Leucism

It is hard to walk around Filey and miss the number of leucistic carrion crows that exist within the town, but what is leucism and why does it occur?

Leucism is a genetic mutation which prevents the body producing melanin (black pigment) and accurately depositing it around the body. Where feathers lack melanin they are white/or paler, this can include parts of a feather or entire feathers. Leucism does not always result in feathers being white, sometimes the lack of melanin makes the feather paler giving it a diluted look (some consider this to be a separate condition). Leucism is slightly different to albinism in that it blocks all pigments not just melanin, where as albinism still allows carotenoids to occur giving other colouration i.e. yellow, red. In completely leucistic individuals the entire body is white, but the eye is not red like in albinism, as leucism only affects the feathers. The red eye in albino animals is a result of the eye lacking any melanin, allowing the red blood vessels in the eye to be seen.

Interestingly the condition must be passed down through generations as it has certainly existed in the Filey carrion crow population for a number of years.  Leucistic feathers are thought to wear quicker, and may make some species more prone to predation, although it certainly does not seem to be having a huge impact on these crows. A smaller passerine is perhaps at a greater risk of been seen by a predator. However chances of survival are higher than albino birds, which usually die soon after fledging due to their poor eyesight and increased vulnerability to predators.



Leucistic Carrion Crow

Saved by a Dotterel

With conditions not improving overnight since yesterdays outing, it was hardly surprising to find similar if perhaps even lower numbers of birds around the Filey area today. Top Scrub was quiet other than decent numbers of greenfinch, feeding on rose hips. A thorough walk of the stubble fields and hedgerows in search of buntings did produce high numbers of reed buntings, a species which has certainly increased locally over recent weeks. In addition a single dunlin and teal were present on the tip scrape. By late morning, enthusiasm was starting to run low and whilst looking at waders on the Brigg news broke of a dotterel up in the northern ploughed fields. Very welcome news on what was turning into an unproductive day. A quick drive up there produced the bird almost instantly, sat on the brow of ploughed field.

 

Dotterel on brow of ploughed field.



This area south of the Blue Dolphin caravan park represents the highest point in the northern part of the Filey recording area, a feature which may certainly have influenced this alpine breeders field choice. Britain represents just about the most westerly breeding location in the Palearctic region, with no breeding occurring in Iceland or Ireland. British birds almost exclusively breed in the central highlands of Scotland. Dotterel leave the breeding grounds each year to winter in northern Africa and the middle east (British/western birds mainly winter in west Africa i.e. Morocco). Autumn records in this region tend to be limited, with spring records being far more common. Autumn birds are typically 1st winter birds in ones and twos. This bird appeared to be on its own, although others could potentially have been over the ridge, none were noted. This field offers exactly the type of habitat that these birds turn up on whilst on passage. A clear preference for flat, open, treeless, areas of land, especially recently ploughed arable land is sought.        





Dont forget the Fungi

With October being one of the most productive birding months of the year it is easy for a naturalist to get caught up in it all and forget about just how good October is for fungi. Certainly along with September these are perhaps the most productive months of the year, in which mild wet weather sparks good fruiting conditions. Here are a few species I found growing within close proximity of where I live.

Yellow Fieldcap Bolbitius titubans - Typically a species of nitrogen rich grasslands, especially where live stock is grazed. Larger specimens tend to grow on old dung piles, this specimen was found on the edge of sheep pasture.

Clouded Funnel Clitocybe nebularis - This species often grows in lines or in "fairy rings". This is essentially a woodland species, that can be found in both deciduous and coniferous woodland. I am yet to find them in the latter, these were found amongst beech woodland.

Amethyst Deceiver Laccaria amethystea - A personal favourite and one which often litters the woodland floor. This is a very common woodland species in both coniferous and deciduous woodland. This species tends to be regularly encountered near beech, which is where this was taken.  

Shaggy Scalycap Pholiota squarrosa - Interestingly a species which can be identified by it smelling like garlic. This species is saproxylic on either deciduous or coniferous wood, living or dead (most often the latter). These were found growing on a dead larch stump.

Jay Eruption

It seems almost ironic that I spent the best part of a day recently trying to photograph Jays in Dalby Forest with no success. These are after all characteristically very shy woodland birds, often all you see is a white rump flash or distant view of a bird flitting between trees. The loud horse cry is usually a clear give away. The North Yorkshire forests sustain moderately good breeding populations, which anecdotally appear to be expanding. So it came as a pleasant surprise to find three birds on the coast "fresh in off the sea" at Filey today, totalling around 8 birds by the end of the day. Jays are not commonly encountered on the coast in the Filey/Flamborough region, an area in which breeding does not occur, due to a lack of suitable woodland habitat.

Jays are a largely sedentary member of the crow family which tend to winter in close proximity to where they breed, even juveniles tend not to disperse large distances. They feed heavily on acorns, which are an important food source during the autumn and winter. During September and October jays intensively collect acorns, which are then cached in ground. However oak is prone to irregular fluctuations in the acorn crop, especially with increasing latitude. When an acorn crop failure occurs this can cause the species to make mass eruptions, in which the usual breeding sites are left as the Jays search new areas to forage. Northern European populations are particularly prone to this eruptive behaviour, especially birds from Scandinavia and Russia.

