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.