Archive for the ‘Thoughts and Musings’ Category

Badger - one of the mammals that practices delayed implantationAs I write this I can be quite confident that in badger setts across the country, female badgers are either giving birth or getting very close to doing so.  Up to mid-February is the peak time for badger births.

The reason I can be so confident is that badgers have amazing control over their reproduction via a process called delayed implantation.  The badgers can mate at any time of year (spring and late summer seem to be particularly favoured times) and yet give birth in February.

What happens is that the egg gets fertilised in the normal way.  Egg and sperm combine and the cells start to divide.   But the fertilised egg does not implant itself into the uterus and continue to develop as would be the case in most mammals.  Instead, the small ball of cells, called a blastocyst, stops developing and goes dormant, drawing just the small amount of oxygen and nutrition it needs to survive.  In late December the blastocyst attaches itself to the wall of the uterus and starts to develop into a full foetus, to be born in February.  This is delayed implantation.  It means that the badger mating I witnessed in August (see Fieldnotes: 8th August 2009 – Sex) could result in cubs being born now.

Delayed implantation is not unique to badgers.  It occurs in a number of other mammals such as stoats, bears, Roe Deer and Grey Seals.  The evolutionary advantages of the process are clear – it means that the young are always born at the optimal time to take advantage of the best food resources in spring.

For badgers, there a few interesting implications.  Ernest Neal speculates that delayed implantation allows the badgers to mate throughout the year, which may help to strengthen clan relationships.  Hans Kruuk makes the point that multiple matings with different males could result in multiple blastocysts, meaning that each cub in a litter could have a different father.  Badger families must get complicated sometimes!  This is even more interesting when you remember that the dominant female badger may kill the cubs of other females to maintain her position.  This control over the genetic make-up of the clan is very much a female thing.  It must be related to the fact that you can never be sure who the father is, but there’s never any doubt about the mother.

Now, I’ve been thinking about badgers, and about delayed implantation, and I’ve got my own little theory.  This is just my own idea, so if it’s wrong then I take full blame.  My line of thinking goes like this: most of the mammals that practice delayed implantation are solitary by nature.  This means that the males and females come into contact only irregularly.

Delayed implantation offers an evolutionary advantage to these species because it means that a male and female can meet up at any time of year, mate, and still have the offspring born at the best time.  It is a way of compensating for geographical and territorial dispersion.

But badgers are different.  Badgers live in social groups where males and females come into contact every day.  For clan-living badgers, delayed implantation offers no great advantages.  Why don’t female badgers simply come into season in December and have cubs via direct implantation?  Neal’s theory about the regular mating strengthening group bonds is one plausible explanation, and there may be a further advantage gained by the genetic diversity of litters sired by different fathers, but I think it tells us something about the evolution of badgers.

I think that delayed implantation is an evolutionary throwback to a time when the Eurasian Badger was a solitary animal.  I think it points to a period in the history of the badger when they didn’t live in social groups and therefore gained an advantage from it much as stoats and seals do today.  In turn, it suggests that clan living is a relatively recent development for badgers.

It isn’t as wild a theory as it sounds.  Other badgers around the world are still solitary – the American Badger, the Honey Badger, the Indonesian Stink Badger, and so on.  Even our own Eurasian Badger is solitary across large parts of its range.  In Mediterranean regions, where food is scarce, badgers are virtually solitary.  Rather than this being an adaptation to the dry conditions, it’s my belief that delayed implantation shows that this is their natural state, with clan living a relatively recent adaptation to the conditions of North West Europe.

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Loch Ness from Fort Augustus

Loch Ness from Fort Augustus

For more years than I care to remember I’ve celebrated the summer solstice in true and outrageously pagan style at one of the great stone circles of Avebury and Stonehenge.  This year, however, I swapped the ritual of standing slightly bleary-eyed and hungover, waiting for the Wiltshire dawn to peep over the horizon, for the celebration of a friend’s wedding.

The wedding festivities took place near Inverness in Scotland.  The main venue was an enormous old country house, where we had the run of the place for three whole days.  It was a great place and a great wedding – the toasts were drunk in decent scotch whisky, which gives you an idea of the kind of night it was.

