Seasonal Update (September 2021)

September marks the start of autumn and the chillier mornings and shorter days trigger deer to start rutting. - Credit: Marc Baldwin / British Wildlife Centre

July wound up on an autumnal note, with 69 mph (111 kmph) winds courtesy of Storm “Evert” and some heavy rain in the south over the last weekend. August started with a widespread mix of sunshine and showers with temperatures climbing into the low teens Celsius (mid-50s F). The first week started with heavy showers on and off through Monday across central and southern England, Wales, and more persistent rain in the Republic of Ireland. Northern Ireland, northern England and Scotland escaped the worst and remained dry for most of the day. Temperatures ranged from 12C (54F) in Lerwick to 21C (70F) in London. The pattern was repeated on Tuesday after a dry night, but with temperatures more widely in the low 20s. Come Wednesday, the north-west of Scotland saw some consistent heavy showers, while Ireland saw a band of rain push north and east and a rash of showers setup a diagonal line roughly from Newcastle to Birmingham. Temperatures peaked at around 22C (72F) in the sunshine in the south-east.

A large area of rain pushed in from the south-west early on Thursday morning, bringing heavy rain and gusty winds to the Republic of Ireland and western Scotland before pushing eastwards through the day such that the whole country saw some rain. The rain was more fragmented on Friday, but still heavy, particularly in Northern Ireland, Scotland, northern England and down the east coast of England. This theme continued into the first weekend, with the south of England seeing torrential rain - parts of the south-east suffering further flooding - for a few hours on Saturday morning as the rain band moved north and fragmented. Pretty much everywhere had some rain on Saturday, but in the afternoon showers were restricted mostly to the east coast of England and Republic of Ireland and western Scotland. Temperatures ranged from 18C (64F) in Stornoway to 21C in the south-east on Saturday afternoon and didn't drop far overnight, with most places in the mid-teens Celsius (high 50s F) at dawn on Sunday as further heavy and thundery showers pushed into Northern Ireland, Wales and along the coasts of western Scotland and northern England. Low pressure was centred over Scotland on Sunday resulting in a wet and blustery day for most, although the rain was much more fragmented in nature than on Saturday and moved through quickly on winds approaching 45 mph (72 kmph) along the south coast.

Parts of Northern Ireland and Scotland saw heavy rain early in August. - Credit: David Reid (CC BY-NC 2.0)

The second week started with sunshine and heavy thundery showers, and some blustery winds along the south coast. Ireland saw extensive heavy rain to begin Monday, as did Wales and central Scotland. As the day drew on the rain became more fragmented and patchier in nature, with the bulk along the south of England and Wales and the Scottish-English border. Temperatures on Monday climbed into the high teens or low 20s Celsius for most. As the week progressed, high pressure built in from the near continent, pushing the low pressures further north in the Atlantic. Wednesday started with heavy rain in Ireland and the western coast of Scotland, which pushed north and east through the day. This rain band missed most of the south and east of England, but west Wales, northern England and Scotland saw persistent heavy rain for most of the day. Away from the rain, however, in East Anglia, temperatures climbed into the mid-teens Celsius on Wednesday. The rain cleared into the North Sea overnight on Wednesday, leaving cloud in its wake across most of southern England and a muggy night, temperatures falling to only 16C (61F) in the east. High pressure from the continent pushed a little further west on Thursday, keeping the worst of the next low for Northern Ireland western Scotland, with rain more fragmented on Thursday and Friday. Quite a temperature contrast established across the UK on Thursday and Friday - highs of 15C (59F) in the north-west to 24C (75F) in the south east.

The middle weekend of the month saw another low pressure system push in from the south-west, although this brought mostly cloud and only some patchy rain to Ireland, Wales and the midlands - the south of England and Scotland were primarily dry with sunny spells for Saturday, with temperatures into the mid-20s. A muggy-ish night to follow, with lows of only about 15C thanks to widespread cloud, with some heavier rain pushing into the northern isles in the early hours of Sunday, remaining lighter in Northern Ireland and northern England. The low didn't move much through Sunday, but what was left of the rain was confined to southern Wales and a narrow band across northern England, with some early drizzle along the south coast. Later on Sunday, Scotland saw some patchy showers moved eastwards across Scotland and the odd spell of light rain in Wales. Temperatures on Sunday ranged from 15C in the north to 23C (73F) in the south-east.

