Here are Jan Flamank's Nature Notes for August 2020. Click on each photo to see a larger photo in a new page. For downloadable pdf versions of each topic see the links below.
The Eurasian Otter
A member of the Mustelidae family, our native otters are surprisingly large, lithe and energetic carnivorous mammals. Semi-aquatic and mostly nocturnal, they can be difficult to see, despite being so large at over 1metre/ 3.25 feet long.
They are excellent swimmers and are the only Mustelid to have webbed feet, with five clawed toes. They swim low in the water, with only their eyes, nose and top of their broad head and back visible above the surface. Their strong ability in the water is helped by their long, muscular tail, which is slightly longer than their body, at up to 16 inches long. This tail acts as a rudder when they are swimming, and also helps them to balance on land when they stand up straight on their hind legs, to have a good look around.
Eurasian Otters are at home in both fresh and sea water, although river otters tend to be more nocturnally active than sea otters, who are diurnal, because they have to feed at low tide. River otters breed all year round, but coastal otters mainly breed in summer, with cubs emerging from their holt in autumn to take advantage of seasonal fish stocks. Coastal otters also need to have access to fresh water, to wash their dense coat clean after a swim in the sticky salt of the sea.
When otters dive for food, they close their nostrils and ears shut and can reach speeds of 7 miles an hour with their streamlined, muscular body. They have large lungs, enabling them to hold their breath for up to 4 minutes underwater. They have incredibly dense, sleek fur to insulate them from the cold water, with a double layered coat that has over 70,000 hairs per square metre!
Otters are carnivorous and have a wide diet, depending on their habitat, but with fish making up about 80% of their catch. They especially love eels, which are rich in fats. They are opportunistic feeders and their diet can also include octopus, frogs, toads, eggs, ducks and rabbits!
Otter poo, known as spraint, is small for such a large mammal, and is a complex messaging service to other otters. It is used to defend their territory, indicate readiness to mate and pronounce which otter has been there. The spraint contains over 100 different scent components, and otters spend a lot of time both marking their patch and ‘reading’ messages left by other otters.
Solitary and secretive creatures, most of us may only see the chain of silvery bubbles at the water surface that gives away their presence underwater. So, think yourself highly fortunate if you manage to see one in its full glory - feasting on its catch, basking in sunshine or preening that magnificent pelt to keep it waterproof and warm.
I saw a family of young otters on holiday in Scotland when I was little, and they were so enchanting, my twin brother and I decided we would like to keep one in the bath at home...... which of course, never happened.
Our smallest native rodent, the tiny harvest mouse weighs the same as a 2 pence piece, about 5 grams, with a body just 8 centimetres long. Although so small, they are expert climbers, using their hairless, prehensile tail, the same length as their body, to help them cling to the stalks of long grasses. They live in reed beds, grass, wet meadows, hedgerows and farm crops of wheat and oats. They are well camouflaged, and hide themselves in dense vegetation to avoid detection by predators, detecting them with their excellent hearing. They have rather poor eyesight, although their large eyes are positioned on the side of their head to give them almost 360 vision.
Helping them to cling onto and climb tall vegetation are their adapted feet, which are relatively broad, and they have an opposable inner toe that gives them extra grip.
Like many small mammals with short lifespans - they live about 18 months at most - they reach sexual maturity quickly and are able to have up to three litters each breeding season. Vulnerable to predation from stoats, weasels, foxes, cats and some birds, they are also at risk in cold, wet weather. They do not hibernate and their very fine, pale ginger fur offers little protection from the elements.
Most known for building a remarkable nest, they weave this small, spherical ball out of grass stems, perched high up in tall vegetation, about 10cms in diameter. The female makes these nests at night, shredding and weaving living, fresh grass leaves, which remain attached to the grass stalk. She lines the nest with more leaves, pulled through the outer wall. There is no entrance as such, they simply push through the wall and then close it up again. This snuggly nest can hold up to 8 teeny young mice, where they are weaned at 10 days, staying for only 16 days altogether, before they are abandoned by the mother and start to fend for themselves. The majority of them are born during August and early September, hence their name.
Harvest mice eat seeds as their main diet, but also include insects in summer and fruits and berries in the autumn months. In the colder months they leave their high, vertical habitat and often hide away by burrowing beneath the soil to try to keep warm. They make a smaller nest in winter, much nearer to the ground for warmth, where they store food to help them survive until the next spring.
Because they prefer the warmth, they are mainly found in southern Britain, but their numbers have drastically reduced due to intensive farming and loss of habitat, like many farmland creatures. We can help them by leaving areas of rough grass, and allowing vegetation to grow up around ponds, ditches and rivers. They are the only native mice to build nests above the ground, intricately woven little balls of grass and a delightful sight if you are lucky enough to find one. They are seen best in winter as vegetation dies away, but will no longer have any mice occupants inside them.