Despite my hopes of running into red squirrels or scottish wildcats, it was not to be.  I did take a stroll around the estate on the morning after the wedding to get a breath of fresh air while most of my fellow guests were still slumbering away.   In the woods of the estate I came across a pristine set of badger tracks on a muddy path, and I was able to follow these back and locate the sett – a grand affair with at least half a dozen active entrances.  It just goes to show that you can dress me up in a suit and try to make me civilised but once a tracker, always a tracker!

But for me, a trip to Inverness had to involve a visit to Loch Ness.  I borrowed a car (thanks Sam!) and spent a day there.

When I was much younger I was fascinated by the idea of the Loch Ness Monster.  As I grew older and developed faculties of critical thought I realised that there wasn’t actually a plesiosaur in a lake in Scotland – come on guys, what on earth were you thinking! – but the story is still a great one.

The Horseshoe Scree on Loch Ness where Torquil MacLeod saw the monster

The Horseshoe Scree on Loch Ness where Torquil MacLeod saw the monster on the shore

The best time to be at Loch Ness must have been in the late 60s and early 70s, when it was home to an assortment of different expeditions.  There was a tremendous enthusiasm about the place, a feeling that there was a genuine discovery to be made, and that if established science was not interested then it was up to the amateurs to show them the way.  It must have been great – the shores of the loch manned by student volunteers with cameras, binoculars and surplus World War II searchlights, while on the water a strange assortment of boats fussed around, playing tapes of mating whales on underwater speakers or ferrying American technicians as they tested their latest sonar gear.  In those heady days anything must have seemed possible.

Where Tim Dinsdale filmed the Loch Ness Monster

Where Tim Dinsdale filmed the Loch Ness Monster

I’ve never been to Loch Ness before, but I have read almost every word ever written about it.  I took my poor, long-suffering wife on a trip around the loch, stopping at obscure places of interest.  I found the layby where in 1960 Torquil MacLeod watched the monster as it basked on the Horseshoe scree on the opposite shore.  I found the approximate location from which Tim Dinsdale filmed the monster in April of the same year, and I was able to follow the route of his thrilling dash to the loch shore in a desperate attempt to get closer to the beastie.  I travelled the road where the Spicers had their classic 1933 land sighting, although it has changed out of all recognition now.

I enjoyed my pilgrimage to the loch immensely, but isn’t it all a bit sad?  I mean, people don’t really believe in it any more, do they?

Ironically, even though the enthusiastic volunteers of days gone by used to battle against mainstream science, they turned to mainstream science and in so doing they proved that the monster doesn’t exist.  Adrian Shine, monster-hunter turned respectable scientist, has spent years building up a picture of the ecology of the loch, starting from nutrient levels and plankton and working up the entire food chain.  The results of this work show that the loch cannot support a single large monster, let alone a breeding population of them.

Although I’d secretly like the monster to be real, I think I am reassured by this.  It shows what amateurs can do.  They didn’t find a plesiosaur, but the slow, patient study – starting from first ecological principles, establishing facts and building on them – has finally answered the question of the beastie in the loch.  In the process it has shown what enthusiasm, resourcefulness and some basic scientific principles can achieve.  It is a story that I, as a very amateur naturalist, still find inspirational.

There may not be a monster, but the story of the search for it deserves to be remembered.

Don’t worry – back to the badgers later this week…

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OK.  Time to bare my soul a little.

Most people in Britain have never seen a badger.  Many have seen a dead badger by the side of the road, but few ever see a live one.  Of those that do, I suspect that most are content to enjoy the experience, to enjoy the badger as an impressive yet endearing part of our wildlife.  As I’ve said before, once people see a badger they seem to become hooked.  Even Ernest Neal, the undisputed authority on badgers, first came across one by accident and this led to a lifetime of work studying these creatures.

But for me it is not enough to just watch badgers.  I’ve gone past the “wow – there’s a badger!” phase.  I want to understand them.  I think I’m becoming obsessed.

