Chaleur humaine

Egrets are memories. At least they are for me.

They are Florida swamps, Breton estuaries, Aveyron river gorges, and Camargue étangs. Summer heat and cottage holidays.

When they are cattle egrets, they are exotic. Exotic in the sense that they are new, foreign, and are starting to colonise England. Little egrets and great white egrets have been moving north for some years and are now distributed across a number of parts of the country, but cattle egrets are more recent immigrants, first arriving around 2008 and, according to the British Trust for Ornithology, first breeding in 2012.

An article I’ve just read in the Guardian newspaper highlights cattle egrets and a host of other species that are also heading north, whilst many of the species we are more used to seeing have been quietly slipping from sight. They have both been heading up… Up north and up-a-height. Why? Well, it’s that usual antagonist again, anthropogenic climate change. Let’s  consider our islands’ natives.

What do we do on a hot day? We soak it up for a while, then reach a point at which we can take it no more and we make a bee-line for the shade. We seek refuge from the heat. Many of our native species have been doing the same – searching for refuge from the heat. The only difference is the timescale. We beat the retreat based on the weather across a single day. Wildlife species are doing it in response to climate change, and more specifically in response to rises in average temperatures over a period of years.

So is it a case of stay and die, or flee north or to higher ground? Well, it often depends on whether there are local refuges from the heat.

I recently went to a talk that Dr. Andy Suggett of the University of York gave as part of the Wild Watch project that Nidderdale AONB is running. As part of a wider research team, Andy has been looking into such refuges. To be a bit more precise, the team has been looking at whether the landscape contains, or could contain, habitats that have microclimates that will continue to be favourable to species that, because they are vulnerable to rising temperatures, could become locally extinct.

Within our variety of landscapes in the UK, a small geographical area can have a very varied topography containing a number of different habitats. Different habitats result from a combination of things such as exposure, shade, height, slope, orientation, hydrology, soils, vegetation structure and cover, and land use. In these varied habitats we also get varied climatic conditions on a similarly small scale. In other words, habitats can have their own microclimates. Daytime maximums in these habitats can often show differences of up to 7C compared to each other and compared to the surrounding area as a whole. Indeed, Andy cited a day in May 2013 where the temperature variability across the UK overall was 5C, but a thermal sensor recorded a ground level temperature range at a particular location of 15-45C depending on what the vegetation was across the site. In other words, this location had a range of habitats with a range of different microclimates, all based on relatively small scale differences in topography and vegetation cover.

The more a landscape varies, the more habitats it contains. The more habitats it contains, the more microclimates there are. More microclimates means that there will be some habitats that have climatic conditions that are far more favourable to species that are otherwise vulnerable to rises in average temperature. All in all, Andy and team have found that the variation in microclimates that can exist locally in a landscape creates “microrefugia”. They refer to this as microclimate heterogeneity. These microrefugia have been found to make a real difference to species seeking respite from the heat. Species that respond negatively to climate change have been found to respond more positively to the microclimate heterogeneity, or variety, in a landscape. And that in turn reduces the risk of local extinction, or extirpation as it’s also known. By the way, although we’re discussing this in the context of rising temperatures, it equally applies to climate change in the other temperature change direction, too.

What does this all mean in terms of practical conservation? Well refugia, whether micro or macro, are likely going to be increasingly important as alternative habitats for species fleeing rising temperatures. Yes, some refugia will serve as little more than vestigial habitats; the last resting places of the relict and the damned – those that cannot flee. But those hoping to stick around, and even some of those already on the move, might find a place to stay in some of the more suitable refugia, so long as the topography that creates the refugia in the first place doesn’t find itself a victim of further agricultural intensification or development for economic “progress”. Whatever the circumstances of our climate refugees, these refugia can at least provide alternative habitats and, with luck, stave off some local extinctions. Refugee camps, in a way. It’s just sad to think of that as being the analogy.

In order for refugia to work, they need to exist. We need to identify them and protect existing ones, perhaps more actively managing them. We will probably need to create many more. And we will need to ensure that they are interconnected so that we don’t just create small islands of biogeographical isolation for species that cannot afford to be isolated. We might even have to assist with some emergency evacuations of some vulnerable individuals – translocation as it’s known in the trade. Or even undertake assisted colonisation. My overall enthusiasm for nature protection and biodiversity improvement is for self-willed natural processes and rewilding, but sometimes we need to intervene. Indeed, most habitats in the UK are managed, and restoring nature in the UK really does, and will, encompass the full spectrum of approaches. And we are talking here about vulnerable refugees. We surely cannot sit idly by. 

