March began on a wonderfully spring-like note across much of England, Wales and Ireland, with blue skies and temperatures creeping into the mid-teens Celsius by the second weekend, although the nights were cold (freezing or just below) and parts of western Scotland were battered by strong winds. The second half was more tumultuous, with a couple of low-pressure systems pushing through, particularly in the north, but overall, temperatures for March were mostly above average for the time of year, with lots of sunshine.
Speed Read of the Month
This month we take a whistle-stop tour of the natural history of Britain's rarest snake, the Smooth snake Coronella austriaca.
News and discoveries
Super seals. If you hold your breath, after some 30 to 90 seconds (perhaps several minutes if you're a world class freediver or navy seal) your lungs will start screaming at you. You might think that this is your body telling you that you're running out of oxygen, but it's actually your internal carbon dioxide alarm going off. This is how we've long understood how mammals identified "hypoxia" (i.e., low oxygen); not by the level of oxygen itself, but by the concentration of carbon dioxide building up in the blood. Or at least that's what we used to think. A new study by researchers at the University of St Andrews looking at how seals manage to plan their dives so efficiently suggests, however, that seals can detect the oxygen levels in their blood. The Sea Mammal Research Unit team showed that carbon dioxide didn't affect how long the seals dived for, indicating they aren't sensitive to changes in this gas in the way the rest of us mammals are. It's suggested that this adaptation has been key in the evolution of marine mammals and potentially other breath-hold diving animals (i.e., birds and reptiles), allowing them to spend most of their life underwater without drowning.
Planning primates. Great apes, such as chimps and orangutans, are well known for their cognitive skills and particularly a propensity to use tools to make life easier. Among primates, humans have probably taken tool use to an extreme, being competent engineers, but new research from primatologists at the Gombe Stream National Park in Tanzania suggests that chimpanzees also engineer some of their tools. When the scientists studied the flexibility of the plant fronds that the chimps were selecting to make termite "fishing sticks", they found that rigid plants were ignored, even if a suitable size, shape, and growing near the termite mound. Instead, the chimps specifically sought out highly flexible fronds to ensure they could use them to navigate the tunnels in the mound. Intriguingly, some plant species (e.g., Grewia spp.) are used by chimps up to 5,000 km (3,100 miles) away from Gombe to make fishing sticks, suggesting the mechanics of these plant materials could be critical for the evolution of this behaviour, and that this rudimentary engineering may be deeply rooted in chimpanzee tool-making culture.
Biodiversity blitz. There must be comparatively few among us who believe that the overall impact of humans on the planet's species and ecosystems is a net positive one, but a new study by scientists at Swiss Federal Institute of Aquatic Science and Technology (Eawag) and the University of Zurich published in Nature points to our influence being widespread and profound. In one of the largest studies ever conducted on human impact on nature, the researchers compiled data from some 2,100 studies comparing biodiversity at nearly 50,000 sites affected by humans, with the same number of unaffected (reference) sites. The metanalysis shows humans are having a highly detrimental impact on global biodiversity, reducing the number of species left on Earth and altering the composition of species communities. In their paper, the authors explain that "we find that all five types of human pressures (land-use change, resource exploitation, pollution, climate change and invasive species) included in our analysis significantly shift the composition of biological communities" and note that they hope their analysis can be used as a foundation for robust conservation action.
Vulpine victuals. Following on nicely from the previous news story, the rapid urbanisation of our planet presents challenges for a range of species, but many have found ways to thrive in our towns and cities. Included among these "synanthropic" species is the red fox, which some surveys suggest is doing better in urban areas than in our countryside nowadays. Many people seem resolutely convinced that urban foxes are living solely off our handouts and raiding our bins (while, perhaps ironically, also warning of the danger they pose to our pets), but the dietary analysis we have to date doesn’t really support the idea that human food is more than supplementary/contributory. A new study has added further weight to this observation. Researchers assessed whiskers from 93 foxes for levels of specific carbon and nitrogen isotopes that are obtained from food. This data, published in Evolution and Ecology, shows a significant difference in the amount of human food in the diet of urban and rural foxes, but even so amounting to only about one-third (just under 35%). The results also suggest vixens utilise human food resources more than dogs, presumably particularly while pregnant and/or raising cubs. The impact of human-derived food on fox biology remains unknown, although anecdotal observations suggest that increased anthropogenic food in the diet can lead to increased body fat, which may impact overall health outcomes.
For a round-up of Britain's seasonal wildlife highlights for mid-spring, check out my Wildlife Watching - April blog.