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Saturday, 31 December 2016

Christmas tweets

It's that time of year ... with some interesting bird behaviour on show, for anyone who can pause amid the Xmas shopping and sales rush. In the dearth of natural food, whether winter insects or fruit, migrant and resident songbirds have been descending on urban areas seeking out berrying street trees and bushes.

Robins might be more likely to appear on the season's greeting cards, but blackbirds - the colly bird of the traditional song - thrushes and redwings can perhaps make a similar claim.  A random cotoneaster, hawthorn or rowan might have 3 or 4 perched on top, at various heights, vying for and defending this precious resource.
St David's street food: blackbird on rowan; a pigeon joins in on some pyracantha
It illustrates the value of some non-native berrying garden and street shrubs, such as cotoneaster and pyracantha. These apparently aren't the first choice of wild birds, but at a certain point the berries will be taken avidly, and must help birds survive through this otherwise lean time.

There's also been a winter version of a dawn chorus, of sorts: I've heard robins starting up pre-dawn in fullish song before 7a.m. In the UK most robins are sedentary, but winter numbers increase with some migrants arriving from the Continent. The British and Irish subspecies is Erithacus rubecula melophilus, found across Western Europe and occurring as a vagrant in adjacent regions. Those that stay, or arrive, must keep and guard a territory throughout the season. Male and female robins do this, explaining why both can sing on winter mornings. The association with gardens and towns is a peculiarly UK phenomenon, not so readily seen elsewhere in the robin's range, where it is more of a shy scrub and woodland bird.

While the blackbirds and thrushes are partial to rowan and cotoneaster berries, spindle bush Euonymus europaeus, a classic Devon hedgerow plant, is said to be favoured by robins. In German the plant is Rotkehlchenbrot or 'robin's bread'. In mild years, the next breeding season can start as early as January. Apparently individual robins can be told apart from the red breast pattern, though this is a challenge.

Exeter's greenfinches, thrushes, blue tits, thrushes and blackbirds were also vocally evident during a Valley Park walk in the milder, almost sunny spell on Boxing Day. A hint of things to come, looking towards the Big Garden Birdwatch 2017 on 28-30 January.

Birds and Berries by Barbara and David Snow (T & AD Poyser, 1990)
RSPB 21 robin facts page

Monday, 12 December 2016

Mystery mouse at Mincinglake

This construction was an autumn-winter DIY project. 
House for a mouse, interior

It's a 'mouse-arium', now completed and stood where the TV used to be: I'm looking after three long term, quite possibly permanent, house guests, or mouse guests. Devon Mammal Group has acquired a number of harvest mice indirectly from the captive breeding scheme at Chester Zoo. These rapidly did their thing, and before anyone knew it there's now an impromptu captive Devon population as well, some needing homes.

These can't just be released into the wild. There are several major questions to resolve first: what is the current status of harvest mice in Devon, and are there many suitable sites out there, with decent potential habitat? Are harvest mice already here? And if not, why not? 

Nobody knows, and there's little understood about harvest mouse distribution in Devon, with very few site records held at DBRC. The national mammal atlas 1993 shows a scattering of records across south Devon, with blank white spaces in the mid and northern areas of the county. This could well be a lack of looking than lack of harvest mice.

This is why Devon Mammal Group has set up a new county wide survey project to discover more. A training day at Stover Country Park in November, with excellent tutoring from The Mammal Society's Derek Crawley, showed us where and how to look; in a couple of hours our novice group found some 18 nests across two areas of the Country Park. The first was found within 5 minutes, a text book example grass-woven pom-pom attached half way up a reed stem amongst dense cover. This attachment to surrounding vegetation above ground level is a diagnostic feature.
Mouse house, exterior

Armed with such new knowledge, trained surveyors will explore sites around their local patches, for harvest mouse field signs of old summer nests. Harvest mice, we learned, need thickly-packed sward. They are tiny, about pygmy shrew size, about 5cm, with another 5cm of tail, and weigh around 7-8g (or as much as a 50p coin), which helps, as they like to climb. For this they have a tiny reach, hence grass and other upright stems need to be close together, and interlinked. Also harvest mice do not collect or transport nesting material to a nest site location, but must use whatever is to hand, or rather paw. 