Despite these eruptions, jays tend to avoid travelling across open water meaning these movements only occur when it is absolutely necessary. It is still unknown what age class predominate these eruptions (if any) or if they are also linked to productive breeding seasons. Certainly in 2012, already large numbers have been reported moving to Britain along the South-East/East coasts. I would expect more reports to come from this region of migrant jays over the remainder of the month.

Jays may be a frequent site along the coast this autumn

In addition to the jays, a single Lapland bunting, good numbers of blackbirds, three great spotted woodpeckers and a small number of song thrush were also recorded amongst the usual species. The bay was quiet with a small number of guillemots and a male eider present.  

Pheasant Nose Rings

Whilst out and about over the past couple of weeks, noticing all the pheasants (its pretty much impossible not too) I have seen a large amount of the poults sporting a nose ring. (See Below).

At first I thought it was my eyes and some kind of parasite was crawling out of its nostril. After managing to catch one, I had a closer look, the ring extends from each nostril and under the top part of the bill in a "C" shape (not joining in the nostrils). Soon it was apparent that most of them had one. After doing a bit of research this ring is actually a way of reducing cannibalism when pheasants are in the release pen or being reared. The ring prohibits the bird shutting its bill and creating a point which it can peck with. Its not supposed to cause the bird any harm either.

Wrench Green Autumn Birds

A late afternoon walk along the river side at Wrench Green near Hackness, produced a number of sizable tit flocks. The riparian corridor which bounds the River Derwent and flows towards Forge Valley often provides good inland bird watching conditions for a variety of woodland species. The river corridor is surrounded by a variety of woodland and scrub habitats and birds tend to filter down from these into the valley bottom in autumn.

It was good to see a large long-tailed tit flock containing good numbers of marsh tits (well into double figures). Willow tits were also heard but not seen, willow tits and marsh tits both breed in the surrounding woodland in relatively good numbers. However willow tits seem to have decreased in the area over the past 10 years or so and are less common than marsh tit. As well as tits the area often produces good numbers of finches. It is a very good bullfinch area, with single flocks containing 15 or more birds and the riverside alder often attract siskins and redpolls in good numbers too. In addition to these both dippers and kingfishers breed along the river and are regularly seen.
    


Long tailed Tit



Lesser Redpoll

Marsh Tit

Predators Paradise

Autumn and winter are without doubt the best time of year to search for predatory mammals, in my experience. The combination of large amounts of pheasants being released for shooting, predator densities being at a peak and vegetation dying back, means you can usually reliably find some signs or if you're lucky and willing to put in the time in see the animals themselves. The landscape around the southern escarpments of the North York Moors has just about every predatory mammal species in Britain available (in good densities) despite gamekeeper pressure. Knowing where to look can provide good results. Species include red fox, otter, badger, weasel, stoat and mink, in addition pine marten continue to be reported in the region too.  Polecats have yet to extend this far east in any real density, however when they do, provided persecution is low the habitat is more than suitable to support them as well.

With the wind not looking promising for migrant birds and few reports turning up, I decided to head inland on a recce. I now have a camera capable of taking decent photos, combined with some bushcraft it would be a nice winter project to photograph some of our more elusive inhabitants. However before doing so, to save time, finding a suitable area is important. Knowing this region well I already had an idea of places which support good predator (and importantly) prey densities. Rather than sitting and waiting, I decided to rove across a valley which supports a wide range of habitat types, importantly mixed woodland, pasture, rough grassland, rivers and streams.

Red Fox - Red foxes are extremely easy to locate, home ranges are well marked and scats are placed in prominent positions. Realistically foxes are probably more easily targeted in urban areas these days and are probably not as high on my agenda as the mustelids. Without really looking I found what probably constitutes to a territory in the region walked. Despite high gamekeeper pressure in this area foxes have enough woodland retreats to escape too, although numbers are probably continually suppressed.

Otter - The rivers and to a lesser extent the streams in this area, hold a number of active territories. Hopefully this winter I will be able to get closer to a photograph by looking for signs. With river levels being high up until recently a lot of the signs were difficult to find as they had been washed away. However I did manage the footprint of a female/immature in some sandy substrate besides the river, indicative of recent post flood activity. Since otters range so far, knowing exactly which aras of the river they use most often could be crucial to getting a photograph.  



Otter print - Otters are well distributed throughout this part of North Yorkshire

Badger - Badgers more so than foxes are super abundant within this region. Setts typically being situated on the wooded convex slopes of the surrounding valley sides, which provide cover and are out of the clay zone, offering a more desirable soil structure, less prone to flooding. Badger presence can soon be determined by checking paths, tracks and damp patches for footprints. In this case where the track ran into a copse, prints passed across it as the animal had moved through the tree cover then out into the pasture to feed on worms. Already knowing several setts in the area, probably produces the greatest chance of a photograph, however the species nocturnal nature and the shade cast by closed canopy tree cover, makes getting one difficult, without a flash.

Weasel & Stoat - Two species which are often seen by chance rather than design. However knowing where to look and knowing where densities are high, significantly increases those chances. Stoats and weasels are both common in this area, cover is abundant for nesting in and prey is also numerous. Stoats occupy the niche above weasels in targeting small/medium prey like game birds and rabbits, weasels tend to target smaller mammals and frequently raid birds nests. In total I managed 3 stoats and 1 weasel, with only a single distant photo from the stoat, highlighting the difficult task of photographing these animals. Stoats are extremely inquisitive (as are foxes, weasels and mink). If you think you may have seen one, it is always worth trying to squeak it. A technique hard to describe, which basically involves drawing air through the mouth to create a squeaking sound. In this case the stoat which had disappeared into a hedge base reappeared and began to approach me, I crouched to appear less of a threat, however the animal soon realised and made a hasty retreat.  

