Important chequered skipper butterfly records at RAMM

In February 2021 Jamie Wildman, a postgraduate researcher in Environmental Science at the University of Northampton, put out a call for information. He sought English records of the chequered skipper butterfly (Carterocephalus palaemon). This species became extinct in England around 1976. Reintroduction trials began 1990. Jamie is studying the species’ reintroduction in collaboration with Butterfly Conservation.

I sent him 54 records from RAMM’s collection. Some months later Jamie emailed me with the news that some of these butterflies hold considerable significance for his study. In the blog below Jamie shares his research. Jamie published a full write up of his work today in the Journal of the Natural Sciences Collections Association.

Background

In 2018, Butterfly Conservation reintroduced the chequered skipper butterfly to Rockingham Forest. This was part of the ‘Roots of Rockingham’ Back from the Brink project. Since the end of that project earlier in 2021, Butterfly Conservation has secured further funding through the Green Recovery Challenge Fund to continue its work on the chequered skipper. As part of the reintroduction project I’ve been researching the ecology of the butterfly and exploring its history in England.

History of the chequered skipper

The chequered skipper’s historic English distribution is poorly understood. Its extinction in the 20th century is generally accepted to have been caused by factors such as the abandonment of coppicing and coniferisation of its woodland habitat along. Loss of margins due to agricultural changes is also a factor. However, the butterfly’s decline is not well documented. There is a lack of hard data detailing how timings of woodland management and other environmental factors coincide with its eradication from sites.

In order to understand how the chequered skipper could be lost despite it once being locally abundant, a research collaboration between the University of Northampton and Butterfly Conservation was established in order to collect historic chequered skipper data. This includes date and locality information from museum and private collections, personal accounts, and other sources of uncollated data.

RAMM’s chequered skipper collection

RAMM houses an impressive collection of 54 chequered skipper specimens originating from several English Watsonian vice-counties. Northamptonshire, Cambridgeshire, Lincolnshire, and Rutland – where the butterfly was most abundant – are all represented in its collection. Most of its specimens are labelled as having been captured at historic strongholds such as Castor Hanglands, Wakerley Woods, and ‘King’s Cliffe’ (Fineshade Woods) in Rockingham Forest. However, RAMM also houses more unusual specimens hailing from further afield in Nottinghamshire. Two specimens are labelled ‘Linby’. This is a small village near Hucknall and Nottingham itself. Their true provenance is possibly the wooded Newstead Abbey area to the north.

Monk’s Wood

One specimen held in the RAMM collection is of particular interest as a memorial to the species in England. Richards collected it on 26 May 1965 at Monks Wood. That makes this specimen the newest (i.e. most recent) known English chequered skipper in a public collection with data meeting quality control standards. It is from Derrick Worton’s collection donated to RAMM in 2015.

Three newer examples dated between 1967 and 1969 held at other UK institutions lack full dates, or their exact provenance is unclear. They cannot be linked to a specific locality or year and have therefore been excluded from analysis. Chequered skipper records from Monks Wood go all the way back to 1829, making it one of the longest-known occupied sites in England. The final textual record from Monks Wood is dated only 6 years later in 1971. The butterfly was declared extinct altogether in England soon after in 1976.

Monks Wood was also home to the now-closed Experimental Research Station. It opened in 1963, and quickly gained an international reputation as a base for ecological research. It was to here that Lynne Farrell would submit her influential report on the status of the chequered skipper in England in 1973 – the foundation for most of our work into the species history. RAMM’s Monks Wood specimen is significant. Not just as a data point, but as a symbol of biological recording, the stories and people entangled with its heritage. It also marks what we’ve lost in the UK, both institutionally and in terms of biodiversity.

Wakerley Woods

‘L.H. Hare’ collected RAMM’s 1959 Wakerley Woods specimen. This is the last specimen known to have been collected at the site, which was its principal locality in Northamptonshire. It is dated 29th March which is much earlier in spring than the chequered skipper’s typical May-June flight period. It is also the earliest stated caught specimen in any given year from Wakerley. The butterfly was collected only two years before the last known Wakerley record (1961), when the species is thought to have been lost from the site altogether.

However, Hare could possibly have mislabelled his specimen. Every one of the 10 other known 1959 specimens housed elsewhere in the UK are dated between the 25th and 29th May 1959. The chequered skipper is typically on the wing for a maximum of six weeks . So it is unlikely to have emerged in late March and continued flying for over two months in such good numbers – especially at the end of its flight period.

Significance of RAMM’s butterfly collection

Much like a criminal investigator identifies suspects, label data must be complete enough to place the butterfly at a particular site at a particular time. This information is then interpreted as a sighting and inputted into the dataset as a record. This is much like someone would submit a butterfly sighting to a county recorder in the present day. Without this information, maps representing the species’ historic English distribution and abundance cannot be produced. Such maps enable us to analyse extinction patterns over time. Specimens not meeting quality control standards are therefore of limited use. Thankfully, RAMM’s 54 chequered skippers place it in the top 10 of UK museums to have contributed useful data.

Understanding the historic distribution of the chequered skipper and detailing how abundant the species was prior to its extinction in 1976 is not achievable without preserved museum specimens. Private collectors have provided 465 records, however 2175 new records originate from UK museums. As this huge quantity of data is publicly available, museums could be useful sources of data for other extinct or declining butterfly species. This could improve our knowledge of habitat requirements and identify causes of decline. It will also provide valuable information for potential future reintroductions that mirror the success Butterfly Conservation has had with the chequered skipper.

Part of a national data set

Read Jamie’s full research: Wildman, J. P., et al. 2022. The value of museum and other uncollated data in reconstructing the decline of the chequered skipper butterfly Carterocephalus palaemon (Pallas, 1771). Journal of Natural Science Collections. 10. pp.31-44.

I added RAMM’s 54 specimens to a dataset containing over 3800 new chequered skipper records. This data will be added to a the Butterflies for the New Millennium (BNM) database created by Butterfly Conservation in collaboration with the Biological Records Centre. Previously the database included just 266 historic chequered skipper records from England. Consequently, museums have had an unprecedented impact on the number of known English chequered skipper records. They prove its historic range, principally in Rockingham Forest and Lincolnshire.