Swifts flying around the Museum tower

Flight and fight

By Chris Jarvis, Education Officer

Last week’s observations of the swift nest boxes in the Museum tower highlighted the drama the colony faces in the struggle for survival. This week’s survey made that struggle even more explicit…

Clambering through the darkened spaces of the Museum tower, lit faintly by the red lights that the swifts cannot see but which help give surveyors a dim view of the ladder rungs and observation platforms, I peered briefly into each nest box to count the birds and eggs.

In one box I came across a dead bird, alone and lying on its back. Carefully bagging up the body for later investigation I continued my count while pondering the cause of its death, the sadness relieved slightly with the discovery of new eggs in other boxes and the promise of new life to come.

The body of a dead swift found during the weekly survey of the colony of birds in the Museum tower

Screams and banging from birds prospecting for nest sites are a regular backdrop to each survey. Birds call and swoop past the boxes only inches from my ears, separated by just a few roof slates. The birds within scream back in answer. But on this occasion, half way down the tower, I became aware of particularly loud and persistent screams and banging, coming from within a box.

A quick peek inside revealed a hectic struggle between at least three swifts, wings drawn back, wrestling and rolling around, pecking and slashing at each other with their sharp claws. It was actually impossible to see if the fight involved three or four birds as the struggle filled every inch of the small box with wings, beaks, claws and feathers.

David Lack first documented these fights in his excellent book Swifts in a Tower. He proposed that they were the result of birds entering an already occupied box in the struggle to find a suitable nest site.

Swifts flying around the Museum tower
Swifts circle the tower prospecting for potential nest sites, screaming and banging to check which are occupied and which are vacant. Image: Gordon Bowdery

Sitting and anxiously listening beside the box, I recorded the fight lasting 15 minutes from the time I became aware of it. Lack documented ‘gladiatorial shows’ that lasted five and three quarter hours; they were painful to watch, he admitted, as the swifts have a surprisingly strong grip and claws capable of drawing blood, but rarely resulted in death.

When the noise died down, I gently lifted the cloth blind to take another look. Only two birds remained, both looking exhausted and fiercely gripping each other’s feet, one lying under the other. A quick flurry and the upper bird disengaged and jumped from the nest box entrance.

Cover of 2018 edition of Swifts in a Tower by David Lack
Cover of the 2018 edition of Swifts in a Tower by David Lack

Lack also mentions in his book that it is usually the bird underneath in these struggles that is the winner and I was relieved when the remaining bird picked itself up and returned to the two eggs, which had somehow remained in the nest, settled on top of them and preened itself. This suggested that the nest’s original occupant had won, driving off an intruder.

The screaming and banging outside the boxes is a check for a screamed response from within. It reveals whether a box is already occupied or empty, before the bird risks entry. Presumably, the fight I witnessed was the result of a bird not hearing a response or perceiving it as coming from another box.

The drama of the fight illustrates the incredible importance of nest sites and the fidelity the swifts have to them after a year on the wing. Nest sites are at a premium and swifts are almost totally dependent on nesting in old buildings as there are so few forests with suitably old, cavity filled trees remaining.

Once a nest is occupied the owners will fight furiously to defend it and David Lack did record occasional incidents of birds fighting to the death. So perhaps this was the cause of the dead bird I had found lying on its back, but that will have to wait for a later examination.

Meanwhile keep an eye on our nest box; you never know what drama may play out next…

It is important to record nest sites and, if you can, put up nest boxes. RSPB’s Oxford Swift City project, which the Museum and Oxford City Council were involved in, annually surveys and records nesting sites so that development in these areas is restricted during the breeding season and developers must include plans to protect and provide new nest sites when repairs to property or new building takes place. If you would like to help with the work of conserving one of the most dramatic annual migrants to our shores visit the RSPB site.

Through the looking glass

With our Life, As We Know It redisplay project now underway, our Senior Archives and Library Assistant Danielle Czerkaszyn takes a behind-the-scenes look at how we captured the contents of the current displays for the Museum’s archive.

The archive here holds a unique collection of natural history books, journals and documents covering a wide range of subjects related to the Museum’s collections and research. It also contains papers and objects on the history of the building, providing an institutional memory of Oxford’s ‘University Museum’ since its foundation in 1860.

From an archive perspective it was really important to document the current layout of the cases, their specimens and text before they were removed from the court to make way for the new showcases in the first phase of our redisplay work.

The museum in late 2019

The displays as we know them – with exhibitions on the Oxfordshire dinosaurs, Alice in Wonderland, the Oxford Dodo, and more – were last changed in 2000. For the last 20 years visitors to the Museum would remember their first time being wowed by the Megalosaurus jaw – the world’s first scientifically-described dinosaur – or charmed by the Dodo made famous in Lewis Carroll’s Alice Adventures in Wonderland.