Now don’t get me wrong – it’s not a bad obsession to have.  It’s quite healthy.  I could be addicted to drink or drugs, but instead I’m becoming addicted to badgers.  It’s a pleasant diversion from work, it keeps my mind active and stops me getting up to mischief, and most importantly it encourages me to get out and enjoy the countryside on my doorstep.

What started out as a good excuse to go for a walk in the woods has now got me learning about animal behaviour, territoriality, social bonding and the whole ecology of woodlands.  As soon as I think I’ve understood how badgers work, I discover something new and realise I actually don’t know very much at all.

All of this philosophical musing has been triggered by a short walk in the woods this morning.  I wanted to go out and have a look at the Pine Tree sett, specifically to see if there was any more evidence of badgers eating the sycamore bark.

Sycamore with gnawed bark

Sycamore with gnawed bark

When I got to the sett I found that there was a lot more evidence of bark eating.  Another tree had been ‘attacked’ and more bark was missing from the original tree.  But from what I’ve seen, I’m not sure that badgers are the culprits.

The bark shows clear toothmarks – lots of them and quite small – rather than a few large claw marks that I’d expect from a badger.  More conclusive was that the damage to the bark now extends to about 8 feet off the ground.  Badgers are actually surprisingly good at climbing trees (and they seem to enjoy it as a game) but I think that this height is beyond them.  I now need to research squirrel feeding, and see if that fits the bill.  Even better, I need to spend an evening here and see if I can catch the culprit in the act.

Bark damage close up

Bark damage close up - scale in cm

Acting on suggestions from people on the Wild About Britain forum, I examined the badger dung in the latrine nearby.  It seemed a bit more green than usual but there were no clear signs of bark in it.  And no – I didn’t bring any home for analysis.  I’m not that obsessed yet!

Badger Dung

Badger Dung

Walking back through the woods, I came across more puzzling animal signs.  For want of a better word I’ll call these ‘nests’.  They were substantial piles of grass that had been pulled up and shaped into a mound, sometimes with a hollow in the middle.  They are undoubtedly the bedding of some animal.

I’ve come across these before, and I wondered if they were piles of bedding that a badger had collected and then for some reason abandoned on the way back to the sett.  After seeing more of them today I think that they are more likely to be nests in their own right, where an animal sleeps.  I found them in dry, sheltered spots.  Here’s one under a fallen tree:

Badger Nest 1

Here’s one under the shelter of a pine tree:

Badger Nest 2

The nests were associated with paths, but whether these were badger paths I could not say.  The whole area is criss-crossed by badger paths and deer paths, and to confuse matters the badgers use deer paths and the deer use badger paths.

Are these nests made by badgers?  What other animals deliberately gather bedding from distance?  If they are badger nests, why are they there?  Why are the badgers not safely underground in their sett?  Are they used as temporary shelter?  Are these badgers part of a sett, or are they some sort of homeless, ‘hobo badgers’, sleeping rough?  If so, how do they fit into the territories of the other badgers?

Do you see now how this whole badger business can become obsessive?  If anyone has any answers, please do let me know.

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Buzzard over the pasture field

Buzzard over the pasture field

I’ve tried to make a point of watching one group of badgers rather than flitting around here, there and everywhere, the idea being that I should be able to learn more by getting to know one group very well.

OK.  Today I changed my mind slightly, and decided to go and have a look at the neighbouring badger sett.

Regular readers may remember that I found this sett a little while ago (see Fieldnotes 7th September).  I hadn’t forgetton it.

In fact, this sett has been central in my efforts to understand ‘my’ group of badgers.  I was able to predict its position by mapping latrine sites, badger latrines being sited on the boundaries of their territories.  When I followed the badger tracks in the snow in January I was able to see how badgers from both of these setts interacted on the boundary between them.

A great deal of badger behaviour is related to establishing and maintaining a territory, so understanding the relationship between neighboring clans is important.  For instance, last year I wondered what happened to the ‘excess’ badgers at the sett, since as a group they seemed to reproducing faster than they were dying.  After reading Hans Kruuk’s The Social Badger I now know that the non-dominant males leave and typically mate with females from another sett, but only ever with those from a neighbouring sett.  They don’t seem to travel any further.  The females almost always stay in their home territory.

