Seasonal Update (August 2022)

Heathers are in bloom on heathland in Britain during August, putting on a spectacular pink-purple display, which is especially breath-taking at dawn and dusk. - Credit: Marc Baldwin

Welcome to midsummer and the first of a slightly new format to my seasonal updates. As anyone who has spent time wandering the pages of Wildlife Online will be all too aware, I have a writing style bordering on punctiliousness, and this has been known to extend even to the seasonal updates. The aim of the new look is to make them shorter, but also to cover more ground. As always, I'm interested to hear readers' views on what works and what doesn't. Thank you, as always, for sacrificing some of your valuable time to read my meanderings.

Weather update

After an unsettled end to June, July started on a largely dry and warm note as an Azorean high built in during the first week, bringing temperatures into the mid- to high 20s Celsius (mid-70s to low 80s F) by the second weekend. Last month was, however, very much a tale of two halves, with much of Northern Ireland and western Scotland seeing repeated spells of wet and windy weather. Of course, the main weather talking point was a short but intense heatwave that occurred during the middle of the month.

Early in the second week, the Met Office issued a rare Extreme Heat: Amber Alert covering most of England and Wales for 17th and 18th July, with temperatures predicted to climb widely into the mid- to high 30s Celsius. The alert was raised to an unprecedented “Red” state for a subset of central and eastern England for the 18th and 19th July as intense heat built in from southern Europe, courtesy of a fragment of the jet stream anchored off Portugal. Overnight lows were widely 25C (77F) in England on the Monday night, with a new record set as temperatures dropped to only 25.8C (78.4F) in Kenley, surpassing the 23.3C (73.9F) recorded overnight at Kew in London during 1948. On 19th July, as predicted, the temperature climbed to a new record, with Coningsby in Lincolnshire recording 40.3C (104.5F); above the 38.7C (101.7F) at Cambridge Botanic Garden on 29th July 2019. Scotland, Wales and Ireland also broke their all-time heat records. For context, the average daytime high for mid-July is 19C (66F) in Scottish Isles to 24C (75F) in south-east England.

Many parts of England and Europe have been suffering drought conditions following an exceptionally dry year and little, if any, rainfall since June. - Credit: Siddarth Machado (CC BY-NC 2.0)

July continued largely warm and settled for southern England, with water restrictions instigated in Hampshire towards the end of the month. Most of England saw only 12% of the expected July rainfall last month, some parts recording no rainfall at all, while Scotland had seen about 90%.

Outside of the UK, much of Europe remained in the grip of the punishing heatwave. Spain and southern France regularly saw temperatures in the mid-40s (~113F), and Portugal reached 47C (116F). Many countries were battling widespread and intense wildfires, and Greece reported many deaths from the heat. On the other side of the globe, Australia was hit by a week of relentless wind and rain in the east at the start of last month, with Sydney receiving eight months' worth of rain in only four days. Floodwater hit 12 metres (39 ft.), causing mass evacuations, many hit as they had just finished clearing up after severe flooding back in March. Parts of the country saw some record lows, with the station of Hillston Airport in New South Wales dropping to -6C (21F) on 15th July. It was also notably cool and rainy in the Middle East last month, with some parts of Oman and the UAE struggling to hit 30C (86F), and rare July rains reaching Dubai. In the US, California was battling wildfires and drought, while Kentucky endured flash flooding and mudslides.

While many of us have been enjoying the prolonged hot and dry weather, it is worth mentioning that the heatwave over Europe has been in evidence for so long it is now affecting the sea temperatures. Indeed, the parts of the Mediterranean Sea has been experiencing what some ecologists have described as “a brutal marine heatwave” since May, with water temperatures now 6.2C (11F) above what we'd expect for July. Oceanographers monitor and classify marine heatwaves, and the one in the western Med is a “Major Category 3”, which has the potential for very significant impacts on marine ecosystems, while also enhancing heatwaves on land.

Overall, by the end of July, we'd seen nearly 150 all-time heat records broken so far in 2022, and one all-time cold.

Website news

A new audio clip of submissive vocalisations has gone up on the fox communication page, and the latest section of the Chinese water deer article, covering endoparasites, has gone live.

News and discoveries

Bear blending. Scientists at the University of California, Santa Cruz, have found evidence of ancient hybridisation between polar and brown bears. When analysing DNA extracted from a 100,000-year-old juvenile female polar bear found on the coast of the Beaufort Sea in Arctic Alaska in 2009, the researchers found significant admixture with brown bears; polar bear ancestry accounts for as much as 10% of modern-day browns. Interestingly, when including genomes from modern polar bears, the flow was primarily one way, from polar to brown, implying that brown bear genes reduce the fitness of polar bears.

A European bee-eater, several of which are currently nesting at a quarry in Norfolk. - Credit: Oscar Valencoso - Salomé Planas (CC BY-NC 2.0)

Rainbow red flag? Climate scientists have warned that the recent discovery of breeding bee-eaters in Norfolk is a worrying sign of how rapidly the climate is changing. Since 2001 there have been six reports of nesting in Britain, with this the first Norfolk record. Ordinarily, this species nests in southern Europe and north Africa, before heading down to southern Africa to spend the winter.

Orcas on top. Back in January 2020, a great white shark being spotted in False Bay was big news. Normally it wouldn't raise an eyebrow, let alone a headline, but this was the first shark to be reported in the bay in nearly two years. The hope was that this was a sign of recovery, but it appears to have been false hope and recently another four shark carcasses, each sporting large holes where the liver and hearts have been removed, have washed ashore in the region. A new paper in the African Journal of Marine Science suggests that the presence of killer whales in the region have driven white sharks away, promoting an abundance of copper sharks and a change in fur seal behaviour that, the authors suggest, will have profound impacts on the local ecosystem.