Finally the last species I managed to record (in approximately 2mile²) was American mink. Very much an enemy of British conservation, albeit a very photogenic one. This part of North Yorkshire is a mink stronghold, don't believe the hype about otters moving them on, they don't! Undoubtedly otters are a negative factor on mink populations, but the two only marginally compete, it is the polecat spreading from the east which perhaps holds the true test for the minks resolve, and provides a larger amount of interspecific competition. Regardless mink have been trapped and shot here for years by the water bailiffs and gamekeepers to no avail. This animal had followed a small tributary up into an area of pasture, where the pheasants will undoubtedly provide an easier foraging opportunity, than the trout  further down the valley, in the river. Mink are far more terrestrial than a lot of the literature suggests, males in particular regularly disperse across watersheds and feed away from water on prey like rabbits and pheasants.

Mink - Tracks in soft mud, where the animal has been following a stream upalong the valley, to reach easier pickings

In total six predators, all in one valley, all open access. That's winters project sorted.

Squeaking a stoat



Otters on the move

Over the past 5 years or so myself as well as many other people have noticed the gradual increase in range and density of Otters across Britain. In North Yorkshire I am fortunate enough to live less than 2 miles from an active territory. This has been occupied as long as I have been interested enough to look. Now it is pleasing to see other areas being occupied by otters. Much of East Yorkshires riparian habitats are unlike North Yorkshires. East Yorkshire is more intensively farmed and has less wild retreats. However the species is doing very well there, especially around the River Hull catchments. A sure sign that issues arising from agricultural intensification and river quality are changing for the better.

It is amazing what small ditches and tributaries otters can be found on. The site where the photo was taken below is a commercial fishery, which the otters access using a series of ditches which run through adjacent open arable land. Otters are strongly territorial mammals and often occupy large linear territories, which contain numerous holts or couches (resting places). Generally the animals in Yorkshire occupy territories between 5 and 10km, with a male territory often overlapping a number of smaller female ones. Otters are more than capable of ranging 10km in a night on hunting trips. The fact otters occupy such large linear territories means that they are extremely active when it comes to sprainting (marking the territory with spraints (droppings)), unlike foxes and badgers they are often far away from parts of the territory at any one time, making it essential to remind intruders that the area is taken.

This increase in numbers is not popular with everyone including fishery and fish farm owners. Where otters can cause financial damage to fish stocks. This is a subject for another post entirely. Otters largely declined across Britain during the 19th century, where otter hunting was a common practice. A small increase in numbers between the early 1900s and 1950s was soon cut short by the introduction of the cyclodiene organochlorine insecticides, with which we usually associate with declines in raptors. This was applied in an agricultural sense as seed dressings and in sheep dip. Like in the peregrine (and other predators), otters store these chemicals in their fat reserves, in which it slowly builds up with each poisoned meal the otter eats, eventually leading to secondary poisoning. In addition DDT (dichlorodiphenyltrichloroethane) is thought to increase blindness in otters. Modern causes of otter mortality are largely linked to road casualties and drowning  in eel fyke nets, lobster creels and fish traps.   

Above is the rather characteristic image showing where an otter (most likely a bitch or youngster) has left the water and moved up the bank. Otter prints show a characteristic set of 5 toes (sometimes the 5th does not register), these are rounded with a small nail. These sit in front of a large pad and are quite different to the star shaped slender toes of a mink. This photo was taken in East Yorkshire.

Last Dragons of the Year

A check of a couple of reliable dragonfly locations yeilded poor results today. Despite the warm weather, both sites are in upland locations and are subject to colder mean temperatures, meaning any dragonflies have either perished with the frosts or moved into warmer lowland areas.

Harwood Dale ponds only produced a single male southern hawker, which was already beginning to show signs of deteriation on the abdomen.

Blue Bank Quarry pond again only produced a single male black darter, a species which I am yet to get a satisfactory shot of despite taking so many photos of them.

With the wind turning easterly these may be the last dragons of the year, whilst my attention turns to migrant birds for the remainder of the autumn.

Late season reptiling

With temperatures starting to drop and days becoming shorter early October is about the latest realistic time of year to catch up with some of the reptile species we more commonly associate with the summer. Harwood Dale, near Scarborough is perhaps under rated in terms of its natural history, in comparison to the expanses of heather moorland and woodlands of the North York Moors. The dale extends from Burniston up to Fylingdale Moor and includes a range of habitats from lowland pasture to upland heath. After heaving some luck with adders in the spring I decided to check an area of, productive regenerating, clear fell, conifer plantation at the northern edge of the dale.

Common Lizard

Autumn is without doubt a productive season to search for common lizards in North Yorkshire, with September being particularly productive. Lizards can be found basking at any time of day as they prepare for hibernation, typically when temperatures exceed 9^oC and there is enough direct sunlight to warrant efficient thermoregulation. Basking at this time of year is often extended due to the lower mean temperatures and features with a south facing aspect are sought, especially ones with a good heat conductivity like stones and logs. Dry stone walls are a particular favourite as they offer good thermoregulation habitat close to cover, especially where vegetation grows up them and is not to heavily grazed. Common lizards do not excavate their own refugia and are dependent on what is already present at a site, meaning favourable areas like dry stone walls can result in high densities in an enclosed area.

