Nature Notes

The long balmy days of July are upon us, and populations of natural organisms are at their most dynamic. We had a “heat dome” in June with record temperatures across Britain and Europe. In England, there is now a natural abundance and activity with new flowers, insects and fledged birds. Also, plenty of predation and animals avoiding being prey. There are reports of nestling bird mortality, possibly caused by the extreme June heat. July temperatures in England are usually high, frosts unlikely. The sea temperature around our coasts is increasing and humans are thinking of, or having, a summer holiday. This is a great month for nature watching! Look out for the striking day flying five-spot burnet moth (Zygaena trifolii) or six-spot burnet moth (Zygaena filipendulae). The yellow and black caterpillars of these moths like to eat a plant called bird’s foot trefoil (Lotus corniculatus), also known as eggs and bacon. The adult moths are black with red spots and will be mating and laying new eggs on their food plants. Both forms of these moths and their caterpillars are toxic if eaten, but they are honest about it, having evolved bright colours to advertise that fact. Predators such as birds also know that. Most brightly coloured insects are toxic if eaten, for this reason. They do not want to be eaten so the ones that are both toxic and brightly coloured tend to survive. Predators soon learn this because they see other animals ill or dying that have eaten a conspicuous toxic insect, or else have tried eating them and got ill, survived, and learned the lesson. However, flowers have done the opposite. Those that are brightly coloured actively attract insects to their nutritious nectar by being colourful. Consequently, the fed insects get a dusting with pollen when taking the nectar, just as the plant intends. Consequently, the insects will pollinate the next flower of that plant species that they visit. This facilitates fertilization of the seeds which are eventually shed from the plant, creating the next generation.

Bright coloration or conspicuousness in nature is known as an honest signal to help with survival. For example, brightly coloured male birds such as the bullfinch with its bright pink breast is telling the dull coloured female that it is strong enough to defend itself even though it is conspicuous. Hence colour can be an honest signal of strength because the bird has survived. The black and brown female is cryptic so that a predator cannot easily see her nesting. Dull or camouflaged animals and plants are described as cryptic. They are trying to avoid being detected. Brightly coloured, conspicuous plants and animals always have a survival reason for being so. Likewise, male crickets and grasshoppers are conspicuously noisy, informing females of their location, but if a predator approaches a noisy male cricket – he will stop stridulating and hide because he is also cryptically camouflaged and has good hearing and sight. This is also a problem for scientists to find and observe them. For this reason, many very interesting things occur in nature that most people do not see.

June brings us the longest days of the year, but not necessarily the warmest. It takes time for the high summer sunshine quantity to translate into warmer seas and landmasses. There is an inevitable lag. The Atlantic conveyer (Gulf Stream) is our cooling system in the summer, often making coasts cooler than inland. The reverse is true in winter, water from the Gulf of Mexico keeps the sea from freezing and moderates the air temperature over the coast, often preventing frosts when inland areas like Uckfield, Framfield and East Hoathly are freezing. Britain is on a similar latitude (51 – 55° N) to inland Moscow in Russia and Saskatoon in Canada. Both the latter seriously freeze up in winter.

Let us enjoy flaming June! It is the time when most birds and other diurnal animals are breeding, especially insects. Many meadow flowers will be blooming good! Insects will be harvesting nectar from these plants and accidentally transferring male pollen from their flower anthers to the female sticky stigmas of neighbouring close and distant relatives. This sets into motion the development of viable mixed gene seeds in the the plant’s ovary, ready for a later explosion of these seeds into an unsuspecting world. It is this gene mixing that has led to the wonderful natural variety that we now see. This can also be a mixed blessing to us humans. If we are gardeners, we want colourful managed gardens of flowers wherever they come from, like polyanthas, hyacinths, pansies, arums and geraniums. Many of these are exotics originating from other countries, non-native to the British Isles. These can cause problems if they escape into the countryside, hybridising with wildflowers and out-competing them, leading to the truly native plants becoming rare. Or else, they simply colonise large areas of land and become dominant. An example of unintended hybridisation is the Spanish bluebell (Hyacinthoides hispanica) with the British bluebell (Hyacinthoides non-scripta). Hybrids are common where gardens meet wildwood. Examples of unintended colonisation by alien invaders include Japanese knotweed(Reynoutria japonica), which is very difficult to eradicate. Also, horizontal cotoneaster (Cotoneaster horizontalis) from the Far East, whose seeds are eaten by birds and pass out in faeces in wild places such as the South Downs where it often thrives. Also, Himalayan balsam (Impatiens glandulifera) which was once planted next to the River Uck in Buxted, and now dominates downstream riverine habitats all the way to Lewes, including Hempstead meadows Local Nature Reserve in Uckfield. Finally, the bridge forming rhododendron (Rhododendron ponticum) which took 14 years to be eliminated from Lake Wood Woodland Trust reserve in Rocks Road, Uckfield. All of these are a problem in Sussex and other parts of Britain. There is, happily, a modern trend for gardeners to plant native meadow plants and seeds in their gardens and to rewild parts of the garden to allow our indigenous flora and fauna to thrive alongside us humans. The rewards can be amazing!

