Seasonal Update - January 2020


Happy New Year! I hope you and your family had a restful and enjoyable festive period. Congratulations on surviving all the cheese, wine and brussels sprouts to see in another year. Is it me or does 2020 sound very futuristic? It feels like I should look out of my window and see flying cars!

December started on a distinctly cold and frosty note for most of the UK, although early models suggesting heavy snowfall didn’t bear fruit. Indeed, the weekend of the 7/8th was remarkably mild, courtesy of a plume of mild desert air that enveloped the country for a few days, bringing gale force winds and heavy rains – Scotland received a month’s worth of rain in a little over 24 hours. We also saw some very mild night time temperatures; it was 13C here in Southampton at dawn on the 6th.

During the second week of December, storm Atiyah brought heavy rain and winds in excess of 60mph (nearly 100mph off The Needles on the Isle of Wight), setting a new British wind power record. Over the course of that weekend, wind power from the storm generated 16 gigawatts to the National Grid, almost 44% of the electricity used by England on Sunday 8th. At one point on the Sunday night, some customers on agile pricing plans who own electric cars were being paid to charge their vehicles.

On the back of three months of above average rainfall, torrential rain during December saw widespread flooding before Christmas. Here in the New Forest the ground was completely saturated with large areas of standing water and many rivers breached their banks. - Credit: Marc Baldwin

An unsettled theme played out for the remainder of December with plenty of low pressure systems bringing mild, wet and windy weather across the UK, including a deep low that resulted in a soggy Christmas Eve and Boxing Day for many. Most parts of the UK saw well in excess of the expected rainfall and, following three and a half months of above average rainfall, there was widespread flooding. Along with the rain, we finished December on an uncommonly mild note, with overnight temperatures in Stornoway, northwest Scotland, falling to only 10C (50F) courtesy of a huge body of warm air drawn up from the Azores. Indeed, temperatures in the final week of 2019 were peaking at 14C (57F) even in the north of England, well above the 6C (43F) we’d expect for late December, although it has a way to go to beat the current all-time record of 18.3C (65F) recorded in the Scottish Highlands on 2nd December 1948.

While we had it unseasonably mild, further south in Europe residents experienced some truly balmy temperatures. A positive NAO in the North Atlantic resulted in strong cyclonic activity and high pressure over Europe, drawing up a large mass of warm air from the Sahara and culminating in unprecedented temperatures of 40C (104F) in parts of Spain.

Our warming climate isn't all bad news and lepidopterists were celebrating the first reports of breeding long-tailed blue butterflies (Lampides boeticus), normally a Mediterranean species, on the south-coast this summer. - Credit: Harum Koh (CC BY-SA 2.0)

Many of us appreciate the milder conditions and it would be wrong to suggest that climate change is bad news for one and all. It’s generally better for our National Health Service, for example, because it reduces admissions of the most vulnerable in society during winter, particularly the elderly, who tend to suffer badly in the cold. Warmer summers and winters also appear good news for several of our migrant species, including the long tailed blue butterfly, a Mediterranean species, 50 of which were observed mating and laying eggs along the south coast of England during the summer. Perhaps less welcomed by gardeners, slugs and snails also benefit from mild, wet winters; they can remain active well into winter and we may see some “bumper crops” next summer. On the other side of the metaphorical coin, a recent survey suggests that this year’s heavy rain has been bad for water voles and that seabirds on the Farne Islands lost chicks in flash floods following downpours in June.

Perhaps worse than consistently mild conditions is the sudden variation in temperatures; from overnight lows of -6c (21F) to 10C (50F) in Scotland within the space of a few days, for example. Such pronounced swings in temperature can severely disrupt hibernation routines of animals such as hedgehogs and bats and, although temperature is only part of the hibernation “story”, we had hedgehogs showing up most nights over the festive period. Shortly before Christmas the Met Office released their annual global temperature forecast for 2020, suggesting that next year will once again extend the series of Earth’s warmest years, since records began in 1850.

If you’re up for getting outside, 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. Remember, too, that this winter’s topsy-turvy weather may be adversely affecting hibernating hedgehogs, so I implore you to help if you can by leaving food and water out overnight. Find out more about how you can help your local hedgehogs on my blog. If you’re interested in the wildlife to be found this month, check out my Wildlife Watching - January page.

Finally, I appreciate that I’m getting very lax again at providing new content for the site, but I’m excited to announce that a feature that was postponed from last year will be starting this year – Walks with my camera. Keep your eyes peeled as the first one will go live around the middle of January.

Discoveries of the Month

Noise pollution interferes with a robin’s ability to compete with rivals

European robins (Erithacus rubecula) are highly territorial birds and, among other functions, singing proclaims territory ownership. - Credit: Marc Baldwin

Many years ago, I remember meeting up with the late elasmobranch biologist Aidan Martin during a layover at London Heathrow. We left the airport and found a pub to have a chat over a couple of beers, but our conversation had to be paused periodically as planes came overhead, drowning out all but the very loudest voices in the pub’s garden. For us, this temporary, albeit repeated, interruption was little more than a mild annoyance, but noise pollution can have serious consequences for people and wildlife alike, particularly when it is long-term disturbance.

Among humans we now have a reasonable body of evidence that noise pollution leads to high blood pressure, stress, tinnitus, sleep disturbance and even more serious conditions such as hearing loss and cognitive decline. The picture is less clear with other mammals, although we have good cause to think that the stranding of some cetaceans (whale and dolphin) may be associated with underwater noise and there are some biochemical data to suggest deer are more stressed when there’s a busy road in their home range than when there isn’t, which we think is associated with the constant drone of the traffic.