Male common lizard basking on a dry stone wall, Harwood Dale.

When lizards enter hibernation they need to have built up substantial fat and glycogen reserves, which helps them survive the winter. Common lizards are not specifically communal during hibernation, although good numbers may gather at a particularly good spot. Hibernacula are usually frost free crevices, holes and cracks below ground, in banks, under logs/stones or disused small mammal burrows. Common lizards are quite tolerant of cold so mortality of adults in particular is usually low throughout cold winters. Mild wet winters are thought to result in higher rates of morality in this species.

In total I managed approximately 20 adults and 12 juveniles, anecdotally some of the common lizard populations here appear to have done very well despite the poor summer, which is interesting and maybe a topic for another post.      

Adder 

In addition to lizards, it was pleasing to find a juvenile adder, one of this year's offspring and evidence of some successful breeding at the site. Amazingly juvenile adders do not feed until well into their first summer of life, spending their entire first winter living from yolk reserves, from their mother.  This stored yolk is extremely rich in protein and can enable you snakes to actually grow in the period between birth and hibernation. This individual (in the photo below) is showing another trait commonly seen in adders, and one which can make photographing them frustrating on occasions. Whilst basking adders often position their eyes into the shade, either in the shadow of a leaf or similar object or by tucking the head below their body. Adders do not have eyelids and subsequently bright sunshine can cause damage/discomfort to the eye, especially in a young snake where the eye is not fully developed.  

Juvenile adder basking in a safe area, close to cover, note the shading over the eye.

 



 

Unfortunately no slow worms were found, undoubtedly if I had dug a bit deeper and lifted some refugia I may have ound some. However due to the disturbance this causes I am reluctant to do this from late September onwards, when damage could be caused to a wide variety of creatures.

Greenfinch and Trichomoniasis

 

Trichomoniasis is becoming a larger threat to British songbirds on a national level but is still not really prevalent in the North and East Yorkshire areas. In July five greenfinch were found dead in close proximity to one another in the Lockton/Levisham area, three of these birds had been rung in Dalby less than 5 miles east. The sudden localised increase in mortality rates, is suggestive of this or a similar disease. However I am unsure whether any testing was conducted on these birds and have not seen them, so other possibilities exist. Regardless this raises the subject of Trichomoniasis as a possible negative factor on greenfinch populations in the locality.

What is Trichomoniasis?

Trichomoniasis is caused by a protozoan parasite called Trichomonas gallinae. It typically causes a yellow plaque like coating and necrosis on the walls of the throat, mouth, oesophagus and nasal cavities. Occasionally in severe infections it may spread around the host and affect organs like the liver. Infected birds are characterized in the later stages by dribbling, regurgitation of food, labored breathing and have difficulty swallowing. Encountered birds are often found fluffed up and relatively unresponsive. Where the infection is weak birds may recover, however typically birds fail to recover and the disease which can last over several weeks in some cases is eventually fatal. Trichomonas cannot survive for more than a few minutes outside its host.

Trichomoniasis commonly occurs in pigeons, however it has been infrequently in other birds like passerines and raptors, until the recent increase in finch populations. It is suggested that Trichomonosis was a key factor contributing to the extinction of the passenger pigeon. In pigeons it usually exists high up in the throat close to the mouth in the pharyngeal region, whereas finches differ slightly in having it lower down closer to the oesophagus. It is believed to have been passed to finches from pigeons, which are a significant reservoir for the disease.

Recent history in British finch populations.

Trichomonosis emerged as a none specific fatal disease of finches in Britain around 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations a year later in 2006. Originally it was identified in British Finch in April 2005, this was followed by a further low mortality of British finches throughout the rest of the year, with a peak in cases between September and November. During the summer of 2006 the number of confirmed cases increased dramatically, more so in greenfinch than other species. Approximately 6300 mortalities were reported, primarily from garden feeding stations during 2006, this compares with 84 incidents in 2005. By 2007 breeding populations of both greenfinch and chaffinch had decreased by 35% and 21% respectively in some areas, according to one study. This represents a mortality of over half a million birds. The disease continues to persist in Britain and is particularly prevalent in the west midlands, Wales and western Britain. Data collected from BTO and RSPB garden bird studies, contributed to by the public have shown a marked decline in greenfinch numbers, more so than other species of "garden" bird.

Relevance to the British greenfinch population

The British greenfinch population increased steadily between the 1980's and mid 2000's. During 2007 a sudden significant decrease occurred. This is suggested to have been largely driven by trichomonosis. It is estimated that a loss of half a million birds occurred around the 2007 period. It is worrying that no similar rates of mortality caused by infectious diseases have occurred in wild British bird populations, other records of trichomonaisis from passerines globally rarely show such a negative impact in a wild population. In the years prior to 2007 the disease has remained a significant negative factor on greenfinch populations.

Why are greenfinch so susceptible to Trichomoniasis?