Andy concluded his talk with some ideas as to what could be done. Better advice on the creation and management of refugia for land managers and conservation practitioners… Better public awareness and engagement… Better identification of potential sites for refugia creation, protection, or management through mapping various factors to identify the places with the optimum characteristics for refugia… Better and more targeted agri-environmental subsidies for land managers…

Of course, the last thing we really want is to create little microrefugia a few metres square, randomly scattered and far apart across the landscape. What we really need to achieve is the almost serendipitous creation of refugia through larger scale habitat restoration. There… I managed to bring it back to landscape scale restoration of nature.

Anthropogenic climate change is artificial. But climate change itself is not. It’s a natural process. It’s just one that has been artificially speeded up and might go too far too quickly. But to the species affected, it seems natural and so they respond naturally. By colonising.

Thus, cattle egrets are coming. They are heading north, like many species. And I do look forward to welcoming them all, although at the same time it will be sad to see those having to pack up and head for the shade, so to speak. These new species blowing in on a southerly wind are not what we sometimes label as “invasive”. They have a drive to disperse and to expand or move their ranges based on where they can find suitable habitats and a cosy niche into which to settle down. Sometimes the niche they seek has already been vacated, and sometimes they are the usurper, pushing out the existing occupier who is no longer the one best suited to that particular abode. Some species, we should remember, are simply returning. We might mourn losses, help refugees, and welcome newcomers, but for species like the common crane, the white stork and, perhaps one day, even the dalmation pelican, it’ll actually be a homecoming and not necessarily be driven solely by climate change.

Not all are going crazy from heat. But many are. Let’s hope we can help as many of them as possible escape the warmth that we have blown across them.

Little egret
Little egret, ‎⁨Etang des Ginès⁩, ⁨Saintes-Maries-de-la-Mer⁩, ⁨France⁩ 07/08/2017.
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Small swift birds

I have heard about the lives of small swift birds.
They dazzle with their colour and their deftness through the air.
Just a simple glimpse will keep you simply standing there.
Legendary journeys made on fragile hollow wings.
The night skies rich with whistling, each and every spring.
And then there’s the day we look for them and can’t find them anywhere

From “Small swift birds” by Cowboy Junkies.

Henshaws college in Knaresborough, North Yorkshire, supports people living with sight loss and a range of other disabilities. It’s claim of being a transformational place is readily apparent to the first-time visitor when taking just the briefest of strolls through its gardens. It’s a sensory journey through a rich and diverse range of flowers and succulents, and, judging by the evening bird song and the wonderful bug hotel, clearly a space enjoyed by more than students, staff, and visitors alone.

Speaking of visitors…

Looking up into a cloudless blue sky on a vivid early summer’s evening in that same garden, I had hoped to see what I’d come to hear about. Perhaps the intersecting of place and time just produced a wrong moment, or maybe the empty sky was corroborating the theme of the evening – Save Our Swifts.

Tanya Hoare is so passionate about her chosen subject that you find yourself succumbing rapidly to what must be some contagion with each fact, picture, and anecdote. 

Listening intently, I learnt from her about a species that I had otherwise only really noticed out the corner of my eye – its arrival, its daily screams over our village from late May, and then its disappearance in early August rather distressingly reminding me that although the school holidays still had a month to run, summer time was ticking away.

What did I learn from Tanya?

Swifts, and more specifically the single species we get here in the UK, Apus apus, are 100% faithful to their nesting sites. Having tiny feet, they have only an extremely limited ability to do anything with them, except briefly perch on the entrance to their nest sites as they come and go. In fact, they even gather nesting materials by snatching whatever is usefully floating on a summer breeze. After fledging at the end of July or so, youngsters are on their own. No further parental catering from that moment on. The kids just hang about for around a week, then take to the skies in early August for their first ever journey south to Africa. They might not touch the ground again until they are ready to breed themselves at 3 or 4 years old. They even sleep on the wing, having the ability to shut down parts of their brain whilst managing to keep the vital flight systems fully operational. Their in-flight safety is their top priority, of course. Congo is their typical wintering area from August through to January, with some wandering to the south and east later on in their African season. Oh, and there’s a great gathering of European swifts over Liberia to reap the harvest of the annual eruption of termites as they, too, take briefly to the skies to mate and, perhaps inadvertently, to be eaten.

