October went out like a lion with gale force winds, even a couple of tornados, and torrential rain across the country on Halloween. We saw trees down, including several on train tracks that delayed delegates getting to the COP26 summit in Glasgow, damage to roofs, and some localised flooding. In the wake of this intense area of low pressure a northerly airflow developed, bringing temperatures back down to the seasonal average of 9-12C (48-54F). In the first week of November we saw a mixture of sunshine and showers, but with that northerly air, temperatures also dropped significantly overnight, resulting in some widespread frosts to start the day, especially in England.
Owing to high pressure over the near continent, the south escaped the worst of the next low pressure that arrived at the end of the first week and brought more heavy rain and severe gales to Scotland. It also made for a striking temperature contrast. On the 5th November, for example, Benson in Oxfordshire woke up to temperatures of -3C (27F), while Oban in Scotland basked at 11C (52F). This mild air spread across the rest of the country during the first weekend, although Scotland was cooler and subjected to gale force winds, and held fast.
The Monday of week two saw 17C (63F) in Flintshire, north Wales, and the second week was mild by day and night for the bulk of England and Wales, with cooler temperatures in the north and in Scotland as a series of weather systems moved through. Come the third week, however, Scotland saw some exceptionally mild conditions, with Aberdeen waking up to 15C (59F) on 18th and seeing highs of 17C during the day, well above the expected daytime high of around 8C (46F). Things turned colder, courtesy of a northerly airflow, into the penultimate weekend and the final week, although Lerwick and parts of Scotland still saw overnight lows of 8C to start the final week while temperatures were in low single figures further south.
The final weekend of November saw the arrival of a deep low-pressure system, named “Storm Arwen” by the Met Office. Arwen came down from the north bringing a strong Arctic airflow and subjected the UK to winds peaking at 98 mph (158 kmph) in Northumbria, along with the first wintry weather - including some heavy snowfall - most had seen this season, accompanied by overnight temperatures below freezing. Indeed, eastern Scotland was put under a Met Office red warning, signalling the storm represented a danger to life and, at the time of writing, at least two people have been killed by falling trees. Arwen was quite a shock after what was, overall, a very mild November.
Outside of the UK, heavy rain and thunderstorms in the Egyptian city of Aswan apparently caused a deadly scorpion infestation during the middle of November, which has killed three people and injured at least 400, according to Middle East Eye. The situation was sufficiently serious to prompt authorities to issue temporary road and travel restrictions and order schools to be closed. Record heat was again recorded in the Middle East during November, as it has been in virtually all months of this exceptional 2021. On the 22nd November the temperature rose to 37.3C (99.1F) at Swiehan in the United Arab Emirates.
NASA released their climate stats early last month, pointing to October being globally +0.4C (0.7F) above the 1991-2020 baseline, and ranked the fourth hottest on records behind 2015, 2018 and 2019. Eastern Europe, central Asia, southwest Australia, California, Kamchatka and Namibia were cooler than average, however.
As 2021 draws to a close, leaving us perhaps in a slightly better position than 2020 did upon its departure, I'd like to thank you taking the time to read my monthly blog posts and for your interest in and support of my work over this past year. I hope you and your family have a fantastic festive season and wish you all the very best for 2022.
In the news
A few of the news stories catching my attention over the past few months include how the human lineage lost its tail, recent data from the Badgers Found Dead Study, and a decline in bird biodiversity in Europe.
- Telling tails. We've known for a while that the human lineage of the primates lost their tails about 25 million years ago, but a new genomic study by scientists at NYU Health in New York has pinpointed the mutation that caused this. Moreover, their data suggest that it sprung up abruptly, resulting in a sudden loss of the tail rather than a gradual shrinking.
- Biodiversity blow. A study by researchers at the Natural History of London suggests that Britain has lost more than half of its natural biodiversity, more than almost anywhere else in western Europe and the most of all the G7 nations, since the start of the Industrial Revolution in the mid-1700s. In the report, the scientists note that “… the UK has been among the most nature-depleted countries in the world for a long time.”
- TB testing road-killed badgers. Last year the government released the long-awaited report of their Badgers Found Dead Study, the results of which show that out of the 610 carcasses tested from across the UK, 51 (8.3%) were culture positive for Mycobacterium tuberculosis. In the south of England five positive cases were identified, all from Oxfordshire, giving the county an overall prevalence of 3.8%. The highest prevalence was detected in Cheshire, although even here it was only 13.5%. Interestingly, the report, by The University of Nottingham, suggests the majority (92%) of positive badgers were what they described as “latently infected”. In other words, they didn't show any symptoms and weren't considered infectious. The Badger Trust argue that these data add further weight to the idea that badgers are not a key source of TB infection in the UK.
- Wing and a prayer. Using an extensive dataset, a study published in the journal Ecology & Evolution last month highlights a significant biodiversity loss in the native birdlife in the European Union. The researchers, led by RSPB conservationist Fiona Burns, estimate a decline of 17–19% in the overall breeding bird abundance since 1980, equivalent to the loss of 560–620 million individual birds. Both the total and proportional declines in bird numbers were high among species associated with agricultural land.
- Beavering a-trout. We know that freshwater ecosystems, despite being extremely valuable, are among the most degraded habitats in the world. New data from the University of Southampton suggests, however, that the return of the beaver can help redress some of the balance. A study, published in the Canadian Journal of Fisheries and Aquatic Sciences recently, shows that when beavers build dams across shallow streams, they create deeper pools that increase both the availability of suitable habitat and the abundance of food for brown trout. This implies that fears beaver dams could be detrimental to trout populations may be unfounded.
I've spent the past few weeks working my way through some trailcam videos from a wildlife monitoring project I'm working on, which means I've not made much progress with the writing of the water deer article. Nonetheless, a couple of new sections have now gone online – Size and General Appearance and Coat Composition and Moulting.
