In my garden is a large oak. I often wonder just how many species are supported by this one tree.
Its roots spread far and wide drinking up the rainwater and helping to keep our village safe from floods. The solid trunk hosts lichen and offers shelter for tiny insects and caterpillars within its fissured bark. Ivy creeps up from below and provides a frost-free environment for treecreepers scurrying ever upwards amongst its waxy leaves. The magnificent canopy provides shade for my garden and then drops its tasty seeds in the form of acorns. In autumn my tree sheds its golden leaves, which provide litter for hibernating hedgehogs and the opportunity for my family to scrunch and crunch and kick through the crispy leaves on a cold morning. No wonder the oak tree holds such a prominent place in the folklore and history of people from all over the world.
Alongside the seasons that arrive and depart with predictable regularity, the tree has its own life cycle that can span many hundreds of years. I measured the girth of my tree and estimated it to be 180 years old. Old and very grand, quite definitely – but certainly not ancient by oak tree standards.
The oak tree is ripe with metaphors. The reminder that great things can grow from tiny beginnings, is the one that first springs to mind for me in the famous ‘out of acorns, mighty oaks grow’. But this beloved tree of mine has held a new significance for me more recently. The very top or crown of the tree has entertained me for years as I have watched the birds – corvids mainly, compete for the best vantage point. My tree has what is known as a ‘stag’s head’ appearance.
There is an old saying that ‘oaks grow for 300 years, rest for another 300 years and then decline for a further 300 years’. Like me, my tree is not yet ancient, but its vascular system is no longer up to the job of maintaining it in its previous glory. In order to preserve the vital parts of the tree, the extremities start to die off, enabling light to reach the inner crown and stimulate new growth in dormant buds. The outer branches are hardy and remain, looking like wooden antlers standing proud and erect – often for decades or even centuries.
My tree still follows the usual cycle of the seasons. New leaves sprout in spring – albeit ones that are closer to the heart. Acorns develop and drop with the potential to provide food or new life. Leaves turn from green to gold and shed on my lawn, leaving the bare wooden structure of the tree looking the same as it always has each winter. As spring returns, the trees energy is placed where it is most needed in the inner crown and the stags head is left as a perch for the birds.
The tree has not died, in spite of unfounded complaints by neighbours that it has become dead and dangerous! It is conserving its energy where it is most needed and providing a new purpose in its final years.
It has taken me a while to write this blog. The natural world has long provided me with rich meaning, both physically as a place to escape to and gaze in amazement, and as metaphor for my life. Like my oak tree, I recognised my own vascular system slowing down, the extremities of both my body and my mind not receiving the nourishment they need to flourish as they once had. Like the oak tree nurturing its new inner crown, I have chosen to place my limited energies at the heart of my being and focus on those core activities, relationships and interests that provide me with the most meaning and purpose. Maybe like the stag headed oak, I will find new purpose in the latter part of my life?
Just like my neighbours who demanded I cut my tree down as it is dead and dangerous, I recognise my own biases in misinterpreting the old and frail as past it or lacking usefulness, and how I may internalise those judgmental thoughts. But like my tree, I am not past it. My ideas still come like the acorns, providing food for thought and potential for growth. Like autumn leaves, I will shed those prejudiced thoughts on what makes a living thing purposeful, and approach winter by hunkering down through the harsh weather ready for new life next spring. And I shall delight in those birds making use of my oak’s topmost branches as they loudly and boldly declare the new usefulness that has come about through the natural dying of the tree.
The United Kingdom is facing it’s first ever red weather warning for extreme heat, and unprecedented temperatures of >40 degrees C are predicted.
News stories give advice on how to stay cool and sleep at night and organisations like Age UK have information sheets available with suggestions for helping our most vulnerable. Of course, a red warning means that EVERYONE, and not just the most vulnerable, need to follow advice about staying healthy in the heat.