(Interestingly, this happened to me too.  I grew up in the north of England, but I left there and married my wife.  My wife is from Bedfordshire, where we now live,  so I migrated away from my clan whilst she stayed in her home territory.  Perhaps the principle works for humans as well…)

Anyway, I digress.  Today, I decided I fancied a bit of a change so I went to see the other sett.  It needs a name to distinguish it from the main sett I watch, and since there are pine trees around the entrance let’s call it the Pine Tree sett.

The Pine Tree sett is not as big as the main one.   Like the main sett it adjoins

The Pine Tree sett

The Pine Tree sett

the pasture field, so the badgers have access to the main food resources (hence the territorial boundary that divides the pasture field between them).  There are three entrances spread out over a hundred yards or so, with a well-used path between them.  The entrances are the classic sideways D shape, with large spoil heaps and used bedding outside.  Nearby were fresh dung pits.  In short, it was as badgery a place as you could ever wish for.

The only problem was that although I watched it for three hours, I didn’t see any badgers.  Very frustrating.

The holes are quite far apart and not intervisible, so it is only possible to see one of them at a time.  I chose to watch at the hole with the largest and freshest spoil heap, but perhaps the badgers were at another one.

It’s a mystery.  It is obviously a badger sett, and obviously in use, so the badgers must be somewhere.  I was at the sett from 6.30pm to 9.30pm, so I imagine the badgers would have come out during that time.  In the other sett half a mile away they’re coming out consistently between 8.00pm and 8.30pm.

I think I need to put in a few more trips to this sett and try watching the other holes.  Hopefully that will clear up the mystery.

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Today I bought a new camouflage shirt to wear in the summer when my jacket gets too hot.

Everyone knows that your clothes should be a drab green or brown (or in my case a mixture of the two with pictures of leaves on) so that you blend into the background and the wildlife can’t see you.

While I was out I also bought some batteries for my red LED torch, because everyone knows that badgers cannot see red light.

Hang on a minute.  These two statements don’t really go together.  If badgers don’t see the colour red, does that mean that red is the best colour for badger watching clothes?  Why didn’t I just buy a red shirt and trousers?  I’d be invisible to badgers then.  I wonder if anyone has ever tried this?

The truth is that camouflage is a complicated subject, and I’m sure a lot of it comes down to personal preference.  Is camouflage really necessary for watching badgers and other wildlife?  I honestly don’t know.  All I can say is that I wear it because I feel more confident that I can’t be seen, and that confidence is important if you’re going to spend hours in a tree waiting for a wary animal to show itself.

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This started off as a reply to a comment on my last post, but it got a bit long so I thought I’d convert it into a post of its own right.  It is an interesting subject, and this isn’t really a reply to the comment so much as the train of thought it triggered off in me.

I talked about trying to keep hidden from the badgers.  As Undergrowth commented,  I’m sure that the badgers are perfectly aware of my presence, even if it is just from coming across my scent as they forage in the wood.  I live in hope that one day they’ll get used to me being there!

And it would be perfectly possible to use food to get the badgers to accept me.  You can train animals to do just about anything with food.  The famous psychologist B. F. Skinner once trained a cat to play the piano.  Skinner trained animals to do all sorts of things – he created the world’s first guided missile using trained pigeons to home in on the target (thankfully never used, not least for the sake of the pigeons!)

I’ve seen how badgers make full use of available food resources, and I’m sure that regular feeding would get them literally eating out of my hand.  I know that many people feed badgers.  The extra food can be a real benefit to the badgers as well as providing some great views for the watchers.  When you think about it, it’s no different to feeding the birds, and I certainly do that.

But the problem is that once you start feeding animals, you lose the natural behaviour.  I’m not saying it’s wrong to feed them – lord knows we’ve messed around with our wildlife in far more serious ways – but I don’t want to go down that route.  I have put out some peanuts for the badgers in the past, but I’ve stopped doing it now.  I want to be able to see the badgers in their natural state.

In other words, I don’t want to just watch them, I want to understand them.  I want to understand what they do, and how they live.

