by Graham Crittenden VC 108 County Moth Recorder
In 2006, Butterfly Conservation launched a project to create a National Moth Recording Scheme (NMRS) to bring together the considerable amount of information being generated by individuals and local recording groups such as HBRG, to create an up-to-date accurate and accessible database of records of all of the 900 or so macro-moth species in the UK.
The NMRS uses the Watsonian Vice county system to define geographical areas and for each VC a County Moth Recorder (CMR) was appointed who collected, collated and assessed all available records. The CMRs maintain their own databases of records and submit them annually to the NMRS. In 2010 NMRS published a provisional atlas of the UK’s 900 or so macro-moths from the 11.3 million records accrued up to July 2010. A revised macro-moth atlas is due for publication in 2018 using all records up to and including 2016. The scheme has now been extended to include the 1600 or so UK micro-moths.
In 2010 the VC108 West Sutherland database held around 14,000 moth records which had been assembled by the then CMR Sue Agnew, mainly from information held in the Inverness Museum and Art Gallery database and by HBRG. Around half of the records came from year-round light trapping carried out post 1992 by Ian Evans and the late Lyn Fairchild at Nedd and Lochinver respectively (NC02 and13), with the remainder coming from field observations by other residents and visitors to the area.
Moths can be found in adult, egg, larval and pupal stages in every month of the year and year-round light trapping is a very productive way of monitoring which adult species are present and their abundance, with the caveat that not all moth species will come to light. You can do this in the comfort of your own garden and will be amazed at the number of beautiful moths that have been living along side you, largely undetected and unseen. You will be fortunate to record half a dozen butterfly species in a rural Sutherland garden, but in the same garden you can probably record in excess of 200 moth species
Given that year-round light trapping has been largely confined to the west coast area and from 2009, the north coast Melvich area (NC86), a vast swathe of inland West Sutherland remains to be surveyed in this way. Spring and summer visiting moth-ers, some armed with generators and battery operated traps, have contributed records, with the majority coming from the west coast and other roadside coastal and inland locations. The map below shows the moth species density for each 10km square, the larger the dot the more species recorded. NC02 has records for 389 macro-moth and micro-moth species and NC54 has only 9. This is a reflection of recording effort rather than true species density.
One of the omissions from the 2010 VC108 database was the moth records from the Rothamsted Insect Survey (RIS) standardised light trap network that operated at 3 locations. These are particularly valuable because they are the earliest year-round records that we have. The locations of these RIS traps and dates of operation were: Kirtomy (NC745635) on the north coast (1972 to 1974), Duartbeg (NC166190) on the west coast, (part of 1997 and 2000 to 2002) and Stronchrubie (NC251190) west inland, (1980 to 1984). There were approximately 5500 records from this source and in assessing the records it must be borne in mind that moths made up only a portion of the insects captured and the identity of the long-dead moths was determined by RIS staff or volunteers when the trap contents were returned to Rothamsted. In addition to the inevitable question marks over species misidentification, the possibility of data entry errors required consideration. As an example, doubts have been raised about the true status of the Common Swift moth in the north of Scotland and I found that the RIS Duartbeg trap had contributed 109 Common Swift records but all these occurred in only a single year. Further checks found that in that year, the number of records of the very common Map-winged Swift was zero but they were regularly recorded in every other year. As the two moths have consecutive British Lepidoptera checklist numbers and this number may have been used at some stage in the original data entry process, the mis-entry of a single digit had resulted in the erroneous records. There are also some intriguing RIS records. The RIS Duartbeg trap had a single record of a Sharp-angled Peacock in 2000 and at that time it was not thought to be a species that occurred in Scotland. However in 2008 an unidentified caterpillar found in Spean Bridge was raised and the adult proved to be a Sharp-angled Peacock and the species is now thought to be local and scarce Scottish species. It’s possible that the Duartbeg moth might have been the first Scottish record but we will never know and nobody has returned to search for the moth. The 2013 discovery of a colony of Blomer’s Rivulet; a moth not previously recorded in Scotland, at Lochaline on the Morvern Peninsula and a single moth trapped at Invermoriston in the following year shows that there are still discoveries to be made.
