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By Martyn Stenning
December 2024
It is early November. As I look out from my study window, an oak tree in front of me is showing hues of brown and yellow among the disappearing green if its leaves. I have mentioned before that deciduous trees are the exception globally. Most planetary trees are evergreen and live in the tropics. The rest live in the boreal ecosystem between latitude 50 and 70. Between these latitudes temperatures often drop to minus 20° C and below. But hey, that is us is it not? Ah yes, but Britain is exceptionally mild for our latitude. We (e.g. London) are roughly on the latitude (55° N) shared by Saskatoon (52° N) in Canada, and Moscow (55° N) in Russia. Most (but not all) of the natural trees in the latter 2 locations are evergreen and conifers. However, most of our native trees are deciduous. We only have 3 native conifers, and 2 of them do not have cones (but berries) as we know them, these are Juniper and Yew. The third native conifer is Scots Pine. All other conifers are alien to Britain. Some conifers are also deciduous, such as the Florida Swamp Cypress and the Larches.
So why are we special? Well, firstly we have the Atlantic conveyer, also known as the Gulf Stream and North Atlantic drift/current. This is warm water brought to our shores in Britain that influences our climate, making us warmer than we should be at our Latitude. Our prevailing wind is also a south westerly, doing the same thing. However, if the wind direction changes to an easterly or northerly, we get correspondingly cooler. Even very cold down to about minus 16° C occasionally. That is when we lose our exotic plants if they are outside.
The flowers of our native plants tend to be rather small such as birds foot trefoil and vervain. If they are abundant such as bluebell and primrose, they make a fantastic show, but to make an impression in our gardens, we like to import large showy flowers like dahlias, tulips and hollyhocks. These may be the first to suffer when we get a sharp frost. However, there is a trend now to plant wildflower seeds in our gardens, and this is good, because many of our insects are best adapted to native plants. Plants did not have flowers until insects appeared. They act as visual attractants to insects. There is now a fantastic dependence by flowers on insects to pollinate them, to produce viable seeds, and also a dependence of insects upon the nectar and pollen that they collect from the plants. However, many insects have also discovered (like we have) that the leaves of many plants taste good and are also nutritious. The insects that eat the leaves also become nutritious and are essential to insectivorous birds such as swifts, swallows and blue tits. Who in turn are essential food for sparrowhawks, hobbies and merlins. All birds of prey eventually die, and are then consumed by microorganisms, insects such as sexton beetles or carnivores such as foxes. So the cycle of life goes on.
November 2024
The air we breathe is made up of about 21% oxygen and 78% nitrogen. The remaining 1% is all other gasses. Breathing in anything else can only damage the body. Our oxygen is produced by photosynthesis, a process undertaken globally by green plants and some green micro-organisms, notably plankton. In return, the air that we breath out contains 4.4% carbon dioxide (CO2). This CO2 is essentially from oxidised carbon released from our bodily metabolism. That is, the digestion of our food and the burning of calories during exercise and other activities. This CO2 is then taken up by the green plants etc which separate the ‘C’ from the ‘O’ and use the carbon to build their own bodies, giving us oxygen in return. We are all part of this wonderful exchange of resources that results in life as we know it. I sometimes think that us humans have forgotten this as forests are cleared and cities are built and expanded into the countryside. Also, why look for a place to live away from Planet Earth? It really is (can be) a “wonderful world” with thanks to Louis Armstrong’s song.