Although after 20 years it is time for a change, the stories and information in the displays are too good to be forgotten. So before anything was removed we began to build the archive for the future.

A display of the fossilised remains of Megalosaurus
The previous display on Megalosaurus: The First Dinosaur

The best way to capture all the information of the displays was through high resolution photography, but this was not as straightforward as we hoped.

The first two obstacles to good photographs are pretty obvious to anyone looking at the cases: glass causes huge amounts of glare; and each case has a big dividing line down the centre where the two sliding glass doors meet, cutting what should be a lovely seamless image into two halves.

To avoid glare and the solve the problem of the dividing line, our photographer Scott opened each individual side of the case, photographed two or three images of the display, and then stitched the separate photos together using Photoshop.

Each case was photographed in two or three segments
The segments were then stitched back together and adjusted for exposure and colour balance to create the final image

Another obstacle to taking good photographs of the displays came from the Museum itself. Some of our larger display furniture, such as the glass case for the Atlantic Bluefin Tuna or the huge T. rex plinth – got in the way of a nice straight shot. Because these items are so large and heavy they were impossible to move, so we had to improvise and do our best.

Capturing the displays before the current cases were removed allowed us to keep an archival record of their contents

Thankfully, we managed to get shots of all 24 displays before they were removed and so a record of each case now rests with the Museum’s archive. If anyone wants to know what the display cases in the court looked like from 2000 to 2020, they will now be able to look back at the images in the archive and recall the magic of the Oxford Dodo exhibit that perhaps first made them fall in love with the Museum.

Our new displays are now in development, and will include some beautiful presentations of the diversity of life, looking at the importance and fragility of biodiversity and human impact on the environment. These new exhibits will show how the biological processes of evolution combine with the geological processes of our dynamic Earth to give rise to the immense, interconnected variety of the natural world.

We look forward to telling you more about that here as the project progresses.

The Life, As We Know It redisplay project is supported by a generous grant from FCC Communities Foundation.

Mammoth tusks and cocktail sticks

By Pete Brown, Move Project Assistant

As part of the Museum of Natural History Move Project Team I have helped move and repackage tens of thousands of specimens since 2017, removing boxes filled at any time over the last 150 years from their old storage location in a deconsecrated church building near Oxford.

At our new facility we have been documenting and repacking the contents in new, clean containers and placing them in environmentally stable, safe warehouses specially adapted for museum storage.

Some objects are trickier to store than others. Things that are long, heavy, curvy and fragile are tricky. Mammoth tusks are long, heavy, curvy, and fragile. This means:

  1. They’re not going to fit in a normal box.
  2. They’re going to be difficult to move around.
  3. That beautiful curve will mean that all the weight of the tusk may be bearing down on just two small contact points where the tusk meets the storage surface.
  4. Because those points are fragile, they’re likely to get damaged.
A lot of weight can rest on small areas of the tusk, putting strain on the specimen and potentially causing damage

The tusk in this article is a prime example. The area nearest the camera in the photo above provided just a tiny point of contact with the floor and was very loose, almost to the point of detaching. It needed to be repaired, and stored in such a way that it wouldn’t get damaged again.

Pete Brown carries out delicate conservation work on the mammoth tusk

I filled some of the missing areas around the fragile area with an easily removable fine acrylic putty to prevent further movement and loss of the original material. A cotton tape sling helped to suspend the fragment in place during the work.

Thick plastazote provided a sturdy, slightly yielding bed for the tusk to lie on in storage, but to prevent the tusk from getting damaged again more needed be done to reduce the pressure on the points of contact.

The dark grey foam material, plastazote, is often used as a cushioned support for museum objects

I cut depressions into the plastazote where the tusk naturally lay to increase the total surface area supporting the weight of the tusk, and fixed plastazote wedges and supports in place with cocktail sticks to again increase the contact area and prevent movement. Cotton fabric ties, fed through slits in the plastazote, also helped to guard against unwanted movement.

Cocktail sticks: not just for cheese and pineapple

The repaired end of the tusk is now only supporting a fraction of the weight it used to, and once the tusk and the plastazote bed are placed into their new custom-made crate it will be ready for long-term, safe, damage-free storage!

The end of the tusk after treatment

To keep up with all the move project action, follow the museum hashtag #storiesfromthestore on Twitter @morethanadodo.

 

Bee beautiful

Our conservator Bethany Palumbo tells us how she restored a beautiful 19th-century papier-mâché model of a honeybee hive, created by master model-maker and anatomist Louis Thomas Jérôme Auzoux

Louis Thomas Jérôme Auzoux

Although the Museum’s collections are mostly of organic specimens, we also hold a fascinating collection of scientific models made to represent the natural world, made from all types of materials, from wax and cardboard to plaster and paint.

