Seasonal Update - August 2019


As 4th of July celebrations got underway in America last month, the Reuters news agency reported that climate scientists were “growing alarmed at the rapidly rising and unseasonably high temperatures in Alaska, where residents are trading in their snow boots for fishing rods and swimming trunks”. According to the US National Weather Service, the temperature in Alaska at the start of July was in the high 80s Fahrenheit (about 30 Celsius) in an area where temperatures typically hover between 55F and 62F (13-17C) this time of year. This year the ice on the Tanana River, in the Alaskan city of Nenana, gave way at midnight on 14th April, the earliest thaw since records began 102 years ago. As a consequence of these unseasonably-high temperatures, the state has seen several wild fires that have burnt an estimated 250,000 acres. In the United States, a large, slow-moving area of low pressure brought mass flooding to parts of Washington, which saw a month’s worth of rain in about an hour at the beginning of the month.

Here in the UK, we’ve seen a north-south divide in terms of the weather. Low pressure dominated Northern Ireland, northern England and Scotland for the first half of July, making for a pretty wet and, at times, thundery start to “high summer”. In the south, by contrast, high pressure anchored over Europe brought mostly dry, warm and settled conditions. The situation reversed towards the end of the month when a low pressure system crossed the southern half of the country, bringing some heavy rain and thunderstorms, before high pressure built back in. The start of the school holidays saw temperatures reaching the low 30s Celsius in the south-east but quickly rose to the highest UK temperature since records began in 1904; 38.7C (102F) recorded at the Botanical Gardens in Cambridgeshire. Added to this, the Met Office published their State of the UK Climate report in the last week of July, showing that ten of the hottest years on record have occurred since 2002.

According to Defra, the UK's overall greenhouse gas emissions are estimated to have fallen by 42% since 1990, mostly through investments in green technologies, but much more needs to be done and we're ranked 15th in the world list of greenhouse gas producing countries. - Credit: Marc Baldwin

With a general ground-swell of concern from the public about the impacts of climate change on the planet, it was disappointing to read the report of the Climate Change Committee (CCC), the UK government’s advisors on climate change, released last month and expressing shock that we have a lack of robust planning to protect people from heatwaves and flooding, with funding for many plans having been cut. Indeed, Lord Deben, who chairs the committee, told MSN News: ““The whole thing is run by the government like a Dad’s Army. We can’t possibly go on with this ramshackle system; it doesn’t begin to face the issues. It is a real threat to the population.” The report did point out that progress had been made in reducing the burning of coal for energy, but noted that the government had held back on the development of onshore wind generation and that tree planting targets had been missed every year since they were set in 2013. Urban green space has also fallen from 63% in 2001 to 55% in 2018, which exacerbates warming and increases the risk of flash flooding from the short, sharp bursts of rain that are becoming more common.

For many the recent focus on climate change in the mainstream and social medias has left a feeling of fear that it’s too late and, for want of a less dramatic statement, Earth is “doomed”. As the venerable David Attenborough told MPs at a UK parliamentary committee last month, however:

“I see no future in being pessimistic, because that leaves you to say to hell with it, why should I care. I believe that way disaster lies. I feel an obligation. The only way you can get up in the morning is to believe that actually we could do something about it. And I suppose I think we can …”
David Attenborough
Loose "bath bombs". Retailers are increasingly responding to consumer demand for less plastic and selling loose fruit and veg and cosmetics, the latter of which can significantly reduce the consumption of plastic bottles and pots. - Credit: Marc Baldwin

And he’s right. There are some simple things we can do. Try and cut down you use of plastics, for example. Our shower is now free of shampoo and shower gel bottles, having been replaced with shampoo bars and bars of soap which we can purchase either “naked” at retailers such as Lush or in plain cardboard boxes that are more easily recycled. Reusable cups and water bottle are another very simple way to help cut waste. Bigger gains can be made by cutting down the meat and dairy in your diet and, where possible, shopping locally. Similarly, looking at your gas/electricity supplier to see how much of their energy comes from renewable sources is worthwhile. Even buying frozen fruit and veg, unless it’s locally produced and you can buy only what you need, can make a small difference – fresh out of season fruit/veg is often flown in, which has a larger carbon footprint than their frozen equivalent that are typically shipped. Frozen foods also have the potential to generate less food waste than fresh. It’s when we all start making these small differences that bigger changes take effect. You should never think it’s too late to start reducing your impact on the environment.