Moving into the third week, a large area of high pressure began to build in the north Atlantic, pushing the low systems and their rain across the North Sea to Fennoscandia. This meant largely dry weather for us, but it setup a northerly airflow which both kept things on the cool side and prevented the heat pushing up from the continent. Monday was a day of scattered showers, which spread gradually south and east, eventually clearing into the North Sea overnight. Most of southern England, Ireland and Wales remained dry. Tuesday was mostly cloudy, with some rain in northern England and Northern Ireland that moved south and east during the day; East Anglia saw the heaviest showers. Tuesday afternoon was mostly cloudy, with some rain in north Wales - temperatures ranged from 14C (57F) in Lerwick to about 21C in London and the south-east. A muggy start to Wednesday, with temperatures falling to only 15C in the much of England and Ireland, a couple of degrees cooler in the north. Wednesday was cloudy across the board, with temperatures a degree or so up on Tuesday. The second half of the week saw a low-pressure system force its way in, bringing rain and gusty conditions to Ireland and western England from Thursday night into Friday and the penultimate weekend. Thursday was a cloudy affair with patchy showers, Friday remained predominantly cloudy across England, Scotland and Wales, while Ireland saw persistent and heavy rain for most of the day.

August was a cloud affair for most of the UK, although we did see a bit of sunshine towards the end of the month. - Credit: Marc Baldwin

The weekend started on a wet note, with pretty much the whole of the UK and Ireland seeing rain at times, more on Saturday than Sunday. Rain arrived early on Saturday and hung around for most of the day, due to the convoluted and slow-moving front, meaning the rain, some of which was heavy and thundery and accompanied by blustery winds, was on the cards for most of the day as the front slowly pushed east. The early arrival of the front also and meant temperatures couldn't climb much, so we saw temperatures in the range of 16C in Scotland to 23C in London. Sunday was generally a day of sunshine and showers, with the bulk of the wet weather confined to eastern England and a rash of showers up through the spine of England into Scotland. Into the afternoon the midlands and Home Counties saw some heavy, thundery showers that resulted in localised flooding. Temperatures remained in the high teens and low 20s.

High pressure built as we moved into the final week of the month, stretching from Spain right up into Fennoscandia, settling things down and bringing more sunshine. As the air circulation around high pressure is clockwise, however, it meant the air was pulled down from the north rather than up from the south, so we didn't get the heatwave to end August that some were predicting. Monday was probably the least summery day of the week, remaining cloudy for most of the day, thick enough in the south to generate some drizzle. Tuesday and Wednesday started cloudy but brightened up across the country. Thursday remained cloudy all day in the east, coupled with a keen northerly breeze along the coast, further west the cloud fragmented, allowing the West Country, Wales Ireland and Scotland see some decent sunny spells. Friday was the opposite scenario, with the bulk of the cloud in the east and sunnier skies in the west. Tuesday and Wednesday saw highs ranging from about 15C in Lerwick to 23C in the south-east, although cooler along the North Sea Coasts, while Thursday and Friday saw temperatures struggling to reach 20C.

Several parts of the Mediterranean, including Greece, Turkey and Italy, continued to suffer prolonged hot, dry weather that resulted in a number of large wild fires. - Credit: EU Civil Protection and Humanitarian Aid (CC BY-NC-ND 2.0)

Overall for the UK, rain and temperatures were around average, but it was an unusually cloudy month.

Outside of the UK, Europe basked in the “African plume” of warm air courtesy of an area of high pressure centred over the western Mediterranean. Unfortunately, the prolonged hot and dry weather resulted in Greece suffering some of the worst wildfires in living memory early last month, necessitating the evacuation of hundreds of people. More than 170 firefighters, 50 fire engines and six helicopters were involved in battling the fires as they encroached on the Ancient Greek city of Olympia. Neighbouring Turkey also endured some of the worst fires in at least a decade, while Algeria and southern Italy experienced fires that necessitated hundreds of people evacuating as the Mediterranean experienced a record-breaking heatwave. Temperatures hit 48.8C (119.8F), an all-time high, in Sicily during the second week of August. Towards the end of the month, Europe did see some heavy, isolated showers, although temperatures remained high.

