Archive for category: News

August is a good month for insects. Ergo, September is a good month for spiders. Many of us will have taken part in ‘No Mow May’ and some will have left the grass and wildflowers to grow on into June, July and August. These 4 months will have allowed many insects to develop, mate and lay eggs. We are going through a biodiversity crisis at present with many species of animals at all levels in steep decline. One root of this problem is a lack of insects. So why is this? One reason is environmental contamination in our water, land and atmosphere. Another may be climate change. This change can affect the survival of some insects positively, but many will also be negatively affected. Many insects have very exacting requirements including a dependency on species specific external temperature. Any change in the environment requires organisms to adapt, usually via natural selection favouring individuals that benefit from that change. The rest die. A consequence of climate change is that many organisms are moving north as the weather (in Britain) becomes milder and warm enough to support them. For others, it may become too hot. One butterfly that I frequently see in France is the large tortoiseshell (Nymphalis polychloros). This butterfly is extremely rare in Britain, but recently, is apparently turning up here more frequently.

One of the joys of summer is seeing and hearing the insects busily going about their complex lives, such as the buzz of the many types of bees in flower-rich meadows, the fluttering-by of butterflies, the stridulating of grasshoppers and crickets. Or the gentle movements of ladybirds hunting aphids and the helicopter-like hovering of the many beautiful types of dragonflies as they hunt for other insects. However, all these minibeasts perform many important functions in the environment. Maybe their two main functions are 1. The pollination of flowers, and 2. Being food for other animals such as larger insects, spiders, amphibians, reptiles, birds and mammals. Insects are a vital component of biological food chains, but most of them disappear from November to March. By creating insect friendly mini meadows in our gardens, we will certainly be assisting the survival of a huge variety of biodiversity, while also creating a fantastic opportunity for ourselves to get to know some of these amazing creatures. For example, we recently had our local grass verge designated for wildlife, and this year it is buzzing with insects including the scarce and beautiful day-flying 5-spot burnet moth (Zygaena trifoli).

The seasons continue to progress as planet Earth causes us in temperate zones to be bathed in the warm sunshine of the long days of summer. We experienced the release of copious wind-blown pollen from trees during the spring flush of leaves and tree flowers such as hazel, oak and birch catkins. June gave us grass pollen, which I have recently watched billowing from the growing hay, like smoke in the breeze. Wind pollination is a very inefficient system and is mostly dependent on wind for transport. The flowers do not have to be attractive either to insects or humans. Very little wind-blown pollen will fertilize a seed. Insects appeared about 480 million years ago (MYA), whereas plants providing nutritious nectar appeared about 125 MYA. The most successful of these produced attractive flowers. With this, the efficiency of sex among plants was revolutionised. While some insects will harvest pollen from wind pollinated trees such as willow. But when plants started producing nectar and bright pigmented signal petals there was an explosion of beauty around the planet. From then, relationship between insects and flowering plants proliferated the diversity and success of the flowering plants that we see today. Apparently, the first flowering plants were magnolias, although there is some evidence that there may have been flowering water lilies before them. Not only did the plants start exploiting the insects (and vice versa), but they also exploited other animals as well.

About 3,630 BC, East Asian humans started exploiting silk moth caterpillars to produce the wonderful silk yarn made into some of the finest human garments. They started transporting it to the Eastern Mediterranean to sell, via the Silk Road. These traders traversed areas such as modern Kazakhstan, where there has always been a large population of Tian Shan brown bears and wild apple trees. The bears are partial to the sweetest apples which they select to eat and memorise their locations, such that the information is passed through generations of bears. The consequence is that trees producing the sweetest apples have proliferated from the seeds that passed through the bears and germinated to generate sweet apples picked by silk traders both to eat and trade with Europeans. The result is the abundant and variable apples of Europe, which in turn were taken to North America by French Jesuits in the late sixteenth century. The successful proliferation of apples in the United States was subsequently aided by the missionary Johnny Appleseed.

Today I am considering predator-prey relationships. The biblical statement in 1 Peter 1:24-25 states: “all flesh is as grass”. If we interpret grass as meaning all green, photosynthetic organisms including plants, algae, and some bacteria, then all flesh is indeed made from green things, as all global energy is ultimately solar. Then flesh eating organisms (including insectivorous plants, fungi, and some bacteria) are feeding on animals that consume plants as food in a chain of consumption and so on.

I saw some footage recently of a leopard in India wandering into an abandoned temple and finding a terrified wild pig in one of the rooms, essentially trapped. The leopard looked at the now petrified pig, and then walked on. The leopard was not hungry. Most of us will have seen the wildlife documentaries on TV showing ‘carnivores’ hunting herbivores. These events are quite infrequent, and it takes a lot of patience to film one. However, even cats like to eat grass sometimes, and sheep love to eat snails, to the point where several snail species living on the sheep-grazed grass of the South Downs are described as “sheep snails”. One of them even has a hairy shell and is known as the hairy snail (Trochulus hispidus). Also, deer like to hunt and eat frogs. A single blue tit nestling will have eaten more than 1000 caterpillars and a quantity of spiders before it leaves the nest. It will be just one of about 7 siblings each eating about the same amount, as will the 2 parents (total c. 10,000 prey items).

