NATURE NOTES - Written by Dr Martyn Stenning
Nature Notes December 2020
I have commented that there is no such thing as disaster in nature, only change. Many changes run in cycles, just like the daily cycle of night, dawn, morning, afternoon, evening and the yearly cycle of winter, spring, summer and autumn (fall). Incidentally, although fall is used in the USA instead of autumn, it is actually an ancient English word commonly used up to the 17th century when it was largely replaced by the Latin word autumn(us). The climate is also changing.
There is also the carbon cycle, water cycle and of course life cycle of every organism that lives. Diseases also tend to go in cycles, and there is a commonly quoted cycle of rabbits and myxomatosis caused by the rabbit myxoma virus. Rabbits control this disease by changing their behaviour. As the population of rabbits breeding underground in warm burrow nurseries increases, the transmission of myxoma virus by the secondary host, which is the rabbit flea, increases. This causes many rabbits to die. Then, those rabbits that breed above ground under bushes, as some do, are more likely to survive because the (cold blooded) fleas are more likely to die of cold during frosts. These rabbits then increase in number but sometimes produce offspring that resume the underground breeding strategy in order to avoid predators such as foxes. This allows the myxoma virus to increase again and so on.
Similarly, there is a well-known cycle of Arctic foxes and Arctic hare numbers. As the hare numbers increase, so fox numbers increase until too many survive to be supported by the over hunted hares and many foxes die of starvation, allowing the hares to increase again and so on.
These population cycles, regulated by climate, disease or predation control the numbers of animals that we see around us. There is no reason to suppose that the same cannot happen among humans. It was predicted by Thomas Robert Malthus (1766 – 1834). We are unlikely to be controlled by predators because we are the planet’s top predator, but we have less control over climate and microbes. In the end, each living thing dies, which is sad for those around it, but then there is room for others to be born, providing joy for those around the birth event.
Dr Martyn Stenning
Nature Notes November 2020
There is no plan(et) B. Earth is our only option. We either preserve it or lose it. I think it is amazing to listen to our oldest environmental campaigner, Sir David Attenbrough and maybe our youngest, Ms Greta Thunberg. Both are apparently in total agreement about the need for concerted global action by everyone to save our only available home, planet Earth. This is an area in which our children will take the lead.
Part of this planet is our garden in Uckfield, close to the border with Framfield. In this garden we have an exotic shrub originally from Mexico called Koeberlinia spinosa. This plant is also known as the crucifixion thorn due to its leaves taking the form of sharp thorns similar to gorse. As I write in early October, this plant is also covered by a mass of sweet smelling tiny white flowers that are providing a late crop of nectar and pollen for a large number of pollinating insects such as red admiral butterflies and bees. Many of the bees are buff-tailed queen bumblebees that have mated with a male and will soon go into hibernation below ground until early spring. After a long sleep underground, they will wake up and lay a few worker eggs to start their colonies. These female workers will start to collect pollen and nectar to provision the colony, fertilising the flowers that they visit as they go, leading to the crops of fruit and veg that we and other animals in turn will eat. After a while, the queen lays some male eggs which will produce suiters for queens produced from other colonies. Our queen will also produce some new queens to mate with suiters from other nests and so on. Additionally, many of these bumblebees will be eaten by insectivorous birds and other animals that make some kind of contribution to our global ecosystem upon which we all depend for every meal we eat, breath we take and waste we produce.
One of the joys of autumn that have stayed with me since being a child is seeing the red admiral butterflies visiting fallen apples, Michaelmas daisies and other autumn produce. Red admiral males are territorial and have to impress a female before mating. Many red admirals then migrate to warmer latitudes for the winter. Others hibernate until the spring. The female will usually lay her eggs on stinging nettles upon which her caterpillars will feed before pupating and becoming adults.
Dr Martyn Stenning