What about our wildlife? We can make sure we have areas of shade and water to drink in our gardens and yards, but unlike some humans who are relishing the idea of a suntan and possibly risking their health in a heatwave, animals tend to take extreme weather more seriously and look after themselves without needing to be told what to do!
How animals keep cool:
Humans are animals – and one of the ways we stay cool is to sweat. In extreme heat, our body opens up the blood vessels that are close to the skin. Blood carries heat from inside of our body to the surface, where it can benefit from the cooling effect of sweat evaporating.
You might not realise your pet dog can sweat too. Dogs sweat through their paw pads but it is not as effective as human sweating, which is why dogs use panting as a cooling mechanism instead. This works because of the cooling sensation of moisture evaporating from their mouth and tongue, and exchanging the hot ait from their lungs with cooler air from outside. The Battersea dogs home has some good summer advice for dog owners.
Camels are renowned for their ability to survive the harsh conditions of the desert and contrary to what we may have heard, their humps don’t in fact carry water, but fat. A camel uses its hump(s) to regulate its body temperature. At night when the soaring daytime temperatures drop dramatically, the store of fat keeps the camel warm. In the daytime it prevents the sun from penetrating the camel’s body so keeps it cool. The energy (fat) stored in a camel’s hump is what keeps it going when food is scarce, and this ungualte’s (an ungulate is a hooved mammal) secret to staying hydrated is down to its oval shaped blood cells and not storing water in its hump. A camel can drink 113 litres (30 gallons) of water in 13 minutes and rehydrates faster than any other mammal.
Birds have a variety of ways of keeping cool:
Birds head for the shade, take a dip in cooling water or change their routine to make use of the cooler parts of the day for activity and the hotter times for rest.
You might see a bird panting or doing a special type of movement by vibrating their neck muscles, called a gular flutter. Some birds, including the heron can open their beaks and then flutter the gular muscles in their throat while breathing rapidly. This quickly carries heat out of the bird’s body and brings in cooler air.
Urohydrosis is used by some birds in really hot environments. Birds have a single opening (called a cloaca) for their digestive, urinary and reproductive tracts. This means their poo and wee comes out mixed together. Some vultures and storks excrete their droppings onto their scaly legs to cool them down. It works in a similar way to sweating or panting. The evaporation of the liquid has a cooling effect.
All the above examples are of warm blooded animals and birds that need to keep a relatively constant temperature. Whatever the outside temperature is, they need to keep their internal temperature regulated. Us humans know only too well how a change in body temperature of only one or two degrees when we are unwell can make us feel dreadful and unable to do much at all. That’s why we need to take it seriously when heatwaves are announced.
Cold blooded animals are different. They get their heat from the outside environment and their body temperature can fluctuate as the outside temperature fluctuates. The size and shape of an animal often indicates whether it will be warm or cold blooded. Large animals like walruses, elephants and rhinos are warm blooded because it would be very difficult to heat up an elephant using an external heat source like the sun! Cold blooded animals tend to be long, thin or flat shaped in comparison.
Reptiles can overheat though and need to find shade so they can reduce their temperature when they get too hot.
How plants keep cool:
Animals can regulate their temperature by moving in and out of shade and heat, or doing activities that help them cool down like panting or even pooing on their own legs! But what about those living things that can’t get up and move?
A plants structure can help it survive extreme heat:
Waxy leaves conserve water, and tiny leaves have less surface area for losing water.
Some plants like cacti have no leaves at all which results in a low surface to volume ratio and reduces water loss.
On a molecular level, something quite incredible happens when plants get too hot:
Plants have a group of proteins called heat-shock proteins or stress-induced proteins. These proteins are found in all living organisms, including us, and are produced when cells are briefly exposed to temperatures above their normal growth temperature.
Plant heat shock proteins can protect cells that are exposed to high temperatures.
What about the insects?
Insects are cold blooded so we will find more of them out and about in the warm weather soaking up the sun’s energy. We often take delight in a beautiful butterfly but find the flies seeking shade in our cooler houses are annoying!