Further north Russia continued to experience very warm weather, with 35.8C (96F) recorded in Yekaterinburg last month and the Middle East was also gripped by a heatwave, with temperatures at Shosh in Iran hitting 51.9C (125F), which is very unusual this late in the season. On the 24th August saw Iceland hit a new temperature record - Hallormsstaður reached 29.4C (85F), which beat the previous national monthly record set back in August 2004. Across the Atlantic, California saw the largest wildfire in state history last month as the North American heatwave continued. In South America, Paraguay endured temperatures at or just above 40C (104F) for most of last month, and August is still winter there. In Mexico, the AWS station in the city of Mexicali beat the national highest August temperature, climbing to 50.6C (123F) on the 27th, while the same day saw Botswana in South Africa record their hottest August temperature on record – 36.7C (98F) at Tubu.

If you're interested in the wildlife to be found this month, the deer rut, a lack of garden birds and a berry bounty, check out my Wildlife Watching - September article.

In the news

A few of the science and conservation news stories that caught my attention last month include selachian virgin births, the origins of animal life and how antidepressants leaching into waterways may be changing the behaviour of aquatic animals:

A new study suggests stroking therapy dogs can help students focus and be generally more positive. - Credit: Marc Baldwin
  • Like a virgin. The largest ever DNA study of newborn white-spotted bamboo sharks by researchers looking to develop artificial insemination techniques to help bolster shark populations has found two instances of parthenogenesis, where the mother produced a pup without using the sperm she'd been inseminated with by the scientists.
  • Man’s Student’s best friend. A study published in the journal AERA Open recently reports that stroking therapy dogs reduced stress in students, helping them think and plan more clearly, more efficiently than traditional stress-reduction techniques. The experiment also demonstrated how animal sessions helped students engage in more positive thoughts and actions.
  • Ancient animals. New data from a joint study by the Australian National University, Max Planck Institute and Caltech University cast doubt on our understanding of when complex life first evolved on Earth, placing it nearly 100 million years more recently than we first thought.
  • Antidepressants in waterways. In recent years evidence has been accumulating that many medications people take routinely pass through our bodies and aren’t removed in water treatment processing, resulting in them making it into waterways. Now a team of researchers at the University of Florida has found that the presence of the selective serotonin reuptake inhibitor antidepressant citalopram in the water caused crayfish to be bolder, emerging nearly twice as fast from their shelters to explore their surroundings and spending nearly twice as long searching for food.
  • Breeding brainy. MRI scans on the brains of foxes raised as part of the Russian fox domestication experiment have shown that foxes bred to be tamer or more aggressive than normal had larger brains, with more grey matter, than the control group that weren’t bred for any particular behaviour. This suggests changes in the brain structure, even those enhancing memory and emotions, can evolve much more quickly than first thought.
  • Sparing snakes. Venom is an important component for many snakes as both a means of defence and securing prey, but it also takes time and energy to produce. New research by scientists at the Chinese Academy of Sciences found that some snakes appear to know how much venom they have left and are less likely to strike when reserves are low.

Discoveries of the Month

Timber! Balancing commercial timber production with Red squirrel conservation

With a growing human population, our impact on the environment continues to increase and very often this results in wildlife being pushed aside. Indeed, balancing the demand for natural resources with the conservation of habitats and the species they sustain is a major global challenge. Here in the UK, timber demand has skyrocketed as a result of lockdown, which saw a surge in DIY projects, and earlier this year the Timber Trade Federation reported that timber stocks were at their lowest in 20 years, and warned of “major challenges ahead of timber shortages” as we head into autumn.

In Britain, Red squirrels (_Sciurus vulgaris_) are often residents of commercial conifer plantations. - Credit: Marc Baldwin

The UK has an estimated 3.2 million hectares of woodland, just under half of which is sustainably managed for timber production. Some 11 million tons of timber is harvested each year with another 10 million tons imported. Alongside the demand for timber comes a need to protect dwindling populations of woodland mammals, Red squirrels in particular. The UK is currently thought to be home to perhaps 200,000 Red squirrels in a handful of scattered populations, many of which reside in commercial forests and plantations. At the same time, Red squirrels are part of the UK Biodiversity Action Plan, which necessitates their protection and conservation, which can be at odds with timber production on a commercial scale.

In order to assess the impact of forestry operations on squirrel ranging behaviour, a team of researchers based in Scotland, led by Louise de Raad at the University of the Highlands and Islands, studied how Red squirrels responded to timber thinning in a 28 ha (69 acre) area of mixed woodland in the Highlands. Between February and September 2017, the scientists radio-tracked 22 squirrels and monitored others who were tail-marked, recording their ranging and habitat use as the basal area was reduced by 10 sq-m per hectare (45 sq-ft per acre). The basal area is the sum of cross-sectional area measured at breast height (1.3 m / 4ft) of all trees in a stand.

