Seasonal Update (May 2022)

Late April and early May offer the quintessentially English spectacle of deciduous woodlands filled with bluebells. - Credit: Marc Baldwin

April opened on a chilly but bright note, with plenty of sunshine on offer over the first weekend albeit with a heavy frost overnight Saturday into Sunday. As the high pressure moved into the Atlantic, however, we saw a succession of low-pressure systems move across the country, bringing more cloud, rain and strong winds, touching gale force at times, during the first week. Scotland caught the worst of the rain and wind during the first half of the first week, but it was broadly cloudy and damp wherever you were. Into the second weekend things dried and brightened up, although we were under an Arctic air mass so it remained chilly.

Week two started on a largely sunny note, with temperatures starting to climb into the mid- to high teens Celsius (low 60s F) before more showers built into England, Wales and southern Ireland for Tuesday then moved their way northwards through the day. As the week progressed, we saw more cloud and the odd shower and temperatures remaining widely in the high teens. A battle between high pressure over northern Europe and low in the North Atlantic resulted in a large area of mild Atlantic air building in, pushing up to Greenland. The result was that the first half of the Easter weekend was mostly dry and warm, with more cloud in the north and west, but with temperatures into the low 20s Celsius in the south-east - London reaching 23.1C (73.6F) on Good Friday. The second half was more unsettled, with a slow-moving band of rain making Easter Sunday a largely wet affair for Ireland and the northern isles, although most of England, Wales and Scotland remained dry and largely sunny with temperatures in the mid to high teens Celsius. Cooler and fresher on Easter Monday for all, with showers from the midlands north.

May still has a lot to offer in terms of blossom, but a very windy spell towards the end of April can result in a lot being stripped from trees. Blossom is energetically intensive to produce and a tree cannot replace it, meaning that mid-spring winds can affect fruit production later in the year. - Credit: Marc Baldwin

The second half of the month was again largely dry, but with more cloud and wind. Overall, in fact, April has been very dry for England and southern Ireland, the south-east having seen only about one-third of the normal rain for the month. This appears to be a continuation of a trend, with seven of the last ten Aprils having seen significantly less rain than expected. The end of the third week was particularly windy and resulted in the loss of quite a lot of blossom, rather ironically just in time for the National Trust's “Blossom Weekend”. The final week was dry but with temperatures 3-4C (7F) below average for the time of year thanks to a persistent northerly airflow. Beginning dry and bright, more cloud moved in as the week progressed and we ended April on a largely cloudy and chilly note with overnight frosts, particularly in the north and west.

Outside of the UK, April started on a wintry note for a good part of western Europe, with low daytime temperatures and heavy frosts overnight. In the east, by contrast, the heat was exceptional: over 33C (91F) in Turkey and Cyprus, 31C in Georgia, 39C (88F) in Israel and Jordan and a staggering 40C (104F) in Egypt. The heatwave in India and Pakistan continued last month, with temperatures hitting 47C (117F) and 49C (120F), respectively. Myanmar and Thailand hit 43C (109F), too. Japan was also very dry and mild for much of April, following on from March being the fifth warmest on record, after 2021, 2020, 2018 and 2002.

Easter Day in North America was still a winter day in most of Canada and parts of the United States. The Canadian Prairies saw near-record cold for mid-April, with -20C (-4F) in Carman and approaching -14C (7F) in Winnipeg. Texas and Florida both saw continued scorching hot and humid conditions. There were also unseasonal heat waves in the southern hemisphere: Australia, New Zealand, South Africa and South America were all affected, and northern Argentina and Paraguay saw what some meteorologists described as a “brutal and record-breaking” heatwave, temperatures exceeding 40C by day and nearly 30C (86F) at night.

If you're interested in getting out and about this month to look for wildlife, check out my May wildlife overview. Additionally, the British Deer Society are running their Deer Distribution Survey and I would strongly encourage readers to record their sightings of wild deer either via the app or by e-mailing the Society directly. The PTES Great Stag Hunt is back up and running for another year, with 111 beetles recorded already - if you see one in the next few months, please take a moment to map it. Hedgehogs are also well and truly out of hibernation now, and if you have them visiting your garden it would be great if you could record them on the British Hedgehog Society's Big Hedgehog Map. You can also use the map to see if there are any hogs reported in your neighbourhood and if you're looking for advice on making your garden hedgehog friendly, check out my wildlife friendly gardening blog.

In the news

A few of the news stories that caught my attention over the last month include Japanese tits that seem to recognise word order, the results of the RSPB Big Garden Birdwatch, and the No Mow May campaign by Plantlife.