Tanya and her husband Edmund will one day struggle to describe some of the features of their house if they ever showcase it on Rightmove. “Bathroom with low flush w/c“? Nope – “Bathroom with low flush w/c with full en-suite nest gallery observation windows”? Yes, that’s far more more accurate. A swallow may favour a barn, and a marten a house. But the swifts journeying to spend their summers with Tanya and Edmund must have their own “Secret Escapes” holiday service. Through numerous alterations and perhaps some very understanding builders, they have transformed their house into a unique place to stay if you’re a swift – off the beaten track, far from the holidaying hordes, and with a choice of views for the discerning avian holiday maker. And there is technology in great abundance. What Tanya and Edmund have done is to rig up their own outside broadcast capability where cables, cameras, recorders, and monitors can capture every arrival, every birth, every drama, and every departure. The bathroom features are actually special double-glazed doors that provide both a means of observation of nests from within the house, and access to the nests when it’s needed. And all this means that the Hoare family has been able to develop a detailed knowledge bank of the lives of their own small swift birds. And that’s important, because the swifts are in trouble.

Between 1995 and 2016, the UK swift population declined by around 53%. They are an “amber listed’ species in the RSPB’s traffic lights system for the state of our nation’s bird species. Whilst red really does mean jeopardy in great abundance, amber is the next, slightly less critical category. But swifts are heading rapidly towards the red list. The wrong wrong direction, the wrong list.

Since learning more from Tanya, I’ve been more observant of the swifts that visit our village daily. There appears to be 5 of them. I’m sure there were more last year. And even more in years gone by. In fact, I’m sure they used to spend more of each day over the village, too, rather than just passing through on their evening commute back to wherever they’re nesting. Snacking as they go, of course, but not pausing to soak up the ambience of the place.

Remember the first fact? That swifts are 100% faithful to their nesting sites? Guess what we’ve been doing a lot of in our country over the years? Demolition and renovation. Our new build homes lack the open and overhanging eaves and crevices of older buildings and, indeed, of older building styles. Our home improvements only improve our homes. Nest sites are, simply and rapidly, disappearing.
But it’s so easy to help save our swifts.

Tanya and her neighbours have been working hard to improve the availability of swift nesting sites in their local town of Sedbergh, with great success. Swift boxes have gone up, and new builds are encouraged to include swift “bricks” into the structure of their walls and gables. New nesting sites are advertised to passing swifts, bearing in mind that younger birds might be in the market for their starter homes if they’ve finally hit breeding age, by calling them in with the sounds of their own kind played at volume and at timed intervals using an attraction call player.

Across the country, people have been setting up their own local swift groups to do the same. We need to do this widely across all of our communities. We should look at the buildings where we live and see if the owners of suitable ones would be willing to host a swift box or two. 

As Tanya explained, perhaps the biggest contribution we can all make is to lobby, ask, and encourage planners, architects, and developers to cater for swifts in the structures and houses they build. 

As a species, swifts don’t usually feature high on people’s list of pressing biodiversity concerns. We welcome them back each summer with often little more than a cursory glance. We notice that they’ve gone some time after they’ve left. And we don’t notice that each year there are fewer.

I don’t think it was swifts, specifically, that the Cowboy Junkies were thinking about when they penned “Small swift birds” as metaphorical thoughts on the passing of time and of our lives. But apart from dazzling colours, and rich night time whistling, they otherwise fit the bill.

Some links that you might want to check out…

RSPB’s Swift action

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Stone the crows

Everything eats something. And when something is cute, vegetarian, or eats creepy crawlies, it’s fine. If it tweets, chirps, and socialises as a charm, a covey, a richness, a trembling, or a pitying, it’s fine.

But when it caws, cronks, squawks, or croaks, and when it hangs out in murders, wakes, parliaments, hordes, mobs, screeches, scolds, mischiefs, clamours, and unkindnesses, it’s better dead than red in tooth and claw. And it’s invariably the antagonist in the avian chapter of our epic saga of the decline and fall of nature on our scepter’d isle.

We are supposedly a nation of animal lovers. But the growing frequency of headlines that scream about the huge and long term loss of biodiversity, and the drastic and wide ranging falls in the populations of many species does, however, contradict our national sense of self righteousness when it comes to nature. You see, we are selective. We croon over the benign, and boo and hiss the villain red in tooth and claw. Quite simply, we root for the underdog and shoot the top dog.

When it comes to birds, we don’t even need an identity parade – we already know who the suspects are… It’s the raptors and, of course, the infamous Crows Gang: Carrion, Raven, and Magpie. Especially Magpie. After all, sorrow comes with every one.

The charge against the accused was lodged in full in the Country pullout of our local paper around the end of May, but then I inadvertently lost it to the council recycling team. But the first witness for the prosecution gave their statement just a week later and was caught in time to capture for posterity…

So these species are clearly out of control. They are implicated as prime offenders responsible for the decline of song birds, farmland birds, and waders from our increasingly manicured and highly managed green and pleasant, deforested, de-wetted, and often monocultural land. Not that i’m subliminally trying to convince you so early in the article that there might be other causes.