Juvenile insects like larvae (caterpillars, for instance) are less able to escape extreme heat. They are less mobile and lack the wings needed to fly away and take shelter in a shady bush (or kitchen with it’s ready supply of food).
Scientists are noting that climate change is having an impact on insects ability to reproduce, and even a slight rise in temperature can have a dramatic effect. Insects are responsible for about 80% of the pollination of trees and bushes on our planet, so it is essential we do what we can to reduce further climate change.
It’s important to remember that every living thing will be affected by the heatwave we are expecting in the UK. Look after your pets, keep those bird feeders and ponds full, create some shady places, water your plants, stay hydrated and why not change your routine to suit the weather conditions, like many of the other animals do.
I could smell the electricity in the air this morning, and my tummy had been warning me of the approaching storm since yesterday evening. I wanted to go down to the woods before the storm started to see what the animals and birds were making of it all. So, Blaze and I took our usual route down the track, Blaze running back and for after her ball. The woods were eerily quiet, the creatures knew what was coming. There was a distant roll of thunder and a few birds squawked and cried before becoming silent again. In the distance a lone farm dog barked.
We headed back home as the occasional huge, heavy drops of rain plopped out of the sky and landed on the track, sending tiny clouds of dust into the air. Blaze was nervy. She wanted to walk ahead – but not too far. She was on high alert and I expect she could sense the electricity; smell the petrichor aroma – that instantly recognisable smell we experience when it rains; and hear the storm as it rumbled around the valley.
We passed the cows in the field alongside the track, and many of them were laying down; the swallows were flying low; and everything seemed to be pushed down towards the earth by the changing air pressure. My tummy continued to rumble just like the distant storm and my husband complained of the pressure in his head.
Each time there was a flash of lightning, I counted the seconds until the clap of thunder came. The storm was getting nearer and fortunately we made it into the house before the rains came.
By lunchtime it was so dark we couldn’t see to read, and I was feeling very, very unwell. Blaze and I sat on the bed and watched the blue cracks of lightning shoot across the sky. I also faffed about on the internet in between the power cuts, researching what I could about how animals “know” what the weather will be like.
Animals have often been attributed with supernatural abilities; ESP; or in the case of Paul the Octupus – an ability to predict World Cup football match outcomes. Our folklore is full of tales of birds and weather prediction:
Hawks flying high means a clear sky. When they fly low, prepare for a blow.
Geese fly higher in fair weather than in foul.
When seagulls fly inland, expect a storm.
Air pressure certainly does affect birds. Swallows, for instance, have sensitive ears; when the barometric pressure drops, they fly as close to the ground as possible, where air density is greatest. Low-flying birds are signs of rain; flying high indicates fair weather.
Studies in the past few years have shown that birds may also be responding to infrasound – those sound waves that humans can’t hear. It appears that some birds may hear the infrasound noise of a distant tornado as the soundwaves travel through the ground. This acts as an early warning signal and enables the birds to fly to safety long before the tornado arrives.
It is likely that animals “know” about approaching weather because of their incredible senses. I don’t think for one moment they can see into the future in a magical way. They can predict the future, but scientifically through using their eyes, ears, and noses. Different animals have different numbers of senses – humans have eight senses, whereas other animals have some extras like magnetoreception, and electroception. As well as that, the senses that other animals share with us can work outside of the ranges humans are used to.
I’ll describe one sense in detail to demonstrate how this works, and I’ll briefly explore some of the other senses.
Bears are thought to have the most sensitive smell. This is essential for helping them survive. Bears often forage for food, and the ability to smell something edible 20 miles away in the case of the Black Bear, or through 1 metre of ice in the case of the Grizzly, means they can conserve their energy and head straight to the food source instead of searching around.
Here’s a diagram showing how different animal’s sense of smell compares:
So how does it work? What makes certain animals specialist sniffers?