Those of us fortunate enough to have gardens or allotments can have an even bigger impact by taking some simple steps. Connect your garden to your neighbours’ with a small hole in the fence to allow wildlife through. Let some of your garden become untidy. Plant a range of plants that flower throughout the spring and summer, providing a prolonged source of nectar for bees, butterflies, moths, wasps, beetles and flies. Build a suitable bug hotel and bee house.

Whatever outdoor plans you have over the next couple of weeks, Butterfly Conservation are encouraging people to get involved in their annual Big Butterfly Count survey. The survey runs until Sunday 11 August and all you need to do is spend 15 minutes counting butterflies – this can be in your garden, local park, even on your walk to work – then simply log the sightings via their website or download the free app for Android and iOS. More details about the count and why it’s important can be found here. As the school holidays are now upon us, why not get the kids involved? 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.

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

Discoveries of the Month

Too wet to whoo? Weather, sex and effect of tagging impacts tawny owl calling

Regular readers of Wildlife Online will probably recall my attempts to get people involved in the British Trust for Ornithology’s tawny owl (Strix aluco) surveys last year. The surveys, one aimed at surveying a particular grid square and the other a simple “stand in your garden and listen” activity, were aimed at trying to get a better picture of tawny owl distribution in Britain. The provisional results, released by the BTO earlier this year, suggest that tawnies have declined in their distribution since similar surveys were carried out in 1989 and 2005, perhaps by as much as 10%.

Tawny owls (Strix aluco) are elusive birds, a quality that makes them difficult to survey. - Credit: Frank Vassen (CC BY 2.0)

Citizen science projects are a great way to connect the public with the wildlife that surrounds them while also tapping into a potentially huge surveying resource. The problem, though, is that the survey technique needs to be relatively simple so as to allow as many as possible to take part. Sometimes, a simplistic survey technique can impact the reliability of the data collected.

Tawny owls, despite being relatively widespread, are a reclusive bird and rarely seen. Indeed, many more people have heard the familiar kee-wick or hoo-hooo that belies their presence than have ever seen the owl. That tawnies are a particularly vocal species means listening for calling owls has been widely employed as a means of monitoring them. Unfortunately, however, the relationship between calling and bird presence is not a straightforward one, and new research from Spain suggests it may detect only a fraction of the population.

Between 2013 and 2015, a team of researchers led by Iñigo Zuberogoitia at the Icarus Estudios Medioambientales in Bilbao radio-tagged and tracked 20 tawny owls in two areas of northern Spain. During the tracking they registered calling of the tagged owls as well as that of their partners and neighbours, and gleaned some fascinating insights into the behaviour of the species that has tangible consequences for surveying them using calls.

Tawny owls form a strong pair bond and will defend their territory together, although Zuberogoitia and his colleagues found that males tended to call more than females. - Credit: doevos (CC BY-NC 2.0)

No differences in calling rates were observed between the two study sites - an observation that was interesting in itself, given that they had different population densities. Overall, vocal activity of the tagged owls was low throughout the study, calling for only about 6% of the survey periods. Males were more vocal than females, although sex only accounted for just over 2% of variation, and the owls were most vocal during the incubation and post-breeding periods, being much less likely to call during the chick-rearing period. Rain and wind also had a strong negative effect, rain alone accounting for about 10% of the variation in calling. Indeed, we know from earlier studies that heavy rain can reduce the detectability of calling owls about eight-fold, relative to still, dry conditions. Writing in the journal Ibis last month, the biologists conclude:

We must consider that censuses based on spontaneous vocal activity may detect no more than c. 12% of the true population even when the census is carried out in the best stage of the annual cycle (i.e. the ‘incubation period’), which in our case was around mid-April, and under good weather conditions (dry and calm nights).

