Frogs hop into spring

It often surprises me how seemingly unfussy frogs are with their spawning grounds. I have seen them in road ditches in Scotland and even taking to an old ceramic toilet buried and filled in a previous garden of mine. On the corner of our village road is a rather sad, shallow pond – or more accurately a large muddy puddle choked with leaf detritus, rubbish and even occasionally the odd fridge. Earlier this month however, ‘Top Town Pond’, as it is called locally(1), was choked by something very different and far more welcome - by frogs making their annual frenzied return and all the more obvious in the few inches of water.

So what makes them choose what seems at face value to be a less than attractive location for their spring romance and productivity? The first evidence that I have noted is that there are always small fish present, even in the height of summer when you might expect this pond to dry out. According to locals the pond is fed by continually by a spring from the nearby Dumble, “a stream which has formed a deep wide channel in the clay that is quite out of proportion to the amount of water normally carried”(1). So although the pond more than halves in volume in hot weather, it never completely dries out making it a safe haven for tadpoles to complete their aquatic life cycle. Another factor is the age of the pond - Many amphibians are loyal to their birthplace, potentially using a number of sensory mechanisms to return each year, such as; odours of ponds, landmarks, the positions of sun, moon and stars, and the earth's magnetic field (2). This pond has certainly been there for a long term, and indeed perhaps its presence determined the location of the Pinfold itself as in times past it served to quench the thirst of stray cattle that would be temporarily placed there awaiting their owners to reclaim them(1). Of course the dramatic decline in ponds over recent decades has meant that our amphibians have had to become less fussy – why else would they use my old toilet!

The pond has now returned to relative calm whilst the clumps of abandoned jellied eggs slowly warm in the rising spring temperatures. In a few weeks however the shallow waters will be churning again to movement of black tadpole shoals overshadowing the resident minnows.

(1) The Westhorpe Dumble Heritage Trail (see http://www.newark-sherwooddc.gov.uk/ppimageupload/Image81741.PDF) (2) Sinsch, U. (1990) Migration and orientation in anuran amphibians. Ethology Ecology & Evolution, 2 (1): 65 - 79

Blackcap warming to English winters

During a recent visit to my parents in Ledbury, Herefordshire, I was delighted to see the distinctive Blackcap (Sylvia atricapilla) frequently feeding from their birdtable. This warbler is probably the easiest to identify with distinctive skull caps, black in males and a chestnut brown in females. Like many other warblers, the Blackcap is a summer migrant to Britain. However since the 1960’s it has been increasingly seen staying over during the winter, particularly in southern England - I have never seen this species where I live in Nottinghamshire. Why have a growing proportion of Blackcaps decided not to migrate during the harsher winter conditions?

Migration clearly requires a high cost to the ‘traveller’, in terms of energy and ‘in-flight’ hazards. If the benefits of staying put over winter outweigh those of migration, you might predict that some would be tempted to stay. It would appear that the Blackcap with more eclectic tastes than other warblers more reliant on insects, has taken advantage of the growing bounty found on English birdtables. It has also been proposed that it is also a good example of how some wildlife is responding to climate change and warmer British winters, which might well lead eventually to complete residency as temperatures continue to rise (Pulido & Berthold). So, although many households welcome this addition to their gardens in winter, its increasing presence may also be a warning signal of continued climate change and less welcome impacts on other wildlife.

I guess it won’t be long before the Blackcap will start to turn up more frequently at birdtables in the Midlands and further North.

Pulido, F. and Berthold, P. (2010) Current selection for lower migratory activity will drive the evolution of residency in a migratory bird population. PNAS, 107 (16): 7341-7346

This antisocial poisonous plant clone is not for sale

I took a stroll in our local woodland yesterday and was surprised to see how much had changed in a couple of weeks. Everywhere new green vegetation is pushing through as the snowdrops fade. Most notable are the Lord’s and Ladies (Arum maculatum) and Dog’s Mercury (Mercurialis perennis). Interestingly both of these species are reputed to be poisonous to animals, perhaps defending themselves as early emergers from the onslaught of grazing. However for Dog’s Mercury the evidence appears limited and contradictory. Watson (1998) describes suspected poisoning in cows, but such reports are rare and there are reports of animals happily grazing on the plants such as Muntjac deer. Interestingly it is also used in remedies for medicinal purposes, such as the ointment, ‘Wound-Care’, used to help accelerate wound healing (Weleda, 2009).