Some people criticize the recent trend to rewild places, previously over formalised by being planted with exotic plants from around the world. Such as, tightly mown lawns and formal flower beds of exotics like agapanthus from Southern Africa or tulips from Central Asia. These plants are truly lovely and make a fine display, however, they are of little practical use to most native British insects, except, maybe for the ubiquitous honey or bumble bees. Apparently, we are in a biodiversity crisis with many native species such as cuckoos, turtle doves, corncrakes, orchids, wild service trees, butterflies, toads and so many more life forms declining on our watch. Indeed, a BBC news item today (10.10.24) said that WWF announced that: “Global wildlife populations have plunged by an average of 73% in 50 years”. It is time for us to celebrate the local and global natural biodiversity by helping wildlife that we encounter. It is amazing what will come into a garden if planted with native plants such as an oak tree (at least 7 m. from a building) or maybe a juniper bush, some native heather varieties such as Ling (Calluna vulgaris) or Dorset heath (Erica ciliaris). Let the buttercups thrive and watch the insects visit them. Encourage birds-foot trefoil which may attract 5 or 6 spot burnet moths to a garden or verge. They fly by day and look wonderfully exotic. If space, dig a pond and see the dragonflies, frogs and newts roll up to breed there, but no fish as they will eat the babies. Fish prefer lakes and rivers. These are just ideas, there is a place for formal gardens which bring joy to humans, and robins rather like them too, but a little wildness from many people may reverse this sad trend among our wildlife. Another striking news item was that hurricane Milton in Florida is a 1 in 1000-year rainfall event attributable to human induced climate change warming the sea in the Gulf of Mexico to a record 31° Celsius (88° F.).
October 2024
Water is the medium of life. My teacher taught me that when I was studying biology at school many years ago. This is also why astronomers are so preoccupied by looking for water on the Moon or Mars. In fact, they think they have discovered that Mars has water but it is 10 or 20 kilometres below the planet surface! So, then the questions are how do astronauts get it out? Why try?
We live on a beautiful blue planet where water makes up over 70% of the surface and can be as much as 11,000 metres deep. We (humans) are 55 - 60% water. If we cannot find any on a very hot day, we are not likely to survive. Space is a very unhealthy place with no available water or food. Moreover, there is not much oxygen there either, so I for one would not be interested to go there. We must look after this planet as there is no plan(et) B as someone has said. We must simply solve the problems we have on our home planet.
Rivers are the vascular system of our natural world. They provide us with the water for our taps in our houses, and ultimately take away wastewater when we flush the toilet and pull out the sink plug. What happens in between keeps us clean, from being thirsty, and removes our bodily waste. It is a miracle that we all take for granted every day. We have faith that the supply company maintains the reservoirs, filters, pipes and chlorinators that provide our potable tap water. Also, the sewage workers (and I have been one in the past) that ensure that the water returning to rivers does not kill the animals (and plants) that live in it. These are some of them, first the invertebrates: Stonefly (Plecoptera) larvae, these are the best sign of good quality water; caddisfly (Trichoptera) larvae, many make little jackets out of fibres or sand; various dragonfly (Odonata) larvae, including demoiselles (Calopteryx spp.) larvae which take up to 2 years to develop before emerging as the most beautiful flying insect I know. Dragonflies are beautiful primitive voracious predators of other invertebrates; freshwater shrimps (Gammarus pulex) are miniatures of their marine cousins. There are also whirligig beetles (Gyrinidae) that dance on the surface of water; also, water skaters (Gerridae) true bugs also with the ability to walk and run on water; leaches (Hirudinea) which are parasitic or predatory worms, some have a traditional use in medicine. Additionally, the vertebrates (like us), including fish such as bullheads, sticklebacks, eels and trout that feed on the invertebrates; also, water voles, otters and kingfishers make rivers their homes if they can.
Scientists collect samples of invertebrates from rivers using a technique called kick netting. They identify them under microscopes and attribute a score (1. poor to 10. good) dependent on what is there, some are more pollution tolerant than others. This determines the quality of the river water and is called the River Invertebrate Prediction and Classification System (RIVPACS) method.
September 2024
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).