I ended my April Nature Notes by saying that we only have one planet Earth. As I write, four of us fellow humans are circumnavigating the Moon as it orbits Earth. Astronomers speak about colonising the Moon and other planets. I am extremely sceptical about this ambition. First, why? No known planet has a breathable atmosphere, or any other essential materials vital for supporting life. Secondly, how? Artemis 2 rocket was 100 metres tall before launch and had to use 990.88 tons of liquid hydrogen and oxygen fuel to escape Earth’s gravity. Just to carry 4 humans. So how would we transport all the materials, including sufficient oxygen/air, to build even a small (air-tight) building on the Moon? Let alone on another planet such as Mars which is 225 million kilometres from Earth. Thirdly, shouldn’t we just ensure that Earth is maintained in a sustainable way? Not only for humans, but also all other species that have no-where else to go. There are up to 11 million interdependent species on Earth, our ecosystem.

I do admit that I am fascinated by the work that NASA is doing, mainly because it is science, and I am a scientist. We should be striving to understand the natural universe that we inhabit. However, I do not believe this study will lead to a “planet B”. Earth is our survival module, and we must care for it for perpetuity. Ecology is derived from the Greek words Oikos Logos, meaning Home Study. We scientists are studying our home planet and trying to keep it sustainable. Sadly, the more we know, the more we realise that as our population grows, the harder it is to support all people, and all other organisms.

There is no life on the Moon or Mars or in the void of space. These are some of the key facts that I have been able to glean on Earth’s global biodiversity:

• Identified vs. Unidentified: Only about 1.2 to 2 million species have been formally described, named, and catalogued by scientists.
• Undiscovered Majority: Roughly 86% of terrestrial species and 91% of marine species are estimated to still await description.
• The Microbial Question: Some estimates suggest that prokaryotes (single-celled bacteria and archaea) could bring the species total up to 1 trillion (10¹²). Most species estimates exclude procaryotes.
• Distribution: Of the estimated 8.7 million multi-cellular organisms (eukaryotes), roughly 6.5 million live on land and 2.2 million in oceans.
• Highest Diversity: Insects (a subset of animals) constitute the largest group, with an estimated ~5 million+ species.
• Viruses are not included in any of these estimates.

Because of the high rate of species extinction due to habitat loss and climate change, many species may be vanishing before being discovered or catalogued. Please enjoy our Earthly Spring (living nature’s re-birth) and all it consists of.

“Oh, to be in England now that April is here” Robert Browning (1812–1889) informed us. Well, here you are, in an English April. Mr Browning’s life overlapped with the beginning of the Industrial Revolution developing between 1760 and 1840. That is when climate change got started. I suspect he would be surprised at what April feels like now, if he were to come back to life.

I have already seen some wild bluebells (Hyacinthoides non-scripta) in bloom near Tunbridge Wells (March 1st!), a sight not usual before about May. I have not yet seen wood anemones (Anemone nemorosa) out this year as I write on 10th March, they normally pre-date bluebells during April, but will these also appear in March? The common bumblebee (Bombus terrestris) will be making the most of these two splendid forest floor plants that are a sign of a woodland being truly ancient. Please do listen out for a cuckoo (Cuculus canoris), and if you hear/see one, please let me know, because they have become so rare, that a year can pass without me hearing even one during recent years. However, there is a plant that should be around when the cuckoo appears, and that is the cuckoo flower (Cardamine pratensis), also known as lady’s smock, mayflower or milkmaids. This common crucifer has lovely pink/purple flowers, grows in damp places and is used by the orange tip (Anthocharis cardamines) butterfly for feeding their caterpillars.

April is also when I used to start surveying the early spider orchid (Ophrys sphegodes) at Castle Hill National Nature Reserve at Woodingdean. Our University of Sussex scientific study of this species was from 1975 to 2006 and has shown that the flowering time has advanced from 1975 to 2006, by approximately 2.5 weeks. As for seeing the first swallow (Hirundo rustica), I and others are seeing a few swallows during the winter months in recent years, suggesting that some of these normally April birds are not bothering to spend winter in Africa in recent years.