The reasons as to why greenfinch are so susceptible are still largely unclear. Greenfinch are a species, which could be classed as a highly vulnerable to infectious diseases. Similar diseases like salmonellosis and colibacillosis are regularly reported in greenfinch populations. As greenfinch are highly gregarious, diseases can quickly pass between individuals and remain viable within the population. Being granivores means that large numbers gather a feeding stations which further increase contact rates. However trichomoniasis is not especially prevalent in other birds which gather in high numbers at feeding stations like tits and sparrows. This suggests that foraging behaviour is unlikely to be a key factor in making greenfinch so vulnerable alone.

The significance of feeding stations has increased over the past 50 years, in which land uses have changed in the wider countryside increasing the species dependence on them therefore increasing the likelihood of birds coming into contact with each other. In addition by feeding throughout the summer, the risk of young birds becomes significantly increased due to feeding adults using feeding sites then returning to the nest.

     

Sparrow Post Breeding Biology

During later summer when the final brood has left the nest hole, house sparrows and tree sparrows often disappear from the immediate breeding area. This sudden desertion of colonies can at first seem quite chaotic to the casual observer. House sparrows tend to be more associated with man of the two species and nest further into towns and cities, they are rarely found in natural situations in Britain.  Whereas the smaller tree sparrow tend to nest more on the outskirts of towns and villages occurring well into agricultural land, away from man. This in part is largely due to house sparrows being the more domineering of the two species, forcing tree sparrows into surrounding areas. Tree sparrow habitat in Yorkshire is typically along/near to the coast, with concentrations around wetlands, which have suitable trees for nesting and areas of farmland plantation in which they can breed and forage on adjacent land.


House sparrow - the larger domineering of the two species

Both species of sparrows are gregarious throughout the year, breeding in lose colonies and wintering in larger flocks. Once fledged the young form small foraging flocks which later merge with other flocks of similar birds from other colonies to form larger flocks. These grow throughout the summer and are eventually joined by the adults in early Autumn, when they have finished breeding. These large aggregations typically disperse onto agricultural land rich in food, like spilt grains after the harvest. The flocks typically roost close to the foraging area, resulting in the breeding areas becoming completely abandoned in some cases throughout this period.  Adults soon return once they have completed a full (annual) moult to reclaim old nest sites, young may remain on feeding areas and slowly return back to breeding colonies later in the autumn (typically around mid-late October). At this point sexual behaviour begins again, with males roosting at nest sites and then displaying the following morning, this activity increases as the winter draws on. Both species regularly group together at this time of year, in these feeding flocks, which can be quite spectacular. In addition finches and buntings often associate with these flocks.  



Mixed feeding flock, coming to feed in a bean crop. Note the larger house sparrow (3rd bird from the left).

Currently these flocks at Filey appear to be centred around a bean crop north of the Old Tip area. It is unknown whether they are foraging directly on the beans or associated insects (or both), sparrows will certainly feed on legumes. The flock offers a fantastic opportunity to study this annual behavioural pattern, currently the large mixed sparrow flock has good numbers of reed buntings associating with it. The flock is at its peak where hedgerows or areas of linear scrub bound the field offering a quick escape from predators, it is presumably these areas in which the birds roost. Both sparrow species typically roost in bushes like hawthorn, moving into more evergreen species and tree holes/buildings, where possible, as the winter draws on.   

Migrant Hawkers

Saturday afternoon provided quite good dragonfly viewing conditions, despite the clear cold start to the day. Warm sunny weather in Autumn can produce good dragonfly watching especially for species like migrant hawker, southern hawker, common darter and black darter, which certainly persist longer into the season than many of the other species in the North/East Yorkshire region. September is usually good for photography as the temperature is slightly cooler making these insects slightly less active. Dragonflies are largely dependent on direct sunlight to warm themselves up, making sunny weather critical for good watching conditions, usually around 9.30-10am onwards, on clear still September days. Every year around late summer/early autumn large numbers of migrant hawkers appear on the coast, some of which will undoubtedly be from local breeding populations, others wandering migrants.

Male Migrant Hawker

Migrant hawkers appear to bask low down in vegetation more frequently in comparison to the large southern hawker and brown hawker, which both appear to prefer trees and shrubs. This male was found on the sunny sheltered side of some scrub, approximately 30cm from ground level. This species appears to have done well in recent years, with a notable northwards expansion of the breeding range. It now appears to be well established within the North/East Yorkshire region with breeding occurring up to the southern escarpments of the North York Moors, where it is largely absent as a breeder due to its intolerance of acidic water, more populations exist further north. The larvae appear unable to stand low summer temperatures, which influences its distribution as a breeding species. This is due to it requiring a warm summer period in which they can rapidly develop into adults (in only a few months), this strategy is dissimilar to other British Aeshnids which take longer to mature. In addition to a breeding population, we also get migrants to Britain, from the continent each year, especially in late summer and autumn.

Ringing Report 22nd September

After a what seems like weeks of westerlies, the wind swung north/north east resulting in a promising window of easterlies, the first real ones of the autumn. The plan, ring on the Saturday, work the scrub on the Sunday. Saturday resulted in approximately 50 new birds, which included blackcap, goldcrest, chaffinch, bullfinch, greenfinch, linnet, goldfinch, blue tit, coal tit, great tit, dunnock, robin, chiffchaff and a single brambling. Certainly a productive session, which also recorded wheatear, house martin, grey plover and brambling overhead. In addition at least two yellow-browed warblers were recorded around Filey, unfortunately being unable to leave the ringing site I was unable to connect with either.