In recent years, several studies have investigated the impact of noise pollution on bird species and, in particular, how it changes their singing behaviour. These studies suggest two effects: the birds change their behaviour to sing more at night, when it’s quieter; and/or they increase the volume of their song. The latter of these is known as the Lombard reflex and is something most of us are familiar with – it’s the involuntary tendency we have to shout over background noise, loud music in a pub for example. New research from Northern Ireland suggests, however, that not only are the songs of some birds drowned out by noise pollution, making them less noticeable to potential mates, but this background noise may also hamper their ability to interpret and respond to the songs of competitors.

European robins (Erithacus rubecula) have been the subject of considerable study on the impact of noise pollution on song birds in recent years. Robins are small territorial birds that sing to declare their territory as well as to attract prospective mates. The structure and complexity of their song changes according to the situation, their song for aggressively warning off an intruder differing from that sung at dawn to tell neighbours that they survived the night. This melodic complexity suggests to scientists that the robin’s song encodes specific information about the competitive ability of the singer, and a team led by Kyriacos Kareklas at Queen’s University Belfast’s School of Biological Sciences recently set out to investigate what impact background noise has on the birds’ ability to “decode” the songs of competitors.

A pair of robins fighting over territory. A good territory is quite literally a matter of life and death and worth fighting for. - Credit: Wildlife Terry (CC BY-NC 2.0)

Between March and April, the peak of the robin breeding season, the biologists recorded 15 birds in Northern Ireland’s Lagan valley. The calls were mixed with various levels of background humdrum and played back to the birds in the presence of a wooden dummy robin, as these pugnacious passerines use both audio and visual cues when assessing a potential threat. The data show that robins do indeed produce highly complex songs during aggressive competitive encounters. Kareklas and his team observed that the song complexity was consistent for individual birds and was a good predictor of their behaviour. Of particular interest, however, was that this behavioural response was only apparent with the control (i.e. unadulterated) recordings. When noise was mixed into the playback, the birds were much less likely to respond aggressively, suggesting that robins struggle to accurately “read” a challenge in noisy environments. The researchers consider that the noise frequency overlaps with some important elements in the song, essentially drowning them out. In their paper to Biology Letters, they conclude:

As a result, contestants receive incomplete information on their opponent’s aggressive intent and do not appropriately adjust their response. This suggests that under noisy conditions, birds may be limited in their ability to use song complexity to defend or acquire resources, such as territory, and outcomes from vocal interactions can be highly unpredictable and affect subsequent contests.”

Reference: Kareklas, K. et al. (2019). Signal complexity communicates aggressive intent during contests, but the process is disrupted by noise. Biol. Lett. 15: 20180841. [10.1098/rsbl.2018.0841]

Baiting white sharks doesn’t appear to alter their diet

Wildlife tourism – where people pay specifically to see wildlife in natural habitats – has blossomed into a multi-million pound industry in the last few decades and is now considered the fastest growing sector of the global tourism industry. With great power, as Stan Lee’s maxim goes, comes great responsibility, and wildlife tourism comes with its own set of management challenges and problems. Tourists can provide vital funding for local economies and conservation projects, and the ecological restoration and wildlife protection undertaken to ensure tourists have somewhere to stay and something to see can have significant benefits to the natural world. At the same time, there are concerns about the damage caused by large numbers of people visiting fragile habitats and the conduct of some tour guides and their tourists.

Charismatic megafauna tends to be a big draw for tourists, as are predators. Hence, large predators are particularly enticing subjects. Unfortunately for tour guides, predators can be elusive and widely dispersed, which often requires luring them in with some kind of bait, and issues have been raised over the impact this may have on their natural diet and overall condition. We know, for example, that wildlife subsisting on a diet of junk food tend, much like us, to carry more fat than those eating a more balanced, “natural” diet. There is also concern that some species may change their diets altogether to take advantage of baiting stations and that this might have knock-on impacts in the ecosystem.

A Great white shark (Carcharodon carcharias) taking bait off South Africa. Shark tourism is a growing industry and scientists are keen to understand its impact on the target species. - Credit: Len (CC BY-NC-ND 2.0)

Sharks are an iconic predator and the notorious great white (Carcharodon carcharias) is a popular species for tourists to cage dive with. Shark tours are not a new venture and we have a reasonable pool of data on their impacts on their target species, which include changes to their distribution, seasonal use of habitats, abundance and behaviour. As far back as the late ‘90s I remember a shark researcher off South Africa describing how white shark tour operators in South Africa would gun their boat engines to “call their babies in”. A recent study from Australian biologists suggests, however, that while such wildlife tours may alter the behaviour of the sharks they target, their use of bait does not appear to affect their diet.

In a paper to the journal Tourism Management at the end of last year, Lauren Meyer at Flinders University and colleagues present the findings of their study on the diet and nutritional condition of white sharks at the Neptune Islands off the south Australian coast. The researchers collected muscle samples from free-swimming sharks off the islands between May 2012 and April 2017 and analysed the lipid content as a proxy for the types of food they’re eating. (The types of lipid in the muscle of an animal indicates whether it has been feeding on fish or the blubber of mammals, for example.) Their samples showed no significant variation in fatty acid profile between the “control” and “tourism exposed” sharks and the researchers concluded that:

White sharks fed on a variety of prey groups, similar to other populations around Southern Australia that are not exposed to ecotourism provisioning. These findings indicate that current cage-diving operations in South Australia do not alter white shark diet and nutritional condition where prey resources are abundant.

Reference: Meyer, L. et al. (2019). The impact of wildlife tourism on the foraging ecology and nutritional condition of an apex predator. Tour. Man. 75: 206-215. [10.1016/j.tourman.2019.04.025]

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