There are several things going on. Let’s take Blaze, my dog and compare her to me:
Her nose is a different shape to mine for a start. I breathe in and out through the same airways inside my nose. If I take a big sniff of something and then exhale, incoming scent is pushed out with the exhaled air. To get a really good smell of something, I have to keep sniffing it without breathing out at the same time – try it, have a good sniff of something nearby.
A dog’s nose is more sophisticated in the way it functions. Blaze’s nostrils, unlike mine, can move independently, helping her locate where scents are coming from. When I throw her ball and she doesn’t see it land, her nose goes to work – and I can see her nostrils quivering and sniffing in lots of different directions until she locates the path of the scent. This quivering, pushes the scent further up her nose so it doesn’t mix with new smells coming in – it helps her stayed focused.
Take a look at the photo of Blaze’s nose below or at your own dog or cat’s nose if you have one. When Blaze breathes out, the exhaled air leaves through the slits in the side of her nose, and the swirl of wind created by this exhalation helps send more new scents into her nose.
Smell Receptor Cells
The average dog has around 220 million smell receptor cells – some breeds have many more. A human has only 5 million scent receptor cells. A dog not only has more cells than a person, it has more types of cells. This enables a dog to detect a greater variety of smells.
A dog has another organ for smelling, absent in a human, called the vomeronasal organ.
It’s not just our sense organs that are important in smelling, tasting and hearing the world. The way our brains process this sensory information is important too. Brains interpret and prioritise the messages that have come via the sense organs. The brain also tells the body how to react. So, Blaze’s brain is clearly working differently to mine – she needs to be able to process information that is important for dogs – things like finding food and a mate. My brain processes differently because I’m a human. I need to find food, just like Blaze but I tend to do it with my eyes not my nose. I may wish to find a mate, but again I don’t do it by sniffing them! Of course, there is a huge amount of diversity within the same species too.
Most mammals are dichromats and get their colour vision from two kinds of visual pigment. But humans and some other primates have trichromatic colour vision and can see a greater variety of colour.
Humans can see only a tiny part of the electromagnetic spectrum. Some creatures can see wavelengths of light that are outside of human vision.
It’s difficult to imagine that some animals see and hear things that we don’t. Some owls can see ultraviolet light. Their prey are voles, which leave urine trails behind them that show up in UV light. Elephants can communicate over long distances using infrasound waves traveling through the ground and whales communicate over vast distances in the ocean, while we wander about on land, oblivious to the cacophony below the waves.
People have different experiences of sensory information too. Some autistic people may be able to hear conversations in a distant room or spot the difference between two almost identical objects. Children have sensory abilities that are lost as they become adults. Babies are born with an ability to differentiate between individual faces on monkeys and humans, but by the time they get to around nine months, a process called perceptual narrowing takes place in their developing brain and they can only distinguish the human faces.
Here’s a couple of fun activities to try:
Which is the odd one out?
When adults look at the images of a snail (above) they typically say that glossy snail A and and glossy snail B are the most similar. The matte-looking snail C seems to be the odd one out. But a baby can tell that snail B and snail C are actually more similar.
Have a listen to these sounds. Depending on your age, you may hear one or more sounds from these recordings of different frequencies.
As we discover more about how our own and other animals’ senses work, it’s not surprising that some animals appear to predict the weather. Our human noses aren’t as good at detecting smell as a bear, for example but we don’t need to be. We can hunt and gather food more readily. But we are particularly good at smelling petrichor – the smell released from the earth when it rains. We can smell it in tiny concentrations of five parts per trillion. Being able to smell rain had an advantage for our ancestors that relied on following the rains for their survival.
Of course, once you appreciate the extra senses that animals have – like the birds ability to migrate accurately between its homes using an internal compass; or the sharks ability to detect its prey using electricity, its no wonder that creatures may be seen as magical or possessing special powers. I imagine that humans who have sensory abilities outside of the standard could be viewed differently too – as magical, supernatural or mentally ill, perhaps? People often look to religion and make believe to explain science they haven’t yet been able to understand.