The brambling (seen above), was a 1st winter female. Brambling are a close relative of the more familiar chaffinch, and predominantly visit Britain during the winter, although breeding is occasionally recorded here. Brambling tend to breed in a broad strip in northern Europe, from Scandinavia to Russia. Brambling are closely associated with beechmast, and areas rich in this can be good places to look throughout the winter. Studies have shown that they stay as far north as the availability of beechmast allows and as snow increases they push further south. The first brambling begin to make landfall around mid-September, like this bird. The key arrival period occurs through October until November. Unlike Chaffinch brambling predominantly migrate at night.  

The other bird at note was coal tit (c.15 of them). All coal tits trapped today, were 1st winter birds. This continues the theory, with regards to local populations, in that young birds leave the natal area during the autumn. In this region the core populations occur in the forests on the southern edge of the North York Moors (Dalby, Cropton, Wykeham et al). Coal tits typically select coniferous woodland to breed in, and tend to have greater breeding productivity in such habitats. Coal tits are well adapted to this habitat, with characteristics like the foot (long toes and claws, not opposable, unlike Blue Tit) and fine bill for foraging for small food items, especially in conifers. Coal tits are typically quite a sedentary species in Britain, although they do make small scale movements such as these irruptions. The exact advantage (if there is one) of leaving the coniferous forest they are adapted for, and in which they have an edge on rival species like blue tit, is largely unknown. Perhaps this is a form of juvenile dispersal to seek new breeding grounds, adults remain in closer proximity to breeding territory, or not enough resources occur in the forest to support young subordinate birds. However the species is more than capable of surviving harsh winters in conifer woodland, using techniques like food caching and the population which remains appears to be dominated by adults (2nd winter). Coal tits have been recorded crossing the sea to Britain from Scandinavia, which raises another possibility.

Pink-footed Goose (Winter Migration)

Over the past week or so increasing numbers of migratory geese have started to show along the Yorkshire Coast. I had my first of the Autumn last Tuesday (11th September), a magnificent flock of approximately 86 pink-feet flying south, quite high (from the office window ;)). Various observations locally and nationally have reported pink-feet moving south for the winter over recent weeks.  

In Europe there are two core breeding populations of pink footed goose. One in Svalbard, which migrates through Norway down into Denmark and across to winter in Holland and Belgium. The larger population, of which we are more familiar with, breeds in Iceland and Greenland and winters in Britain. Both populations are entirely migratory and consist of c.260,000 birds, which is the entire global population for this species. Interestingly very few of these birds winter in Ireland, with Norfolk and a number of regions in Scotland (Morey Firth, Fife) being perhaps the key wintering site in Britain.

The majority of the birds in Greenland depart from the breeding/moulting grounds in late August, and move towards Iceland where they then join the breeding birds there. The first pink-feet tend to be reported in Britain around early-mid September, increasing in numbers until the middle of October. They tend to move through Scotland as would be expected and stop off at a number of regularly used sites. There is considerable movement in the winter between areas in Britain, before they begin to return north around February and March.

These two individuals dropped in at Filey dams last week and remained for several days.  

Wasps and Winter (Hibernation)

With temperatures dropping and daylight decreasing, the regions wildlife has already begun to brace itself for the long winter. Whilst amphibians, reptiles and mammals like hedgehogs are mostly all still active throughout September, many species of insect have started to enter torpor. Some of the valleys on the southern edge of the North York Moors had frost (on the morning of the 19th) recently. Frost is often a catalyst for many small animals to enter hibernation, as it reduced food availability, decreasing temperatures and hours of daylight, the one which is most significant to a species depends what the species is. Wasps for the most part tend to enter hibernation long before the first frost appears on the ground. It is only the fertile female "Queen" wasps that hibernate, once they have mated in late summer there is little need to be active, as they will not begin to build a nest and form a colony until the following spring. When fertile queens are produced (which ultimately decides when they hibernate) is governed by the amount of sperm the queen has, usually sometime in mid-late summer. Queen wasps mate once, store the sperm and use it through the following year to create a colony, as it begins to run low, the queen begins to produce fertile males and females which leave the colony and breed. Males die soon after breeding but females enter hibernation (as mentioned above).

 

This Queen  Dolichovespula media (Median Wasp) was found under a well decayed hawthorn log on the edge of what is quite a productive area of oak woodland for invertebrates, in the Scarborough area. D.media is a recent colonist of North Yorkshire (and Britain). A species which I first recorded in 2008 (one of the first North Yorkshire records). These impressive social wasps are second only to hornets in size in Britain, and queens have quite elaborate brown markings around the thorax, as can be seen in the photo. Dolichovespula (of which there are 3 species regularly encountered in Britain) tend often to hibernate within rotten wood, whether it be in a tree hole or under a log (like this one), they will occasionally overwinter in a building like a shed, like the more common Vespula species.  Social wasps (and bumblebees which have a similar stratergy) often overwinter on north facing aspects, which retain a more stable temperature and are not excessively heated by the sun.