The Summer Moult
We are enduring some very hot and humid conditions at the moment, and I for one, find it rather saps my energy.... so what must it be like for all the furred and feathered, warm bloodied wildlife we share our small island with? Phew.
Nature and evolution is packed full of amazing adaptations, to enable a myriad of species to survive across diverse habitats. But climate change is affecting our whole planet, and we are having much more extreme weather to deal with. Adaptations and evolution take a hugely long time, so I feel we really need to adjust our often destructive human behaviour, so we can all continue to share this small planet, and without exploiting nature any further.
All of us pet owners will know that our cats, dogs, rabbits and chickens lose lots of their thick fur or feathers, and are adept at finding cool places and shade to rest in during the hotter weather. They will also drink more water. Garden birds rely on clean water too, both to bathe in and to keep hydrated, so please keep any birdbaths you have clean and full.
One of the annual changes that ducks, and other waterfowl employ at this time of year, is their summer moult. This summer moult is not due to heat though, but all about ridding themselves of their rather tatty plumage after the rigours of the breeding season. This ensures they have feathers in really good condition to protect them for the colder months ahead. Their new feathers also help to keep them waterproof, when coated with the oil they preen themselves with regularly.
Male mallards - drakes- are much more brightly coloured than the drab females, but at this time of year, they are all looking rather brown and ragged, as they go through their moult, which for males is called eclipse plumage. The moult means that they are less able to escape predators as their flight feathers are poor, but they can hide amongst the lush vegetation, with abundant food readily available, until the new feathers gradually replace the old ones. This can take time, up to 3 months for some species of mallard, but their striking new plumage of iridescent green is gorgeous.
Juvenile garden birds, born earlier in the year, also moult now, developing their fully adult feathers, and migrant birds acquire strong new flight feathers to help them on their extraordinary journeys of 1000’s of miles.
Raptors can’t afford to moult in the same way, as they need to hunt for food every day, so cannot lose power in their flight. They replace just one or two feathers at a time, so only minimal gaps are evident in their wings.
Gulls have a much longer process, where they develop different sets of wing feathers over the 4 years it takes them to be fully mature.
Some male songbirds also have a second moult, in early spring or summer, but this time it is all about sexual display, and having the best plumage possible to attract a mate.
So, when we sit in the shade, keep the curtains closed, take off some layers and have a bit of a siesta during this hot spell, we can think about how our native wildlife is coping with the heat, and hopefully put out some cool, clean water for them to enjoy too.
Late Summer Snippets
I thought it might be fun to set out a few snippets of info about some of our native wildlife, as we go into the late summer season.
The close up image here was taken by David Maitland, in his hen house. It shows a native Queen Tree Wasp, brooding her eggs in the first few cells she makes in the ‘starter’ nest, made of fine layers of chewed wood. Later, the newly hatched female wasps will continue to build the nest into a much bigger structure, capable of housing up to 5,000 wasps. That’s a huge amount of chewed wood..... all laid down to make a strong, and very beautiful nest, just for that year.
Honey bees collect tree resins, which they make into propolis. This is a sticky substance used to repair and seal any gaps in the nest walls, which protects the colony from drafts and any wasps who may want to enter the hive to raid their stores of honey.
The Purple Emperor is our largest native butterfly, and whilst it was a rare sighting above oak tree canopies, in the last 50 years it has become more widespread, probably due to warmer weather from climate change. One of the very few benefits of the temperature rise.
Rising sea temperatures are also encouraging more jellyfish to appear on our shores. An abundant, rather lovely and totally harmless species is the moon jelly, so called due to its transparent bell. It feeds on plankton, and it can develop into huge, dense swarms on our shoreline in summer.
Seahorses have a narrow, elongated snout, with big cheeks on each side, which make the shape of their head hydrodynamic – perfect for slipping through water with almost no ripples to alert their prey. Once near their prey, they use a technique called pivot feeding. This means they can rapidly flick their snout upwards, like a catapult, sucking in the small crustacean in under a millisecond, by puffing out their big cheeks.
Some female moths have evolved to be flightless, like the female Vapour Moth. She is evident in tree tops from July to September, and has only vestigial, tiny wings. She stays on the trees, emitting chemical pheromones to attract the flying males who will then mate with her. This adaptive behaviour saves all the energy used in flight, and instead she uses it on the vital business of reproduction.
Pigeons are very noisy in flight. This is because they have very stiff flight feathers that produce a mechanical, purposeful sound on every downstroke. It is also used as a way of signalling danger to the rest of the flock, as pigeons don’t use alarm calls like many birds do. Male nightjars and short eared owls also use mechanical sound - they both clap their wings during aerial displays, showing their strength.
© Jan Flamank August 1st 2020. All rights reserved. Images used in the documents have been sourced free for use in this social, educational, non-commercial setting.