I think it is important to remember that just because I don’t see something like a bird does, doesn’t mean that the bird can’t see it; or is making it up; or is magic.
Storms fill me with the wonder of the natural world and the power of nature is breath-taking. Learning about how the world works and how all the different creatures experience it, is awe-inspiring.
I distracted myself through the thunderstorm this afternoon by writing this blog. All of a sudden, a small tortoiseshell butterfly flew frantically into my face and fluttered around my patterned blouse before crashing against the closed window repeatedly, as if it was in a mad rush to escape. It must have quietly been sharing my room during the storm and it “knew” it was over and it was ready to go outside again. I opened the window to release it and the birds were singing a different song to this morning – declaring to the world that it was safe to come out. We headed off to the local gardens for some fresh air and enjoyed the buzzing of the busy insects catching up on the hours of nectar they had missed.
The Towy valley has been full of mist the past couple of days and it’s been a treat to use some of my other senses to enjoy the natural world. I try and get out for a walk with my dog Blaze before work and we both like to check out what has been happening around the village and watch how the seasons progress.
Blaze is what is nowadays known as a ‘mixed breed’ but used to be called a mongrel. She has whippet, springer spaniel and Bedlington terrier in her mix so can run very fast, find things by their scent, and retrieve balls all day – never ever tiring of it or getting bored!
I walked down towards the track and past the school which was starting to come to life with people dropping their children off for the day. As usual, there were a few cars parked up, but unusually, as I passed each vehicle, I could smell the freshly washed occupants! Each car’s passengers had left a cloud of their own individual smell. It was as if the frosty air had frozen individual scent bubbles along the road.
Blaze and I carried on down the track and she too was fascinated by the smells she could follow. It’s no wonder that spaniels are used as detection dogs – their sense of smell is many times more sensitive than humans and they have mobile nostrils and a wet nose as well for determining the direction of the odour.
Blaze’s keen sense of smell pointed to where animals may have crossed the frosty path and gave me a clue as to potentially good sites for my trail camera. We wandered back home, me thinking about what I may be able to capture on my camera and Blaze sniffing at every leaf. By now the school was busier and the perfumed bubbles of frozen mist had turned into a sickening diesel filled fug clouding the village. It was perfectly still and there was no air flow at all – quite magical but also slightly creepy.
I got in and sorted myself out for work. My husband had been de-icing the car and came back into the kitchen. “Gosh, you smell cold” I said. The smell of the chilled air that had attached to his clothes was released into the warm kitchen. I pondered this for a while. What other types of weather can you smell?
Before rain we often smell that sharp, pungent smell of ozone – a form of oxygen. The Greek word ozein means ‘to smell’. And lots of people love petrichor, the smell you experience after rainfall. I like the post storm aroma but a friend dislikes it and my son describes it as the worst smell in the world! When you realise what it is then it kind of makes sense why they’re not keen. Petrichor was first described in 1964 by mineralogists Isabel Joy Bear and R. G. Thomas of Australia’s Commonwealth Scientific and Industrial Research Organization. It occurs when airborne molecules from decomposing plant or animal matter become attached to mineral or clay surfaces. During a dry spell, these molecules chemically recombine with other elements on a rock’s surface. Then when it rains, the combination of fatty acids, alcohols and hydrocarbons is released.
Is this aroma of any use to creatures or is it only something us humans are particularly sentimental about? Studies with indigenous aboriginal people in the Australia’s Western Desert have found they experience what is referred to as cultural synaesthesia. The smell of the approaching rain that arrives at the start of the wet months of the year is hugely important to them for turning the arid, red desert into a lush, green landscape with increased sources of readily available food. These people experience the smell of approaching rain as the colour green and it is important to them as a connection with their ancestors as well as being protective and cleansing. Freshwater fish are thought to recognise petrichor when the rains wash into the rivers signalling spawning time and a similar process takes place that helps camels find oases.
I can smell cold, heat and rain and I have always been able to predict the weather by using my senses. What types of weather can you smell?