This is also why I go to so much trouble to stay out of sight.  Even though the badgers are sure to know that I’ve been there, I still want to make as little impact as possible.  I don’t want the badgers to associate me with fear or danger.  If they come to associate my scent with someone crashing about the undergrowth or blundering into view, then they’ll learn to avoid me in the future.  I don’t want them to become friendly with me, just kind of neutral.

It sounds like a lot of trouble, but it means that ‘my’ badgers are truly wild.  What I see is as close to natural behaviour as possible.  That’s important for me.

As always, these are my own views.  I know that some people will disagree and that’s fine.  There are many situations where feeding badgers is a good thing for all concerned.  Just not for me any more and not at this sett.

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Only in silence the word
Only in dark the light
Only in dying life
Bright the hawk’s flight on the empty sky

Ursula Le Guin

Regular readers will know that there are two species (apart from badgers) that I have been trying to see in my local area: the Red Kite and the stoat.

Since my wife saw a kite a few weeks ago I’ve been looking out for it, and my failed attempts to find and watch stoats are legendary (see A total absence of stoats).

Today was a beautiful, bright, warm spring day.  I drove out the DIY shop in the afternoon, and as I came back into the village I looked across the fields and there, gliding effortlessly across the sky, was a Red Kite.

It was unmistakeable.   Its primary feathers were splayed out and its forked tail stood out clearly against the blue of the sky as it soared on the warm air.  A magnificent bird.  I allowed myself to feel a little satisfaction at having caught sight of it at last.

Another 500 yards further down the road, and there was a stoat, lying dead in the middle of the road.

Nature can be cruel sometimes.

I parked the car and walked back.  The stoat was in the same place that I had seen one almost a year ago.  It was probably the same stoat.  I suppose I had a hope that it was just stunned.  The body was still warm and there wasn’t a mark on it, but it was quite dead.  It must have been killed no more than minutes before.

I’ve never seen a stoat close up before, and it was a beautiful creature.  Sleek and lithe and every inch the predator.  I somehow felt unwilling to leave it there by the road for the carrion birds – the crows and magpies and yes, the kites – and I took it away and buried it.

I guess this is the great game of nature being played out.  Still, where there’s one stoat there must be more.  I still want to see one, but under happier circumstances.

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As a psychologist I find coincidences strangely intriguing.  Since I started writing this blog they seem to happening regularly.  Take the sparrowhawks for example; or the time I mused about never having seen a long-tailed tit and then saw a whole flock of them the very next day.

My last post was about the kites that I watched in Hong Kong last week (the birds of prey, not the flying toys).  This morning I received an e-mail from my wife saying that she had seen an unusual bird of prey as she drove to work.  Now, my wife is no twitcher, but she knows the birds and animals of the area pretty well, and she certainly knows something new when she sees it.  She described the bird as being the same size as a buzzard, feeding on a dead pheasant by the roadside and, crucially, having a forked tail.

There’s no doubt about it, this was a Red Kite – the forked tail clinches it.  Red Kites are not unknown in Bedfordshire, according to the Bedfordshire Bird Report 2007, but they aren’t common either.  They are outliers of the large population in the Chilterns.  Put it another way, I’ve never seen one, and I look out for these things.

To see a Red Kite in our area is thus a fairly rare and improbable event.  So, what are the chances of one appearing literally at the end of my road, just at the same time that I’m writing about them?

Carl Jung, the famous (and slightly mad) psychologist saw coincidences such as this as evidence of synchronicity – a meaningful relationship that reveals hidden aspects of reality and illustrates the working of the collective unconscious – the cosmic governing intelligence that connects all things.

More prosaically, it could just be one of those things.  I’ve wrote about quite a few things on here, and only a very small number happen the next day.  I still haven’t got a good look at a stoat, for instance, despite really looking.  What might be happening is that I pay more attention to those events that do coincide, and give them more significance because they are unusual.

Was the Red Kite some sort of cosmic messenger offering dark hints about the mysteries of the universe?  Am I in some way summoning birds and animals with the power of my thoughts?  Was it just a random thing – no explanation, and no point looking for one?  Or am I still a bit jet-lagged, and should I settle down and stop thinking about these things?

