Seasonal Update (November 2021)

As the nights draw in and temperatures begin to drop, autumn and winter are the best times to admire the night sky - it doesn't require staying up so late and colder produces clearer views. - Credit: Marc Baldwin

Autumn kicked off on an unseasonably warm note, with temperatures several degrees above the seasonal average for most of September. The last week of September heralded a change to the more familiar autumn conditions that we expect, and this unsettled theme, with sunshine and showers across the UK and temperatures in the low to mid-teens Celsius, is how we started October. Indeed, the first day of October swept in with a deep low-pressure system that brought strong winds and heavy rain to the whole of Britain and Ireland, with rain turning patchier in the afternoon and mostly confined to the north and west. The first weekend was a similarly autumnal situation with heavy showers moving west to east on Saturday and Sunday, accompanied by strong winds and temperatures in the mid-teens Celsius.

The end of October saw a series of low pressure systems bringing persistent and heavy rain to much of the UK causing localised flooding. - Credit: Marc Baldwin

Overnight on 4th/5th October, 35mm rain fell in St James' Park in only six hours, 26mm (1 inch) of which fell in an hour, causing significant flooding in the capital. Several other areas were also badly hit, including parts of Essex, Norfolk, Suffolk and Newcastle. Outside of the UK, in about a day on 3rd/4th October, Tropical Cyclone “Shaheen” produced up to 15 inches of rain along the northern coast of Oman, where the average yearly rainfall is 3-4 inches. It is only the third known storm to make landfall in the region, and the first since 1890. At least 13 deaths were attributed to the storm.

Following the heavy rain, we saw some exceptionally mild weather towards the end of the first week courtesy of tropical air sucked up by the remnants of ex-hurricane “Sam” tracking towards Iceland and producing temperatures in the high teens Celsius - above the seasonal average of 15C (59F). The early hours of 8th October saw the mercury fall to only 17C (63F), making it the warmest early October morning on record. After a brief cooler spell around the middle of the month, we saw a high of 21C (70F) in south-east England, which is extremely warm for that stage in October. Last month ended on a very wet, windy and unseasonably mild note across the UK, with temperatures only beginning to drop over the final weekend. The last week also saw some serious flooding in Scotland and northern England following days of heavy rain.

Globally, we saw temperature records broken all over the world, and some intense heat even way up in the northern hemisphere during the first half of October. The Arctic, Russia and northwest Canada were particularly warm for the time of year. Along with the record temperatures, we've seen some signs of increasing drought, including Lake Mead, the largest reservoir in the US, in which the water has dropped more than 140 feet in the last two decades, the federal government declaring an official water shortage in its Overton Arm after it completely dried up. At the same time, for some European areas October was the seventh colder-than-average month out of 10, and with a significant margin. Some alpine stations have a year-to-date negative anomaly below -1C.

In the news

A few of the news stories that caught my attention over the last month or so include heat-loving female bats, some hope for dementia sufferers, and genetic data shedding new light on coat pattern evolution in dogs.

New research from South Africa suggests hyaenas have a complex behavioural repertoire to help keep play from getting aggressive. - Credit: Marc Baldwin
  • Batty for warmth. A new study by scientists in Israel looked at the difference in roosting behaviour between male and female bats. Based on data from nearly 2,500 individuals from 18 species sampled across 53 locations in the country, the data show females were found at higher ambient temperatures than males. It remains to be seen whether females actively select warmer areas, or somehow make the roost warmer.
  • Demolishing dementia. Startling statistics from the NHS suggest that 1 in 14 UK adults over 65 have some form of dementia, affecting an estimated 850,000 people. New research from Tohuku University in Japan has identified a safe treatment candidate, a molecule called SAK3 that not only halts the nerve degradation in mice but also reverses some of the damage. The scientists observed that SAK3 administration seems to promote the destruction of misfolded proteins, suggesting it might also hold promise for treating Parkinson's and Huntington's disease.
  • Obstreperous octopuses. Scientists at the University of Sydney have filmed octopuses deliberately throwing objects at other octopuses, often hitting them. The cephalopods hold objects such as algae, silt and shells under their bodies and use their siphons to generate powerful jets of water to launch them at targets. Often this seems to be females warding off over amorous males. Males sometimes anticipate the projectiles and duck out of the way, but not always.
  • Canine coat colour. An international genetic research team based at Bern University have unravelled the complex and controversial story behind the inheritance of coat colour in domestic dogs. The team identified five, rather than the accepted four, different colour patterns in dogs and traced the very light colour coat colour in dogs and wolves back to a genetic variant that appeared more than 2 million years ago.
  • Playful posing. While studying the behavioural interactions between 24 wild spotted hyenas on the Greater Makalali in South Africa, biologists at Pisa University in Italy noticed that these animals nod their heads and make faces at each other when they want to play fight, ensuring that the situation remains friendly.

Discoveries of the Month

Crop damage by red deer varies with habitat type

Deer are a popular and iconic group of animals, and many people enjoy seeing them. Our ancestors probably viewed deer primarily as an essential wild resource, providing meat, fur/leather and antlers that could be fashioned into tools or jewellery for trading. In more recent history, however, there has been increasing conflict with farming and forestry interests as both commercial plant production and deer numbers have risen.

