Tag Archives: object of the month

Object of the Month – June 2023

This is the cast skin / exoskeleton (exuvia) of a dragonfly larva, found in Elsenham in August 2005. The shape of the eyes and the length (40mm) suggest it’s a hawker dragonfly, while the finder’s description of the adult dragonfly being green and yellow means it is probably a southern hawker, which are common in July and August.

Dragonfly exuvia © Saffron Walden Museum

These dragonflies spend 2 or 3 years as a larva, or nymph, living underwater, before coming above water to shed their skin and emerge as an adult.

Southern hawker dragonfly by Tom Wiersma, via Wikimedia Commons.

Dragonflies, like all insects, have a hard exoskeleton which does not grow with them. After hatching from an egg, dragonfly nymphs gradually grow into adults through a series of moults to shed their skin, which allows it to grow in size each time, emerging as an adult directly from the last moult.
The nymphs look similar to the adult, with a long body and six legs. Nymphs in the last stages of growth have wing buds that you can see on this specimen.
This method of growth, through nymphs with wings developing on the outside, is called incomplete metamorphosis.

This is different from other insects including flies and butterflies, which hatch as maggots or caterpillars. This is the larva of the insect, and it looks very different from the adult. The larva in these insects also has to moult to increase in size, but the final moult is different. It creates an inactive pupa (called a chrysalis in butterflies) where the final radical transformation into the adult takes place. This method of growth from larva to pupa to adult is called complete metamorphosis.

Visit the Museum to learn more about the two types of metamorphosis in the Discovery Centre, and take a closer look at two exuviae from our Malaysian stick insects.

Exuvia of female Malaysian stick insect © Saffron Walden Museum

Exuvia of male Malaysian stick insect © Saffron Walden Museum

Image credit:
Female Southern Hawker – Tom Wiersma, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons. Accessed 25.5.2023.

Object of the Month – May 2023

Fossil Sponge from Radwinter

Saffron Walden Museum offers a free identification service for objects from north-west Essex. People often find interesting stones in their garden or in fields. Many of these are flint nodules. Flint is a hard rock that comes from chalk, a soft white limestone that is 200 metres thick in north Essex and Cambridgeshire. Chalk was formed as a limy mud on the floor of a tropical sea that once covered most of Britain and north-west Europe during the Cretaceous period 65-145 million years ago. The sea water contained dissolved quartz, or silica, originating from the skeletons of tiny sponges. As the mud was compressed into chalk the silica became concentrated as nodules or layers of flint. When the chalk became exposed as dry land, erosion by rivers released the flint and redeposited it as thick layers of gravel. Flint is often found as brown, iron-stained pebbles. Unweathered nodules, fresh from chalk rock, are black with a white outer surface.

Fossil Sponge, Radwinter

Occasionally flints contain fossils of sea urchins or cockle shells. You can see some of these fossils in the Museum’s geology gallery – The Earth Beneath Your Feet. This circular stone from Radwinter is a sponge called Porosphaera globularis which is fossilised in flint rock. The animal lived in the Chalk Sea that covered Essex 80 million years ago, during the age of the dinosaurs. The flint has been stained brown by iron in the soil. Circular flint nodules are often fossilised sponges, or they have formed around the nucleus of a sponge. The size can vary, from flints the size of musket balls to nodules the size of cannon balls.

Object of the Month – February 2023

A picture of a taxidermy common eider duck. It has a black cap to its head, a yellow beak, white head, neck and back and a black underside, with yellow legs and feet. Against a painted backdrop of a rocky mountain and hazy clouds.

This month we’re celebrating the Lost Language of Nature project, putting the finishing touches to this common eider. James and Charlotte have cleaned its plumage, repainted its beak and feet, and refreshed its base to help preserve it for future exhibitions.

Common eider mounted skin

Eider ducks are famous for their soft downy feathers which help keep them warm in freezing conditions. ‘Down’ comes from the Old Norse word ‘dúnn’, the word for the fluffy feathers of young birds and the same feathers which insulate adult birds. In adults, the down is hidden beneath the larger contour feathers which give birds their colour, patterns and shape.

A fluffy white feather on a black bacground

Down feather © Wouter Hagens, CC BY-SA 4.0, via Wikimedia Commons

These wild ducks can be ‘farmed’ sustainably for their down feathers, which are taken from the nests once chicks have fledged. This down is used to make traditional eiderdown pillows and quilts. In the UK, eider ducks are sometime called St Cuthbert’s duck or Cuddy duck, according to the belief that St Cuthbert’s holiness protected Farne island and its population of eider ducks.