White storks are something of a "poster child" for the success the rewildling project at Knepp in Sussex has seen, but a new study illustrates how there's more to it than some iconic species; increases in tree and shrub cover are now visible from space. - Credit: Marc Baldwin
  • Articulate avians. A researcher at Kyoto University's Hakubi Center for Advanced Research in Japan is the first to have demonstrated that some birds appear to communicate using words and grammar. In an intriguing series of experiments, the scientist found that he could use specific word calls to elicit specific behavioural responses to predators in Japanese tits (Parus minor), but when the word sequence of the calls was changed the birds didn't respond in the same way, suggesting they recognised and responded to specific ordering, or grammar.
  • Birdwatch winners and losers. Last month the RSPB released the results of their Big Garden Birdwatch survey, which showed house sparrows (Passer domesticus) were once again the most commonly recorded species; blue tits (Cyanistes caeruleus), starlings (Sturnus vulgaris) and robins (Erithacus rubecula) also retained their previous rankings, while blackbirds (Turdus merula) and great tits (Parus major) dropped. Comparative data from 1979 also reveal a staggering 219% increase in magpies (Pica pica) and 1,132% increase in wood pigeon (Columba palumbus), while house sparrow numbers have fallen by nearly 60%, robins by 26% and starlings by almost 82%.
  • Shark stranding. Back in the middle of March a four metre (13 ft) long female Greenland shark (Somniosus microcephalus) stranded near Newlyn Harbour in Cornwall. The shark, estimated to be about 150 years old, was returned to the sea but later found stranded just along the coast where it died. Its body underwent a post mortem by biologists from the Cornwall Marine Pathology Team and Zoological Society of London and the shark was found to be suffering from meningitis caused, the pathologists believe, by Pasteurella bacteria isolated from the brain fluid.
  • Amazon alarms. New climate modelling that accounts for how plant communities respond to climate change has shown seasonal changes in temperatures linked with the loss of plants from the Amazon rainforest. The model suggests that the large quantities of carbon lost as the rainforest dies or is cleared triggers swings in seasonal temperatures.
  • Remarkable rewilding. The Knepp Estate in Sussex is something of a paragon of rewildling in the UK, showing just how much can be achieved in a relatively short timeframe. Indeed, a new study by Zoological Society of London conservationists has used satellite images to calculate that, between its inception in 2001 and 2020, tree cover is 40% higher and the 1,400 hectare (3,460 acres) site has seen a six-fold increase in shrubs. Given that the UK is now one of the most nature depleted countries in the world, Knepp reminds us that we can turn things around when the motivation exists.
  • Hell no, we won't mow. For the third year running, Plantlife is encouraging gardeners to leave the mower in the shed for another month. I've seen this cause much consternation in gardening groups online, but it's not necessary to let your whole lawn revert to jungle. Just leaving a section longer for the month, when many wildflowers will bloom, can provide an important nectar resource for our beleaguered pollinators.

Website news

A few new sections of the water deer article have gone live in the last week or so looking at the species' population and abundance. More will follow in the coming days along with some updates to the some of the existing species profiles.

A Chinese water deer doe with her fawn. Please be aware that we're now entering the deer calving/fawning season and if you come across a baby deer please leave it alone. Deer mothers leave their young lying up in cover while they're off feeding - the fawn has not been abandoned and does not need intervention unless it is obviously injured or in danger. - Credit: Ray Watson

Discoveries of the Month

On the road to predation?

Roads pose a number of problems for wildlife, being a source of pollution, fragmenting habitats and imposing significant mortality. When we think of pollution associated with roads, we often tend to picture exhaust fumes, rubber contamination and runoff, but an issue that we've only recently begun to understand is that of road noise.

Many of us can testify how pervasive road noise can be. Indeed, the First Time Buyer website suggests that being situated near a busy road reduces property value by 10-20% on average, with as much as 40% being knocked off the value of those within earshot of busy motorways and dual carriageways. It seems that other species are just as sensitive as we humans and in earlier seasonal blogs we looked at how noise created by road traffic can impair bat foraging, affect long-eared owl distribution, stress out roe deer and interfere with robin breeding competition. Now, a new study by scientists in the USA suggests it may also increase small mammal susceptibility to predation.