This means the best places to start looking are among banks of thickly growing coarse grasses like Cock's-foot, or reeds, which haven't been cut or grazed for over a year or more, forming an impenetrable grassy forest. In high summer, nests should be impossible to find in this matrix of stems; instead the ideal time to survey is autumn-early winter, after vegetation dies down and before the attrition of winter weather destroys the old nest structures.

So .... a mouse mission, off on the trusty bicycle to check out some of Exeter's Valley Parks and other wilder, grassier, green spaces.

Mincinglake mouse habitat
Ludwell, Duryard and Barley Valley were now grazed down to short grass, and unsuitable. DWT's reserve at the Old Sludge Beds, where harvest mouse nests have been recorded in the past during reed-cutting management works, was not accessible off the boardwalk path. At Mincinglake, with unmown, extensive stands of Cock's-foot and other tall grasses, it was a different matter. 

Crouched peering face first while teasing through the dense sward might have looked slightly odd to any dog-walking onlookers. Two hours of this did not meet with any particular success, though there were plenty of vole signs in the form of runs and piles of nibblings under the matted canopy layer of collapsed old stems, and the habitat still appeared promising.

Teamwork is probably the answer: a few days later a group 30 strong from University of Exeter spent a similar amount of time here, discovering one genuine wild Exeter harvest mouse nest. It's official and wildlife-newsworthy - so little is known, but harvest mice are at Mincinglake, a valuable record for the city and the county. It fills in a blob on Devon Mammal Group's map,
though it took 60 person hours to find field signs of them.

If old nests are hard to find, practical chances of seeing live animals in the wild must be zero. Here are some pictures from the mousearium instead. It's fascinating viewing, watching them investigate new objects, pathways and food items. They are welcome to stay as long as they need.

Better than TV: watching the mousearium residents

UPDATE end of December 2016
Success! Wild harvest mouse nest found at Mincinglake over the Christmas break. Merry Xmouse!
Living on the sedge: Harvest mouse nest in clump of Pendulous sedge

For more harvest mouse info, visit this great harvest mouse webpage.

For anyone interested in surveying for harvest mice around Devon, further Devon Mammal Group workshops are to be held through 2017.

Tuesday, 15 November 2016

Murmuration by moonlight

Monday 14 November 2016

Wheeling flocks of hundreds of starlings over the Exe reed beds as the supermoon rose gleaming over the horizon ... is what we should have seen. Instead we were victims of meteorology. Over 30 of us stood in the dank gloom between the sewage works and the roar of the motorway, under a duvet of smothering cloud, looking at nothing.

We knew wildlife frequently fails to read the text books, or event programmes, but, we thought, at least there would be the incidental astronomy of the biggest supermoon of the century, the largest for 70 years, to view. No chance; not even the bright pinpoint of Venus could pierce the ambient fug.

So, no murmuration, and no moon either. Starlings have declined significantly, by some 80% over recent years*, but that wasn’t necessarily the reason for their absence from the Exe reed beds this evening. Flocks regularly re-locate their roosts from place to place, perhaps pursuing good feeding grounds or communal warmth, or to reduce individual risk from predators, three of the explanations postulated for flocks to converge, and the resulting murmuration displays**.  

Before the start time, a small group of 20-30 starlings was seen heading over Riverside Valley Park towards the city centre. Murmurations needn’t be a coastal or rural phenomena, and a University of Gloucestershire and Royal Society of Biology survey study over 2014-15*** received murmuration records from urban Manchester, Belfast, Edinburgh, Glasgow, Belfast and Port Talbot, not just Brighton pier. They have certainly been seen over the Exe reed beds from the Old Sludge Beds nature reserve and from Topsham. Just not on 14 November 2016.

Although missing during the organised event, the starling murmuration season continues all through winter, with flocks progressively increasing in size as birds arrive from the Continent, so there should be other chances for an independent trip to the site to view the spectacle near Exeter. Autumn dusk can be an interesting atmospheric time in any case: snipe and redwing were calling, and we saw and heard common and green sandpiper, plus a bolt of blue kingfisher; ranks of cormorants warmed their feet on the high tension power lines; gulls and corvids rotated above, perhaps tracking an insect swarm, or a thermal generated by the motorway, or both. A late pipistrelle bat flitted briefly overhead.