Grassy and muddy ground wiht a grey nest of fluffy eider down. Three eggs are in the middle of the nest.

Eider nest © Paul Gierszewski (Gierszep), CC BY-SA 4.0, via Wikimedia Commons

Saffron Walden Museum wants to hear your stories about wildlife and nature in your life, or that you know from parents and grandparents, to help create more interesting, relevant and diverse displays in the future. Fill in a postcard in the Museum to join in or search online for ‘Lost Language Saffron Walden Museum’.

Learn more about this Object of the Month in the Museum throughout February.

Object of the Month – October 2022 – Alpine Swift

Dark alpine swift (Tachymarptis melba) on a white perch

This month we’re celebrating the Lost Language of Nature project, with repair work to this alpine swift. This bird has been cleaned and had its base refreshed to help preserve it for future exhibitions, and will be on temporary display in the Museum throughout October. Alpine swifts spend the warmer months around the Mediterranean Sea and further east, or in southern Africa, and spend the cooler months in parts of east and west Africa. This one was found or killed in Hinxton, Cambridgeshire, in 1832. They are related to the common swifts we see in Britain but are noticeably bigger. Old beliefs about swifts said that they had no feet, and the scientific name of the common swift and related birds – including the alpine swift and hummingbirds – even comes from the Ancient Greek for ‘without feet’.

We’d love to hear your stories about wildlife and nature in your life – rhymes, songs, saying, or names for plants and animals that you know from parents or grandparents. Fill in one of our special postcards in the museum, or click here.

Anyone and everyone has a story to tell, and your stories will help us create more interesting and relevant displays for everyone who comes to the museum in the future.

Alpine swift after conservation work

Swift work

This alpine swift is 184 years old and needed a good clean with special smoke sponge to remove dust and dirt from its feathers. Conservation work like this is always done very carefully, trying to avoid harmful chemicals, and using techniques that can be easily reversed if needed.
We cleaned its glass eyes with rubbing alcohol (isopropyl alcohol) and a hand-made cotton swab. The dust and dirt on the feathers can allow mould to grow, which damages the feathers because it produces acidic waste products. This bird had some possible mould patches underneath its tail and on top of its right wing, which we also cleaned with rubbing alcohol to kill and remove the mould.

We removed the swift from its base to paint the base white – you can see green splashes on the bird’s feet where the base was painted green in the 1930s without removing it. Birds are attached to their stands using wires from the bottom of the feet, and we had to cut one to remove the base.

Underside of bird with feet upwards. Wire protruding from foot on left of picture.

Alpine swift removed from perch, wire on right foot cut.

A new wire then needed attaching so the bird could be put back on its perch. We wound green florist’s green wire around the cut wire underneath the swift’s foot, and secured the new wire to its leg using Japanese tissue paper and conservation-grade PVA glue like tiny papier-mâché.

Underside of bird with feet upwards. New wire protruding from foot incentre of picture.

Alpine swift removed from perch, new wire on left foot.

Object of the Month – June 2022

June’s object of the month celebrates the Lost Language of Nature project, with repair work to this hen harrier. With Lost Language of Nature, we want to hear your stories about wildlife and nature in your life, or rhymes, songs and sayings for all kinds of animals that you might have heard from parents or grandparents. For example, different old names across the country for hen harriers include Blue sleeves, Vuzz kitt, Grey gled, Furze kite and Goss harrier; or Ringtail for females, like this fragile mounted skin. Head to our website for more information https://www.swmuseumlearning.com/the-lost-language-project

This bird came to the Museum in the 1800s, and was taken from the area around Saffron Walden. Today, hen harriers only live in the north of England, north Wales, in Scotland and on Scottish islands, including Arran and Orkney.

Hen harrier on temporary base during conservation work.

Hen harriers today

Hen harriers are one of the UK’s most endangered birds of prey, with only an estimated 545 breeding pairs left in the country. They are on the RSPB’s Red List of endangered species in Britain, but listed as ‘Least Concern’ globally by the International Union for Conservation of Nature.

Work carried out by the RSPB suggests that over 2,500 pairs could survive in the UK. They live in open areas with low vegetation, like heather moors.

Between 2014 and 2019, the RSPB ran the LIFE project to learn more about hen harriers in Britain, their movements throughout the year and to understand why their numbers are so low. They tagged over 100 birds that they tracked using satellites, and found that some fly 1000 miles to spend the winter in Spain and Portugal. Not all birds do this though – the brother of one of these wandering birds always stayed within 50 miles of where he hatched.