Dog’s Mercury is dioecious (=two forms) with clearly different male and female plants, in particular the floral parts (the plants in the image are male, showing catkin like spikes emerging from leaf axils - Rose, 2006). However this species expands mainly asexually by vegetative propagation, with rhizomes extending underground and sending up frequent aerial shoots. This produces large single sex clonal stands which appear to remain quite distinct, rather than mixing with adjacent ones (Wilson, 1968 – cited in Jefferson, 2008). Have a look and observe that most patches are distinctly male or female. Improved light conditions (such as canopy openings in woodlands) appear to favour male plants (Vandepitte, 2009b) which may exaggerate their separation from females.

Although it is a widespread and common plant in woods and shady places, its distribution appears to be limited by a strong affinity to ancient woods in Britain (Peterken & Game, 1981). There is also evidence of local declines through factors such as increasing deer browsing (Hall, et al. 2004), coppicing and other disturbance that opens up woodland canopies, bringing increased competition from other plant species. So with poor mobility and growing threats, it is probably declining gradually in parallel with the loss of older and precious ancient woodland (Grimes et al, 2007). So please look again at this apparent modest plant and see it as an indicator of the health and heritage of our woodlands which should not be put up for sale to the highest bidder.

Hall, J.E., Kirby, K.J & Whitbread, A.M. (revised 2004) National vegetation classification field guide to woodland. Joint Nature Conservation Committee.
Grime, J.P., Hodgson, J.G. & Hunt, R. (2007) Comparative Plant Ecology: A Functional Approach to Common British Species, 2nd ed. Colvend, UK: Castlepoint Press.
Jefferson, R.G. (2008) Biological flora of the British Isles: Mercurialis perennis L. Journal of Ecology, 96: 386-412
Peterken, G.F. and Game, M. (1981) Historical Factors Affecting the Distribution of Mercurialis perennis in Central Lincolnshire. Journal of Ecology, 69 (3): 781-796.
Rose,F (2006) The Wild Flower Key – How to identify wild flowers trees and shrubs in Britain and Ireland. London: Penguin Books Ltd
Vandepitte, K., Roldán-Ruiz, I., Leus, L., Jacquemyn, H. and Honnay, O. (2009b) Canopy closure shapes clonal diversity and fine-scale genetic structure in the dioecious understorey perennial Mercurialis perennis. Journal of Ecology, 97:404–414
Watson, P.J. (1998) Suspected dog’s mercury (Mercurialis perennis) poisoning in cattle. Veterinary Record, 142 (5): 116–117.
Wilson, J.F. (1968) The control of density in some woodland plants. PhD Thesis, University of Lancaster, Lancaster, UK.
Weleda (2009) Wound-Care [online]. http://usa.weleda.com/our-products/shop/wound-care.aspx [Accessed December 17th 2009]

Wild foraging: Bitter-cress sandwich

I’ve been curious for some time about how realistic it is to integrate ‘wild’ foods into my diet and whether they can make a significant contribution. Firstly I should identify what I mean by a wild food. These are essentially plants or fungi that are not cultivated with the intention of consumption, but grow freely in the countryside or disperse into gardens.
So my plan is to pick one species at a time testing it out on myself first, possibly family & friends, and then report on ease of identification, how easy to find and palatability. I should stress that I will abide by the laws & codes of conduct of the countryside, ensure that I do not compromise the future local viability of the species, and avoid plants that may be contaminated by pollutants (agricultural & roadside). I am lucky that our current rented garden should keep me going for some time as it is fairly representative of the local countryside with woodland, hedgerow, open spaces and an area of cultivation.

So to my first plant subject - the easily overlooked Hairy Bitter-cress (Cardamine Hirsuta). This was an easy first choice as it grows fairly rampantly in the garden, particularly on the vegetable patch and on a steep bank. It is also available now in mid-winter, a real bonus with the scarcity of fresh salad plants. I have in the past weeded it out from the vegetable plots wastefully, not realising its dietary potential. On this occasion I pulled up a good sized plant (about 5 inches in diameter) already with tiny white flowers and a characteristic basal rosette of about 20 leaves. I can identify this species fairly easily having spent some time focussing on it last year. However it closely resembles Wavy Bitter-cress (C.flexuosa), the key difference being that it unusually for a crucifer (member of cabbage family) only has 4 stamens in the flower. I assume that the Wavy Bitter-cress is less palatable, as I could not find it recorded in wild food sources. The Hairy Bitter-cress had a distinctive peppery taste, stronger in flavour that normal cress and not too dissimilar to rocket. I ate it first with bread and cheese and the next day with beans on toast (also enjoyed by my wife). We found it perfectly acceptable and indeed a pleasant alternative/addition to the meals. I would certainly recommend it, saving on buying expensive bags of rocket or pots of cress.