And, despite being denied the opportunity to witness the supermoon in full refulgent glory, there will be a nearly complete moon for the next couple of evenings, for a ‘slightly not quite so super’ moon. Supermoons are not so uncommon: each full moon at perigee on its elliptical orbit around, and when closest to, the Earth, gives the supermoon effect. The 14 November event was special because the moon was exceptionally close: at 221,524 km distance, compared to more typical 356,400 km****, and with the moon rising within hours of becoming full at 1.52pm, this was a kind of extra enhanced supermoon, not recurring for 18 years.     

Many thanks to all those who joined us and persevered through the event. Because the wildlife didn't share the same level of commitment, I couldn't bring myself to take a photo, but here's the poster, as a memento of what could have been, with Dawn Monrose's great picture of the elusive avifauna. Maybe we'll try again for the next extra-supermoon on 25 November 2034. 

References and sources
*      RSPB website
**    Andrew J King & David JT Sumpter 2012 Quick Guides Murmurations Current Biology 22 (4): pR112–R114 open access
***   University of Gloucestershire and Royal Society of Biology study, led by Dr Anne Goodenough 
**** Peter Grego 2010 Philip’s Moon Observer’s Guide revised ed. Octopus Publishing / Philip’s, London; SNAPPA science website

Thursday, 27 October 2016

Back to back bulbs and bats

Ludwell Life woodland action morning Sunday 23 Oct
Wild About Gardens bat event Monday 24 Oct 

Rain. Downpours over the last couple of days will be good for the wildflower bulbs Ludwell Life planted on Sunday, but were not so welcome for our Wild About Gardens bat talk & walk on Monday evening. The silver lining had more than its quota of accompanying cloud.

Ludwell Life's October practical task saw a dozen of us enhance the woodland area alongside the Panny watercourse. When originally planted over 20 years ago, it wasn’t foreseen how the Norway maple would self-seed so prolifically, blocking out the understorey for most other species and the underlying ground flora.
Sweet sweet bulbs: clearing patches for planting

The first step was to remove Norway maple seedlings, leaving space for the field maple, holly, and surviving elms to grow. Underneath these we planted clumps of wildflower bulbs for next and future springs: wood anemone, wild daffodil, snowdrops and native bluebells, at their various spacings and depths. These flower early in the season, before the overhead leaf canopy casts dense shade. Some hopefully will put on a flowering display next spring and attract all sorts of early butterflies, bees and other insects; others may take some years to establish.

We ran out of water by the end, but the Sunday evening weather took care of that. 

Future monthly activities at Ludwell are to continue: November’s will include tree planting. All volunteers are very welcome at these friendly events; details will be posted on the Ludwell Life website in due course.

On to Monday evening, and Wild About Gardens Week's theme this year was bats: how to encourage them with garden planting schemes, ponds and logpiles, which support invertebrates, aka bat food. Also through providing roosting sites around the home, via the various different sorts of bat box, bat tiles, tubes, soffit boxes and bat bricks. And finally understanding, on the larger scale, how hedges, watercourses, lines of trees, and darker areas free from artificial light enable bats to find their way around the urban landscape.   
Half a dozen hardy souls braved the misty gloom, armed with bat detectors. What might have been detected was our thoughts on whether October was a good time of year for a bat event. But in the damp and drizzle, we were able to see how some of these ideas have been put into practice in DWT’s Cricklepit Mill wildlife garden.

