Seasonal Update - November 2019

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As we enter the final month of autumn, the colour change is finally under way here on the south coast, after a largely mild and very wet few weeks. Meteorologically, Britain saw extremely unsettled conditions last month, with several large areas of low pressure bringing torrential rain and, at times, gale-force winds to our shores. Storm systems are not particularly uncommon at this time of year, October and November being our stormiest months, but after a drier-than-usual year we received a lot of rain in one go, which led to widespread flooding. This was an inconvenience for many of us and a major issue for those whose houses were affected; but to maintain a sense of perspective, more than 40 people were killed when Typhoon Hagibis, the largest and most powerful storm to hit Japan in decades, made landfall early in the month.

The weather models don’t really align for the next few months, resulting in contrasting stories appearing in the media about what we can expect for the end of autumn and winter. Generally, it seems this month is going to continue October’s unsettled theme, with wet and windy conditions in the south and south-west particularly. At the start of last month, the Daily Express carried the headline that the UK is on heavy snow alert because “Britain faces coldest winter in decades”. Similar stories were carried by other tabloids and news agencies last month, but the ECMWF seasonal model update released on 10th October begs to differ. The European Centre for Medium-Range Weather Forecasts, or ECMWF, is an independent body of meteorologists based in Reading who supply mid-range weather forecasts based on one of the largest supercomputers in the world and a huge archive of accumulated climate data. The latest ECMWF suggests that 2019/20’s winter will be unsettled, with a large area of low pressure dominating much of the north Atlantic. As a result, winter is much more likely to be mild, wet and windy than cold and snowy. This pattern looks set to dominate until the spring.

David Attenborough, addressing an audience at the premier of the BBC's new series, Seven Worlds, urged people to reduce, or eliminate waste. - Credit: John Cairns / The Bodleian Libraries (CC BY 4.0)

A lot has been happening in the world of conservation over the past few weeks. In a month when the Office for National Statistics released predictions that the UK’s population is set to increase by 4.5% to just over 69 million over the next 10 years, David Attenborough addressed an enthralled audience of children and parents attending the first screening of the BBC’s new Seven Worlds series in London, urging them to reduce waste. In answer to the question “What can I do to save the planet?”, posited by a seven-year-old boy, the 93-year-old BBC broadcaster and conservationist responded:

Don’t waste electricity, don’t waste paper, don’t waste food. Live the way you want to live but just don’t waste. Look after the natural world, and the animals in it, and the plants in it too. This is their planet as well as ours. Don’t waste them.”

Elsewhere, a new study has linked deforestation with an increase in the spread of both malaria and Ebola. The research, published in the Proceedings of the National Academy of Sciences suggests that the fires and illegal logging in the Amazon rainforest increase the suitable habitat for mosquitoes, while altering fruit tree distribution affects fruit bat behaviour and movements, in turn increasing the risk of Ebola spread. Over 13 years, a 10% increase in deforestation appears to be linked to a 3% increase in malaria infections; almost 10,000 additional cases every year.

In starkly contrasting, but related, stories, the Trump Administration signalled its desire to end all road-building in Alaska’s Tongass National Forest, raising concerns among conservationists that this is likely to lead to gross overexploitation (logging) within the forest. At the same time, a recent report in The Economist suggests that the cooperative Yet Metsä Group, which operates a timber mill in some of Finland’s large forests, has been sustainably managing the country’s woodland for generations, ensuring all parts of the harvested trees are used and developing cutting edge methods for recycling and replacing plastic packaging.

Finally, one other piece of conservation news that caught my eye this month was a recent study published in Science Advances, which found that crop biodiversity on farms is essential for attracting both pollinators and pest predators. The research revealed that pollinators and pest predators (e.g. ladybirds, wasps, ground beetles and even birds and bats) were much less likely to hang around on farms with only one, or a handful of, crop species – this, in turn, resulted in increased damage and reduced rates of pollination, resulting in overall poorer provision of “ecosystem services”.

November is pannage season in the New Forest, the period during which about 400 pigs are given free-range to feed on the acorns and beech mast. - Credit: Marc Baldwin

If you’re up for getting outside for the start of autumn, as usual, the Wildlife Trusts have a series of nature-themed events up and down the country, as do the RSPB. If you feel like being proactive this month and live near the coast, Surfers Against Sewage is looking for people to organise cleans of their local beaches – details here. The Forestry Commission is running a series of events this month – full list here. Don’t forget that November marks the end of the pannage season here in the New Forest, the 60 day period during which pigs are turned out onto the Forest to eat acorns. You can learn more about the practice in my pannage blog. November is also the month when many of our hedgehogs will start entering hibernation, and I implore you to help if you can by leaving food and water out overnight and by keeping an eye out for very small animals that may not have time to put on sufficient weight before hibernation, particularly if the Daily Express are right and the winter’s going to be a cold one. Find out more about how you can help your local hedgehogs on my blog.

Interested in the wildlife to be found this month? Check out my Wildlife Watching - November page.

Discoveries of the Month

Going where no pig has gone before

For centuries, we have been trying to come up with a comprehensive description of all the traits that separate us from other animals. Until relatively recently, one such characteristic was the use of tools. Some 2.6 million years ago our ancestors in Ethiopia were knapping flint, quartz, obsidian, and such into sharp-edged devices that could be used to cut meat and bone. For many years, the manufacture and use of tools was considered an exclusively human activity, until, that was, Jane Goodall noticed something curious while watching a chimpanzee in the Gombe National Park. In 1960, Goodall was watching the fantastically-named “David Greybeard” feeding at a termite mound when she noticed him sticking blades of grass into the mound and pulling it out before running it through his mouth. When the chimp left, Goodall examined the grass and found that termites had attacked the grass, hanging on with their powerful jaws, and could be pulled out of the mound and then essentially “scraped” off by passing the grass through the teeth. This was the first example of tool use documented in a non-human species, but it wasn’t the last.