Zuberogoitia and his colleagues also stress that there is some skill involved in recognising and detecting vocalising owls, particularly during imperfect conditions or seasons, and that this is a crucial aspect to consider when recruiting survey personnel. In other words, citizen science initiatives such as the BTO’s surveys are an important means of collecting data on presence, but caution should be applied when inferring absence.

Reference: Zuberogoitia, I. et al. (2019). Factors affecting spontaneous vocal activity of Tawny Owls Strix aluco and implications for surveying large areas. Ibis. 161: 495-503.

SQEXIT? Southern England’s red squirrels are genetically distinct from those in Europe

The red squirrel (Sciurus vulgaris) is an ironically-iconic species in Britain. Long considered a pest to forestry and actively exterminated from many plantations during the 18th and 19th centuries by “squirrel destruction clubs”, they’re now widely coveted by wildlife enthusiasts and photographers, with many travelling the length of the country to see them. Generations of children grew up reading Beatrix Potter’s The Tale of Squirrel Nutkin, in which a red squirrel took the lead role, inspired by Potter’s summer holiday watching squirrels at the Lingholm estate in the Lake District in 1901, and today the species makes the top five list of our most beloved mammals.

Unfortunately, population surveys suggest the distribution of reds in the UK has shrunk by some 70% since the 1940s, and the Red Squirrel Survival Trust estimates that, without significant conservation effort, the red squirrel could be extinct in the UK within a decade. In a bid to redress this decline, the red squirrel was added to Schedules 5 and 6 of the Wildlife & Countryside Act (1981), which provides the highest level of wildlife legal protection, prohibiting any deliberate disturbance including inflicting injury or death, trapping, or destroying nests. Historically, part of this conservation effort has also seen introductions from continental Europe, particularly Scandinavia, with European genes having spread widely through the British population although not, new research suggests, among populations on our southern islands.

New genetic data suggest that red squirrels (Sciurus vulgaris) from the south coast, such as this one from Alverstone on the Isle of Wight, may represent unique lineages that are of conservation importance. - Credit: Peter Trimming

In a paper to the journal Ecology and Evolution published last month, a multidisciplinary team of scientists led by Emilie Hardouin and Kathy Hodder at Bournemouth University presented the results of their genetic study of red squirrels on the Isle of Wight off the Hampshire coast and Brownsea and Furzey Islands off Dorset. Tissues samples were collected during routine post mortems and subjected to D-loop analysis and compared to a European database of squirrel genetics.

The results of the analysis showed significant genetic differentiation between these island populations and those in both mainland Britain and continental Europe. The Scandinavian haplotype that is relatively widespread in populations on the mainland wasn’t found in any of the island populations, implying that these individuals may represent the remnants of the original British population. The data also show that squirrels swim the 300m (328 yds) between Brownsea and Furzey, the two populations being genetically similar and apparently sharing a common origin, possibly the population near Cannock Chase in northern England. The Isle of Wight, which is home to the largest population of Reds in southern England with an estimated 3,000 animals, had a more diverse population than Brownsea - which is not unexpected given that it’s about ten times the size - but the origin couldn’t be determined.

Perhaps most interestingly, the scientists identified several “private haplotypes” in these three isolated southern England populations, representing unique lineages which could be valuable for the conservation of the species. In other words, there are groups of genes found in Dorset and Hampshire squirrels that don’t appear to be in any other British or European populations and in their paper the researchers conclude:

Our study demonstrates the uniqueness of the Brownsea, Furzey, and the Isle of Wight populations providing evidence for a putative unique genetic makeup on those islands. Despite these caveats, until the functional genetics of the red squirrel is better understood, it remains important to conserve island populations, especially where molecular evidence demonstrates their differentiation from mainland.”

Reference: Hardouin, E.A. et al. (2019). Conservation of genetic uniqueness in remaining populations of red squirrels (Sciurus vulgaris L.) in the South of England. Ecol. Evol. 9: 6547-6558.

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