Street and leat bat detecting    Photo: S Butcher
Night-scented plants, such as soapwort, bladder campion, catchflies, night-scented stock, tobacco plant, evening primrose, jasmine and different honeysuckles, which will flower in sequence through the year, are good for attracting moths, a key food item. Alongside midges, gnats and flies, of which bats can consume some 3000 a night, there are also some perhaps surprising non-flying, aquatic and diurnal invertebrates on the menu, such as spiders and the odd millipede and earwig, according to a Mammal Review paper (N Vaughan 1997 The diets of British Bats, vol 27 (2), pages 77-94).
It reflects a diverse range of foraging techniques, not just in flight, but also gleaning from leaf and water surfaces, and would explain why generic wildlife gardening features, such as ponds and logpiles, as well as providing habitats for insects and other wildlife, also benefit bats at the same time.   
Just after dusk, despite the unpromising drizzly weather, we were joined by 5-6 soprano pipistrelles, flitting around the edge of the tree canopies on Cricklepit street and leat in characteristic flight pattern. At the this time of year bats will be needing to feed at every opportunity, evidently tolerating some light rain and lower temperatures in the run up to hibernation. We can do a bit to help in our gardens and open spaces, and maybe a damp October evening was not such a bad time to think about our local bats after all.    
Some more information

Friday, 14 October 2016

German cousins

The striking firebug Pyrrhocoris apterus is very rare in the UK, known since at least 1865 from one Devon offshore islet site only, near Torquay, a Devon speciality. But it's common on the continent, here hitching a ride on my wrist at the Olympic stadium in Munich, where I was visiting last week.

Bug o'clock (photo: C. Kurz)

It feeds on tree mallow, especially the seeds, and on lime trees. 'apterus' means without wings, and is the distinguishing feature from other red and black bugs; it perhaps suggests why it hasn't been able to colonise the mainland yet, or since 1865.

For more information about Devon bugs, see Keith Alexander's excellent mini-article, from which some of the details above have been taken (link here - uploads Word document directly).

Monday, 3 October 2016

Outside the whale

A visitor from the deep washed up at Red Rock Beach near Dawlish at about 6am on Thursday, not a customary thing to see from the train window.

UK Strandings Investigation Team took samples and confirmed identity as a Fin whale Balaenoptera physalus, the second largest in the world. This is a pelagic, temperate and cool water ocean species, long and slender, built for speed, with two sub-species, one each in the northern and southern hemisphere. The global population is estimated at around 100,000 - 120,000, recovering from 38,000 in 1997*, perhaps less than 10% of its pre-whaling level.  

Fin: final resting place on Dawlish beach

This was the third Fin whale washed up in the UK in 2016; typically 2-3 such incidents occur annually out of around 600 stranding reports each year**. Another Fin whale was stranded two weeks ago on Shetland

At 16-17m, this one was as big as a lorry, but still not fully grown (largest can reach 26m) and was thought to be a sub-adult, weaned and maybe relatively recently independent, about 3-4 years old. Turned slightly on its back, the fin was not visible though the black and white baleen plates, and a white patch on the right side of the lower jaw, are distinctive feature of the species***. 

This month's BBC Wildlife magazine says that from July onwards fin whales regularly turn up along Cork and Waterford coasts in south east Ireland, sometimes also seen around Scotland and the south west of England, peaking in October - November as the whales venture closer to shore in pursuit of shoals of sprat and herring.

A fin whale had been observed in the English Channel over the last few months, which may have been this same, now deceased, individual. Coastguards had been tracking the carcass for the last few days, in case it may have been an upturned boat. It is thought to have died about 2 weeks ago, and been drifting on tides since.

The baleen plate of brushes - instead of teeth - meant this clearly wasn't a sperm whale, one of the toothed whales, as in some early reports. The baleen is what filters out the zooplankton and small fish from the huge mouthfuls of water the whale takes as it feeds, filling up the expanding mouth pouch and forcing the water out through the brushes, trapping the food inside.

Interestingly there seemed to be a couple of bite marks in the jaw blubber. Apart from a puncture wound in the side, which may have
occurred after death, there were no signs of obvious injury, such as from a collision. The results of the sample analysis may provide more information in due course.

Although still fairly intact on the outside, the carcass was too decomposed internally, hastened beneath the thick cushion of insulating blubber, for a post-mortem. Any approach from downwind, from as far away as Dawlish Warren, suggested as much.  

The leaking from the wound congealed with the sand, which stuck well to footwear, so that a reminder of this encounter was carried around for some hours afterwards.

Teignbridge council are responsible for Dawlish beach, and now also the large and unusual clean up operation of what could swiftly become a health hazard.