Pervasive plastics. Scientists studying the prevalence of plastics in the environment, with particular reference to mammals, have found plastic in the droppings of four (nearly 60%) of the seven species they studied, including wood mice and hedgehogs. Polyester (widely used in textiles), polyethylene (single-use packaging), and polynorbornene (rubber industry) were the most common. Biodegradable plastics (bioplastics) accounted for 27% of the particles found.

Hammering it home: woodpecker heads are more like hammers than helmets. We used to think that woodpeckers had shock-absorbing heads. After all, how else could they bang their heads repeatedly against trees for so long without suffering brain damage? The conventional theory goes that a woodpecker's head is packed with spongy bone, particularly so in the frontal region of the skull, just in front of what we call the “naso-frontal joint”, between the upper beak and the braincase. This region of bone was thought to be the prime candidate for shock absorption. Alongside the spongy bone, there are several muscles around the beak that could also absorb impact energy. New research by a team of scientists led by Sam Van Wassenbergh at the University of Antwerp, however, has turned the conventional theory on its head. The biologists analysed high-speed video of woodpeckers and modelled their movements alongside the skull morphology. Their biomechanical models show that the birds' anatomy actually works to minimise impact, more like a stiff hammer. More interesting still was the finding that any shock absorbing capability would actually hamper their ability to peck.

Foxes feed primarily on small mammals, birds, insects and fruit, but their adaptability means they'll take advantage of any opportunity. New research in the Cairngorms suggests this includes dog faeces. - Credit: Tambako The Jaguar (CC BY-ND 2.0)

A crappy diet? Any seasoned dog owner knows that their pooch might eat dog poo while their back is turned. Recently, however, an Anglo-French team of researchers has found evidence that foxes do the same, although they probably don't look quite as pleased with themselves afterwards. A large-scale metabarcoding study of red fox and pine marten scats collected from the Cairngorms National Park in Scotland revealed a high occurrence of domestic dog DNA in fox droppings. In their paper to Ecology and Evolution, the scientists explain: “Dog faeces being highly calorific, we found that foxes, but not pine martens, regularly exploit them, seemingly as an alternative resource to fluctuating prey.” They go on to suggest that increasing recreational use of the Cairngorms by humans (and their dogs) may serve to inadvertently decouple the local foxes from their main prey.

Seasonal highlight – the roe deer rut

For most deer species, August is the last month of relative tranquillity before the rut gets underway in a few weeks. The roe deer (Capreolus capreolus), however, is different. Males (bucks) will have established territories by now on which they scent-mark by scraping the ground with their feet, urinating and thrashing small tree saplings with their antlers. Bucks bark (below), both to notify other males that this patch is theirs and to draw in females (does) from the surrounding area. The rut is weather-dependent but tends to run from about 20th July to 20th August, with much of the activity occurring at the start of August during hot and humid weather and little after about the 12th.

A roe deer (Capreolus capreolus) barking during the rut in the New Forest. - Credit: Marc Baldwin

Roe deer rut during the midsummer, and bucks can be easier to approach as they're preoccupied. - Credit: Marc Baldwin

In higher density populations, does may share the spring and summer ranges with bucks and, except for winter when the territorial system tends to breakdown, rutting may take place within this area. Where densities are lower, however, roe may move to established rutting grounds a kilometre or more from their usual ranges. I have observed this here in the New Forest, and it is a phenomenon the late New Forest-based naturalist John Fawcett also described in his compendium of the species' natural history. Indeed, it's not uncommon to come across unaccompanied kids in August - she'll return home to her kids once she's been mated. During the rut, does may hang around on or near a buck's territory and as she moves around, she leaves behind a scent trail that any passing buck will follow intently. Scent is hugely important to roe at this time of year and their scent glands are at their peak of activity during July and August. I've seen bucks pass my not-so-well-hidden form completely oblivious because they're so focussed on the female they're tracking.

Courtship may involve several minutes of chasing, the buck driving the doe until she stops and stands to be mounted. This pursuit appears to often be in circles or a figure of eight around a tree or bush, producing a flattened track of vegetation known as a “roe ring”. This frenetic activity explains why it is not uncommon to stumble across roe bucks lying in quiet forest stands that don't immediately get up and flee when they spot you; they're exhausted! In fact, this may be the last time you'll see a mature buck until the end of September.

Successful ovulation, even fertilisation, appears to be dependent on a doe reaching a critical body weight. The period for which the doe is in estrus (i.e., on heat) is unclear, but observations suggest anywhere from two to five days, and there seems to be an intense peak during this cycle. While in season the doe will mate with the dominant buck (and sometimes other bucks) several times. In his 1995 book on the species, Richard Prior wrote how:

Later in the rut, and especially after the first mating, does are more willing to be touched by the buck, and may accept more than one.”

A roe buck following a doe during the rut. - Credit: Dominic Regan

After successful fertilisation, the embryo undergoes a period of embryonic diapause, the ball of cells floating free in the uterus and slowly increasing in size before it implants during December, after which development continues as normal. Despite early speculation that water deer might also undergo diapause, roe are currently the only deer known to exhibit the phenomenon. This diapause allows roe to rut during summer, providing more time to recover condition in time for winter, but still give birth the following spring when conditions are likely to be best for their kids.

For a round-up of Britain's seasonal wildlife highlights for August, check out my Wildlife Watching—August blog. In addition, with specific reference to deer, the UK government has begun its consultation on deer management in Britain and is requesting input from interested parties. If you're a land owner, deer manager or just someone with a keen interest in deer population dynamics, I urge you to take part in the consultation. The response of the British Deer Society provides a nice summary of the situation.

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