Hibernating wasps adopt quiet a characteristic position, which can be seen in the photograph above, in which the antenna and wings are tucked below the body and held by the middle pair of legs. This is primarily done to protect them. The front pair of legs are also tucked below the body. The hind legs are usually used to keep the wasp in an upright position and are left untucked (not seen in my photo). The water dropplets are due to condensation, as the wasps body is colder than the surrounding air. Wasps like many other animals suffer high rates of mortality over the winter, however this is not always directly linked to cold winters. Warm winters pose numerous problems to hibernating animals, in that they regularly wake up and use valuable body fat reserves, especially if temperatures fluctuate. A warm spell followed by a cold one can have very negative implications in some situations. So in some ways a stable cold winter can be quite beneficial.  Regardless of the cold the biggest killer of wasps over winter is probably predators including ground beetles, centipedes and birds like great tits, which often roost in similar situations to where wasps hibernate.   

Brown Hare Vision (or lack of it)

Brown hares are typically a creature of open countryside, which provides small amounts of cover i.e. tall vegetation, hedgerow bases and woodland edge, where forms can be created. The species is most numerous on arable agricultural land, particularly in this region. However they certainly exist in good numbers on pasture, in the North York Moors particularly where heather is flanked by improved cattle pasture, and in most of the valleys. They also like the vegetative regeneration which occurs after heather burning. Although a clear avoidance of closely cropped sheep pasture occurs, unless interspersed with cover.

A walk along such habitat produced the usual brown hares, which probably benefit from the red fox control on the moor, and usually occur in good populations, even on top of the moor. One such animal (below) had really well developed cataracts in each eye. Brown hares often forage well into the night which would make this animal highly vulnerable to foxes and possibly even badgers, when both are more active and the hares eye is likely to be completely blind. The red fox is the most significant predator of brown hares in Europe, to the extent that they can be a limiting factor on population growth. Up to 80% of leverets (young hares) can be predated in some populations. Brown hares usually have 360 degree vision, although in my experience their head-on vision appears to be quite weak. This hare would appear to be almost completely blind, however as you would expect they have exceptional hearing. Despite the local gamekeepers controlling foxes, several scats were quickly found without much looking, so it will be interesting to see how long this distinctive individual remains in the area.

Western Conifer Seed Bug

Whilst the pectoral sandpiper at Filey and Monarch butterfly and lesser yellowlegs at Flamborough, may have claimed the attention, in respect to recent North American vagrants, over the past week, another North American species the Western conifer seed bug continues to gain a stronghold in the region, almost unbeknown. Although the westerly wind which have brought across the more notable species are unlikely to have contributed to its arrival in North Yorkshire. The species was initially reported from Italy in 1999, from where it spread rapidly across Europe. It is thought that the initial Italian find was due to animals imported with timber. Now the species readily breeds across Europe, each autumn sees an influx along the south coast of England.

I was lucky enough to find an individual in 2011, which symbolized one of the most northerly British records to data (in East Yorkshire). This year the trend has continued and the species remains, in the region (North Yorkshire). As their name suggests they are a species with primarily feeds on conifers. They tend to be closely associated with Scots pine Pinus sylvestris in Britain as well as lodgepole pine Pinus contorta, Corsican/black pine Pinus nigra and Douglas fir Pseudotsuga menziesii. It is reported to a lesser extent on spruce Picea and larch Larix. Like many insects (especially none-native ones) wintering sites involve buildings, large numbers of this species can group up and enter houses, where they spend the winter in loft spaces. Naturally bird nests, squirrel dreys and cracks in bark are used. It is perhaps in houses where they are most likely to be encountered, especially in the spring when they try to leave the hibernacula to breed. Nymphs of the species have been found in Britain indicating some breeding has occurred.

This species can be a significant pest to conifer plantations in the USA and Canada, however so far it has not exhibited any significant signs of damage to British nurseries.  FERA have monitored the species and seem unconcerned about its potential impact in Britain, subsequently there is no need to report sightings other than for ecological data recording purposes.    

  

With a basic knowledge of British shieldbugs Leptoglossus occidentalis can easily be separated from other species. It is notably quite large and elongate and has distinctively flattened hind tibiae. This specimen was recorded in North Yorkshire in a garden.

Badgers and Bovine Tuberculosis

Where better to start than to dive in at the deep end and take a closer look at what must have been (and still is) the biggest wildlife storey in the news over recent years, the case of badgers and bovine tuberculosis. With recent news that the government is about to give the green light to a full scale badger cull  in England, which could see in excess of 100,000 animals culled, I thought I would give my view on it.

What is Bovine TB?

Bovine Tuberculosis is bacterial disease caused by the bacillus Mycobacterium bovis and is similar in many ways to Mycobacterium tuberculosis the human form of the bacterium. In-fact it is likely that M.bovis evolved from M.tuberculosis and was originally spread from humans to cattle following their domestication. Cattle then passed the now mutated disease back to humans and on to other mammals including badgers. The disease basically consists of the formation of tiny tubercles on internal organs, most often found in the lungs, within these the bacteria multiply. When one bursts it spills out bacteria spreading the disease around the hosts body. TB often causes the animal to become weak, lethargic and eventually die. What makes it complex, certainly in the case of badgers is some animals appear not to show signs and suffer, where the disease lays dormant acting as a reservoir for the disease. Badgers seem to have a remarkable tolerance to the bacterium and generally between 50% and 80% of tuberculous individuals have no observable lesions. In some studies badgers with TB and ones without it co-exist in the same sett over years without it spreading between them. Some animals do succumb to it and often leave the sett in a very poor condition. Approximately 35,000 cattle are slaughtered each year as a result of Bovine TB, making it a real problem for British Farmers.