Light trapping is not the only way to find moths and many records from the more remote and inaccessible areas of VC108 have been made by people searching for the mines and galleries made on plants by the feeding activities of micro-moth larva. Often, moth larva feed only on specific plant species so a good botanical knowledge is of assistance in finding micro-moths. The larval food plant of the micro-moth Parornix alpicola is Mountain Avens and VC108 is the only place in the UK where the moth has been recorded.
In the past, recording micro-moths has to some extent been the preserve of the professional or serious amateur entomologist but with the help of recently published field guides and internet resources, many of these moths can now be identified. A very practical problem with micro-moth identification is that of getting a good look at a moth that might be only a few millimetres in size however digital cameras now allow us to take a picture, magnify it and at our leisure, identify the species or the family it belongs to. Not all micro-moths can be positively identified to species level by eye, particularly when wear and tear to scales has occurred. The recent inclusion of micro-moths in the NMRS has recognised this problem and regional panels of micro-moth experts have been set up to help CMRs to assess records. Finding micro moths in the field is particularly satisfying. On a walk in the Naver forest at Syre in 2017 I stopped to admire and photograph a Bird Cherry by the side of a forest track and noticed a 4mm micro-moth perched inside a flower. This was later identified as Glyphipterix forsterella, first recorded in the Lochinver area the previous year.
The micro-moth Pammene aurana, another 4mm beauty, was recorded in VC108 for the first time in 2016 – it was noticed taking the sun on a leaf in my garden at Melvich. Another was seen by Stephen Moran on Rabbit Islands, Tongue a few days earlier.
Many micro-moth records, particularly those from many years ago, have been lost or, more likely, recorded in a field note book which is no longer readily accessible. A recent comparison of the NMRS VC108 micro-moth records with an authoritative source of micro-moth distribution in Scotland, showed that no data was available on the where, when and who for several dozen species, even though they have probably been reliably identified.
Walkers and climbers get to places where moth recorders, often shackled to their light traps and generators, cannot. Therefore a casual sighting of a moth in a remote spot with a date, location and photo if available, can add to our knowledge of moth distribution. In 2013 a rather blurry photo of a moth taken by a visitor walking on Arkle was later identified as the VC’s first Broad-bordered White Underwing.
So what is the status of our knowledge on moths in West Sutherland?
- We now have over 40,000 moth records, with the earliest record being the micro-moth Xenolechia aethiops collected in 1892 in the Lochinver area. However with the overwhelming majority of records are post -1992.
- Some 325 macro-moths and 260 micro-moth species have now been recorded. In around 2000, Stephen Moran estimated that 169 species of macro moths had been recorded in VC108 but no figure for micro-moths was available (quoted in Appendix 1 of Enjoying Moths by Roy Leverton, Poyser Natural History, 2001).
- Records are available from 88% of the 10km squares wholly or partly within VC108 but for 13% of the squares the number of records is in single figures.
- The top 10 most abundant moths recorded in VC108 are: Hebrew Character, Magpie Moth, Silver-ground Carpet, Square-spot Rustic, Dark Arches, Ear Moth (aggregate), Rosy Rustic, Large Yellow Underwing, True Lover’s Knot, Diamond-back Moth.
- It is difficult to draw conclusions on the distribution of moth species within West Sutherland when the recording effort is so uneven geographically. The same applies to any long-term trends in species abundance given the paucity of records pre- 1990.
- New moth species continue to be added each year, some genuine new finds and others old records unearthed from various sources. In October 2016 a schoolboy found a dead moth lying on the road near Scourie, it was identified as the truly spectacular, Death’s Head Hawkmoth, the first recent record for West Sutherland.
Finally, a plea for moth records from HBRG members. There are now several ways by which moth sightings can reported to local recording schemes, noted in publications (like The Highland Naturalist) or uploaded to the internet for identification. It has therefore become more arduous for CMRs to trawl through these various sources to locate records and sometimes they lack any photographic evidence and information on the where, when, and who, to make them acceptable records. So when you see moths in VC108 or elsewhere in the Highlands, copy the record to the relevant VC CMR along with any accompanying photographic evidence. Contact information for CMRs can be found at the Butterfly Conservation Highland Branch website http://www.highland-butterflies.org.uk. You’ll get help with identifying the moth and feedback on your record.
Graham Crittenden, 55 Melvich, Sutherland, KW14 7YJ