In the UK, hen harriers are protected under Schedule 1 of the Wildlife and Countryside Act, meaning it is illegal to kill, injure or capture the birds, their eggs or nests, or even disturb the birds and their young while they are nesting. Despite this, the study showed that the numbers of breeding hen harriers fell by 24% (about one-quarter) between 2004 and 2016. In particular, the project monitored seven Special Protected Areas in parts of the country where land is managed for driven grouse shooting. In these seven areas, hen harrier numbers fell by over 80%, which suggests that there is deliberate human action to reduce their numbers in these areas.

References

https://www.rspb.org.uk/birds-and-wildlife/wildlife-guides/bird-a-z/hen-harrier/

https://www.rspb.org.uk/our-work/conservation/projects/hen-harrier-life/about-the-project/

https://community.rspb.org.uk/ourwork/skydancer/b/skydancer

https://community.rspb.org.uk/ourwork/skydancer/b/skydancer/posts/hen-harrier-apollo-bomber-migrate-1000-miles-to-spain

https://www.rspb.org.uk/our-work/conservation/projects/hen-harrier-life/best-places-to-see-hen-harriersnew-page/

Object of the Month – February 2022

February’s Objects of the Month are minerals with connections to love and relationships, in honour of St Valentine’s Day on 14 February.

4 mineral specimens on a white background. Lines of shade cross the image.

Amethyst geode (top left), sapphire (bottom left), ruby crystals in sheet of mica (middle), lapis lazuli (right).

Amethyst is the birthstone for February, but as a symbol of love, St Valentine is said to have worn an amethyst ring so Christian couples in Ancient Rome could identify him. Valentine was a priest who carried out forbidden Christian marriages and married young couples, when the Roman empire persecuted Christians and preferred their soldiers to be unmarried men.

Lapis lazuli can represent truth and friendship, and in Christianity represents the Virgin Mary. With the blue of the sky and gold of the sun, it represents success in Jewish traditions, while beads found in the ancient town of Bhirrana from 7500 BCE are its oldest known use by people. The remains of Bhirrana are in the Indian state of Haryana.

The deep red colour of high-quality rubies means it is associated with love and passion in modern societies. Throughout history it has been popular in Burma (Myanmar), Hindu culture and China as a protective gem in battle or to secure good fortune when put beneath a building’s foundations. In the UK, it is the traditional gift for a 40^th wedding anniversary.

Sapphires are popular for engagement rings, as used for Lady Diana’s engagement ring from Prince Charles. Sapphire is the traditional gift in the UK for a 45^th wedding anniversary and can symbolise truth and faithfulness. Ruby and sapphire are actually the same mineral (corundum), with different colours depending on small amounts of other metal atoms included in the crystal. Chromium makes the ruby red, while blue sapphires are coloured by iron and titanium.

Object of the Month – October

Dark stone with faint tracing of a fossil flower in two petal shapes

October’s Objects of the Month are pieces of fossilised plants.

Fossils can form in different ways depending on where they form and the type of plant or animal. Most fossils come from the hard parts of animals such as bones, teeth or shells. For plants, wood is the most common material to fossilise because it is quite hard, and takes longer to rot away than other parts.
Soft leaves and flowers need to be buried quickly in deep sediment like mud or volcanic ash where the low oxygen levels mean they won’t rot. Once underground, plant material can fossilise in different ways.

Compression

This flower is probably preserved by compression, like pressing and drying it in fine mud over millions of years. Heat and pressure deep underground turned the mud to stone and forced moisture and gases from the leaf at the same time.

The main ingredient in living plants is carbon, so a thin, black, carbon-rich film is all that’s left. In most fossils, new minerals replace the original material. But because this is a compression fossil, the carbon-rich film is the exact same carbon that was in the plant millions of years ago. Soft-bodied animals like squid can also be preserved like this.

Impression

Dark stone showing inpression of a fern leaf, with fronds alternating in an exaggerated sawtooth pattern

This fern leaf, or frond, is preserved as an impression. When something soft is preserved by compression, the shape of it is also preserved as an impression, like pressing a leaf into soft mud or clay and then removing it.

This fossil is one part of a small rock nodule which was split in two to show the leaf – this part shows the impression of the frond. Because compression and impression fossils usually form together, the word ‘adpression’ describes both at the same time.

Petrification

Wedge of dark fossil wood, narrow at left. Lines of pale grey run top-bottom showing growth rings.

Fossilised wood is often called ‘petrified’ wood, meaning wood ‘turned to stone’. It happens when the materials (cellulose and lignin) that make up the solid part of wood are replaced by minerals, turning it to stone.