A recent study in Massachusetts suggests that road noise affects the ability of small mammals, such as this white-footed mouse, to appropriately risk assess their surroundings, making them more vulnerable to predators. - Credit: Joseph Gage (CC BY-SA 2.0)

Between July and September 2020, a team of biologists led by Michael Sheriff at the University of Massachusetts Dartmouth exposed eastern chipmunks (Tamias striatus) and white-footed mice (Peromyscus leucopus) to four independent treatments with varying levels of noise and predation risk at a woodland site in southern Massachusetts. Essentially, this involved playing a mixture of predators calls and road noise through speakers at the test site and comparing the control. The team then used remote cameras to monitor a phenomenon known as “giving-up density”. Giving-up density, or GUD, is the remaining quantity of food when the “quitting harvest rate” is reached. In other words, at what point does forager leave a patch when there's still viable food remaining.

The analysis of the dataset showed that the treatment had a significant effect on the GUD. Small mammals exposed to (only) predator calls ate about one-quarter less food than those in the control, while those exposed to (only) road noise ate about the same as the control. Interestingly, however, those exposed to the risk and road noise experiment also ate the same amount of food as the controls, suggesting that the presence of road noise made it difficult for the small mammals to recognise there were also predators about. The mice didn't show any change in vigilance behaviour in any of the experiments, while chipmunks were about 12% less vigilant when road and predator calls were played versus only predator calls.

In a paper currently in press with the Journal of Zoology, the authors conclude that the presence of road noise seems to alter risk perception in small mammals, causing them to deem risky environments less dangerous. They point out that:

Such noise-induced effects could have severe consequences to the population dynamics of small mammal prey and their predators if such changes in behavior alter their survival.”

Reference: Giordana, A. et al. (2022). Prey responses to predation risk under chronic road noise. J. Zool. Early View. doi: 10.1111/jzo.12968.

Hogging the food. Hedgehogs preferentially use gardens where supplementary food is provided

The most recent (2019) State of Nature report suggests that Britain is one of the most impoverished countries in the world, with 41% of species having registered strong to moderate decline in the last five decades. Part of the problem is the rate at which our woodland and countryside has changed, and it has long been known that the rapid pace of rural development and the shift towards monoculture and more intensive agriculture has resulted in problems for many species, including on of Britain's favourite mammals, the hedgehog.

Nationwide, hedgehogs are having a tough time at the moment. Fortunately, they seem to be doing slightly better in urban areas, where many of us relish seeing them and even provide supplemental food. A new study in Reading suggests hedgehogs preferentially choose gardens to forage in, but nearby habitat, visits from foxes and rain all affect the chance of a visit. - Credit: Marc Baldwin

In recent years there has been a drive towards rewilding, and, despite its many critics, it invariably has a role to play in the restoring our lost biodiversity. In terms of local and immediate action, however, it is in our gardens that we can perhaps make the biggest difference. A few simple changes can produce a refuge for wildlife and we now know that it can have tremendous mental health benefits, too. The main focus of gardening for wildlife must be provide natural habitat and food sources - flowerbeds, blossom, fruits, log piles, water and so forth. To help increase the appeal further, many of us turn to offering supplemental food, whether that's putting out some nuts for the birds or laying on a spread fit for a king for the local foxes and badgers. Supplementary feeding is not without its problems, but done correctly it can help sustain and even boost some wildlife populations. We're only now starting to understand how provision of food affects hedgehog behaviour, but a newly published study suggests that it can attract these animals to gardens.

Abigail Gazzard and Phil Baker at Reading University and Richard Yarnell at Nottingham Trent University used radio and GPS tags to track 28 hedgehogs around a housing estate in Reading for three summers between June and October. On average each hedgehog visited eight gardens in a night, although some mooched through as many as 27, illustrating just how important hedgehog highways are. Males preferred the back gardens of detached houses, followed by those of semi-detached properties, while females showed no real preference. The presence of a pond, rain and frequent visits from foxes were negatively associated with hedgehogs, and they were less likely to venture into gardens with high quality habitat within 500m (550 yds). Compost heaps were a significant draw, however. Writing in Mammalian Biology, the researchers note that the presence of supplemental food wasn't the initial attraction to the garden, but once food is left out it may become a major influence:

These data suggest that the primary positive action that householders can undertake for urban hedgehogs is providing supplementary food. However, householders often feed hedgehogs after they know they are already visiting their garden. Consequently, the presence of artificial food may make it difficult to identify other important influences affecting garden use.”

Reference: Gazzard, A. et al. (2022). Fine‑scale habitat selection of a small mammalian urban adapter: the West European hedgehog (Erinaceus europaeus). Mammal. Biol. Early Access. doi: 10.1007/s42991-022-00251-5.

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