Seasonal Update (August 2021)

Some very hot days last month made for some nice misty scenes for the early riser, but summer was short-lived. - Credit: Marc Baldwin

June ended on a mostly dry and bright note in the UK, and July began on a similar footing, albeit a muggy one. The first couple of days were mostly dry and sunny, with temperatures reaching the mid-teens Celsius (high 50s Fahrenheit) in the south, and high teens (mid-60s F) further north, with the odd isolated shower in the south towards the end of Thursday. Overnight low cloud and mist, particularly around the coasts, kept temperatures in the low teens Celsius (mid-50s F) and dampened the brightness to start the day on Friday. Friday dawned dry for most, bar heavy showers to start the day along the England-Scotland border; scattered, heavy and thundery showers popped up widely during the afternoon.

The first weekend of July was mostly dry on Saturday, with early cloud burning back sufficiently to produce some sunny spells into the afternoon, although temperatures were disappointing. Sunday saw an area of low pressure begin to push in from the north Atlantic, starting the day wet for most of the UK, with only the south of England starting on a dry, but cloudy note. Showers on and off were the order of business for Sunday, some heavy and thundery, and it remained particularly dull and cloudy around the coasts of eastern Scotland, north-east England and eastern Northern Ireland. Northern Ireland and Scotland were hit by torrential rain and hail during Sunday afternoon, causing widespread flooding and prompting The Met Office to issue a yellow warning for thunderstorms across central and northern parts of the UK. The showers moved north on Sunday night and Monday morning, with cloud pulling in over southern England, Wales and most of the Republic of Ireland. Temperatures started off in the low to mid-teens Celsius on Monday morning.

Unseasonably strong winds were a feature of July, touching nearly 70 mph (111 kmph). - Credit: Marc Baldwin

Monday started dry in the south and wet in the north, with showers moving gradually north and fizzling out as the day progressed. Temperatures rose into the low 20s Celsius (low 70s F) in the south and high teens in the north. Towards the end of the afternoon, a large area of low pressure moved up from southern Europe, bringing unseasonably heavy rain and strong winds for early July. The rain pushed north quite quickly on Monday night and Tuesday morning, with showers and gales following in the afternoon, gusting to just over 50 mph along the south coast. The main rain band moved northwards during Tuesday morning, leaving torrential but patchy showers in its wake. Temperatures struggled into the low 20s Celsius.

As the first full week of mid-summer drew on, things dried out and we saw a bit more in the way of sunshine. Wednesday was a showery affair across the whole of England and Wales, but with lighter winds, and only the occasional shower in Scotland and Ireland. Following a cloudy night across the board, Thursday saw fewer showers still and in the sunshine we saw temperatures creep into mid-20s Celsius (high 70s F). A bit of patchy rain hung on in eastern Scotland overnight Thursday into Friday. Friday was an east-west split, with the west country and southern Ireland seeing some heavy downpours while the rest of the UK remained dry with temperatures in the low 20s Celsius.

The second weekend started on a very wet note in the south as a large area of rain swept along the south coast. Things dried up into Saturday afternoon and for most of Sunday before more rain arrived during the afternoon in the south. The rain was patchy across much of the UK but more concentrated along the south coast during Sunday night, spreading up the country through the day, the heaviest and most persistent being in the south and east of England and western Scotland. Temperatures remained low for the time of year, reaching the low 20s Celsius at their highest on Monday. The rain fizzled out overnight into Tuesday, although not before it caused some severe flooding in the south and east - some areas on the south coast saw a month's worth of rain in only a couple of hours.

From Wednesday onwards there was an improving picture as high pressure started to build in the south-west, bringing mostly sunny conditions and a bit of patchy cloud Wednesday and Thursday. In the sunshine we saw temperatures climb into the mid-20s Celsius, cooler along the east coast courtesy of a northerly wind around the eastern edge of the high pressure that was building in. Things continued to warm up into Friday and the middle weekend, although during Friday and the first part of Saturday a weather front clung on in the far north-west, bringing more cloud and some light rain. Temperatures on Friday ranged from around 21C (70F) in Glasgow to 27C (81F) in Cardiff, and rose further through the course of the weekend, the hottest official temperature being 31.6C (88.9F) at Heathrow on Sunday afternoon, although both thermometers in our garden were reading 32.6C (90.7F) around lunchtime on Sunday.