I have seen several yellow brimstone (Gonepteryx rhamni) butterflies already. They lay their eggs on alder buckthorn trees/shrubs (Frangula alnus). This is quite a rare tree, but commonly found in mixed species hedgerows. Many other trees will have broken bud between the time I write this and when you will read Nature Notes in April. I always feel that this transformation of the countryside can be a very personal experience accompanied by the chorus of courting birds and the buzz of insects. We really must do our best to minimise the damage done by us humans on the natural world and fit in with it rather than dominate it. Nature can be managed, because we are part of it, but we should use a soft touch minimising its destruction while maximising our appreciation of it as space is a very hostile place and we only have one planet Earth.

There is now a clear picture of where we are in seasonal progression, from the shortest, darkest days of December to the equinox of the 21st of March, by which time you may have read these notes. Buds of many trees are swelling. As I write on 9.2.26, the countryside is festooned with yellow male hazel (Corylus avellana) catkins, starting in early January. Look carefully at the hazel twigs and search for the tiny bright red female flowers, waiting to receive windborne pollen from another hazel tree that maybe many miles away. Hazels are monoecious, meaning each plant has both male and female flowers. The breeding season of hazels is long, spanning from the end of December (nowadays) to March. The emergence of male catkins usually predates opening the female flower so the tree can avoid self-fertilisation and benefit from outbreeding vigour, i.e. mixing of genes from unrelated individuals. This helps to avoid inbreeding depression, which is fertilizing itself or a close relative. The latter is always going to be a bad idea if good health for offspring is to be preferred. I have mentioned this before in relation to oaks (also monoecious), which can avoid inbreeding by rejecting pollen from local trees in favour of pollen from distant ones. The object being to produce healthy offspring (outbreeding vigour). All chromosomes are in pairs to ensure that the paring of male and female gametes is with characters that are different so that the number of important traits such as disease resistance and other health-giving characters are maximised by the mix. Most global organisms will be doing this in one way or another. Many animals achieve this by young males and females dispersing different distances on becoming independent from their parents. That way they are less likely to pair up with a relative.

Right now, birds are also preparing for reproduction. Wood pigeons (Columba palumbus), dunnocks (Prunella modularis), bluetits (Cyanistes caeruleus), great tits (Parus major), goldcrests (Regulus regulus), house sparrows (Passer domesticus), blackbirds (Turdus merula), song thrushes (T. philomelos), tawny owls (Strix aluco) and many more are actively courting and checking out nesting sites. Daffodils (Narcissus sp.) are emerging early and some primulas are also in flower. Daisies (Bellis perennis) also. The occasional bumble bee (Bombus sp.) is emerging from hibernation and other insects such as gnats (Nematocera) are also flying on the warmest days when the temperature rises above 8 degrees Celsius. Earthworms (e.g. Lumbricus spp.) are also working on homogenising the soil, and there is an air of expectant excitement. The first common frogs (Rana temporaria) are croaking, mainly at night, in the garden pond in preparation for spawning. A regular February routine. Most badgers (Meles meles) give birth during February. The young emerge from the sett with the warming of spring. Look out also for spring flowers such as violets (Viola spp.), ladies’ smock (Cardamine pratensis) and stitchwort (Rabelera holostea).

The frozen chill of Winter presents us in Britain with a wonderful opportunity to see birds that we cannot normally see here. Most of them come to our warmer land from the even colder lands of Iceland, Arctic Scandinavia and Siberia. For example, on a recent visit to Folkestone beach, I counted about 900 dark bellied brent geese (Branta bernicla) flying up the English Channel. These small geese, not much larger than a mallard (Anas platyrhynchos), breed during the long warm summer days of northern Siberia but cannot survive there during the dark freezing days of winter. I have also seen and heard many redwings (Turdus iliacus), which are a type of thrush that visit our islands in their thousands every year. There is another Scandinavian thrush that you may see called the fieldfare (Turdus pilaris), which is a bit larger and has a slate grey head. Another exiting bird that arrives in some winters is the waxwing (Bombycilla garrulus). They feed in flocks on different types of berries. It is a very good winter for berries currently, e.g. holly (Ilex aquifolium), hawthorn (Crataegus monogyna) and Cotoneaster spp., so the birds should be able to survive well this year.