Deer can pose a problem for both forestry and agriculture when numbers get too high. Tracking data from Sweden suggest proximity to woodland predicted the probability of deer visiting crop fields. - Credit: Marc Baldwin

We don't have any current data on the cost of deer damage to agriculture or silviculture in Britain but, based on a study commissioned by DEFRA in 1998 and the 2002 agricultural census, Charles Wilson estimated that deer cost English agriculture around £4.3 million (US$6.9m or €5m) per year - the range given was £1.1 million to £5.6 million. It seems that those farms growing cereal crops were hardest hit, with an estimated annual cost of £2.4 million (US$3.8m or €2.7m). Subsequently, York University's Piran White and colleagues presented their data in the Economic Impacts of Wild Deer in the East of England report, suggesting a cost of £7 million to possibly more than £10 million per year; around £3.2m (US$5m or €3.6m) of this was damage to agriculture in the region and most of this to cereals. Outside of the UK, in 2017 the US National Agricultural Statistics Service (NASS) estimated that losses of field crops, vegetables, fruits, and nuts to deer exceeded $765 million per year.

As agricultural impact is clearly a concern and deer populations continue to rise in many countries, it becomes increasingly important to understand how variations in habitat and landscape can influence the impact deer have on crops. Between 2006 and 2011, a team of researchers GPS tracked 38 adult red deer (Cervus elaphus) in two areas of Sweden to understand how their use of crops and forestry varied in the two regions.

A Red deer (_Cervus elaphus_) hind in broadleaf woodland in the New Forest. - Credit: Marc Baldwin

The research team, led by Johan Månsson at the Swedish University of Agricultural Sciences' Grimsö Wildlife Research Station, found significant differences in the habitat use by the red deer in the two areas. The data show that in the northern study block red deer were often found in arable land (accounting for 45% of their time), while forests and wetlands were preferred in the south. Indeed, deer in the southern block spent only 21% of their time in arable habitat, despite the area being dominated by agriculture. In both areas, however, the probability of finding red deer among crops was inversely proportional to distance from woodland. In other words, where crops were grown near woodland it was more likely that the deer would visit them. A significant preference for fields with unharvested crops was observed in both locations, highlighting the potential for crop damage.

Writing in the journal Agriculture, Ecosystems and Environment in September, the scientists reaffirm the widely held belief that deer management needs to be heavily based on local habitat type and both the type and distribution of crops grown in the area. They also suggest a targeted approach by farmers could be employed:

To minimize the risk of damage, landowners should avoid cultivating the most selected crop types (e.g., rape seed) and prioritize scaring or culling, e.g. for targeting nuisance individuals or limiting local population density in such high-risk settings and/or in close proximity to forests. Moreover, our results also reveal that part of the field in close vicinity to forest may be used as lure crops (strips of game crops along forest edges) to divert keep deer from more sensible crops further away from the edge.”

The transitional nature of habitat use seen in this study also implies that the location of crops may also have an impact of browsing damage within woodland and forest plantations.

Source: Månsson, J. et al. (2021). Habitat and crop selection by red deer in two different landscape types. Agric. Ecosys. Environ. 318: 107483. doi: 10.1016/j.agee.2021.107483

Understanding wildlife roadkill: improving conservation and protecting drivers

Last month I wrote about a recent study looking at understanding the patterns of deer-vehicle collisions and mentioned how every year an estimated 42,000 to 74,000 deer are hit by vehicles on UK roads, and that's likely to be a significant underestimate as many go unrecorded. In addition to the toll this takes on humans and deer, these accidents push up the price of motor insurance. More widely, however, roads take a significant toll on wildlife populations, acting as the leading source of mortality for some species and a major barrier to migration for many more. Back in April, the insurance comparison website GoCompare published an analysis suggesting that just over 270 animals are reported killed on Britain's roads every week, amounting to 14,649 run over every year. The A1 and M6 were among the worst roads for animal accidents.

A hedgehog killed on an urban street. One recent study suggested as many as 335,000 hedgehogs may be killed on Britain's road network every year. - Credit: Marc Baldwin

To stand any chance of reducing wildlife road traffic collisions, we need to understand when different species are at highest risk of being run over. Project Splatter, a citizen science roadkill recording scheme overseen by Cardiff University, provided the foundation for a new analysis of wildlife roadkill patterns by a team based at the university's School of Biosciences. The team, led by Sarah Raymond and Amy Schwartz, used data collected by the project between 2014 and 2019 for the 19 most commonly hit species, 11 mammals and eight birds. The resulting dataset of just over 54,000 records was used to identify how collision risk varied by species and time of year.

The results of the analysis, published in PLOS One last month, show most species had either a unimodal (single) or bimodal (double) peak in roadkill, the three exceptions being the red fox, which showed no seasonality in recording - possibly a reflection of foxes being drawn to carrion on the roads and masking their movement-associate mortality - and the Reeves' muntjac and polecats that displayed inconsistent recording. Badgers and barn owls were most likely to be killed on the roads in late winter or early spring, with a smaller peak during the autumn. This bimodality corresponds with the main breeding periods for badgers, although in 2019 there was an unusual peak during the late summer. Roe deer were also most at risk during the spring and again during the autumn. Hedgehogs, gulls and magpies were most at risk during the summer when they're breeding and/or provisioning young, while rabbits and grey squirrels displayed peak mortality during late summer and early autumn.

In their paper, the scientists propose a targeted approach to help reduce the number of wildlife collisions:

Reducing wildlife-vehicle collisions is clearly desirable in terms of wild animal welfare and conservation, but it would also pay dividends in terms of improved safety for vehicle drivers. The insights provided by this study could provide ways of minimising roadkill, for example by installing temporary road warning signage at times of greatest risk for car drivers, and at roadkill blackspots for species of conservation concern (e.g. otters).”

This study also illustrates the value that citizen science projects can have in generating data that can have “real world” applications in wildlife conservation.

Source: Raymond, S. et al. (2021). Temporal patterns of wildlife roadkill in the UK. PLOS One. 16(10): e0258083. doi: 10.1371/journal.pone.0258083

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