Seasonal Update (August 2020)

Dawn in Hampshire on a morning in August 2015. - Credit: Marc Baldwin

July was a month of waiting for the promised summer weather to turn up. It started on a cool and wet note with a couple of low pressure systems crossing over us from the Atlantic bringing some heavy rain, particularly to Northern Ireland, northern England and Scotland. Temperatures were slightly below par for the time of year, only reaching into the mid or high teens Celsius. Persistent rain across western Scotland caused localised flooding, and a very deep area of low pressure - unusual for the time of year - crossed the UK over the first weekend of the month. The result was more autumnal than summery, particularly in the north - 60mph winds in the north, 40mph in the south.

The second week was originally forecast to be warm and dry (a “heatwave” as the media reported it), but turned out to be largely dominated by low pressure bringing a lot of cloud and some heavy rain, thundery in northern England and Scotland, until high pressure started to nudge in at the start of the third week. So, in the second week, the “heatwave” was pushed back to week three, but the influence turned out to be rather weak and although the majority of southern England had some cloudy but dry and warm (around the seasonal average) weather, much of Wales, the Midlands and north, including Scotland, saw more heavy rain and temperatures below par for the time of year. At the start of the third week, it was week four that looked set to bring summer back to Britain.

The second half of July last year saw our highest July temperature on record - 38.7C at Cambridge Botanic Gardens on 25th July. This year temperatures were around the seasonal average in the high teens and low 20s Celsius. High pressure kept things mostly warm and dry for England, but low pressure systems continued to bring weather fronts (rain and wind) across Northern Ireland, Scotland and Northern England. The last Saturday of the month was wet across the country and the final week started with heavy rain and winds touching gale force. Fortunately for the heliophiles and all the parents on holiday with their restless kids, summer did reappear right at the end of July for a couple of days, with temperatures widely in the mid-20s and even touching 32C (86F) in southeast England.

If you’re interested in the wildlife to be found this month, including the roe deer rut and wasp spiders, check out my Wildlife Watching - August page.

Website news

Several minor updates have been made to the red fox, badger and squirrel articles, while the hedgehog breeding sections have been revised. There is also new content in the form of a Speed Read piece on the European adder and a new feature article looking at how you can make your garden hedgehog-friendly. The next article in process aims to cover the natural history of the Chinese water deer.

In the news

A few headlines making the conservation news this month include predictions of new summertime temperatures in Britain, new data on plastic waste and the response of some conservation charities to Prime Minister Boris Johnson’s ‘build, build, build’ speech last month.

The Met Office are predicting 40C (104F) will become a common summer temperature unless concerted action is taken to reduce greenhouse gas emissions. - Credit: Marc Baldwin
  • Searing summers? The summer of 2018 was the hottest on record in England, while our highest temperature to date was recorded last July. A new study, published in Nature Communications by meteorologists at the Met Office Hadley Centre in Exeter, suggests that the UK is likely to see summer temperatures of 35C (95F) each year and may see 40C (104F) every 3.5 years if emissions continue to rise at a rapid rate. Interestingly, the analysis suggests that cutting emissions can have a profound impact, reducing the frequency of 40C summer temperatures to once every 15 years.
  • Plastic proliferation. The second series of the BBC’s Blue Planet showed us how our discarding of plastic waste is having a devastating impact on the marine environment. The result was a countrywide effort to clean up beaches, recycle more and reduce our plastic consumption. Unfortunately, efforts have died down in many areas now, particularly during and in the aftermath of “lockdown” and, globally, the production and demand for plastics continues to rise. A new report, published in Science, predicts that unless global action is taken to combat the problem, some 1.3 billion tonnes of plastic will end up in the environment by 2040. Strikingly, the study also highlighted how two billion people in the southern hemisphere have no access to decent waste management and have no choice but to dump or burn their rubbish.
  • Build, Build, Build. On 30th June, Boris Johnson announced what he considered “the most radical reforms to our planning system since the Second World War”, aimed at making it easier to build homes in areas of high demand. This rang alarm bells for several conservation organisations because many fear a weakening of environmental protections. At the end of last month the Campaign to Protect Rural England published a letter signed by 17 conservation charities, including the RSPB, Bat Conservation Trust and Woodland Trust. The groups urged the government to take environmental protection seriously, particularly in the wake of the first wave of the Coronavirus pandemic, during which many people developed a greater affinity for the green spaces around them.
  • Brilliant bats. Shortly after covid-19 emerged, bats fell under the public spotlight as a potential source for the virus. Coincidentally, a massive new research project published in the journal Nature last month has revealed some tantalising new insights into the genome of these fascinating mammals. The data provide insight into how bats are related to a large group of carnivores, pangolins, whales and ungulates, called the “Ferreuungulata”, as well as finding “fossilised viruses” in their hugely diverse genome that help us understand how they’ve developed a tolerance to viral infection over their evolutionary history.