August 2024
Many people, including me, like to assist their local bird populations by providing nest-boxes for spring breeding, and bird feeders, especially during winter. However, Britain’s birds are never more abundant than during August. Most passerine (sparrow-like) birds breed from March to July, so the country is now replete with fledglings learning how to feed themselves as their exhausted parents retreat to moult. You will begin to see moulted feathers, frequently encountered on the ground when you are out and about from July to September. Meanwhile, if you keep your bird feeders charged with sunflower hearts in the summer, you, like me this morning, could see adults and young of species such as greenfinches, blue tits, goldfinches, nuthatches, coal tits, robins, house sparrows and great tits eagerly having their breakfast. Also, dunnocks, blackbirds, robins, wood pigeons and song thrushes will be picking up the spilt food underneath. Chaffinches may also appear both on the feeder and below. The best feeder to get is the RSPB Squirrel Buster Mini seed feeder and fill it with sunflower hearts. With other feeders, you will just be feeding the invading grey squirrels. By giving young birds, a good start in the summer, they are more likely to survive the winter to breed next year.
My research has recently focussed on how blue tits use aromatic herbs to enhance the health of their nestlings. We humans frequently use herbs to enhance our health, e.g. lavender bags among our clothing stores, aromatic herbs such as parsley, sage, rosemary and thyme among others in our food. It is also likely that perfumes that we apply to our bodies are beneficial plant extracts such as lavender and myrtle. Well, blue tits do likewise, but the aromatic herb they prefer in Britain is called ground ivy (Glechoma hederacea), a relative of the mint grown in our gardens which is spearmint (Mentha spicata). They also may use this and other types of mint, also red dead-nettle (Lamium purpurium). Herbs used by blue tits in other Eurasian countries include lavender, yarrow, veronica, lesser calamint, fleabane, lemon balm, yellow archangel. The benefits of these plants have been found to include higher levels of haemoglobin in the bird’s blood and beneficially lower blood sugar levels. Other effects include lower numbers of insect parasites, fungus and bacteria in nests. Physiologically, the plants seemed to have anti-inflammatory benefits and help the nestling’s feathers to grow faster ready for fledging.
July 2024
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.
June 2024
As spring turns into summer, we watch the world around us flourish. We see trees resplendent with new leaves. The sequence of flowers – snowdrop, crocus, daffodil, tulip, oxeye daisy, orchid, rose - means that the ecosystem around us is working in a dynamic way to maintain itself, attracting insect pollinators, breaking up carbon dioxide and water to make sugar and oxygen (6CO2 + 6H2O → C6H12O6 + 6O2) feeding the plants, herbivores and omnivores and ultimately the carnivores, all of which, like us, are breeding, and populating the planet. I saw a disturbing statistic recently; the world’s population of humans is increasing by about 1 million per week. The worrying thing about this is that every human, that is you me and the new one being born will require a lifetime of food, and the only source of that is the subject of this note – nature.
Farmers, hunters, foresters, ecologists, engineers, and gardeners all manage nature with the intention of helping it to serve all of us with food, oxygen, water, waste disposal and raw materials that we need to survive. That is ecology, an ecosystem. In today’s world, we cannot live well without those that manage nature. But we can try. We can all cultivate a few food plants. I once grew some wonderful green peppers in troughs on our windowsills. I was also lucky to have a garden to grow potatoes and keep 2 laying hens. So, we were always able to have fried eggs with mashed potato and grilled green peppers. Then for dessert we had locally picked wild blackberries stewed with apple from our tree. We may not all be able to grow our own food, but we are all part of nature. Every green plant (inside or outside our homes) will make oxygen. If we look after them, they will contribute to the planet. If you have a garden that extends beyond 7 metres from any building, plant a shrub or tree and you will make a larger oxygen contribution, plus serving the local insect and bird community. Remember that all that you eat will generate waste, hold your local authorities responsible if the local river or stream seems polluted. Remember that it is your waste that you pay them to dispose of responsibly. That way you will save the lives of countless water creatures and birds such as kingfishers, grey wagtails, ducks, coots, and moorhens that depend on them for food. Then ultimately the foxes, stoats, otters, and buzzards that will prey on those. Remember, our rivers are the vascular system of terrestrial ecology.
May 2024
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.