We are lucky enough to own a model made by esteemed French anatomist Louis Auzoux (1797-1880), who in the late 19th century developed a method of building strong yet light papier-mâché models that could be taken apart and rebuilt, allowing internal elements such as tissues and organs to be studied in detail.

Model of a honeybee hive in box with six bees, by Louis Auzoux

While Auzoux made many models demonstrating human anatomy, he later expanded his business to include magnified models of plants and insects. The model we have is of a honeybee hive, containing six beautiful bees.

The hive, painted with a protein-based paint and varnished with gelatine, is large enough to allow the viewer to see the fine details of the hive, including individual chambers containing tiny larvae.

As you can see in the image at the top of the article, the bees themselves are also intricately painted, with rabbit hair used to simulate their natural fuzz, and delicate wings constructed from metal wire.

While there was much to admire about this model, it was in received in poor condition. Previous restoration attempts had introduced many materials that were now failing. There were fills, constructed of paper, applied to areas in an attempt to hide cracks in the original model. These were covered in oil paint, which was dripping over the original paintwork and had become brittle and discoloured.

Oil paint layers were peeling from the model

The whole hive was coated in a layer of cellulose nitrate film, a popular coating in the mid-20th century which was used as protection and to create a gloss finish. This coating doesn’t age well, resulting in peeling. It had also been applied to the bees themselves, clumping together the bee ‘fuzz’ and disguising the paintwork underneath.

The priority for treatment was to return the model to its original form while stabilising it for the future.

I undertook treatment in several stages over the course of six months. First, the cellulose nitrate film was removed from all areas using acetone, which could be applied with a cotton bud and fortunately didn’t affect the paint layer beneath.

Fill material used to cover previous damage had become discoloured

The next stage was to remove the discoloured oil paint from the hive. This was done manually using metal and wooden tools lubricated with white spirit, which were used to gently scrape the surface under magnification. This revealed old fills on the hive, made from a combination of plastic tape, paper and old adhesives which also needed to be removed. They were easily softened with water and gently peeled away.

Once all unstable introduced materials were removed, work began to stabilise the original model. The bees were suffering from paint cracking and peeling, as seen in the magnified photograph below.

Peeling paint at 6x magnification

We decided to consolidate this using gelatine as it would be in keeping with the original construction and could easily be reversed if necessary. Gelatine was mixed in water and warmed to make it a thin consistency, and then applied with a paintbrush. Once the paint flakes had softened they could be gently pressed down. Gelatine was also used with acid-free tissue to stabilise the cracks and areas of surface loss on the hive.

With the hive and bees now clean and stable, the quality of this piece and its incredible paintwork can really be admired. We hope to put it on display soon for all our visitors to enjoy!

Restoring the Great Lizard of Stonesfield

by Paul Smith, Museum director

One of the unusual things about the collections in the Museum is that some of the specimens date back hundreds of years, and so have been researched by generation after generation. Sometimes these specimens have been damaged and repaired, and in some cases this has happened many times, leaving a complex history of research and conservation.

One high profile example is the type specimen of the theropod dinosaur Megalosaurus bucklandii – the world’s first scientifically described dinosaur. This specimen itself is the lower jaw, pictured above, which has been in the collections of Oxford University since 1797 at the latest.

Working with the Centre for Imaging, Metrology, and Additive Technology (CiMAT) at WMG, University of Warwick, we have been unraveling the conservation and repair history of the fossilised jaw using an innovative combination of modern technologies.

Identification of repair using X-ray computed tomography (XCT ) from the Megalosaurus bucklandii type specimen. The two colours indicate two different types of plaster material. Scale bar is 10 cm.

Earlier studies had mapped the presence of plaster used for repair, but X-ray CT scanning of the type used in medical procedures rapidly revealed a number of different phases of repair. In each of these repairs the plaster was of different composition and was used in different places.

One type, shown in red on the image above, was used to infill fractures and to make the specimen more robust; a second type, shown in green, was used to repair the teeth and, in some cases, to recreate the teeth. Interestingly, the extent of plaster revealed by the CT scanning is actually less than previously interpreted with the naked eye.

The two types of plaster were then analysed chemically to better understand their historical use, revealing quite different compositions. The more abundant ‘red’ plaster is mixed with quartz sand and calcite grains, possibly from the rock matrix surrounding the fossil, to make it look more similar.

Carbon is also abundant and grains rich in lead are present. Carbon is not common in the rock itself, and the carbon in the plaster has probably come from a varnish such as shellac being used to coat the repair.  The presence of lead was more puzzling. Further analysis eventually showed that the grains were made of red lead – lead tetroxide – which was used historically as a pigment in paint. The red lead in the repair may have been used to colour the plaster, but it may also have been applied to make the density of the plaster more similar to that of the fossilized bone, and so replicate the weight of the specimen better.