The dawn of a new year, following the winter solstice on 21st December, brings new behaviour in the bird world. Many birds, such as male blue tits (Cyanistes caeruleus) taking control of nest-boxes and wood pigeons (Columba palumbus) repairing nests, are starting to court females already. I have also heard male song thrushes (Turdus philomelos) singing loudly to defend their territory and attract females. However, the recent cold spell must have challenged them greatly. Birds tend to moult in the late summer and early autumn, so they should have a good new plumage of warm and colourful feathers. They also have a wonderful arrangement of blood circulation to keep their tiny legs and feet warm. The warm blood from their heart flows down their legs via their artery into their feet against the colder blood passively moving up their legs in the vein back to their warm body. The legs of a bird are covered with hard scales, just like those of a reptile. Indeed, some taxonomists still regard birds as reptiles, referring to them as little dinosaurs that never went extinct. There is some truth in that, because early birds were evolving from dinosaurs at the time, 66 million years ago, when the Chicxulub impactor, an asteroid, apparently eliminated the “non-avian” dinosaurs. It was apparently not a meteorite (a meteorite is an object that survives atmospheric entry and lands on the ground). It was apparently estimated to have been about 10 to 15 kilometres (6 to 9 miles) in diameter, impacting in what is now Mexico. The birds were able to survive because they were endothermic (warm blooded) and able to fly away from unhealthy environments. Tortoises and other extant reptiles, which are exothermic (cold blooded) also survived by burying themselves (hibernation). These animals still do this these days during the coldness of winter, and if the daytime temperature gets too hot when it is called aestivation.

The world is changing. Nature doesn’t make value judgements; it simply reacts to circumstances. Christians believe that God provides. Correct, because nature is the tool set and the resource base. What occurs, is nature’s reaction to circumstances. ‘We reap what we sow’. This proverb describes a reaction of nature to conditions occurring due to our virtues and mistakes. We are sadly generating a greenhouse from carbon emissions. But we must take collective responsibility for stewardship of planet earth. Naturally, we must also react.

In nature, such things do naturally happen, but with many times smaller impacts, e.g. volcanic eruptions. Also, natural crises due to meteorite impacts. Volcanos produce gases released from magma as it rises, they then produce:

1. Water Vapour (H₂O): The most abundant volcanic gas, typically accounting for more than 60% of emissions and sometimes exceeding 90%. It is largely harmless apart from generating lightning and floods.

2. Carbon Dioxide (CO₂): This gas typically makes up 10% to 40% of emissions. While essential to the atmosphere, initially, it poses a significant local hazard because it is denser than air and can collect in lethal concentrations in low-lying areas, causing asphyxiation.

3. Sulphur Dioxide (SO₂): This is the third most common gas, often comprising a small percent of the emissions. It has a pungent odour and irritates the eyes, skin, and respiratory system. In the atmosphere, it reacts with moisture and sunlight to create volcanic smog (“vog”) and acid rain, and in large eruptions, the resulting sulphate aerosols can even have a short-term cooling effect on the global climate.

Before mammals and us, Earth was dominated by plants, reptiles, amphibians and fish, also invertebrates and micro-organisms. They lived and died and remained buried beneath the moving sediments of the planet. They decayed naturally into a sludge that became crude oil. Then humans appeared. The first oil wells were dug, and the oil refined from the mid 1850s in North America. Since then, the production of burnable oil has escalated to the vast industry that now pervades the modern world and fuels many different industries, but particularly travel. The outcome is the increasing concentration of atmospheric carbon dioxide and other products of combustion, mimicking some of the effects of scores of volcanic eruptions. This caused the current increase in global temperatures, particularly the oceans, leading to climate change. As the evaporation of global water accelerates, the amount of energy in the atmosphere is raised increasing air movement and the total volume of water in the sky. This in turn leads to more precipitation (rain), floods, and stronger winds. The only way to reverse this process is to refrain from burning fossil fuels. The human population passed 8 billion on November 15th, 2022, together we must decrease the use of fossil fuels. Small positive changes from many can lead to success!

Insects such as fleas spend the winter in the direct company of their endothermic host animal, which could be a bird or mammal. Reptiles such as lizards and snakes or amphibians such as frogs and newts, like invertebrates such as slugs and spiders are exothermic. They are entirely dependent on the external temperature for active life, so they will go into dormancy, i.e. hibernate. Some spiders have adapted to humans and are happy to live in peoples houses all winter such as the domestic house spider (Tegenaria domestica). This is the one that is sometimes seen running across the floor in a warm sitting room on a winter’s evening. Or else there is the cosmopolitan cellar spider (Pholcus phalangioides), sometimes called daddy long legs. These tiny animals with long spindly legs hide in ceiling corners or behind furniture and make long random cobwebs which catch small insects such as mosquitos and house flies.

Few mammals hibernate. Bears (Ursus sp.) do, reducing their body temperature from 37.7℃ to about 31℃. Dormice drop their body temperature to that of their surroundings optimally between 1 and 4 ℃, where the least amount of energy is consumed. Their heart and breathing rate drop by about 90%!