Despite some unsettled weather, the UK did get a short-lived heatwave, which saw temperatures climb into the 30s in the south. - Credit: Marc Baldwin

Monday was another dry, sunny and very warm day across all but the far north and west of Scotland, which was subjected to some persistent cloud that kept temperatures down in the mid- to high-teens Celsius, while the south and east of England hit the low 30s once again. A line of showers formed briefly on Monday afternoon in a diagonal line roughly from Birmingham to London, but were patchy. Tuesday was a rerun of Monday with a few more sporadic thundery showers in the south-east quarter and with temperatures down a notch, peaking around 28C (82F) for all but Wales and the south-west, where the Met Office issued an extreme heat warning valid until the Thursday night. Temperatures reaching the low 30s for several day and not dropping far at night prompted the alert and was the first of the summer. Heathrow hit 32.2C (90F) on Tuesday, which was officially the hottest day of the year so far.

The heat sparked off some torrential thundery rain and hailstorms around London and the south-east on Tuesday and Wednesday afternoon. The Met office issued a second extreme temperature warning for Northern Ireland, valid until Friday night as temperatures hit 31.3C (88.3F) at Castlederg in County Tyrone on the Wednesday - provisionally the hottest day since record began in 1910 - and remained high overnight. Thursday and Friday were similarly hot and sunny in the west, with a little more cloud and a breeze along the east coast. The far north remained comparatively chilly under cloud, Lerwick with highs of only about 15C (59F), and we saw the odd isolated thundery shower across England. Overnight Friday into Saturday an area of low pressure pushed in from the south-west, bringing heavy thundery showers.

The penultimate weekend saw the heatwave break down with heavy thundery showers, particularly on the south coast and in the south-east. Wales also saw some heavy rain on Saturday, while the rest of the country remained largely dry and sunny, with temperatures up in the mid-20s Celsius. After a muggy night, Sunday started off mostly cloudy for all but south-west Scotland and pretty much the whole of Ireland. The low was centred over northern France, resulting in areas of patchy heavy rain, including some thunder and lightning, stretching from East Anglia north-east out across the North Sea. Temperatures again climbed to the mid- to low 20s.

High pressure from the north-east Atlantic started to build in during the final week and on Monday the showers were restricted along the eastern coast of England and Scotland for the first half of the day; showers popping up in the west later in the day. The rest of the week was one of sunshine and heavy showers, along with a yellow weather warning issued by the Met Office for the Thursday and Friday, with winds touching an unseasonably strong 69 mph (111 kmph) along the Cornish coasts and through the English Channel.

Both the UK, part of Europe and Asia were hit by major floods following torrential rain. - Credit: Andrew Wilkinson (CC BY-SA 2.0)

Outside of the UK, the heat dome continued to exert its influence in North America and Canada and during the second weekend authorities evacuated residents in Nevada after a huge wildfire swept in from California - one of just over 80 reported across the US last month. Temperatures in Death Valley hit 53C (133F) during the second week of the month. Heat was also the issue in eastern Europe, with temperatures holding well into the 30s Celsius (90s F) for most of last month. Across the Atlantic, the heat, coupled with farming practices in Turkey that have seen a huge increase in demand for water, has resulted in severe drought that killed at least a thousand flamingos at Lake Tuz, designated a “specially protected area” two decades ago.

In west Europe, the weather system that brought heavy rain and flooding to the UK early in the month moved south and was caught in an especially undulating jet stream, resulting in parts of Belgium and Germany seeing torrential rain - three months' worth in only 24 hours. Three states in Germany declared major incidents after the Volme, Kyll and Ahr rivers burst their banks. In the state of Rhineland-Palatinate, four people were killed and 30 reported missing after severe flooding caused buildings to collapse. Across Germany and Belgium, at least 111 people were reported dead and more than 100 missing. France, Luxembourg and The Netherlands were also badly affected.

Around the middle of July, China also experienced some extremely heavy rain which caused severe flooding in towns and villages in the centre of the country, causing 12 deaths and displacing at least 10,000 residents to shelters. Following a year's worth of rain in only three days in Hunan Province, tube stations were flooded, leaving commuters stranded in chest-high water; flood waters of a metre (3 ft.) were widely reported.

