Seasonal Update - March 2019

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It’s hard to believe 2019 is already two months old. Most of February passed me by as I sat in front of my laptop working through the nearly 600 videos my two trailcams recorded over the four weeks they were left in a small tract of woodland on a friend’s farm. Some of the videos will be going up on the Wildlife Online YouTube channel later this month.

February got off to a cold start while I toiled, and storm “Erik” arrived early in the month, bringing 80mph winds and causing widespread damage. On the other side of the globe, while parts of Australia were suffering through one of the worst droughts in living memory, Townsville saw a year’s worth of rain in seven days, causing widespread flooding. Come the middle of February, high pressure anchored over Europe resulted in an extreme southerly jet stream that brought warm air up from the Azores. The result was some extremely warm - for the time of year - temperatures across the UK.

February saw the warmest Valentine’s Day on record, with temperatures reaching 17.5C (63.5F) in Rhyl in Wales and, during the penultimate week, Aberdeenshire recorded 18.3C (65F), which is Scotland’s warmest February temperature on record. I’m sure I even smelled the Proustian scent of barbeque on the last weekend of the month. Indeed, the Met Office confirmed that the 26th February was the warmest February day on record, the mercury hitting 21.2C (70F) at Kew Gardens in London. The seasonal average during the same period is about 6C (43F) in the north and 8C (46F) in the south. All this came against the backdrop of an unprecedented walk out by school children protesting at the lack of action by the British government on climate change and a report from the Food and Agricultural Agency warning that the world’s capacity to produce food is being undermined by our failure to protect biodiversity.

The Happy Hedgehog Rescue are spearheading a nestbox monitoring survey to establish whether temperature fluctuations in the box are a good indication of occupancy. The aim is to use this as a non-invasive method of monitoring box usage and prevent having to open boxes and disturbing the occupants, particularly during the breeding season. - Credit: Jayne Morgan (The Happy Hedgehog Rescue)

If you’re up for getting involved in some citizen science this week there are two recently-launched programmes that are looking for volunteers. The Happy Hedgehog Rescue, a hedgehog rescue in Hampshire run by long-time friend of Wildlife Online Jayne Morgan, is setting up a hedgehog box monitoring study. The basic premise is that a digital thermometer is inserted into the hedgehog house, with the digital display on the outside, and temperature measurements are recorded regularly and posted to a citizen science group on Facebook. The hope is that it will be possible to identify nest usage based on the temperature profile, which will prevent unnecessary nest disturbance. It may also help elucidate winter activity in hogs. For more information, check out Happy Hedgehog’s Facebook page or e-mail Jayne at info@happy-hedgehog.co.uk.

If you’re not fortunate enough to have hedgehogs visiting your garden, perhaps you have sparrows. Either way, the Wigston Sparrow Project want to hear from you. We’ve known that this once familiar garden bird has been struggling in the UK for many years, with populations having fallen by an estimated 71% between 1977 and 2008. In a bid to better understand the distribution of this species the project, normally focusing on sparrows in Leicestershire, has flung open its doors to accept records from across the UK. In the words of the survey’s founder:

The Sparrow Census, with your help, aims to gather valuable data to build a bigger, better, clearer picture of just what is happening with our House Sparrows than ever before! I hope that moving forward, the data collected in this census will assist conservationists, scientists, NGO’s, Government and every single one of us in protecting, conserving and championing the humble House Sparrow.

You can read more and take part in the survey here.

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 are 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 - March blog.

Discoveries of the Month

Evacuate the dance floor. More work and less dance makes bee colonies more productive

In a 1947 German paper entitled Die Tänze der Bienen (“the dances of the bees”), Austrian ethologist Karl von Frisch described what he called Tanzsprache, or “dance language”, in a subspecies of the honeybee Apis melliferathe. Von Frisch demonstrated that bees used repeated, structured movements within the hive to inform other members of the colony on the direction, distance and quality of nearby foraging grounds. Two types of “dance” were identified: “round” and “waggle”. The waggle dance is the one employed to describe feeding sites further afield, and about 10 of the 500 or so known bee species and been observed using it.

A returning honey bee worker "waggle dances" to tell other member of the colony where's she found food. She repeatedly communicates that the profitable food location is about 750m (~0.5 miles) from the hive and about 270 degrees from the sun's azimuth. Video by Dr. Margaret Couvillon and Dr. Roger Schürch, courtesy of the LASI Bee Research & Outreach programme at Brighton University.

Von Frisch’s studies on the behaviour and ecology of bees won him the Nobel Prize in Physiology and Medicine in 1973, although more recently the efficiency of and evolutionary drivers behind the waggle dance have been the subject of some controversy. Indeed, work by Christoph Grüter at the Universidad de Buenos Aires in Argentina suggests that bees rely more on information they've gathered themselves on food sources and the odour and location indicated by the dancer is secondary (“backup”) information at best. Now, some new research from scientists in Switzerland suggests that changes we humans are making to the landscape may be making the waggle dance less useful.

During the summers of 2014, 2016 and 2017, a team of researchers led by Robbie I'Anson Price studied 12 colonies of honey bees at the University of Lausanne campus. The scientists looked at whether the dances changed between “disorientated” bees (i.e. those exposed only to artificial light) and “orientated” ones (kept within view of the sky) and, to their surprise, they found that the disoriented colonies were actually more efficient, losing significantly less weight (29% less, in fact) than the oriented ones. Reviewing the film footage of the bees, it became clear that workers readily learned to ignore information from disoriented bees (based on spending much less time watching them than oriented dancers), leaving to forage for themselves instead.

