Seasonal Update - February 2022

Despite frequent cold weather and frosts, as we move into February the days begin to draw out noticeably and there's a sense that spring is nearby. - Credit: Marc Baldwin

After a mild Christmas for most of southern Ireland, southern England and south Wales, where temperatures extended into double figures Celsius along the south coast, January started in a similar vein, with temperatures approaching the mid-teens Celsius (mid-50s Fahrenheit). Indeed, while it was cooler in Scotland and northern England, most of England, Wales and Ireland recorded their warmest New Year's Eve on record, with daytime highs of 16C (61F) in Nantwich, Cheshire and midnight temperatures widely at 14C (57F).

Temperatures were up and down over the first half of the month, with overnight lows varying from -10C to 10C (14-50F), as the UK was “washed” with waves of mild air. The situation reversed around the middle of month; mild in the north and cold in the south. On 14th, Aberdeen woke up to 10C, while Brecon was at -4C (25F). It was milder across the UK for the middle weekend and into the third week, with temperatures just above average for the time of year, before cooling down in the south. The fourth weekend was cold in the south and unseasonably mild in the north, remaining mild for most of the final week. The end of January saw gale force winds felling trees, cutting power and, tragically, killing two people as Storm Malik swept Scotland on the last weekend. Malik was followed by Storm Corrie, which brought more strong winds to Scotland and this time a little further down into northern and central England on the Sunday.

Outside of the UK, the winter has been tumultuous. Unalaska Airport on the Aleutian Islands recorded an incredibly mild 13.3C (55.9F) at 03:00 on Christmas morning, while rain fell in the inner parts of Alaska, which is a very rare event during winter. On 28th December Kodiak in Alaska hit 18C (65F), 11 Celsius (20F) warmer than their previous record. Colorado experienced some devastating wildfires early in the new year, while further north, parts of Canada saw record lows well into the -30s Celsius (-22F). New Year's Day then made history in the USA as hundreds of records were broken, with summer-like temperatures in the Eastern Plains. Falcon Lake in Texas hit 37.2C (99F), the highest January temperature in US history. By the end of the first week of January, most of the USA was under wintry conditions, with snowstorms battering the north-east coast. Badoura in Montana dropped to -40C (-40F), and after recording (89F) Texas cooled down again. Tragically, at least 22 people died after heavy snow trapped thousands in their vehicles in the northern Pakistan hilltop town of Murree. As many as 1,000 cars were stranded when more than 1.2 metres (4 ft.) of snow fell over the second weekend.

February is the month when we typically start seeing ponds and ditches full of frogspawn, although the recent very mild winters has resulted in spawn being laid as early as December. - Credit: Marc Baldwin

New Year's Day was exceptionally warm in Spain, with temperatures between 23C and 26C (73 and 79F) in several provinces, including Castilla La Mancha and the Basque Region. Argentina was swept by heat waves since early spring, with many records broken. On the 11th, Buenos Aires fell into darkness as intense heat pushed infrastructure beyond limits when temperatures hit 41.1C (106F) in the city. Mardie in Western Australia reached 50.5°C (122.9F) on 12th January, while nearby Onslow hit 50.7C (123.3F), equalling Australia's hottest temperature on record.

The unseasonable swings in temperature are making nature less predictable, but if you're interested in getting out and about this month to look for wildlife, check out my February wildlife overview.