Discoveries of the Month
Ungulate of Olay?
When it comes to managing wildlife populations, it is important to have a handle on demographics. In other words, you need to know roughly what proportion falls into the different age brackets. In recent years, a great deal of work has been done to understand how ageing affects reproduction, physiology and phenotypic performance (e.g. body mass and foraging efficiency) in mammals. Studies of animals raised in captivity have helped make some strides forward in our understanding of the mechanisms involved in the ageing process at the molecular level, but it's difficult to apply these directly to wild populations.
Aging is the very complex and time-dependent deterioration of physiological processes that happens in virtually all living organisms. These process changes begin at the molecular level and often manifest as changes to our DNA, especially with the addition of what are called methyl (CH3) groups into the structure of the molecule; a process called DNA methylation. The recruitment of these methyl groups can suppress genes and impair the DNA's ability to copy itself. Looking at the patterns of DNA methylation in a variety of cell types - particularly those of the white blood cells, brain and liver - allows the chronological age to be accurately predicted for several mammal species, including humans. Recently, a Franco-American team of geneticists has applied DNA methylation analysis to one of our most familiar cervids, the roe deer (Capreolus capreolus).
For nearly five decades, scientists have been monitoring the populations of roe deer living in two enclosed forests in France using mark-recapture techniques: Trois-Fontaines in the north-east, and Chizé in the west. The Trois-Fontaines deer live in a high-quality habitat with a temperate climate, while Chizén roe are subjected to a Mediterranean climate compounded by poor quality soils that make it a much less productive environment. The research team were able to tap into this long-running and comprehensive dataset to investigate the degree and patterns of DNA change in deer of known age. Blood samples were taken from animals caught in the woodlands during 2016 and 2017 and genomic DNA extracted from their white blood cells. This genomic DNA was used to build an epigenetic clock, which assesses how cells have aged.
The genomic data highlight a very tight correlation between the epigenetic and chronological age in both populations. Moreover, this method appeared substantially more accurate than the age estimated by assessment of first molar height (i.e. tooth wear). Perhaps the most interesting finding from this study was, however, that the rate of epigenetic ageing was slower in does than bucks. In their paper, currently in press with Molecular Ecology Resources, Jean-François Lemaître and his colleagues explain:
“Our analyses of the sex-specific clock reveal that beyond 7 years of age, females were consistently biologically younger than their chronological age when estimated with the male clock. This suggests that old female roe deer might show a lower degree of biological ageing than males. Yet, we detected no evidence that the epigenetic acceleration was higher in males than in females at any life stage…”
It's not news that females almost invariably live longer than males in almost all mammals, but this tantalising finding hints that they may actually age more slowly, at the cellular level, than males.
Reference: Lemaître, J-F. et al. (2021). DNA methylation as a tool to explore ageing in wild roe deer populations. Mol. Ecol. Resour. In Press. doi: 10.1111/1755-0998.13533.
The smell of success? Using scent to reduce fox predation on native fauna
The red fox (Vulpes vulpes) can make a living almost anywhere on Earth, such is their adaptable nature and catholic diet. This is broadly a good thing in the eyes of the fox-lovers among us, because it means these often-misconstrued mammals are as at home in our towns and cities as they are in the countryside, affording us some remarkable observation from the comfort of our homes. Such flexibility is not such great news in places outside of their native range where foxes have been introduced, however, such as in Australia.
Non-native predators are a particular problem because they subconsciously capitalise on what we call prey naiveté. In other words, because the local wildlife has never encountered a fox before it hasn't evolved the defensive behaviours to cope. This makes native fauna particularly vulnerable to predation, and may be the final straw on top of climate change and man-made habitat destruction. Indeed, while we have no official estimates of fox numbers in Australia, I have seen estimates suggesting as many as seven million now inhabit the continent since they were first introduced in the mid-1800s, and authorities have observed declines in many smaller native species that appear to be associated with fox population growth and expansion.
A variety of methods are employed against foxes in Australia in a bid to drastically reduce, ideally completely eliminate, their populations. In recent years, the futility of this task has become increasingly apparent, and researchers have turned their attention to finding ways to keep foxes and native mammals apart instead. One such line of investigation exploits the fox's acute sense of smell.
Scent plays a crucial role in fox society and, as well as using it to communicate with one another, foxes will also modify their behaviour in response to odours. Using scent stations, Tim Andrewartha and colleagues studied the vigilance of foxes in two different pastoral locations in south-eastern Australia. The researchers used odours from a small carnivore the foxes in this area would never have encountered (bettong), a small mammal that is now extinct in the region (quoll), and from rabbits, which are present in the area and predated by foxes.
The results of the study, published in the journal Conservation Science and Practice last month, revealed that foxes were very vigilant around the quoll scent for the three-week duration of the observations. The presence of other small carnivores may indicate good hunting grounds or den sites and are worth investigating. The foxes also remained very interested in the rabbit scent for the duration of the experiments, but lost interest in the bettong scent during the second week. The researchers suggest that the reason foxes lost interest was that their investigation went unrewarded (i.e. they never encountered any food that smelt like the bettong, unlike the rabbit scent that smelled like prey they're already taking) and, in their paper, suggest:
“… a pre-exposure of foxes to the odor of a locally extinct prey species could help to reduce the impact of foxes on the species immediately after translocation/reintroduction. This finding is important because it provides a complementary approach to fox management beyond the traditional approach of lethal removal of foxes from the landscape.”
Reference: Andrewartha, T.A. et al. (2021). Outfoxing the fox: Effect of prey odor on fox behavior in a pastoral landscape. Cons. Sci. Pract. e516. doi: 10.1111/csp2.516.