Happy foraging.

Chaffinch killer conundrum

There are many threats to birds in winter. Most weeks recently I have seen at least one bullet-like Sparrowhawk chase zooming through the bird feeding area, occasionally getting lucky. The cold weather itself must take its toll, particularly on smaller birds. So I was curious when I found a dead chaffinch (Fringilla coelebs) lying by the French windows, as to the cause of its demise. Initially I thought it had flown into the window, but the curtains were still drawn making that unlikely, as well as there being no tell-tale feathers or marks on the glass. Our cat had been out for an early morning stretch, but normally she carries back her prey to the front door and at least has a go at eating some of it. I picked it up to dispose of the bird, and noticed how badly affected the legs and feet were; grotesquely disfigured with extensive wart like growths. On one foot there was only one visible claw remaining, which made me wonder how it could perch and move about without significant inconvenience. Otherwise the bird seemed perfectly normal.

I have seen this before in Chaffinches, often seeing several affected individuals in the same area. The condition is commonly referred to descriptively as ‘fur foot’ or ‘bumblefoot’. According to the website http://www.ufaw.org.uk/infectious-diseases.php#id11 similar deformities are often caused by the Fringilla papillomavirus (FPV), which as you can see by comparing the Latin name of the Chaffinch is associated with this bird and to a lesser extent the closely related Brambling (Fringilla montifringilla) with which they often mix. It is this flocking behaviour of these birds in winter that probably aids its dispersal to give high local infection rates. The condition is not too dissimilar to human warts, with excessive growth of skin. From some quick website research people frequently report seeing chaffinches behaving relatively normal despite varying degrees of such malformation. Indeed the http://www.ufaw.org.uk/ link states that the condition can actually spontaneously disappear. However, it must put affected birds at some disadvantage and it is probably a wise precaution to reduce spread at concentrated feeding areas such as bird tables, by occasionally cleaning with mild disinfectant and moving their location (note to diary).

Returning to our crime scene by the French windows, we might surmise now that the Chaffinch was probably more likely the victim of our cat, rather than from a sudden death syndrome. Was ‘Purdey’ put off by the warty legs, or just too lazy to bring it to the door? Whether it was a cat attack or not, it is a useful reminder to refit Purdey’s collar with its warning bell!

Bullfinch not nettled by nettles

We are lucky to get occasional visits by bullfinches in our garden, with the stunningly coloured males. Indeed their Latin name Pyrrhula pyrrhula would appear to have its origins with the Greek word ‘pyrros’, meaning ‘the colour of fire’, which certainly is in keeping with the male Bullfinch’s flame coloured breast. Presumably this is where the word pyromaniac comes from.

Our bullfinches usually visit as a pair feeding on the buds and berries in the garden. However I have noticed them also occasionally feeding on nettle seeds. I always assumed with their largish beaks that they were better adapted to larger food items rather than small seeds. Indeed it is their propensity to eat the flower buds of fruit trees that has not always made them popular with gardeners and commercial fruit growers. According to Newton (1967) the key factor in determining what proportion buds were included in their diet was the size of the ash (Fraxinus excelsior) crop, such that when it was poor, the bullfinches resorted to buds much earlier causing greater damage. He did also emphasise that the seeds of the nettle (Urtica dioica) are important in their diet, along with those of Dog’s Mercury (Mercurialis perennis), Bramble, Garlic Mustard (Alliaria petiolata), Dandelion (Taraxacum officinale agg) and Common Chickweed (Stellaria media). Breeding birds develop special pouches situated beneath their lower jaw which acts as a temporary storage chamber to collect food for their young (Newton, 1967).

According to some websites nettle seeds can provide humans with quite a medicinal punch to treat various ailments, concentrating ingredients found in the leaves. Whether this ‘flame-boyant’ bird gets such a kick, it is of course impossible to say, but they certainly seem to enjoy them. Maybe I should give them a try!