The recent legal challenges by Wild Justice to the way that Defra and Natural England had been running an unlawful licensing regime for the control of certain predatory species of birds reminded us that there are armed vigilantes out there effectively acting on circumstantial evidence alone and lynching the suspects without a fair trial. But although some are simply worried about an urban misunderstanding ultimately curtailing their fun, many of these people are acting with the best intents and are genuinely concerned about the decline of songbirds and moorland birds. And of course there are plenty of others, perhaps like Angry From Wherever who, on the face it, potentially align their views with the loudest rural voices and base their understanding of the issues on the premise of who said what about what to whom. And then he said.. And then she said… 

I’m rural born and bred having grown up in, and still live in, farming communities. My relatives were farmers. I worked on farms from time to time as a teenager; mainly with cows, sheep, and cauliflowers. I know how firmly rooted traditional views can be when it comes to predation and the perceived need to control it by lethal force. But I’m also originally trained in a science. Yes, Geography is a science – I have 2 qualifications ending in “Sc.”. So I’m a scientist. Indeed, a fully operational Master. Now Geography’s real value is in providing a framework for organising and relating knowledge from a range of fields. Surely worthy of a capital letter. Geography puts our understanding of natural sciences, physical processes, societies, and economies within the context of place and time and helps us organise, communicate, and understand our world. Ooh, that’s good. I think that may appear in many of my articles!

Science is all about building up knowledge that is based on observation and data, and which produces explanations and predictions that can be tested and re-tested systematically by others. Science lacks emotion. It doesn’t, or shouldn’t, really take an opinion or a view that cannot be supported without facts. And there are no such things as alternative facts. There are emotional and passionate scientists, of course. They are usually human, after all, and have normally taken a path that reflects their personal interests and passions.

Now Wild Justice is not specifically seeking to stop predator control through lethal means, but rather to stop the casual and uncontrolled killing of so-called “pest” species, including the names topping Britain’s Most Wanted, the Crows Gang.

In trying to explain the rationale behind their challenges to a public and media that seems uniquely able to block both ears whilst simultaneously humming loudly and keeping a finger on a trigger, they point out that numerous studies have generally and consistently concluded that there is no evidence-based scientific justification for the rampant killing of our infamous gang of corvid hoodlums for the purpose of conserving other wild birds.  The data collected by decades of research does not show or support any link between the populations of the predatory species and the declining populations of those that are predated.

So is the shooting down of fugitive carrion crows a classic example of a miscarriage of justice? Have we hanged the wrong magpie in a classic case of mistaken identity?

There is plenty of data, and so no doubts, that show there have been rising populations of many predator species, especially raptors and also, to some extent, members of our syndicated Crows Gang over recent decades. However, these rises are considered to be less about over-population and more about the recovery of populations in the decades since we banned some of our least delightful, but sadly most effective, pesticides. Which both directly targeted and indirectly affected a range of species.

Time to consider population dynamics…

Now, it’s a big subject and here I really do run the risk of jumping headfirst into a deep end in which I will struggle to swim and could even hit my head on the hard floor. Beyond basic regression analysis, my statistical methods days are long behind me. But if I delve back into my dim and distant past and, more specifically, my undergraduate studies in biogeography, I know that populations of predators and of prey species generally align over time. They are dynamic with a tendency towards being cyclical with predator populations peaking sometime after those of prey species. The population size of predators is limited by, amongst other things, food availability and breeding habitat availability. If prey species do well, perhaps because of an abundance of food, of habitat cover, and of availability of breeding territories, then their numbers may increase. In response, predator numbers may also follow with increases – after all, their food has just grown in abundance! And plenty of food means that breeding territories can be smaller and, so, there can be more of them.

But there comes a point at which the populations of the prey species are limited in some way from growing any further, perhaps because there is eventually a lack of breeding territories. The knock-on effect is that this then limits the predator populations because their food (our cute and chirpy prey species) is no longer growing in abundance. Which means that the predators too have reached a limit both in terms of food and, consequently, have also probably run out of space for breeding territories. The lag in the population growth of the predators as they head towards their habitat’s “carrying capacity” then starts to impact the now-stable and limited populations of the prey species. Which then declines due to over-predation. And this decline means a reduction in the availability of food for predators, which in turn becomes a limiting factor to the predator population. Which adjusts accordingly.

Are you still with me?