Discoveries of the Month

Stay away from the light? Does artificial lighting put hedgehogs off using feeding stations?

I’ve written about increasing urbanisation on several occasions in the blog, and here in the UK there’s a continuing trend towards city-living by humans. Indeed, according to Statista, just shy of 84% of the UK population now lives in an urban area, an increase of nearly three percent over the past decade. Globally, Price Waterhouse Cooper estimate that about 1.5 billion people live in towns and cities, and with this lifestyle comes a need for development which has obvious ecological impacts. PWC suggest that, over the next ten years, New York, Beijing, Shanghai and London will, collectively, need to spend US$8 trillion (£6.2 trillion or €6.8 trillion) on infrastructure.

Artificial light from streetlights is a common feature of villages, towns and cities across the world, but while it may make us feel safer it can disrupt the behaviour of many nocturnal animals. - Credit: Marc Baldwin

Increasing pollution and the loss of green space to concrete and tarmac are well-recognised problems that development of urban areas can cause for wildlife, but the impact of artificial light on nocturnal species can often be overlooked. Most street lights are an order of magnitude brighter than the light cast from the moon and stars and we tend to see an increase in the amount and intensity of “artificial light at night” (abbreviated to “ALAN”) with urban development.

Owing largely to their widely protected status, most of the data we have on the impacts of ALAN on nocturnal mammals exists for bats; we know that street lights, for example, can attract some species (e.g. pipistrelles) while repelling others (e.g. greater and lesser horseshoes). Recently, however, a collaborative study between The Mammal Society and the University of Sussex in Brighton was undertaken to ascertain the potential impact of artificial light on hedgehog activity.

The researchers, led by Fiona Mathews at the university’s School of Life Sciences, lent out trail cameras to 33 volunteers throughout England and Wales who indicated on a survey that they had hogs regularly visiting feeding stations in their garden. Over a period of 14 days between mid-July and late August, each feeding station was exposed to two lighting regimes - no artificial lighting for the first week and constant artificial light falling on the feeder for the second. Hedgehog sightings per ten minute block of time were then recorded for each treatment and the results subjected to statistical analysis using Generalised Linear Mixed Models.

A hedgehog slinking across our patio. In my experience, this behaviour is observed when the hedgehog is active before it is fully dark (i.e. around dawn, as here, or dusk or in spot lighting) and indicates that some individuals may feel vulnerable in such lighting conditions. The new Mammal Society study suggests, however, that artificial lighting does not prevent hedgehogs using feeding stations and this has been my experience, too. - Credit: Marc Baldwin

Perhaps the first notable result was the low incidence of visiting, with only 3,470 (15%) of the recording blocks being positive for hedgehogs. More comforting, however, was that the number of visits to “dark” and “light” treatments were similar (1,724 and 1,746, respectively) and hogs were observed feeding during 78% of the dark and 76% of the light blocks. Writing in the journal Animals last month, Mathews and her colleagues conclude:

“… our results indicate that there is no consistent overall effect of lighting on indices of hedgehog activity and feeding at supplementary feeding stations, or on the timing of these behaviours.”