We may cringe when we see a lion bringing down an elephant or buffalo in Africa, but their physiology commits them to eating meat when they are hungry, and there are probably many days/weeks between such kills. But we are also omnivores, eating both plants and animals, most of the latter are not hunted as such, but raised in a protected and engineered habitat and fed on the best vegetation to maximise their bodily health and killed, ready for us to eat. We also eat the wild animals from the water such as fish and molluscs. All these are hunted by other humans on our behalf. Our effort is usually just to visit a market of some kind and collect them already prepared for cooking where required and consumption. We are still predators, because we depend on another organism to survive, whether it is a plant or an animal or even a fungus like mushrooms, alone or in cheese, yeast in bread, wine and beer and bacteria in yoghurt.

One thing we can rely upon in nature is the change of seasons. Now, as we emerge from winter to spring, the tilt of the planet causes us, in Britain, to be bathed in slightly more solar radiation (sunshine) every day. Nature is responding to this as I write in February. I have seen my first celandine, wild primrose and daffodil flowers of the year along with many other signals such as gnats dancing and male territorial birds such as blue tits, great tits, robins, starlings, dunnocks, house sparrows, and song thrushes singing seductively to passing females and warning off same sex competitors. I have also been told of bumblebees flying, which they do as early as possible in the spring to breed. Hazel male catkins are expanding to become huge and blow in the wind like little flags to release their pollen; a bold reminder that spring is developing. Look more closely and you may find the less well known tiny scarlet female flowers on the apex of some of the buds on other parts of the tree. This is because hazel is a monoecious tree with both male and female flowers on a single plant. Insects are ambivalent about these flowers as they are largely wind pollinated. Hence the difference in sex flower size as most pollen will be lost before finding a female flower. There seems to be strong natural selection for genetic variation in flowering time for this tree, as catkin appearance time is very variable, from early January to March.

Breeding is actually on the mind of most animals just now, and the equivalent for plants also. Frogs are on the move, trying to get back to their natal pond to lay and fertilise huge amounts of spawn. I suppose the urge to return to the place where they were a tadpole is strong, as the mere fact that they survived suggests it is a good place to breed. Sea trout will be running up the rivers and streams to the head-waters to do the same. The gravel beds they use are called ‘redds’. The male newts also will be developing crests to impress the females to whom they will waggle their tails in the hope of inducing and allowing them to fertilise the female’s eggs that they wrap up in water weed leaves to grow into larval baby newts, also called ‘efts’. The numbers of insects we see will increase hugely as the season develops. Many of these will be collecting nectar from the emerging flowers, fertilizing the ova with pollen as they do so, and then taking the nectar and some pollen to feed themselves and their youngsters. Many of these insects then become baby bird food.

In the bleak midwinter we are all, with nature, missing the warm sunshine. Some of us, with nature (e.g. some species of butterflies and many birds) fly south to find it. Others, with nature (reptiles, amphibians, hedgehogs, bats, dormice and most invertebrates such as insects, spiders, woodlice etc.) hunker down and hibernate, to varying degrees. Others, like owls and me sometimes, simply embrace it and make the most of it. Bird-watching on a bright winter’s day can be very rewarding. I went walking on the South Downs recently and saw red kite, buzzard, flocks of fieldfares and redwings from Scandinavia, yellowhammer, partridges, skylarks, meadow pipits, sparrowhawk, kestrel, possible woodcock, bullfinch and loads of starlings, crows, pigeons and gulls.

Female badgers give birth underground in winter (mostly February) and nurse their young there until spring, just occasionally emerging to feed and drink. Polar bear females similarly bury themselves (in snow deposits) to give birth. They stay buried until spring with huge bodily fat reserves and frozen water all around them to eat/drink. All nature is preparing itself for the coming spring – a time of increasing plenty.

We in England probably regard trees deciding to drop their leaves, i.e. being deciduous, as being normal. However, globally, it is the exception. Only 4 native British tree species, yew, scots pine, juniper and holly, or 5 if you include box Buxus sempervirens – a potentially large shrub really, are both native and evergreen. The remaining 29 tree species are all deciduous. We all realise this when we try to tidy lawns in autumn. These deciduous trees form a band around the temperate northern hemisphere. There are a few deciduous trees around a similar band in the southern hemisphere, but much less land there to support them.

In the northern hemisphere we have enormous tracts of land (Eurasia and North America) that are ecologically divided into arctic, temperate and tropical. Most trees in the non-temperate zones are evergreen. In the tropics, daylight and temperature vary little, and in arctic zones thin leathery leaves have evolved to secure any energy available to them which they prefer to hang on to during the bleak midwinter months.