As a geographer, my visual interpretive abilities far outweigh my mathematical and statistical prowess, so i’ll use a picture to help you visualise what I mean and what is more fully explained by Lotka–Volterra equations, also known as the predator–prey equations (a dive into which I am not prepared to take, you’ll be relieved to learn):

So that’s a very, very simple view of how populations of predators and prey species tend to reflect each other, albeit with a time lag, and tend to become limited from exponential growth, falling as they often do into a cycling pattern. In extreme cases, this is a “boom and bust” cycle.

Now this is not to say that there aren’t times and places where predators have a far greater impact on prey species. The boom part of the predators’ population cycle can, and does sometimes, have a disastrous impact on the prey species before the limiting factors come into play.

After reading and getting thoroughly annoyed at the aforementioned and fairly sensationalist article in the paper, resulting in the subsequent follow-up letter a week later from Angry From Wherever, I decided to delve into the scientific paper that the original article was quoting, or perhaps misquoting. Because science, and the raw fuel of science, data, is what should be informing us, and journalists should be articulating it to us properly.

The science in this case, although funded by a charity with, as some commentators might allude to, a greater sympathy for specific groups of species (prey) than others (predators), was undertaken by a university led research team. This team actually found that individuals within a population of a predatory species such as our dandy ringleader, Pica the Magpie, can differ greatly in how likely they predate other bird species compared to others within their own predator population. 

The researchers found, through observations and the data collected and analysed, that there was little evidence supporting a general link between rising numbers of members the Crows Gang and declines in their feathered and shelled snacks. But the data did show that where there are some particularly thuggish individuals in the Gang that have developed a tendency towards more targeted and persistent predatory behaviours, some disproportionate impacts on prey species than would otherwise generally be expected did occur. It found that where such individuals are, er, “removed” from a habitat where they are having a disproportionate impact, this might help vulnerable populations of prey species avoid an overall significant decline. But as with many of the studies into predator-prey relationships and population dynamics, that particular study generally found little evidence of any real link between an increasing populations of the Crow Gang and a subsequent decline in the populations of prey species, specifically songbirds.

So although the science, conducted by scientists, in a science department at a university, and using data collected, processed, analysed, and interpreted using scientific methods, was presented in the newspaper under a pessimistic headline bemoaning how our songbirds are being ever more decimated by the ravenous horde, the science again had actually suggested differently. 

So why are populations of some songbirds, farmland birds, and waders continuing to show long term declines?

Food. Shelter. And the decline in the availability of both. 

Which is a longer way of saying “habitat loss”.

And as we know, species populations are limited by the abundance, or lack of, both food and shelter.

Hedges get cut. Scrub and trees get removed. Pesticides remove insects. Monocultures of arable crops reduce the variety of foods. Native flowers and grasses are replaced with more silage-friendly species. Silage is cut earlier than hay traditionally was. And it’s rolled before it’s cut. Meadows are grazed and compacted to fine lawns and sterilised of flowers and shrubs. Dead wood is removed. Verges are cut. Slurry poisons the water courses with excessive amounts of nitrates and phosphates. Moors are burnt to favour specific vegetation in order to encourage unnaturally high populations of some species over others. And if there is a reduction in the management of an ecosystem, be it from a decline, a loss, or a change in natural or human stewardship, natural succession may, at least in the short term, reduce habitat variety and cover, perhaps favouring a short term boom in predator populations. I could go on.

Any bird is more likely to be weakened, ill, or even starve without enough food. Food comes from the habitat. Which is in long term decline. And when the prey species also declines in response to these diminishing resources, the lower population size in turn becomes increasingly impacted by the effects of that other limiting factor, predation.

With less cover and less food, predators can more easily spot their lunch, especially if it’s a ground nesting bird or a conveniently fast-food takeaway in the form of that bird’s eggs. And less cover means fewer nesting sites. Which might also force prey species to nest closer to the breeding territories of their enemies, which because they are breeding, need to find food for many more hungry mouths.

So, as the science continues to demonstrate with real data over and over again, the decline of many bird species is far more strongly linked to habitat loss that comes with the intensive agricultural uses of our land and other development activities, rather than the inexorable and uncontrolled rise of the Crow Gang.

Conversely, habitat creation creates cover and food. Which in turn support healthy populations of prey species which are far less vulnerable to being predated. And directly removing or fooling (by cunning stunts such as diversionary feeding) delinquent individuals from a predator population probably does help.

But cleansing the fields and moors of Pica and his mates? Surely that’s just identifying a fall guy to take the rap as we continue to intensify agriculture, clean and tidy and develop the land, and generally deflect the blame from our ongoing crimes of habitat destruction.

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