two swifts looking out from their nesting area

A Swift Return to Summer

By Chris Jarvis, Education Officer

Amidst reports during the last week of Swifts being sighted feeding over the nearby Farmoor reservoir, Museum staff have kept their eyes to the skies eagerly waiting to be the first to spot our resident birds returning to their breeding site in the nest boxes of our tower. A wet and windy weekend caused by a deep depression over Britain meant little opportunity to feed on their diet of small flies and other invertebrates that make up the aerial plankton they relish, and which normally drifts unseen above our heads in large numbers on still summer days.  The high winds would certainly also have made any attempt to land, for the first time in a whole year since they left their nest boxes and for the first time ever for those just reaching maturity, extremely precarious, and so it seems our Swifts headed farther afield, possibly back to continental Europe, for a few days to await better conditions.

swifts flying around the museum tower against a cloudy sky
Swifts flying around the Museum tower by Mark Garrett

However, this morning, the 5th of May and right on cue, we were treated to the first two Swifts performing a low, high speed fly-by of the tower. Having flown around 14,000 miles in the last year from the Museum’s tower to their winter feeding grounds in southern Africa and back again, the Swifts have arrived on exactly the day of their average time of arrival over the last couple of decades.  We know this because the Swifts in the tower are part of an ongoing study which is the longest running study of any bird colony in the world, started by David Lack in 1947, our Keeper of the Swifts, George Candelin still climbs the spiral stone stairs and ladders each week under red lights to carefully and quietly monitor each nest box throughout the breeding season an count and ring each chick noting down all sorts of other data as he does so from wind speeds to egg rejections, weights and even altercations between birds in boxes over rights to nest sites.  Whilst you can’t be involved in the weighing and ringing of the birds, we do offer the next best way of getting involved; our nest box webcams, which you can find on our ‘Swifts in the Tower’ page, allow you to watch all the action live as it happens from the arrival of the adults to the final fledging as the next generation takes wing for the first time. Hidden microphones will also allow you to hear as screaming parties bang their wings against the nest box covers in order to ascertain if they are occupied and the keening noises of begging chicks!  George’s stats and comments will also be downloaded to the Swift’s Diary each week enabling you to get a full picture of what’s happening across the colony’s 147 nest boxes as the season progresses.

Swifts have markedly declined in numbers over the last few decades, and their breeding season is one of the few times anyone has to measure population changes and you can get involved, too.  Check out if there is a Swift City project near you like Oxford Swift City @oxford_swift or @EdinburghSwifts to get directly involved in monitoring projects or just record your Swift sightings to the RSPB at their Swift Mapper site. All your observations give us a really good idea of how these enigmatic summer visitors are doing!

Update-in the half hour it has taken to write this blog post: the number of Swift’s flying around the tower is up to 5-and they’re screaming!

Summer is here!

The astounding story of the fake butterfly specimen Papilio ecclipsis – would you be fooled?

For April Fool’s Day, our Senior Collections Manager Darren Mann recounts the story of an elegantly fake butterfly – Papilio ecclipsis – asking whether it was a piece of scientific fraudulence or practical joke that went awry.

James Petiver, a 17th-century London apothecary, was renowned for having one of the largest natural history collections in the world. Petiver (1665-1718) published some of the first books on British insects and created common names for some of our butterflies.

Volume 3, Plate II of Jones Icones – the two lower images are of Papilio ecclipsis

On plate 10 of his Gazophylacium naturae et artis — an illustrated catalogue of British insects (1702) he figured a unique butterfly that “exactly resembles our English Brimstone Butterfly were it not for those black Spots, and apparent blue Moons in the lower wings”. It was given to him by his late friend and butterfly collector William Charlton (1642-1702). This butterfly was later named Papilio ecclipsis by the father of taxonomy himself, Carl Linnaeus, in his 1763 work Centuria Insectorum Rariorum, and it became known as the Charlton Brimstone or the blue-eyed brimstone.

Petiver’s collection was purchased by Sir Hans Sloane (1660–1753), who later donated his entire ‘cabinet of curiosity’ to the nation, becoming the foundation for the Natural History Museum, London, originally part of the British Museum. It was here that wine merchant and naturalist William Jones (1745-1818) examined and later figured Petiver’s specimen in his Icones, an unpublished masterpiece of some 1,500 watercolour images of butterflies.

Jones’ Icones, held in the Museum’s archive, is the subject of numerous articles and is still examined by butterfly specialists the world over. Many of the specimens figured by Jones are no longer in existence, being ravished by pests or lost over time, so all that remains of these butterflies are the painted images within.

A drawer of British butterflies from the cabinet of William Jones. The Common Brimstone butterfly is the fourth from the right on the top row

When visiting London, Danish entomologist Johann Christian Fabricius (1745-1808) studied the paintings that Jones made and described over 200 species of butterfly new to science. Fabricius also visited the British Museum where he examined Petiver’s specimen of ecclipsis. In Entomologia systematica (1793) Fabricius revealed the enigmatic ecclipsis to be no more than a painted and “artificially spotted” specimen of the Common Brimstone (Gonepteryx rhamni). So, the dark spots and blue eyes were merely artistic licence, but whose?

Iconotypes, published by Thames & Hudson, will be available from October 2021

Petiver’s specimen, seen by both Jones and Fabricus in the British Museum in the late 18th century, had mysteriously disappeared by the following century. It is said that when Dr. Gray (1748-1806), Keeper of National Curiosities at the Museum, heard of the deception he became so enraged that he “indignantly stamped the specimen to pieces.”

It is still unclear whether this was an example of scientific fraud by Charlton, or if it was intended as a practical joke that went awry.

There remain two specimens of ecclipsis in the collection of the Linnean Society. Although it is uncertain who created these, it is believed that these replicas were made by none other than our very own William Jones, as he was one of the few who had the artistic skills to undertake such work. The forthcoming publication of Iconotypes, showing Jones’ Icones in all its splendour, will hopefully demonstrate how he had both the knowledge and the skill to recreate these fascinating fakes.

Links and References
Salmon, M., Marren, P., Harley, B. (2001) The Aurelian legacy: British butterflies and their collectors. University of California Press.
The Linnean Society https://www.linnean.org/
Vane-Wright, R. I. (2010) William Jones of Chelsea (1745–1818), and the need for a digital online ‘Icones’. Antenna. 34(1), 16–21