Whatever it is, one thing’s for sure.  I’m going to get out at the weekend and see if I can track down the kite.  They’re wonderful birds and it would be great to have them living locally.

And don’t worry, give me a few more good nights’ sleep and I’ll stop this esoteric rambling.  There’ll be more badgers soon, I promise!

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Another day, another fall of snow.  I took a stroll up to the pasture field tonight.  The snow is 20cm deep at the top of the hill, and yet there were still the tracks of a couple of badgers.

One of these tracks followed the same general route as one on Monday – out of the wood and down the hill, following the footpath across the pasture.  The other came out of the wood from some distance away, went up to the first track and then doubled back on itself.

As I said, the general line of the first set of tracks follows the footpath up to the wood, and there are three separate badger latrine sites within half a mile along this path.  This has got me thinking.

Badger latrines generally act as territory markers, and it is common for two neighboring badger clans to share a latrine on the border (see my post on mapping badger latrines for more details).  Suppose the badger tracks mark the boundary between two territories, and that the two badgers were from neighbouring setts?  This would explain why the tracks came from opposite directions, and why so many tracks on Monday all converged on this area.  The badgers were walking along the boundary line – staking out their territories from both sides.

If this is true, it also explains why the latrine sites are on the same line, and why the badgers on Monday were taking such an interest in each others’ tracks – they were from different clans.

Such ‘border patrol’ activities are mentioned in the literature.  For instance, I’ve finally read Hans Kruuk’s The Social Badger (and excellent it is, too), and he describes witnessing aggressive encounters between badgers on these shared paths between territories.

Lastly, on Monday I thought that the badger tracks showed that the territory of my badgers is much bigger than I thought it was.  This may not be the case.  If I was walking along a boundary between territories, I was looking at tracks from two different badger clans, one on either side of the border, rather than one big territory covering the whole area.

Curiouser and curiouser.  This means that my tracking in the snow may have pinpointed the precise line between two badger clans.  As a theory, this boundary idea fits all the facts.  I wonder how I could prove it?

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Badger cub

Badger cub

Thinking about the badger sett has got me thinking about badger paths.

Badger paths are an absolutely classic sign of an active sett.  Badgers are well-known to be creatures of habit, and will follow the same route night after night and even generation after generation until the vegetation is worn away and quite deep paths are formed.   The urge to follow paths is obviously very strong.  There are many examples of fences being erected across badger paths and the badgers simply barging through.

But why is this so?  Why do badgers follow such regular paths?

To understand why, you have to stop thinking like a human and think like a badger for a while.

I’ve already mentioned the senses of the badger (see About Badgers).  Badgers have poor eyesight, but a very good sense of smell.  Unlike humans, who rely on visual information to navigate, the badger ‘sees’ the world as a landscape of scents and smells.  This makes perfect sense for an animal that is active in the hours of darkness.

Badger paths then, are not visual paths, but scent paths.  Each path carries the scent of the badgers that have used it.  When a badger is following a path, it is literally following the badgers that have gone before.  As a system it is simple and effective – the badger can find its way around a completely dark wood by using these trails, and in times of danger it can always follow them back to the sett.  It is difficult for humans to understand a landscape of smells, but to the badger, these paths must stand out like a bright shining road would to us.

But nothing with badgers is ever simple.   Many mammals have interdigital glands.  These are glands between the toes that leave scent when the animal walks.  Cats have them,  for instance.  When a cat scratches a tree it is not sharpening its claws.  It is leaving scent from its interdigital glands to mark its territory.

It seems likely that badgers also have interdigital glands.  This means that every time a badger uses a path it is not only leaving a signpost for itself and for other badgers, it is using the path to mark out the territory of the clan. Badgers use scent to identify members of their own clan, so a badger can easily tell which paths belong to them, and which belong to the neighboring clans.

So badger paths are not just the result of ingrained habits or an easy way for the badgers to get from one place to another.  Seen in conjuction with other territorial markers such as the latrine sites and scratching trees, paths are a sophisticated part of the social behaviour of badgers.

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