Newton, I. (1967) The Feeding Ecology of the Bullfinch (Pyrrhula pyrrhula L.) in Southern England. Journal of Animal Ecology, 36(3):721-744

Four & twenty blackbirds eating my Bramley pie

There’s no need to tell you how cold it’s been recently. But please bear with me as I beg your sympathy. Last night we recorded minus 14.5 degrees at the Pinfold. We have ice so thick on our windows that we cannot see out, have reached a limit on the number of clothes we can wear indoors and still move, and the family are complaining of chilblains. But compare this with our wildlife without resource to heaters and extra layers, with food covered in snow and water frozen. Within an hour of putting out warm steaming water this morning for the birds, enjoyed quickly by three eager robins, it was frozen. I guess many birds have departed west where it has been a little warmer, but those that remain have to be ever more resourceful.

The Bramley apple tree in our garden has had a bumper crop this year and we have struggled to keep up with the windfalls, despite consuming quantities of stewed apple, apple snow, apple crumble and apple pie. This has left a lot of half bruised, half rotten apples scattered under the tree - until the cold snap, these appeared of little interest to the birds. However in the last few days redwing and blue tits, but mainly blackbirds, have been gorging on them with increasing squabbling over the best ones. This gave me the opportunity to look more closely at the Blackbird (Turdus merula), and I was struck by one male that had a particular orange/red beak with a matching eye ring. Other blackbirds had either bright yellow or brown colouration. I have to be honest and say that I had never noticed this colour variation before and so wanted to investigate why.

The colour of the blackbird’s beak and eye ring is controlled by plasma carotenoid levels. There are many studies, with widely different species, that have considered how females use such colouration to evaluate the quality of a potential mate. It would seem that more colourful males are considered more attractive - But why? Researchers, Bright, et al. (2004) proposed that larger male blackbirds may have larger territories or be better at defending territories during male-male interactions, ensuring access to carotenoid food sources. So, a more colourful beak would equal a more successful male. More recent research however by Biard, et al. (2010), found that there was a relationship between bill colour and relative intensity of different parasitic infections, such as lice. They suggested that these could then act as colour signals for females to assess the relative condition and health of males to help make mating choices.
Now it just so happens that apples have a particularly high concentration of carotenoids. I wonder therefore if it is likely that the males most successful at eating our Bramley’s will be more likely to catch the eye of females in spring.

.....and so to re-coin a phrase, ‘the early blackbird that snatches the apple, catches the mate’.


Biard, C., Saulnier, N., Gaillard, M. and Moreau, J. (2010) Carotenoid-based bill colour is an integrative signal of multiple parasite infection in blackbird. Naturwissenschaften, 97:987–995

Bright, A., Wass, J.R., King, C.M., and Cuming, P.D (2004) Bill colour and correlates of male quality in blackbirds: an analysis using canonical ordination. Behaviour Processes, 27; 65(2):123-32.

Are Yew poisonous

Our bathroom has some intimacy with a large Yew tree (Taxus baccata), the fulsome evergreen branches hanging a metre off the window unnoticed for much of the year. But in the autumn the multitude of mini matt red barrel-shaped berries colours up this dark patch of garden. This week whilst attending to some toiletry I noticed two squirrels feasting on the yew’s fruit. Having always heeded the warning that almost every part of the yew tree is poisonous, I was curious at how these animals coped with the toxins, or wondered if the tree was as dangerous as we are led to believe. Indeed it opened up a bigger question; how do animals know what is and isn’t poisonous?

Numerous scientific studies have determined that most tissue of the yew tree, including the seeds and foliage are rich in taxin(e), a complex mixture of toxic alkaloids (Thomas & Polwart, 2003), and hence it’s genus name of Taxus. The toxins appear to impact primarily on the cardiac tissue of humans and other mammals, leading to heart failure and potentially death. Other effects reported in humans include dizziness, vomiting, abdominal pain and convulsions (Wilson, et al., 2001). This toxicity remains prevalent all year round and even when dried, but peak concentrations are found during the winter (Wilson, et al., 2001). Most incidents of poisoning appear accidental occurrences, with contaminated feed to livestock, but there are a few human reported cases.

The poisonous nature of the Yew has been known for ages. Primitive cultures made use of yew juice dipped arrows as an animal poison for hunting and the Celts committed ritual suicides by drinking extracts from yew foliage (Wilson, et al., 2001).

However, interestingly there is one part of the tree that does not contain taxin which may well explain the recent diet of our squirrels; the aril, or soft succulent scarlet tissue surrounding the seeds and forming the berry. So our ever-clever squirrels can enjoy the fruitful bounty of yew without toxic effect, but I wonder what they do with the seeds – do they spit them out or pass them out undigested in a parcel of ready-made fertiliser. This seems like a clever strategy of the yew to direct wildlife to only consume those parts of it that aids its seed dispersal. However for us humans, BEWARE -only the wiliest of wild foragers should attempt to eat the yew berries, ensuring none of the deadly seeds are consumed.