Reconstruction of Megalosaurus bucklandii by Julius T. Csotonyi

The second type of plaster, used to repair the teeth, lacks the lead of the first type but contains barium. Barium hydroxide was often used as a consolidant and sealant for plaster, which would explain its use here.

Having a full understanding of the repair history and the position and extent of plaster helps us in a number of ways. It allows researchers to understand which parts of the lower jaw are original and anatomically reliable, and it helps the curators and conservators to know which parts of the specimen are more fragile during handling and display.

By combining cutting-edge scanning technologies with heritage material we are able to shed new light on the conservation history, and future, of important specimens such as Megalosaurus bucklandii.

Read the full paper here.

Pieces of a plesiosaur

We’ve just opened a brand new, permanent display called Out of the Deep, featuring two beautifully preserved plesiosaur skeletons. Remarkably, both of these marine reptile fossils have skulls, which is more unusual than you might think. Dr Hilary Ketchum, collections manager in the Museum’s Earth Collections and curator of Out of the Deep, describes how the skull of the long-necked plesiosaur made it safely from a quarry to a museum display.

At the bottom of a clay pit in 2014, palaeontologists from the Oxford Clay Working Group discovered a 165-million-year-old fossil plesiosaur skeleton, and they knew they had found something special. Plesiosaur bones are fairly common in the quarry, but skeletons are rare. Skeletons with skulls are rarer still. Fantastically, at the end of their newly-found plesiosaur’s neck was a skull. Barely visible underneath the clay, only the tip of the snout and a few teeth were exposed.

Can you see the skull? Fossil hunting in the quarry takes time, patience and a good eye to distinguish between bones and clay. Image: Mark Wildman, Oxford Clay Working Group.

Plesiosaur skulls are usually made up of around 33 bones, not including the tiny bones from inside the eye sockets, called the sclerotic ring. The skull bones are among the smallest and most fragile in the entire skeleton. This means they are much less likely to be preserved, and less likely to be discovered, than the larger and more robust backbones and limb bones.

A plaster jacket was made around the skull while still in the quarry.
Image: Mark Wildman, Oxford Clay Working Group.

When the plesiosaur skeleton arrived in the Museum in 2015, the skull and some of the surrounding clay was encased in its protective plaster field jacket. As tempting as it was, instead of cracking open the jacket straight away, we decided on a more technological approach. Professor Roger Benson and Dr James Neenan took the specimen to the Royal Veterinary College to use their enormous CT scanner, normally used for scanning horses and other large animals, and took thousands of X-rays of the jacket. This allowed them to build up a 3D model of the fossil inside – our first tantalising glimpse of the whole skull!

The CT scan of the plaster jacket (left) revealed the location of the skull inside the jacket (middle). The jacket was then digitally removed (right) to reveal a 3D image of the skull.

Having the CT scan of the skull was like having a picture on a puzzle box
Juliet Hay, Earth Collections conservator and preparator

Although the CT scan was incredibly useful, we still had to proceed with the preparation with caution. It was possible that not all of the bones had not been detected by the scanner, especially the incredibly thin bones of the palate.

After opening the plaster jacket, Juliet began to carefully remove the clay from around the fossil bone.

Slowly and carefully, Juliet and I removed the soft clay from around the skull. The weight of clay pressing on top of the skull for millions of years had crushed it, breaking some of the bones into a lot of smaller pieces. In order to keep track of them we attached a number to each piece of bone and photographed it from several different angles before removing it from the jacket.

Each individual bone was mapped using a numbering system. The numbers were attached with the conservation adhesive Paraloid B72 in acetone, so that they could be easily removed later.
The plesiosaur’s pointed teeth being revealed.

When all the bones had finally been removed from the clay, we had over 250 pieces. Next came the challenge of the three-dimensional jigsaw!

With knowledge about plesiosaur skulls from my PhD, and some extra expert help from Roger Benson and Dr Mark Evans, Curator of Natural Science and Archaeology, New Walk Museum and Art Gallery, I was able to build up the skull, piece by piece, until it was nearly whole again.

After many months of painstaking work, the beautifully preserved skull of this long-necked plesiosaur can finally be seen in the Out of the Deep display.

Amazingly, the skull is even more complete and more beautifully preserved than we could tell from the CT scan. The sutures between the individual bones can be seen in exquisite detail, and even though I work with fossils every day, I still find it amazing that it is 165 million years old.

*

With special thanks to:

Oxford Clay Working Group: Mark Wildman, Carl Harrington, Shona Tranter, Cliff Nicklin, Heather Middleton, and Mark Graham, who uncovered and excavated the long-necked plesiosaur.

Forterra, for generously donating the plesiosaur skeleton to the Museum, after it was discovered in a Forterra quarry.