Minerals dissolved in groundwater seeping through the sediment settle as solids in the microscopic cell walls of the wood as the cellulose and lignin slowly rot. This can create a perfect stone copy of the original structure of the wood.

See these objects up close in Curiosity Corner throughout October.

Object of the Month – June 2021

A humpback whale leaping out of the sea. One flipper visible pointing left.

Humpback whale photographs taken by Barry Kaufmann-Wright in New Zealand, in 2013.

BK-W © Saffron Walden Museum

Image 1 of 5

BK-W © Saffron Walden Museum

Barry took and kept over 72,000 photographs in his lifetime, almost all of wildlife and the countryside. Barry grew up in Buckinghamshire but his first job was at Jersey Zoo, working for the famous naturalist Gerald Durrell.
When he returned to the UK, Barry joined Essex police and was posted to Thaxted, where he began duties as Wildlife Crime Officer and, later, Wildlife Liaison Coordinator for Essex. His photographs from all over the world are a modern treasure in the Museum’s collection, which also includes two slide projectors which he used when giving talks – up to 250 times a year (that’s 5 per week)!
Barry’s wife Pat very kindly donated his photographs and equipment following his death in 2016.

Humpback whales live in oceans all over the world, except the far north of the Arctic Ocean and around Antarctica in the Southern Ocean, where the sea is covered in ice. Whales are mammals, so sea ice stops them coming to the surface to breathe air.
They are grouped into four major populations in the north Pacific Ocean, Atlantic Ocean, Southern Ocean and Indian Ocean. They usually migrate between summer and winter ranges, but there are year-round groups around Britain and Norway, and in the Arabian Sea between India and east Africa.

– They can grow up to 16 metres long
Humpbacks are one of the largest whale species. Females are slightly larger than males, usually up to 16m (50ft) long. They can weigh 30 tonnes – the same as 2½ double-decker buses.

This picture shows the size of a humpback whale compared to a human swimming next to it, and its long pectoral fins. Image: Jjw, CC BY-SA 4.0 via Wikimedia Commons

– They have ‘big wings’
The scientific name of the humpback whale, Megaptera novaeangliae, means ‘big wing of New England’. Their ‘big wings’ are their giant pectoral fins – one female had fins that were 6m (20ft) long, as tall as a giraffe!
The ‘New England’ part comes from where humpback whales were first discovered by European whalers, off the coast of New England in the far north-east of the USA.

– Each animal’s tail is unique
A whale’s tail is called a fluke, and has a wavy pattern along the rear edge. Like our fingerprints, this wavy pattern is unique to each whale and is an easy way to identify animals in a group.
Compare this image to Barry Kaufmann-Wright’s photograph of a humpback’s fluke, above.

Image: Terry Howard CC BY-SA 3.0 via Wikimedia Commons

– They use nets to catch fish
Humpbacks migrate between summer and winter ranges and only eat for 6 months of the year, in the cooler waters of their summer range. Hunting and eating for 22 hours a day means they can build up enough fat reserves to survive their winter breeding season without eating.
Some populations of humpbacks have learned to feed in groups using the ‘bubble net’ technique and use vocal calls to work together. The whales swim in circles below a school of fish, blowing bubbles from their blowholes to create a ‘net’ that the fish won’t swim through. When one whale gives a feeding call, all the whales swim upwards inside the net with their mouths open to catch the fish.

A humpback whale using the bubble net technique on its own. Image: Christin Khan, NOAA/NEFSC, Public domain, via Wikimedia Commons.

– They sieve their food
Humpbacks are one of a group of whale species called baleen whales, which have bony, comb-like plates inside their mouths. With a mouth full of water and food animals, baleen whales partly close their mouths, and push water out through the baleen plates using their tongue. The baleen lets the water through but keeps in food such as fish and krill, which the whale then swallows.

Baleen plates and bristles in the mouth of a young gray whale. Image: Marc Webber/USFWS, Public domain, via Wikimedia Commons

Whale ear bone, probably from North Pacific right whale (Eubalaena japonica)

The North Pacific right whale is a baleen whale like the humpback.
This bone is the tympanic bulla and may have come from a North Pacific right whale. It’s a hollow shape but made of heavy, dense bone which helps sound resonate in the whale’s middle ear, inside the head. In life, it would have been attached to the petrosal bone, which has snapped off.

Smaller bones called the hammer, anvil and stirrup would sit inside the hollow space, and actually transmit the sound from the outer inner to the inner ear, just like in humans.

The North pacific right whale got its name because it is a large whale (up to 18m long but weighing 80 tons) with plenty of valuable blubber, it moved slowly, and would float after it was killed. It was the ‘right’ whale to go for because it was easy to catch and made lots of money for the whalers.