April 2024
Back in France now to work on our conservation project there. We were delighted to see thousands of Eurasian cranes (Grus grus) flying over our place on migration mainly from Iberia and North Africa. Cranes fly in V-shaped formation in groups of up to c. 500 birds, making memorable and fluty croaking calls, often heard before the birds come into sight. When setting off, cranes will often find thermals, rising currents of warm air on which they spiral to an altitude of up to ten thousand metres, before flying north to their breeding grounds. Cranes are closely related to coots (Fulica atra) and moorhens (Gallinula chloropus), both common British breeding birds. When you hear these birds call it is understandable that all 3 species are related with similar complex vocal apparatus. However, their external body forms are of course quite different. All three are wetland birds in the taxonomic order of Gruiformes (crane-like birds). The French word for crane is grue, also true for mechanical cranes.
Cranes breed across Northern Eurasia, with small numbers in Norfolk and Somerset. Their main breeding range includes Scandinavia, Siberia, Mongolia and Northern China. Cranes spend winter in the sub-tropics of NW and NE Africa, parts of Iberia, Northern India and SE Asia. The experience of thousands of cranes flying on migration is one of the most moving and spectacular phenomena of the bird world. Many East African wintering cranes migrate via Israel. Autumn migration south is from August to October, and then north to breed from February to early March. Cranes are omnivorous foragers, eating a wide range of food from roots and seeds to small mammals and birds. They particularly like maize and frogs. Small numbers of cranes over-winter on a maize farm c. 40 km from our place in Aquitaine where they glean un-harvested seeds. Cranes are well known for their courtship dances with much strutting and head bobbing. Cranes pair for life, but if one dies, the other may repair with a new partner. The normal annual clutch is 2 blotchy brown eggs taking about 30 days to incubate before hatching. Crane eggs are often preyed upon by members of the crow family and foxes among others, but adults put up a strong defence. Removed eggs are often replaced within a few weeks. The precocial hatchlings develop rapidly, running around with their parents and swimming within about 24 hours. Breeding begins at the age of 3-6 years and life expectancy is up to 30 to 40 years, but in practice, most wild cranes are thought to live from just 5 – 12 years.
March 2024
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.
February 2024
Nature likes to redress an imbalance. If a tree falls over, a dozen or so young ones will compete to replace it. If you cut off the branch of a tree, a new one will grow quite quickly. If a female blue tit loses her mate to a sparrowhawk, a new young floating male will often move in to take his place. If you plough up a meadow, the plants are replaced by opportunist weeds of cultivation unless they are controlled by a weedkiller and a crop is planted instead. Any change generated by humans will generate a natural response. Even the monoculture crop will generate an influx of organisms wanting to consume it. To get the crop, these arrivals will have to be controlled by pesticides, that will also be lethal to other organisms.
Nature is also attempting to redress the imbalance caused by human induced (anthropogenic) climate and other changes in some most extraordinary ways. For example. We are burning more fossil fuel now than ever before, especially due to the global number of vehicles being driven increasing daily. A consequence of this is that the carbon dioxide produced is acting like a greenhouse and heating up the atmosphere and global surface. More ocean is being exposed as the ice caps are melting.
Now, 71% of the global surface is water. The amount of water leaving the oceans and entering the atmosphere as vapour is proportional to the temperature, so global warming is causing much more water to be held within the atmosphere. The more water vapour there is in the sky, the more clouds form which also store energy that can be manifest as lightning and wind. The consequence of this is more powerful storms and heavier rainfall. This rainfall causes erosion of our tarmac roads, often by freeze and thaw of water in cracks and fissures. Also, by simple flow erosion. This in turn causes pot-holes. In turn, the pot-holes cause damage to the tyres and structure of vehicles, and while those are off the road, they are not burning fossil fuels. Nature tries redressing an imbalance. Meanwhile, car owners rush to get their vehicles repaired or replaced and so the cycle goes on. Man has become a geological force of nature. This has caused geologists to suggest renaming the epoch that we are living through as the Anthropocene (human new) epoch. Officially, we are in the Holocene (meaning wholly new) epoch.
January 2024
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.