Seasonal Update (September 2020)

September's the month when things usually start to cool down, with chilly, misty mornings. - Credit: Marc Baldwin

After a tumultuous July, weather-wise, ending with a couple of days of uncommonly hot and humid weather, August got off to a cooler-than-average but dry and bright start as we sat between weather systems over the first weekend. Cloud, wind (gale force in the west) and some relentless rain spread into Scotland and Northern Ireland early in the first week, with sunshine and showers for England. The heat returned at the end of the first week, with widespread heat and humidity. Temperatures climbed into the mid-30s Celsius (95F) on the first Friday of the month across south-eastern England and this set the stage for much of the following week, particularly in southern and south-east England. Indeed, the second week saw four successive “tropical nights”, where temperatures didn't fall below 20C (68F) overnight, in England; another new meteorological record.

A thundery low brought humid air and heavy thunderstorms, some containing large hail, from the near continent during the second week. Parts of northern England and Scotland saw the brunt of the stormy weather - areas in central and eastern Scotland experienced widespread flooding following seven hours of torrential rain. The latter half of the second week saw more rain in the south and temperatures slowly beginning to decline.

The middle weekend of the month brought mostly cloudy skies, and some heavy and squally storms. One YouTube video taken at a service station in Peterborough showed strong winds and a violent hailstorm that lasted for 15 minutes. Some parts also saw flash-flooding, Wellingborough for example; there were a couple of small water spouts recorded and even a tornado in the Bristol Channel. This unsettled weather was a theme for the month, courtesy of a series of low pressure systems spanning much of the UK, although the heaviest of the rain was in northern England, southern Scotland and Ireland. Temperatures were slightly below the seasonal average to begin with, but picked back up towards the end of the week; it remained humid, particularly overnight, with night time lows of 17C (63F) along the south coast.

On 14th September the pigs go out onto the New Forest, marking the start of the pannage season. The swine perform an important function for the Forest's Commoners, reducing the number of acorns, too many of which can cause toxicosis in their ponies. You can learn more in the article linked below. - Credit: Marc Baldwin

The third week saw some prolonged torrential rain and unseasonably strong winds as storm “Ellen”, named by the Irish Meteorological Service, passed over the UK. Ireland bore the brunt of the wind, just topping 100mph (161 kmph), while parts of southern and south-west England and Wales saw 70mph (113 kmph) gusts on Friday, remaining windy into the penultimate weekend. Another deep low (storm “Francis”) arrived early in the final week of the month - heavy rain and 81mph (129 kmph) winds recorded in the English Channel. The month ended on a showery and windy note, with temperatures down on the seasonal average, although, with unusually high pressure anchored over northern Europe, there's hope for an “Indian Summer” this month.

Meanwhile, across “the pond”, 54.4C (130F) was recorded in Death Valley, California, on 16th August, and this looks set to take the record for the highest temperature reliably recorded on Earth. At the same time, the state has been battling devastating wildfires following a combination of hot weather and lightning strikes. Further east, a category 4 hurricane (hurricane “Laura”) made landfall in Louisiana, bringing widespread flooding and damage, in the last week of August. On the other side of the world, many Australians were treated to a rare late winter snowfall last month, with Tasmania seeing its most significant snowfall since the early 1970s.

If you’re interested in the wildlife to be found this month, including the deer rut and baby snakes, check out my Wildlife Watching - September page. September also marks the beginning of the Common of Mast, or pannage season, with the pigs heading out onto the New Forest on the 14th.

Website news

More minor updates have been made to the hedgehog and squirrel articles, and there are a few more planned over the coming weeks as I attempt to include some new studies. The most recent updates have incorporated information provided by readers who have watched their local hedgehogs chin-wiping or squirrels caching stones. I’m always interested to hear from people who have witnessed these curious activities, or any other interesting behaviour. Additionally, new SpeedReads have been added covering the Eurasian beaver and the European slowworm.

In the news

A few headlines making the conservation news this month include the first list of endangered British mammals, how painting turbine blades may help reduce bird strikes, and the benefits of rewards during dog training.