In the news

A few of the stories that caught my interest over the last few weeks include urban leopards, social sharks and MRSA in hedgehogs:

Amur leopard (_Panthera pardus orientalis_). - Credit: Tambako The Jaguar (CC BY-ND 2.0)
  • City kitty? Despite now being a critically endangered species, the Amur leopard (Panthera pardus) was once present in urban areas across a diverse range of locations in Korea, according to an international team of zoologists. Evidence suggests the cats survived in Seoul until the 1970s, finding the South Korean city to offer a good combination of abandoned palaces and stray dogs.
  • Maligned mammals. In the first study of its kind in the UK, researchers have identified a worrying decline in Britain's small mammals. The harvest mouse (Micromys minutus) and weasel (Mustela nivalis) appear to have been worst affected, occupancy shrinking, on average, by 3% and 4% each year, respectively. The scale of the weasel's decline has resulted in it being classified as “Vulnerable” to extinction under IUCN Regional Red List Criteria.
  • Tigers together. A new study by researchers looking at the impact of dive tourism on sharks in the Bahamas has found social preferences among tiger sharks (Galeocerdo cuvier) visiting feeding sites. Using acoustic tracking and social network analysis over a three-year period, the biologists observed the sharks chose social groups to hang out in, although these tended to become more random when bait was provided.
  • Stay in school. There are many explanations covering why fish school, but recent data from researchers at Florida State University suggest that American shad (Alosa sapidissima) can hear the ultrasonic clicks of hunting dolphins when in a shoal, and use it to avoid being eaten. The scientists found that while individual shad couldn't detect the click train, the school acted like an echo chamber for the incoming sound, bouncing off the regularly spaced fish.
  • Hedgehogs and MRSA. Several news outlets picked up on a new research paper that reported on the evolution of methicillin-resistant Staphylococcus aureus (MRSA). The research found that the Trichophyton erinacei fungus living on hedgehog skin produces chemicals that kill bacteria, including an antibiotic called KPN. KPN killed MRSA only when its genes for antibiotic resistance were removed, suggesting the genes are key for the bacteria to coexist with the fungus on hedgehogs. It must be remembered, however, that hedgehogs have probably carried these antibiotic resistant bacteria for at least 200 years without causing outbreaks of mecC-MRSA infection in humans. The advice remains to keep strict hygiene when handling, treating and/or feeding hedgehogs.

Website news

Some minor updates have been made to the hedgehog section and a new video added to the squirrel play article showing a squirrel playing at a nature reserve in the USA. The QA covering fox and badger predation on hedgehogs has also been updated and I've been continuing to work on the Chinese water deer article, with part five almost complete. I have also uploaded some new sections of the profile, with the coverage of sexing and field signs now online.

Discoveries of the Month

Squirrel security? The influence of pine marten presence varies with habitat

Thanks to work in Republic of Ireland, we've known that recovering pine marten (Martes martes) populations seem to have a negative impact on grey squirrels (Sciurus carolinensis) and a corresponding positive one on reds (Sciurus vulgaris) for nearly a decade. Since then, scientists and conservationists have been working to unpick the intricacies of this relationship.

Pine martens can have a beneficial influence on Red squirrel populations by suppressing and/or displacing Greys, although it appears the relationship is significantly enhanced in broadleaf woodland. - Credit: Marc Baldwin / British Wildlife Centre

Initially, we thought that it was the density of pine martens that made the difference, but subsequent investigation suggested that their presence alone was sufficient to reduce grey squirrel presence. Some of the science also tells us that martens may eat more greys than reds, the former being rather easier to catch. Now a team of researchers, led by Joshua Twining at Cornell University's Department of Natural Resources, has looked at the influence that habitat has on this predator-prey relationship.

A multi-species survey was conducted in Northern Ireland between 2015 and 2020. In 2015 camera traps set on feeders were used to monitor 332 sites, with 172 and 207 sites surveyed using the same methods in 2018 and 2020, respectively. The results of the camera trapping were subjected to a hierarchical modelling framework to estimate the co-occurrence of pine martens and grey squirrels. The results of the analysis were published in the Proceedings of the Royal Society B last month.

The data show an interesting trend. Red squirrel presence was increased by the presence of pine martens, but this was only the case in broadleaf woodland. Indeed, in conifer plantations pine marten presence was negatively associated with red squirrel occurrence. The results also revealed that the presence of grey squirrels was detrimental to red squirrels, and that pine martens suppressed greys regardless of habitat type. It seems that the overall picture is a positive one for red squirrels when pine martens are present, but that habitat plays a significant role. In their paper, the researchers note that:

Combined, these results demonstrate that while habitat modification has the potential to disrupt established predator—prey interactions between coevolved species, these negative effects are far outweighed by the benefits of competitive release where a dominant invasive competitor is controlled by the recovering predator.”

