to the more familiar sound of drumming Great Spotted Woodpeckers, but the flat and relatively weak delivery, and longer duration, is noticeable with just a little experience. The Lesser Spotted Woodpecker’s advertising call is hard to miss, being a high-pitched ‘pii-pii-pii-pii...’ It is reminiscent of a Kestrel’s call but is of a much purer tone, somewhat higher pitched and tends to go on for longer, up to 15 notes.

With real luck and patience, pair bonding displays involving short flights on exaggerated wingbeats (‘butterfly flight’) and spread wings when settled can be observed. Males and females can be distinguished by the colour of the crown, red on males and white on females. Once the nest cavity has been excavated, a hollow which can be as deep as 18cm, between four and six white eggs are laid, which hatch after 11 or 12 days. The young fledge after a further 18 to 20 days.

The reasons behind the stark decline of Lesser Spotted Woodpecker have been uncertain, with theories including habitat fragmentation and pressure from the increasing Great Spotted Woodpecker, a generalist woodpecker which is able to take advantage of garden bird feeders. It has recently been shown that low breeding productivity is driving the population decline. Although no trends were found in nest survival during the egg stage or chick rearing, the number of young fledged has declined year-on-year, probably due to starvation of young.

The Woodpecker Network follows up sightings of Lesser Spotted Woodpeckers to monitor breeding success, sometimes using nest inspection cameras to get a rare glimpse at the goings on inside the nests of this fascinating bird, to learn more about the challenges faced by the species.

Please report sightings of Lesser Spotted Woodpecker via BirdTrack and to The Woodpecker Network, complete with a six-figure grid reference. Remember that Lesser Spotted Woodpecker sightings at any time of year are likely to relate to breeding pairs in the area and are worth following up in late winter and early spring.

David Campbell
Recorder, Sussex Ornithological Society

 

 

February: Common Shrew, Sorex araneus

Sorex araneus - Derek Middleton

Common Shrew Sorex araneus
Photo: Derek Middleton

Sorex araneus - Derek Middleton

Common Shrew Sorex araneus
Photo: Derek Middleton

The evolution of modern-day shrews extends back almost unchanged for more than 48 million years. They're an incredibly successful group, belonging to an ancient lineage of insectivorous mammals, some of which were remarkably 'shrew-like' and shared the planet's surface with the mighty Dinosaurs of the Jurassic. The Common Shrew Sorex araneus lives up to its name, the most abundant member of its family, found typically in woodland, grassland and hedgerows in significant densities. Their frenetic but elusive nature rarely offers us more than a glimpse of them, but they are in fact our second most numerous mammal after the Field Vole Microtus agrestis (excluding urban rodents), with estimates of between twenty and fifty living within an area the size of a football pitch. Their prehistoric ancestry has left them with a rather unspecialised body plan and some primitive features including poor eyesight and the retainment of a cloaca, a single posterior outlet for the digestive, reproductive and urinary tract. This is markedly different from all placental mammals and is shared by birds, reptiles, amphibians and cartilaginous fish.

The solitary and bad-tempered Common Shrew is rather diminutive, usually weighing in somewhere between a 10 pence and £2 coin. They may be tiny, but don't let that fool you for they're one of our most voracious predators, a fierce fizzing ball of unstoppable energy. Their little hearts may beat at between 500-1000 beats per minute and they live life at a furious pace. A large surface area to volume ratio means they can't retain heat for long, so to stay warm they have a considerable metabolic rate and short life-span. They'll rarely survive much beyond a year. Their supercharged metabolism sees them in almost perpetual motion, day and night, taking just short naps before resuming their necessity to eat. And boy do they need to eat. The Common Shrew's life is quite simply dominated by food, for it must feed every two to three hours and eat almost its own body weight each and every day, a disturbing thought when extrapolated into human terms. They'll munch their way through insects, spiders (arachnids), worms (annelids) and slugs and snails (molluscs) sometimes tackling prey even longer than themselves. Their manic lifestyle and low fat reserves leave them unable to hibernate during the depths of winter - somewhat remarkably their body size, major organs and brain will all shrink, a helpful method of reducing their energy requirements.

Though some aspects of the Common Shrew's anatomy are primitive, they happen to have decent hearing and employ both a superb sense of smell and acute sense of touch, courtesy of a lengthy nose and super sensitive whiskers, known as vibrissae. The shrew's olfactory lobes (relating to smell) are notable, guiding it whilst it explores and probes its territory, the flexible nose working in a frenzy until the whiskers brush a potential item of prey. Incredibly, they have an additional trick up their mammalian sleeves for they produce ultrasound, helping them navigate their natural micro-world in the same manner as a bat. The aggressively territorial shrew may emit ultrasonic sounds when fighting, courting, when agitated and possibly even when hunting - spring and summer are the perfect time to listen for high-pitched twittering from the hedgerow. Shrews have many predators but are often found dead and abandoned owing to a rather repellant liquid secreted from glands on their skin. In their short lives, the polyandrous female will mate with multiple males and may yield up to four litters. Once a few weeks old a shrew family may relocate through the amusing process of 'caravanning', where the young grasp the tail of the preceding shrew and follow their mother, forming a 'chain-like' interpretation of a favourite British pastime.