The researchers go on to point out that ground beetles, a favoured prey item of hedgehogs, are known to be attracted to artificial light and imply that a lack of photoaversion may allow hedgehogs to take advantage of these feeding opportunities. In my experience, hedgehogs initially avoid direct light, slinking around the edge of spot lights, but readily adjust to it, and this no doubt helps them exploit urban areas.

Source: Finch, D. et al. (2020). Effects of artificial light at night (ALAN) on European hedgehog activity at supplementary feeding stations. Animals. 10: 768. doi:10.3390/ani10050768.

Smile for the camera: Red and roe deer more sensitive to trail cameras where they’re hunted

Many readers will be familiar with trail cameras - they’re an increasingly common addition to gardens and woodland these days, used by everyone from ecological consultants conducting wildlife surveys to homeowners curious about what’s digging up their flowerbeds. Their use in scientific studies has also increased significantly in recent years, where they’re often employed to help track animals and estimate populations. A literature review published in 1999 found that there were about 107 studies published between 1950 and 1997 that used camera traps. Ten years later, according to a review paper published in 2010, that number had risen to 782.

Remote cameras ("trailcams") are frequently employed for wildlife surveys and increasingly popular with householders wanting to watch and learn more about the wildlife visiting their gardens. - Credit: Marc Baldwin

Trail cameras, like any tool, have their benefits and limitations, but one significant selling point is the premise that the infrared wavelength (~850 nm) used by these units is invisible to mammals, meaning they go about their activities undisturbed. While it’s true that some animals, hedgehogs for example, are either insensitive to or simply ignore IR light, many mammals can see it. Certainly, I have seen deer, foxes and badgers respond to my trailcams in a way that clearly suggests they can see the light. More recently, some manufacturers have begun to use “black light”, with a longer wave (~940 nm) in a bid to reduce potential disturbance, and a new study by German biologists set out to compare the response of red deer (Cervus elaphus) and roe deer (Capreolus capreolus) to these different approaches.

The researchers set up two study sites, one in the Bavarian Forest National Park (BFNP) in south-eastern Germany and the second in the Northern Black Forest (NBF) to the south-west. In the BFNP, they deployed 120 camera traps set to use white, standard IR and black flashes, while 780 deployments using standard IR and black flash were made in the NBF. Each study site was divided into blocks and camera traps were setup at crossing points, collecting data between April 2017 and December 2018. The photos were reviewed and catalogued before being subjected to a logistic regression to calculate the probability of a deer looking at the camera trap or fleeing from it.

The results, currently in press with the Zoological Society of London’s journal Remote Sensing in Ecology and Conservation, show that both species were more likely to react to IR flashes than black light ones, and that red deer were much more prone to responding than roe. Deer approaching a camera or walking past one were more likely to stop and look than those photographed walking away. Interestingly, the data also revealed that both species were less likely to react to the flashes in the BFNP than in the NBF, and the scientists suggest that this may reflect that fact that deer in the NBF are subject to much greater hunting pressure, making any disturbance that much more important.

Deer are a popular target of camera traps and new research from Germany suggests that they may see and even flee from the UV light emitted by these units, with Red apparently more likely to react than Roe. Here a Chinese water deer (_Hydropotes inermis_) investigates one of my trailcams. - Credit: Marc Baldwin

Overall, the researchers advise that, while standard IR was suitable for population estimation, where practicable, black flash camera should be used for studying deer behaviour, because:

The impact of black flash on animal behaviour was similar to that of not using a flash during daylight hours, suggesting that black flash operates at a wavelength that is not visible for deer.”

Source: Henrich, M. et al. (2020). The influence of camera trap flash type on the behavioural reactions and trapping rates of red deer and roe deer. Rem. Sens. Ecol. Cons. Early View. doi: 10.1002/rse2.150

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