Visayan warty pigs (_Sus cebifrons_) are the first members of the Suidae (pig family) to be documented using tools. - Credit: Marc Baldwin

Since Jane Goodall’s startling discovery, scientists have observed a variety of animals making and using tools to help improve their foraging efficiency, although it is the higher primates and corvids that appear to use the most complex tools. Until recently, one group of mammals that had never been seen to make or use tools was the Suidae, the pig family. Last month this changed and a video of “Priscilla”, a Visayan warty pig (Sus cebifrons), taken at the Ménagerie at the Jardin des Plantes in Paris went viral showing her going where no pig has gone before, so to speak.

The Visayan warty pig is a critically endangered swine species native to Cebu, Negros and Panay, three of the Visayan Islands in the central Philippines. Habitat loss and hunting have resulted in these pigs becoming extinct on three other Philippine islands and it is now a priority species bred in zoos around the world, including a population of four animals at Jardin des Plantes. According to the European Endangered Species Program, there are currently just under 1,400 warty pigs held in captivity around the world.

Following several incidents where a piece of bark was found to have been moved around the pigs’ enclosure, always to be found lying next to a nest pit, a team of researchers led by Meredith Root-Bernstein at the Université Paris-Saclay started watching the animals. In October 2016, Root-Bernstein observed a sow hold a piece of bark in the centre of her mouth and use it to “quite energetically and rapidly” push soil back out of the scrape she was making – she was using this bark as a makeshift spade to dig her nest.

Over the course of the study, two adult females were observed to dig with sticks and bark, and the male made a largely unsuccessful attempt to dig with a stick. Of particular interest was the observation that the tools were only used in the final stages of nest construction. To start the nest, the pigs used their feet and snout and only turned to bark and sticks once the nest scrape had been established. This is exciting because not only does it represent the first known case of tool use in a member of the pig family, but is also shows cognizance on the part of the pigs, choosing the tool only when it was needed and, presumably, most efficient.

Reference: Root-Bernstein, M. et al. (2019). Context-specific tool use by Sus cebifrons. Mamm. Biol. 98: 102-110.

Squirrels relax when birds chatter

Public information plays a big role in all our lives, from finding out what the traffic is like for the commute to work to coordinating action during disasters. We’re also pretty good at acting on public information provided by the other species with which we share the planet. As a naturalist, you quickly learn to recognise that the mobbing cries of birds means there’s a predator around and, with a bit of practice, you can even recognise subtle differences that suggest whether it’s an aerial predator, such as a raptor, or a ground predator, such as a cat or fox. Perhaps more fundamentally, we may investigate the barking of a neighbour’s dog. It turns out that, much like tool use, we’re not the only ones to tune into this.

A Grey squirrel (_Sciurus carolinensis_) feeding in an ash tree. New research suggests that squirrels use the chattering of birds as an "all clear" signal that there are no predators about. - Credit: Marc Baldwin

As the study of animal behaviour has blossomed, so too has our understanding of the associations that can form between different species and how “connected” species are within an ecosystem. In the early 1980s, for example, Paul Newton studied the foraging behaviour of chital (Axis axis), a species of deer, in India’s Kanha Tiger Reserve. Newton found that the deer tended to follow troops of langur monkeys (Presbytis entellus) around, eating some of the things they dropped while foraging in the trees. Not only did this provide access to a variety of food that would otherwise have been out of reach, some four kilograms per day on average; the deer also came to learn the alarm calls of the monkeys, helping reduce their vulnerability when predators were around. Recent research from the USA suggests that even some common garden visitors have evolved this associative behaviour, with grey squirrels (Sciurus carolinensis) eavesdropping on garden birds.

In 2016, biologists Marie Lilly, Emma Lucore and Keith Tarvin at Oberlin College in Ohio subjected some of their local grey squirrels to playback experiments during which they played recordings of buzzard calls and general bird “chatter”, i.e. the contact calls made by birds in their day to day activities when not in the presence of a predator. The researchers noticed that when the squirrels were played just the buzzard call, they immediately became more vigilant, looking around for the danger, freezing or running for cover. They’d remain vigilant for several minutes following the call. When the researchers played the call followed by bird chatter, however, the squirrels significantly reduced their level of vigilance, going back to whatever they were doing much more quickly. These observations suggest that the squirrels were using the chatter of birds as an “all clear” signal that the danger had passed.

Writing in the journal PLoS One last month, Lilly and her colleagues warn that, given this eavesdropping behaviour that seems to promote squirrel fitness (allowing more time to forage), noise pollution, an increasing problem for wildlife across the world, may prove disadvantageous if it drowns out these often subtle environmental cues:

While our study does not directly address the issue of noise pollution, it identifies a novel component of information networks that anthropogenic noise might cover up. Indeed, relatively quiet chatter noises may be more susceptible to interference from anthropogenic noise than loud alarm calls. If bird chatter were masked by anthropogenic noise, this publicly available safety cue could be lost to the network of eavesdroppers. The lack of safety signals might cause squirrels and other eavesdroppers to allocate more energy towards vigilance behaviors and less towards foraging, potentially compromising fitness.

Reference: Lilly, M.V. et al. (2019). Eavesdropping grey squirrels infer safety from bird chatter. PLoS One. 14(9): e0221279.

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