Image: John Durban (NOAA), Public domain, via Wikimedia Commons

More than 15,000 were killed by whalers in the 19th and 20th centuries. Today, estimates say there are fewer than 400 North Pacific right whales left, split between an eastern and a western population, making them the smallest known population of all whale species, As a whole, they are listed as Endangered on the IUCN red list, while the eastern population is Critically Endangered, with less than 40 animals.

Use this link to listen to a song about the dangers of whaling, based on the songwriter’s own experiences in Australia in the 1950s – www.swmuseumlearning.com/general-5

Object of the Month – February 2021

Water voles are probably best known from the character ‘Ratty’ from The Wind in the Willows. Recently described as “Britain’s fastest, declining mammal”, they are making a comeback thanks to careful wildlife management and the return of a locally extinct predator – the polecat.

Water voles are about the same size as a brown rat, but with a furry, much shorter tail, and small ears. Today, they are a semi-aquatic mammal, relying heavily on streams and rivers for food and shelter – they use their teeth to dig burrows into steep banks to shelter and raise their young.

Do water voles need water?

But it wasn’t always this way. They don’t show any of the usual adaptations for a water-based mammal, such as webbed feet and a ‘keeled’ tail (flattened sideways but taller top-to-bottom), both of which make otters very strong swimmers.
In the 1500s, rewards for hunting ‘rats’ may actually have referred to ‘water voles’ that lived entirely on land. Their burrowing habits and herbivorous diet would have made them an agricultural pest, which would explain the rewards paid for hunting them. Modern water voles are always found on waterways, so any hunting must have succeeded in wiping out fully-terrestrial water voles.

A population vole-ercoaster

In the 1990s and early 2000s, the number of water voles in the UK plummeted, making them Britain’s fastest-declining mammal. Surveys of water vole territories in Essex showed that 81% of recent territories were still occupied in 1990, but by 2005, only 7.5% of territories were still occupied in certain areas.
Such a drastic decline couldn’t just be down to habitat loss, and they are resistant to pollution – water vole colonies live in the banks of streams which run from landfill sites along the Thames estuary, and on rubbish-choked streams near Rainham.

Studies by Essex Wildlife Trust showed that crashes in water vole numbers closely followed local increases in the number the invasive American mink. These animals are not native to the UK, and became established after escaping or being released from fur farms from the 1950s onwards. Mink will hunt water voles in their burrows and in water, and a female can destroy a water vole colony in one breeding season. The water vole’s usual predators only hunt on land, and are too big to fit in their burrows.

Essex Wildlife Trust began work in 2007 to control mink numbers in key water vole strongholds, allowing water voles to recover, and spread. In 2012, more areas were put under mink control, and water vole colonies were relocated from sites destroyed by development along the Thames and M25. Surveys in 2013 showed that these colonies had survived and spread, with several new colonies established along the river Colne and its tributaries.

Ratty’s new best friends

Since 2000, wildlife surveys have found an ever-increasing number of polecats, a native predator which had been extinct in Essex for over 100 years. Polecats were hunted to near extinction across the UK by gamekeepers, who treated them as dangerous vermin, and they were also easily caught and killed in rabbit traps, which fell out of use in the 1950s. Polecats have probably spread into Essex from a targeted release in Hertfordshire in 1982-3.

Natural Sciences Officer, James Lumbard, with the skin of a recenltly-mounted polecat. The polecat was brought to the Museum after being found dead at the roadside. Image © Saffron Walden Museum.

Informal tracking and recording also suggests that the return of polecats may be helping water voles spread and recover more quickly, by reducing mink numbers. The same is true for otters, which are now returning to Essex, after being declared locally extinct in 1986. Both of these animals are native predators that rarely hunt water voles, but will compete with the American mink for food and territory, and are also big enough to hunt or kill mink. There are no studies to confirm it yet, but it could be very good news for water voles, and wildlife-lovers across Essex.

References

Are the otter and polecat combining to reduce mink numbers? East Anglian Daily Times, first published 31 March, 2019. Accessed 29.1.2021: https://www.eadt.co.uk/news/business/rise-in-polecats-and-otters-hit-mink-2562736

Mammals of Essex by John Dobson and Darren Tansley, 2014.

Image credit: Female Southern Hawker – Tom Wiersma, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons. Accessed 25.5.2023.

BK-W © Saffron Walden Museum

Image credit:
Female Southern Hawker – Tom Wiersma, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons. Accessed 25.5.2023.