Wind turbines can be a major mortality source for bats and birds, but new research suggests bird strikes can be dramatically reduced by painting one of the turbine blades black. - Credit: Marc Baldwin
  • UK Red List of Mammals. At the end of July, The Mammal Society published the first “Red List” for British mammals, approved by the IUCN and using the same criteria used for their global Red List. This smaller scale review suggests that 11 species (about a quarter of our mammal fauna) are classed as endangered, with some familiar characters including the wildcat, red squirrel, water vole, hazel dormouse and hedgehog. The aim of the List is to help conservation organisations, scientists and government target actions and resources more effectively to address habitat decline and improve species conservation.
  • Eco-legislation can make difference. A long-running study by researchers at the RSPB’s Centre for Conservation Science, the Centre for Ecology and University College London has been looking at the historic ranges of a variety of species in Britain. A recent paper produced by the collaborative and published in the journal Nature suggests that several species of lichen, liverwort and moss were boosted by the introduction of the Clean Air Act in 1956, which resulted in a reduction in air pollution. Several freshwater species were also observed to “bounce back” from declines with the implementation of EU legislation requiring member states to clean up waterways.
  • Paint it black: reducing turbine bird strike. In the drive to reduce carbon emissions, there is an increasing shift towards renewable (“green”) energy, and wind has a key role to play. Unfortunately, birds and bats are very prone to collision with the turbine blades and estimates in the literature suggest that, globally, as many as 328,000 birds may die this way each year. New research on the Norwegian archipelago of Smøla suggests, however, that painting just one of the turbine blades black can reduce bird collisions by up to 72%.
  • Turing into bird behaviour. Equations developed by the legendary computer scientist and mathematician Alan Turing have been used as the foundation for a new model that nicely predicts how flocks of long-tailed tits use woodland and partition up the resources therein. The new research, by mathematician Natasha Ellison at the University of Sheffield, is the first to apply such computer modelling to non-territorial species.
  • Kindness is king when training dogs. For centuries dog owners subscribed to the ‘alpha dog in the pack’ hypothesis, suggesting that respect was won from your pet pooch by “showing it who was boss”. We now know dogs are vastly more intelligent and behaviourally complex than we gave them credit for, and that reward-based training yields longer lasting benefits more quickly than punishment-based training. New research by scientists at the University of Lincoln found that pet dogs rewarded with treats came back more quickly when called and were generally more obedient than those given an electric shock from an E-collar.

Discoveries of the Month

Into the twitterverse: Shrews vocalise more in new places

A juvenile Common shrew (_Sorex araneus_). - Credit: Stephanie Powley

Animals employ sound for a host of purposes, from reassuring their young to letting a predator know they’ve been spotted or attracting a mate. Sound can be more than a communication tool, however, and some species have evolved to manipulate the way sound waves interact with the environment, helping them move around and find food. Bats and dolphins are perhaps the best-known examples of such “echolocating” animals, using complex high frequency calls to interrogate dark or often featureless surroundings. Simpler forms of echolocation are utilised by a wider variety of species including birds and even blind humans.

During his doctoral research in the late 1950s and early 60s, Tulane University zoologist Edwin Gould proposed that shrews, with their relatively poor eyesight, were able to use a high pitched “twittering” vocalisation as a type of echolocation that helped them avoid objects in their environment. In a 1964 paper, he and fellow researchers noted how shrews in unfamiliar environment twitter much more than those to which they were well acquainted, but were unable to explain why. Now, new research by scientists at the Max Planck Institute for Ornithology in Germany suggests it may be a mechanism shrews use to familiarise themselves with new environments.

Max Planck biologists Sophie von Merten and Björn Siemers set up two experiments to assess the way common, pygmy, and bicoloured shrews reacted when they were placed in new environments. In the first experiment the shrews were given free access to an unfamiliar terrarium and the researchers measured the rate at which they vocalised while they were in there. They were allowed to become familiar with the terrarium and each day were moved into a basket for weighing before being returned. For the second experiment, the shrews were exposed to a predator (buzzard) call, before being captured and weighed to see how they responded to stress.

The results of the study, published in Mammal Research, showed that all the shrews made a lot of twittering calls when they were first given access to the terrarium and this call rate declined over the subsequent days, as the animals became accustomed to their surroundings. The shrews didn’t, however, increase their call rate when subjected to stress, suggesting that this initial twittering in the terrarium wasn’t linked to the stress of being somewhere unfamiliar.