Thomas, P. A. and Polwart, A. (2003) Taxus baccata. Journal of Ecology, 91( 3): 489-524.
Wilson, C. R., Sauer, J. and Hooser, S.B. (2001) Taxines: A review of the mechanism and toxicity of yew (Taxus spp.) alkaloids. Toxicon, 39 (2-3): 175-185.

The Upside-down bird

We recently started feeding our woodland birds again after a summer break, and within hours of filling peanut & fat ball hangers they were back as if there had been no break in supply. The feeders are being dominated by the tits, including; Great, Blue, Long-tailed, Coal & Marsh. Many of these are likely to be new to the ‘Pinfold café’ after last year’s harsh winter.

The tits have been joined this autumn by at least two regular Nuthatches (Sitta europaea). I’ve seen these birds many times scurrying up and down tree trunks, but I’ve become intrigued recently by their apparent preference for feeding upside down, particularly on the hangers. This reverse mode is relatively unique to Nuthatches. Their natural foraging technique involves working their way down tree branches looking for invertebrates, before flying to the top of another tree and repeating the exercise. The only explanation that I can find for such novel feeding is that by adopting a different approach they see invertebrate prey that other birds, such as woodpeckers and treecreepers, overlook from more conventional angles. Nuthatches appear to be aided by having an extra-large and stronger hind toe (hallux) for gripping the trunk at tight angles, and a stubby tail to reduce a potential incumbency. Perhaps they get so used to this productive technique that they continue to feed upside down on hangers through habit rather than efficiency. Their characteristic posture on the hanger is body facing downwards but frequently looking upwards checking for threats (see photo), making for a rather rubber-necked pose.

It is therefore no surprise that due to the modus operandi of the Nuthatch, that they are frequently known as the ‘Upside down bird’. Other species of Nuthatches from around the world feed in a similar way, which have prompted other nicknames, including Topsy-turvy bird, and Devil down-head.

Spring lunacy

At the beginning of September I attended a course in Pembrokeshire on rocky shore invertebrates. The course was carefully timed to coincide with the largest ‘spring’ tide of the year so that we could explore the furthest point of the lower shore. The term ‘spring tide’ has actually no connection with the season but is derived from the Saxon ‘springan’, “to bulge” or “to rise”. The dictionary definition is “the rising of the sea (to an exceptional height) at particular times” (Onions, 1952). These “exceptional” tides are caused by the combined gravitational effect of the sun & moon every two weeks at a new and full moon. The largest ‘spring’ tide occurs near the equinox during September when the sun and moon are most closely aligned and so referred to as an “equinoctial spring tide” (Oakley 2010). A similar tide occurs around the March equinox.

(Photo of Painted Topshell above - Image credit: Asbjørn Hansen via http://www.flickr.com/)

This is therefore a very special time for the seashore naturalist, when animals and plants are so rarely exposed for observation. On my visits to rocky shores near Dale Fort, large kelp forests were exposed dotted with Blue-rayed Limpets (Patella pellucidum); small flattened versions of the Common Limpet (Patella vulgata) found high up the shore and characterised by brilliant iridescent kingfisher blue lines across their dorsal surface. Painted Topshells (Caliostoma zizphinum), the most colourful of this group of sea snails looking like vibrant spinning tops were found amongst amid rocks encrusted with brightly coloured star ascidian colonies, looking as alien as their name suggests . Crabs were also revealed, more typical of sub-littoral habitats (below shore level), such as the pie-crust edged Edible Crab (Cancer pagurus) and dirty looking Broad-clawed porcelain crabs (Porcellana platycheles). Most exciting was a Decorator crab (Macropodia sp) covered in little seaweed tufts in an attempt to camouflage itself, and a small skeleton like sea-spider scuttling along the tide line at its lowest point.

(Photo of Edible crab above - Image credit: Christophe Quintin via http://www.flickr.com/)

It was a fantastic opportunity to capture a rare glimpse of such wildlife, but all too soon the tide turned and they became submerged again beneath the advancing waves, some not to be exposed again for perhaps many months.

Why not book your place soon for the next equinoctial spring tide at a rocky shore near you!

Oakley, J. (2010) Seashore Safaris. Cardiff: Graffeg Books
Onions, C.T (Ed) (1952) The shorter Oxford English dictionary on historical principles. 3rd ed. Oxford: Oxford University Press.