On a lighter note, if you're interested in the wildlife to be found this month, including the roe deer rut, the end of the shrew breeding season and the stunning wasp spider, check out my Wildlife Watching - August article. There are also a few late stag beetles still staggering around and if you happen to spot one, please take a moment to log it on the PTES Great Stag Hunt survey.

Website news

A few minor updates have been completed on the site over the past month and a new Speed Read covering the Common frog is now live. Additionally, my diligent proof-readers have completed their reviews of the first section of my new article on the Chinese water deer and it will be online soon. I have completed part two and the proofers are currently working their magic.

In the news

A few of the science and conservation news stories that caught my attention last month include a previously unknown extinction event, how jays aren't easily duped, and how wasps are precious rather than pests:

Some Australian authorities are imposing a cat curfew, with hefty fines for owners that fail to comply. - Credit: Marc Baldwin
  • Rigorous rats: New data collected by researchers at the University of Portsmouth suggests that male rats are much choosier when it comes to making friends than females, even going out of their way to avoid interacting with some individuals.
  • Curbing cats: From the start of October, cat owners in the city of Knox, in Melbourne's eastern suburbs, will be required by law to keep their cats in day and night. The local media reports suggest that owners failing to comply will be charged about £50 for the first offence, up to a total of £290. The new measures are aimed at protecting both the cats and the local wildlife.
  • Smart eye-deer: A new study on animal vision by scientists at the University of California-Berkeley suggests that deer can keep an eye out for predators even while they have their head down feeding. When deer lower their head to graze, their eyes rotate to keep alignment with the horizon. Moreover, each eye rotates independently, the left eye rotating clockwise and the right eye anti-clockwise. This is a phenomenon known as cyclovergence and means the deer can always maintain their panoramic view of their surroundings.
  • All white: Data from Oregon State University published earlier this year suggest that the population of great white sharks in the waters off California is small, but otherwise healthy, holding steady at around 300 animals.
  • Vultures venture back: Some fifty years after being declared extinct as a breeding species in Bulgaria, Europe’s largest bird of prey, the Griffon vulture, is making a comeback in the Eastern Balkan Mountains, thanks to a long-term restoration project funded by the EU’s LIFE tool. At the end of last year, the 25 breeding pairs had produced a total of 33 chicks.
  • Courageous crayfish: According to a joint study by biologists in Florida, New York and Australia, antidepressants leaking into waterways could be making crayfish bolder. The researchers found the crustaceans exposed to moderate levels of the selective serotonin reuptake inhibitor antidepressant Celexa, chemically known as citalopram, spent significantly less time hiding and more time out and about foraging for food, leaving them more vulnerable to predators.

Discoveries of the Month

Bovine-badger timeshare could help spread TB

You may not know exactly what it is, but chances are you’ve heard mention of bovine TB and the role that badgers are widely considered to play in its maintenance and transmission. Bovine TB, abbreviated simply to bTB, is an infectious bacterial disease that spreads between cattle, causing lesions in the lungs. The disease spreads rapidly and, owing to its highly infectious nature, a positive test necessitates the destruction of the herd, resulting in huge distress and a considerable financial impact to the farmers involved. Indeed, one 2018 report to the UK government estimated that:

Tackling bovine TB in England is estimated to cost the taxpayer around £70 million a year, with costs to farmers running to a further £50 million.”

The average cost per breakout is thought to be around £34,000, driving calls to find a solution to the problem.

Unfortunately, badgers and cattle often utlise the same pasture making it important to understand how the two may come in contact. - Credit: Marc Baldwin

A complicating factor in the transmission of bTB is the influence of the wildlife reservoir in disease maintenance. Unusually for a livestock disease, the tuberculosis bacteria can infect, and be sustained by, badgers. This means that not only can badgers become infected by the bacteria, but many of them will carry on as normal, suffering few (if any) ill effects and shedding the bacteria as they go about their badger business. Doubly unfortunate is that badgers are typically found in areas where livestock also wander, meaning that the badgers can become infected in one area and then go and shed the bacteria somewhere else. They’re also not averse to visiting livestock sheds on their nightly wanders.