In their paper to Science Advances last month, the researchers report that disoriented bees aren’t more efficient foragers in themselves (i.e. they don’t bring back more pollen per flight period than oriented bees), but that they can spend more time foraging because they waste less time watching dancers and waiting for information. As such, the data show that the foraging activity of colonies, measured as the mass of foragers leaving the colony in the morning, was about 23% higher in the disoriented bees than the oriented ones. So, more trips could be completed in any given day and, therefore, more food collected at the colony level.

The short-term availability of flowering plants cultivated by humans may mean methods of conveying food distribution among bees are largely redundant outside the main flowering season(s). When flowers are in short supply or sparsely distributed, bees are better off striking out alone to forage. - Credit: Marc Baldwin

L’Anson Price and his colleagues carried out this study during the summer, which is a notoriously difficult time for bees, and the authors concede that the waggle dance may still be an important component of bee foraging behaviour at other times of the year, particularly during the spring. In their paper, however, they note:

Human-modified temperate habitats are often characterized by few large floral patches (mass-flowering crops) that may be easy to find and profitable in spring; however, once these have finished flowering, the environment becomes bereft of isolated high-quality foraging sites and the dance’s value may be diminished. In these environments, there are likely to be many foraging sites; however, their quality is such that the cost of recruitment to these sites may outweigh the benefits.”

In other words, dancing may be worthwhile in spring when there’s an abundance of flowers (many planted by us); but in summer, when most things have finished flowering, the bees waste valuable foraging time sitting around watching dances and are better off going out to look for food independently. These findings also highlight the importance of planting species in our fields and gardens that provide a protracted nectar source for bees - hydrangeas, blanket flower (Gaillardias), asters, catmint, lavender and Phlox will provide a valuable nectar source during the summer months.

Reference: I'Anson Price, R. et al. (2019). Honeybees forage more successfully without the “dance language” in challenging environments. Sci. Adv. 5: eaat0450.

Dormice know their green cross code

The Hazel dormice (Muscardinus avellanarius) is a protected species in Britain and several conservation charities are involved in monitoring and preserving the highly fragmented populations. New research suggests some simple roadside verge management can help dormice cross even major roads, increasing their dispersal potential. - Credit: Danielle Schwarz (CC-BY-SA-3.0)

Britain’s mammals can be a difficult group to study. Many are small, largely nocturnal and present in low densities, which also hampers conservation efforts that depend on reliable population distribution and abundance data. One of Britain’s least seen small mammals is the hazel dormouse (Muscardinus avellanarius) and while this species is relatively common across Europe and Asia, its distribution is limited and highly fragmented here in the UK.

In Britain, the hazel dormouse is protected under the Wildlife and Countryside Act (1981), listed as a “Priority Species” under the UK Post-2010 Biodiversity Framework, and also considered a “European Protected Species” under Annex IV of the European Habitats Directive. All this legislation essentially means that it is illegal to disturb or harm dormice and that the government should take steps to protect them and their habitat, considering them when reviewing plans for development, for example. As such, it is important to understand how dormice adapt to changes in their environment and, given our increasingly fragmented countryside, how they’re affected by disconnected habitats.

It is well-known that roads can impede the movements of small animals. Tracking data collected by Paul Bright and Pat Morris in the late 1980s showed dormice would rather undertake long detours than cross open ground, implying that roads had the potential to reduce their potential for dispersal. More recent studies have suggested, however, that dormice are less fazed by roads than we initially thought, and a recent genetic study in Germany strengthens that case.

In a fascinating paper to the journal Folia Zoologica published at the end of last year, a team led by Kathrin Friebe at the University of Kiel presented their analysis of 177 tissue samples collected from hazel dormice along a 34km (21 mile) stretch of the major A21 motorway in Schleswig-Holstein, northern Germany. The data show that dormice in this region were loosely grouped into five “subpopulations”, but with a considerable overlap, suggesting a good rate of intermixing. Indeed, some populations were very closely related, suggesting they represented the migrants and offspring from nearby subpopulations. In the paper, Friebe and her colleagues explain:

Contrary to the previous assumption that dormice hardly ever cross roads, the present study shows that dormice not only cross even major roads, but also hold close relationships to individuals living on the other side of the motorway.”

The type and structure of vegetation along roads is an important factor in helping dormice (and potentially other small mammals and insects) cross them. - Credit: Marc Baldwin

Equally important, the study found that the western subpopulation was the most genetically different from the others, despite not being far from them. The difference, the authors conclude, is that the area to the west is missing well developed roadside shrubs. The authors suggest:

… roadside shrubs are a suitable habitat even for reproduction. Due to successful reproduction the population is viable, dispersal takes part and even significant barriers like motorways can be surmounted successfully and repeatedly. From this we assume that well developed and well managed roadside habitats can have a key role for dormouse conservation in fragmented landscapes, as they act as both a valuable “spring-board” for connections across roads and a corridor for connection along them.”

Reference: Friebe, K. et al. (2018). The significance of major roads as barriers and their roadside habitats as potential corridors for hazel dormouse migration – a population genetic study. Folia Zool. 67: 98-109.

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