A Common shrew (_Sorex araneus_) on snow. New research suggests that shrews vocalise more in unfamiliar environments. - Credit: Hanna Knutsson (CC BY-NC-ND 2.0)

Von Merte and Siemers point to research in bats that demonstrates how they call more in unfamiliar environments to help them gain more information about their surroundings, although they point out that the structure and frequency of the calls are different, making it highly unlikely shews could use the echoes to find and catch prey. Instead, the suggestion is that the twittering provides a ‘broader sweep’ of the shrew’s surroundings. In their paper, the authors conclude:

Thus, echo-orientation, i.e. the interpretation of those reverberations, could provide the shrews with useful information on cover, obstacles, and escape routes. Once a shrew has learned about the general structure of an environment by means of echo-orientation, it possibly detects and evaluates smaller details and changes with other senses like touch or olfaction.

Source: von Merten, S. & Siemers, B.M. (2020). Shrew twittering call rate is high in novel environments—a lab-study. Mamm. Res. 65: 469-479. doi: 10.1007/s13364-020-00488-w

City break. Can gardens play a role in urban mammal conservation?

The recent publication of the Mammal Society’s UK Red List is a timely reminder that many species, even those that may be very familiar to us, are struggling to survive in an increasingly urbanised and human-dominated world. Several studies in the last decade or so have highlighted how towns and cities tend to be created in areas of high biodiversity in which many species overlap. Consequently, there has been a growing interest from conservationists in the potential for “green remnants”, by which we mean urban green spaces such as parks and gardens, to provide resources and alternative habitat for wildlife. Chris Baines summed the situation up nicely in his 1985 book How to Make a Wildlife Garden when he wrote:

Gardens with plenty of botanical diversity and cover and play a role in connecting habitats for urban wildlife. - Credit: Mark AC Photos (CC BY-SA 2.0)

There is no doubt that gardening with wildlife makes a positive difference. Certainly it helps our birds and butterflies to survive, but most importantly it brings so many people face to face with nature on a daily basis.

An issue with green relics is that they are typically fragmented, meaning that animals often find moving between them difficult and there is a need to find ways of connecting them up. With that in mind, a recent study by Australian scientists has assessed the suitability of urban areas in terms of mammal conservation, with some positive results.

The team, led by Bronte Van Helden at the University of Western Australia, studied how the influence of garden characteristics affected the presence and distribution of western ringtail possums (Pseudocheirus occidentalis), brushtail possums (Trichosurus vulpecula) and the southern brown bandicoot (Isoodon fusciventer). A web-based questionnaire was distributed to households in Albany and Bunbury asking residents about their gardens and the presence of these (and other) species. Based on the responses, the distribution of mammal presence in the gardens could be mapped and analysed statistically.

In all, 649 questionnaires were completed, and the data, published in Urban Ecosystems, show that some garden characteristics could accurately predict the presence of these mammals, and indicate that gardens have a role to play in species conservation in an expanding urban environment. Of particular interest, the analysis suggests that characteristics predicting brushtail possums and bandicoots differed between the two cities, implying that important garden features can’t be generalised across different cities. Nonetheless, it is clear that gardens cannot be overlooked as a thread in the tapestry of species conservation, and the researchers conclude:

Our results suggest that vegetation in the form of garden attributes can be manipulated by private landholders to encourage garden use by mammal species, however garden features that are important cannot be generalized among species or cities. To successfully exploit the opportunity that residential gardens can offer for native fauna conservation, species-specific knowledge of the garden features that encourage use by native animals, increased community awareness and participation in ‘wildlife-friendly’ gardening is required.”

It is suggested that planning regulations, government incentives and community group-led initiatives can all be mechanisms for encouraging such wildlife-friendly gardening.

A brush-tailed possum (_Trichosurus vulpecula_), one of the species found to benefit from urban wildlife gardens in this Australian study. - Credit: Marc Baldwin

Source: Van Helden, B.E. et al. (2020). Mammal conservation in a changing world: can urban gardens play a role? Urb. Ecosys. 23: 555-567. doi: 10.1007/s11252-020-00935-1

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