Should you happen to see a shrew, how do you know if it's definitely a Common? This is a remarkably good question, for the Common Shrew is actually just one of three shrew species that you might spot on the British mainland. Excusing the larger and much darker Water Shrew Neomys fodiens, the main point of confusion will be with the diminutive Pygmy Shrew Sorex minutus. In actuality there are a few key points that'll aid differentiation. The Common Shrew has more typically tri-coloured fur - a darker back, slightly paler flanks and a pale belly. The Pygmy Shrew is bi-coloured - with a medium brown back and pale belly. They are also only two thirds the size of the larger Common Shrew, with a longer tail in relation to their body size. Think 6-8cm for a Common with a tail half that length. Compare this to a Pygmy at 4-6cm with a tail two thirds the length. Of course, there's always going to be some crossover, but with a decent view the differences should be apparent.

Please submit any sightings of Shrews (Common or otherwise!), with photos if possible to iRecord.

James Duncan
Mammal

 

 

January: Common Shrew, Sorex araneus

Sorex araneus - Derek Middleton

Common Shrew Sorex araneus
Photo: Derek Middleton

Sorex araneus - Derek Middleton

Common Shrew Sorex araneus
Photo: Derek Middleton

The evolution of modern-day shrews extends back almost unchanged for more than 48 million years. They're an incredibly successful group, belonging to an ancient lineage of insectivorous mammals, some of which were remarkably 'shrew-like' and shared the planet's surface with the mighty Dinosaurs of the Jurassic. The Common Shrew Sorex araneus lives up to its name, the most abundant member of its family, found typically in woodland, grassland and hedgerows in significant densities. Their frenetic but elusive nature rarely offers us more than a glimpse of them, but they are in fact our second most numerous mammal after the Field Vole Microtus agrestis (excluding urban rodents), with estimates of between twenty and fifty living within an area the size of a football pitch. Their prehistoric ancestry has left them with a rather unspecialised body plan and some primitive features including poor eyesight and the retainment of a cloaca, a single posterior outlet for the digestive, reproductive and urinary tract. This is markedly different from all placental mammals and is shared by birds, reptiles, amphibians and cartilaginous fish.

The solitary and bad-tempered Common Shrew is rather diminutive, usually weighing in somewhere between a 10 pence and £2 coin. They may be tiny, but don't let that fool you for they're one of our most voracious predators, a fierce fizzing ball of unstoppable energy. Their little hearts may beat at between 500-1000 beats per minute and they live life at a furious pace. A large surface area to volume ratio means they can't retain heat for long, so to stay warm they have a considerable metabolic rate and short life-span. They'll rarely survive much beyond a year. Their supercharged metabolism sees them in almost perpetual motion, day and night, taking just short naps before resuming their necessity to eat. And boy do they need to eat. The Common Shrew's life is quite simply dominated by food, for it must feed every two to three hours and eat almost its own body weight each and every day, a disturbing thought when extrapolated into human terms. They'll munch their way through insects, spiders (arachnids), worms (annelids) and slugs and snails (molluscs) sometimes tackling prey even longer than themselves. Their manic lifestyle and low fat reserves leave them unable to hibernate during the depths of winter - somewhat remarkably their body size, major organs and brain will all shrink, a helpful method of reducing their energy requirements.

Though some aspects of the Common Shrew's anatomy are primitive, they happen to have decent hearing and employ both a superb sense of smell and acute sense of touch, courtesy of a lengthy nose and super sensitive whiskers, known as vibrissae. The shrew's olfactory lobes (relating to smell) are notable, guiding it whilst it explores and probes its territory, the flexible nose working in a frenzy until the whiskers brush a potential item of prey. Incredibly, they have an additional trick up their mammalian sleeves for they produce ultrasound, helping them navigate their natural micro-world in the same manner as a bat. The aggressively territorial shrew may emit ultrasonic sounds when fighting, courting, when agitated and possibly even when hunting - spring and summer are the perfect time to listen for high-pitched twittering from the hedgerow. Shrews have many predators but are often found dead and abandoned owing to a rather repellant liquid secreted from glands on their skin. In their short lives, the polyandrous female will mate with multiple males and may yield up to four litters. Once a few weeks old a shrew family may relocate through the amusing process of 'caravanning', where the young grasp the tail of the preceding shrew and follow their mother, forming a 'chain-like' interpretation of a favourite British pastime.

Should you happen to see a shrew, how do you know if it's definitely a Common? This is a remarkably good question, for the Common Shrew is actually just one of three shrew species that you might spot on the British mainland. Excusing the larger and much darker Water Shrew Neomys fodiens, the main point of confusion will be with the diminutive Pygmy Shrew Sorex minutus. In actuality there are a few key points that'll aid differentiation. The Common Shrew has more typically tri-coloured fur - a darker back, slightly paler flanks and a pale belly. The Pygmy Shrew is bi-coloured - with a medium brown back and pale belly. They are also only two thirds the size of the larger Common Shrew, with a longer tail in relation to their body size. Think 6-8cm for a Common with a tail half that length. Compare this to a Pygmy at 4-6cm with a tail two thirds the length. Of course, there's always going to be some crossover, but with a decent view the differences should be apparent.

Please submit any sightings of Shrews (Common or otherwise!), with photos if possible to iRecord.

James Duncan
Mammal