Why Badgers?

People often argue that mammals other than badgers carry TB and could contribute to the spread of Bovine TB and act as reservoirs. This is true, however the significance of this is unlikely to be high in most species with the exception of perhaps deer. A host species need to be able to carry the infection and interact with cattle regularly. Deer populations are on the increase and could certainly become a more significant reservoir for the disease in the future, especially given that they are capable of ranging further more quickly in comparison to badgers, which are relatively sedentary especially in areas with high population densities. However deer have not always been as numerous in comparison to how prevalent bovine TB has historically been, especially the large species like red deer and fallow deer. Badgers are undoubtedly a key reservoir for the disease as they are relatively vulnerable to infection and their biology means they often come into closer contact to cattle, in comparison to many other wild mammals. Badgers regularly feed in grazed pasture where they are directly close to cattle, they also urinate on the pasture causing an indirect risk, they regularly feed on stored cattle food, drink from water troughs and some radio-tracking studies have even noted them as physically interacting with cattle. In Britain, badgers are the only known maintenance host for M. bovis, although there are some “spill-over hosts” (i.e. populations in which infection will persist where a maintenance host is present in the ecosystem), including Red foxes. Despite this the exact transmission from badger to cow and back from cow to badger is still poorly understood and may involve a number of transmission route ways. It is widely accepted that cow to cow routes are the most significant way in which cattle spread the disease, although cattle are less likely to act as long term reservoirs due to health checks.       

Badger Culling - What we know

With the evidence suggesting that Bovine TB was linked to badgers, the idea of culling as a control measure was investigated. This has occurred almost continually in one way or another since the 1970's, usually in the form of trials. Thankfully unselective and inhumane methods such as the use of hydrogen cyanide to gas setts was soon outlawed. This was replaced by live trapping and shooting, which still operates to an effect today. In the 90's Professor John Krebs began a Randomised Badger Culling Trial, this trial had a key aim to determine the extent to which the removal of badgers reduced TB in cattle. The trial used two culling regimes, Proactive - where badgers were eliminated as far as possible from the area and Reactive - where culling occurred in a small area as a direct result of a TB outbreak. In addition no cull control areas were also studied, something which previous trials had not investigated in sufficient detail. Culling trials in Ireland did however show that by culling 100% of badgers in an area you can reduce TB, this is unethical and not a practical solution to the problem.

The results of this trial offered conclusive and interesting evidence (which appears is being ignored once again). The Reactive culling resulted in an increase in the rate of TB in cattle by on average 27 per cent. The proactive cull resulted in a lower rate of TB in cattle in culled areas, than in control areas, showing the removal of badgers did reduce TB. However only by a rather low 20%, not a lot given the time and money spent culling. What makes matters even more interesting is the rate of bovine TB actually increased by 25% ( on average) in a 2km band around the culling area. The increase in TB surrounding the cull area effectively cancels out the results of culling inside the cull area. Certainly good enough data to abort a cull and look at other ways forward, and look at a genuine was to control the disease in cattle, in my opinion.

The reason for this is known as the perturbation effect. Culling alters the spatial social organisation of badgers, which results in abnormal behaviour, not only in culled areas but in areas surrounding the cull site. Badgers are territorial animals which more of less constantly remain within the territory, or in close proximity to its boundary. Culling causes badgers to increase their territories size, range further and disperse more frequently. Larger territories often have more poorly defined boundaries increasing the (indirect and direct) interaction of animals from neighbouring setts. All of this moving around also causes TB to move around and spread at an increased rate.      

Ways forward

I personally think the most realistic way of reducing the disease in cattle is to deal directly with the cattle rather than badgers. Cattle are easier to work with, easier to conduct research on and easier to access. Research into vaccinating cattle needs to be continued and looked at as a realistic way forward. However it is not as straight forwards as it would seem in that so-far no 100 effective vaccine has been found. Vaccinating cattle would also mean that you would no longer be able to conduct TB tests on vaccinated herds as they would be diagnosed as TB-positive. So any development of a vaccine would also require the development of a new TB test. Recent promising advances have been made using Bacille Calmette-Guerin (BCG), the vaccine used on humans. To make things worse EU Legislation forbids vaccination of cattle as it may increase the spread of the disease, as vaccinated cattle cannot be reliably tested. Trials are ongoing in Gloucestershire to test the efficiency of vaccinating badgers. In my opinion administering drugs to a wild animal like a badger would be very difficult, it would involve applying an oral vaccine to bait, which would be impractical as it would be impossible to ensure the whole sett had fed on the relative quantity of vaccine. This would then have to be regularly carried out to vaccinate young animals weaned after the initial bait was set up and animals new to the sett/area, which have dispersed from other areas. In addition to cattle vaccination, increased bio-security of stock sheds and food stores would help reduce the risks of infection i.e. increase ventilation and have lower numbers together, as would better fencing where possible (a method much cheaper than a national cull believe it or not). Certainly stricter farm bio-security, continued research into a more efficient vaccination for cattle and tighter measures of cattle movement would be positive steps forward.       

Hopefully the sight of badger prints in our countryside will not become a rare occuarance. As the autumn draws on badger feeding activity greatly increases as they put on addition subcutaneous fat reserves to help see them through the hardships of winter, making it a great time of year to find these distinctive prints.