The data from this tracking session, published in the journal Forest Ecology and Management last month, show that, overall, the thinning operations didn’t negatively impact either the survival, space use or the density of the squirrel population. Indeed, Red squirrel density was actually slightly higher after the thinning operations. In their paper, de Raad and her colleagues note:

Our results show that red squirrel survival was relatively high compared to sites without forest operations and breeding activity continued with no detectable impact of forest operations.”

These data correspond well with previous studies in Europe that suggest the right level of thinning can be conducive to squirrel conservation and even beneficial, as mild to moderate thinning generates a mosaic of stand heights and can promote cone production.

Commercial timber production can be at odds with wildlife conservation, but new data suggest that thinning operations don't have a negative impact on Red squirrel ecology in plantations. - Credit: Marc Baldwin

Source: de Raad, A.L. et al. (2021). Managing forests for the future: Balancing timber production with the conservation of Eurasian red squirrel (Sciurus vulgaris). For. Ecol. Man. 493: 119164. doi: 10.1016/j.foreco.2021.119164.

Hogging the food. Supplementary feeding of hedgehogs

Many of us relish watching the wildlife that visits our gardens, and the Covid pandemic spurred a new wave of interest in the species with which we share our neighbourhoods. Various surveys have been conducted both here and in the USA aiming to assess the number of households who feed the wildlife in their gardens, with some data suggest it’s as high as 75% of us. Indeed, it has been estimated that we spend nearly £300 million (€350m / US$413m) per year on food for wildlife, with a great many specifically targeting the mammals that show up.

Hedgehogs are a species many homeowners enjoy seeing in their gardens and frequently leave food out for. Complete (dry) cat or dog biscuits and fresh water are ideal. - Credit: Marc Baldwin

One species that is often the subject of supplemental feeding here in the UK and in much of Europe is the hedgehog. Having suffered, and continuing to suffer, a substantial decline in Britain, hedgehogs are something of a “poster species” for the general public doing their bit to help wild mammal conservation. Most of us find hedgehogs endearing and by taking simple steps to conserve them we are also helping other species that benefit from the same measures. Added to this are a network of dedicated rehabilitators across the country who work tirelessly to hand-raise and repair hedgehogs brought into their centres, which we hope helps to bolster local populations.

Along with some basic steps, such as reducing the use of pesticides, suppressing the urge to make our gardens too tidy, and cutting holes in fences to connect gardens, many householders are also encouraged to leave out food to give their visiting hogs an energy boost. A subject of contention, however, has long been what foods are suitable for hedgehogs and we now know that bread, milk, peanuts, sunflower seeds and mealworms should all be avoided. In a bid to get a better understanding of the suitability of commercially available foods for hedgehogs, a team of Swiss biologists assessed the nutritional adequacy of five products from three different brands, including both wet and dry diets. The scientists tested the food for five nutritional parameters: crude ash (CA), crude protein (CP), crude fibre (CF), ether extract (EE) and nitrogen-free extracts (NfE).

The results of the study showed that only a single food had a CP and NfE content equivalent to a hedgehog’s natural diet, with the others having less protein and higher nitrogen-free extracts, suggesting a high cereal content. The researchers caution that feeding high quantities of these easily digestible carbohydrates could lead to health problems, such as the obesity we observe in domestic cats. They also note that products labelled as “complete feeds” were often misleading and contained oats, sunflower husks and mealworms. Writing in the Journal of Animal Physiology and Animal Nutrition, University of Zurich biologist Angela Gimmel and colleagues conclude:

“… the use of the three analysed dry hedgehog diets should be discouraged as they do not resemble the natural diet of E. europaeus and are likely nutritionally inadequate. They therefore could potentially have a negative impact on the health of E. europaeus—especially if fed as a complete diet during rehabilitation. The commercial wet hedgehog diets should only be used supplementary and should not be considered as complete feed.”

Source: Gimmel, A. et al. (2021). Feeding the European hedgehog (Erinaceus europaeus L.)—risks of commercial diets for wildlife. J. Anim. Physiol. Anim. Nutr. In Press. doi: 10.1111/jpn.13561.

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