Summing up, the team point out that it is necessary to consider species interactions when modelling how a species may respond in the face of changes we make to their habitat:

Here, we show that in the presence of invasive species, human modification of habitats does not alter the beneficial impacts of native predator recovery on native prey species through competitive release. However, in the absence of invasive competitors, habitat composition has the potential to benefit, or alternatively, to have deleterious impacts on native prey populations following predator recovery.”

Reference: Twining, J.P. et al. (2022). Habitat mediates coevolved but not novel species interactions. Proc. R. Soc. B. 289: 20212338. doi: 10.1098/rspb.2021.2338.

Good fences make good neighbours?

Over the past few updates, I've covered several papers looking at the impact of roads on wildlife and some of the suggestions for helping predict, ultimately reduce, these collisions. We know that certain times of the day or year put us at greater risk of hitting an animal on a road, as does driving through certain habitat or linear landscape features, where hedges or treelines are split by roads for example. It's a problem across the globe and an important one for a number of reasons. Not only can it have a negative impact on the numbers of a given species, the presence of roads and traffic can stress animals out, potentially impairing their reproduction and/or survival, fragment habitat and, of course, cause considerable expense and injury, sometimes worse, to those behind the wheel.

Badgers are frequently killed on roads across Europe. New research suggests that fencing large motorways, which can be significant sources of mortality, can result in higher mortality on the surrounding country roads. - Credit: Marc Baldwin

Identifying the issues is one thing, but what are the solutions? As we've seen over the past few months, some of this will likely involve more dynamic ways of alerting drivers to periods of particular risk, to prevent them tuning the danger out as we tend to do when we become complacent on our journeys. Another option, however, is fencing of roads. Fencing doesn't solve the issue of habitat fragmentation, unless wildlife bridges or underpasses are included, but it can have a significant impact on reducing mortality of larger species. In Canada, for example, fencing of a section of the four-laned Trans-Canada highway through Banff National Park reduced deer collisions by some 80% over pre-fenced levels, although it did also concentrate the remaining 20%. Similarly, here in the New Forest in Hampshire, fencing of the A31 dual carriageway and A35 single carriageway in 1964 significantly reduced the number of Commoner's livestock killed on the roads, although the stock fencing had little impact on wildlife mortality.

To better understand the impact that fencing can have on the road mortality of medium-sized mammals, a team led by Krzysztof Nowakowski at the University of Zielona Góra studied the influence of the opening of the A2 motorway in western Poland on peripheral badger populations. The data collection started in 2010, two years before the motorway opened, and continued until 2015, with traffic volume peaking at just over 9,200 vehicles per day in 2014. They also looked to the surrounding A, B and C roads for road-kill and, overall, the data on 92 dead badgers was assessed.

The results of the study indicate that the opening of a new, fenced motorway actually increased the mortality of badgers on the smaller local roads, rather than lowering it. The peak of road-kills occurred mostly on country roads in the year the motorway was opened, which the scientists suggest was because these roads now functioned as access routes to the motorway. They also observed that three of the main setts in the country road vicinity were abandoned after the opening of the motorway. In their paper to Environmental Management, published last month, the researchers conclude:

The mortality rate of this mesopredator has even increased on the motorway access roads. In the light of our results, it seems sensible to extend the motorway animal mortality monitoring to local roads and to apply protective measures, such as fences and animal crossings, not only on the motorway, but also in its vicinity.”

Reference: Nowakowski, K. et al. (2022). Long arm of the motorway - The impact of fenced road on the mortality of European badgers. Environ. Man. 69: 429-437. doi: 10.1007/s00267-021-01570-y.

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