Whale meat again: advised to clean footwear thoroughly if don't want them to remind you of dead whale for the next couple of days

Over the weekend the carcass is likely to be rendered and removed piece by piece. Next time from the train window there won't be a trace, except for the lingering memories prompted by faintly smelly shoes.

* from figures on Wikipedia for Fin whales taken in the Southern hempisphere between 1905-76
** Rob Deauville of UK Cetacean Strandings Investigation Programme, quoted in Daily Mail online
*** David MacDonald & Priscilla Barrett 1993 Collins Field Guide Mammals of Britain and Europe 

Monday, 26 September 2016

Ivy bee event goes ahead smoothly shock

Ivy League event 25 Sept 2016

Sometimes organising a wildlife-spotting event is a tense matter of hope and prayer that the featured species will actually turn up.

No such problems yesterday, luckily dodging the showers, for a warm blue-skied autumn afternoon looking for the Ivy bee Colletes hederae, with colleagues from Exmouth Local Group.  

This handsome solitary bee was busy in numbers, swarming at ankle height round the coastal grasslands of the Maer, and the mini-quarries of bare earth where it excavates its nests. Faster than the eye can follow, only when stopped for some digging were there chances for a good view, and non-blurred photos.
Head in the sand - busy burrowing out a nest site

Not recognised as a separate species until 1993 (from the similar C. halophilus and C. succinctus), and first sighted in the UK in Dorset and at a single location in Devon in 2001, it has gradually been spreading its range since. Ivy Hedera helix , which flowers late in the year, is its predominant, and often sole, pollen and nectar source of choice; hence, in sync, the Ivy bee is also late flying; in more sense than one, it's our latest solitary bee.

Although solitary, where the habitat is suitable, as it definitely is at the Maer, large numbers can nest in aggregations, a fascinating, often overlooked, spectacle, right under one's feet.

Potted (natural) history: Ivy bee reveals itself to budding naturalist

From the nesting site on to the other main component of the life cycle, stopping off to check out a dense clump of ivy. Ivy bees were conspicuous foraging here, alongside numerous other bees, wasps, hoverflies and other insects, at this important late food source. A successful event, which the wildlife also turned up to.

Eristalis hoverfly (note looped vein in wing)

Some further information about the Ivy bee:

Monday, 5 September 2016

Knotgrass in my backyard

Life after concrete (reprise)

Knotgrass Polygonum aviculare 
The sort of plant which catches the attention of herbicides, in the name of botanical cleanliness. But Wait! Stop before you spray!   

Not just a weed, this is a bare ground coloniser, taking nature's first steps to fill a vacuum. It has noted wildlife value: as the 'aviculare' part of the name suggests, birds such as finches and sparrows feed avidly on the seeds
Knot overlooked ... supporting wildlife on Cathedral Green

Added to which, the long flowering period can support insects from May - NovemberRight now Knotgrass clumps are flowering in profusion around Cathedral Green and St David's church, in the worn bare areas among the grass

The tiny clusters of 1-6 flowers emerge at the bases of the upper leaf stalks. The three inner stamens are bent over so that pollen falls directly on the styles; the others point outwards for any passing insects. But this isn't all: there are also concealed flowers under the membraneous sheaths (the ochreae) around the stem 'joints' (the joints give the plant the other part of its scientific name: Polygonum 'many - kneed'). These hermetically sealed flowers do not open (or in technical terminology, are cleistogamic), which, along with the arrangement of inner stamens, ensures some self-pollination at least. It is said Knotgrass may produce similar cleistogamic subterranean flowers underground as well, among its roots and runners, alongside which the tap root can penetrate up to 45cm deep into the ground. 

As a multi-pronged pollination and propagation strategy, these would be useful adaptations for an annual plant, which dies off every year, but for which the seed bank must persist biding its time in the soil for years, until the next unpredictable opportunity brings seeds to the surface where they can expeditiously germinate.

As well as a pioneer species to kickstart vegetation recovery on bare ground, Knotgrass is a host plant for over a hundred different invertebrates: some 9 beetle species, 2 flies, 8 bugs, and 93 moths, especially among the the Geometer moths.  

Tolerating a bit of Knotgrass in the bare patches and nooks and crannies among the concrete would be small, simple and effective action to help our urban wildlife.