Given the role that we know badgers can play in the epidemiology of tuberculosis in cattle, a lot of work has been directed at trying to better understand the specifics. Rosie Woodroffe and her colleagues at the Zoological Society of London have been at the forefront of this data drive for several years now. The use of special GPS collars has suggested that badgers and cattle come into physical contact less often than we first imagined, but new data collected by the team suggests that there may be “close contact” within the same area over time even if they don’t actually meet.

Between May 2013 and August 2015 data were collected on the locations through time of 421 collared cattle and 54 collared badgers on five Cornish farms with confirmed cases of bTB in both species. The researchers defined close contact as the two animals being within five metres (16.5 ft.) of a GPS fix within the same 36-hour period. The data set shows that neither species avoided using areas visited by the other in the previous 36 hours and that, overall, an average herd of 176 cattle would come into contact with an area where a badger had been in the last 36 hours six times in any given 24-hour period. Badgers, by contrast, would come into contact with a location where a cow had been within the last 36 hours just short of once per night. While they caution that these results should be interpreted with caution owing to the relatively small number of contact data, writing in the Journal of Zoology, Woodroffe and her team note:

The movement patterns we observed among cattle and badgers suggest that both species could potentially encounter environmental contamination left by the other, well within the survival period of M. bovis.”

A sedated badger being fitted with a GPS collar by researchers at the Zoological Society of London. GPS collars can tell us a lot about how far badgers range and even, with the right combination of sensors, what other animals they interact with. - Credit: Seth Jackson / ZSL

The scientists suggest keeping badgers out of cattle pasture is almost impossible, so alternatives in terms of vaccination should be considered, while the fencing of sites of badger contamination, such as latrines, might assist in the control of the spread to cattle.

Source: Woodroffe, R. et al. (2021). Successive use of shared space by badgers and cattle: implications for Mycobacterium bovis transmission. J. Zool. 314(2): 132-142. doi: 10.1111/jzo.12863.

The colour of combat: Are black squirrels more aggressive than greys?

The name Grey squirrel is a reference to the appearance of the type specimen when this species was first described by German naturalist Johann Friedrich Gmelin in 1788. While it remains the most common colour morph, it's not the only one we see in this species. Albino, white, black, silvery, erythristic and even “cinnamon” have been recorded, the latter apparently well-known from the New York State area. There's a widely held belief, perpetuated largely by some sections of the tabloid media, suggesting that some colour morphs are dominant over others. In particular, the melanistic (black) morphs are reputedly more aggressive than the greys and actively displace them.

Melanistic Grey squirrels are now commonplace across much of East Anglia and the Home Counties but, contrary to popular misconception, there's no evidence they are any more aggressive than the standard Grey morphs. - Credit: Marc Baldwin

The argument goes that the coat colour in these “mutant” black squirrels is associated with an increase in the production of testosterone, making them particularly pugnacious. The science on this is lacking, however, with only a couple of studies having investigated this so far. One experiment found no difference in aggression or dominance between the colour morphs, while a second did find that black morphs were less likely to flee from predator calls played to them than the grey morphs. Now, using data from the Central Park Squirrel Census, scientists at Rutgers University have analysed the responses of black morphs to the presence of the people and other squirrels to understand if their colour affects their behaviour.

Based on just shy of 3,000 reports of squirrels that included grey (83%), black (3.5%) and cinnamon (13.5%) morphs, Lee Cronk and Ryne Palombit compared black vs. “non-black” morphs in four interactions: chasing another squirrel; approaching a human; displaying indifference towards humans; running away from a human. The data, currently in press with Acta Ethologica, show grey morphs were significantly more likely to be seen chasing another squirrel than melanistic animals, while black morphs were significantly more likely to run away from people than were grey morphs. A particularly interesting finding was that black morphs were most common in sections of the park with the highest squirrel densities, which is often indicative of increased aggression. In their paper, however, Cronk and Palombit suggest an alternative hypothesis:

It is possible that life in such hectares might be more stressful (socially and/or energetically). Given that research with other species has found an association between melanism and an ability to better resist stress, the possibility that the same might be true for eastern gray squirrels would be worth exploring in future research.”

Source: Cronk, L. and Palombit, R. (2021). Eastern gray squirrel (Sciurus carolinensis) color morphs do not differ in aggressiveness. Acta Ethol. In Press. doi: 10.1007/s10211-021-00372-z.

Related reading