Verifying moth records in Berkshire: 1 - overview

See also 2 - database procedures >>

What happens when you send in moth records for the county database?

Well, the first thing that will happen is that you will be thanked! We are always pleased to receive records, even one sighting of one moth can add to what we know about the county.

We also have a responsibility to check the records to ensure that they are accurate, as far as is humanly possible. We're keen that our records do reflect what is really happening to moths in the county, and records from the database are also shared with other organisations (see our Records Position Statement), including Butterfly Conservation and the Thames Valley Environmental Records Centre. These organisations use wildlife records to inform conservation projects and within the context of planning decisions, so again it is in everyone's interests to make the data as accurate as possible.

Incoming moth records for Berkshire are reviewed by the county verifiers (Martin Harvey and John Thacker), who check them against three main criteria:

• How difficult the moth is to identify (e.g. some species require dissection to be fully identified, and must be recorded at 'aggregate' level if this hasn't been done)
• How rare it is nationally and in Berkshire (species that are new to the county or have few previous records need documenting fully for new records to be accepted)
• What time of year it has been found (moths do sometimes turn up at odd times of year, but anything outside the normal flight period needs good evidence that it is correct)

We do our best to provide feedback to moth recorders about any interesting or unusual records, and will query anything that seems unlikely - hopefully this is always done in a polite and diplomatic way! The database procedures used to do this are described here for those who want to know the details. For some species photos or specimens may be requested, or confirmation from another recorder may be advisable. The Moth Group and the county recorder can advise on this, and see also our document listing the more difficult species.

How can you help?

The most important thing you can do is make sure you have documented all the relevant evidence. If you have found something unusual it is always best to get as much supporting evidence as you can to confirm the record. Such evidence might include:

• Keeping a specimen of the moth (‘voucher specimen’) to pass on to the county moth recorder or other Moth Group member (a live specimen may do the job if it can be passed on quickly).
• Getting a good photo (preferably several photos from different angles, and record the size as well).
• Getting a second (and third, fourth …) opinion from another experienced moth recorder.

If you have found a moth at an unusual time of year it's good to get a photo or keep the specimen, but also please do make a comment about it as part of your record - if someone records a summer moth in March and makes no comment about it being unusual, or having been double-checked, it looks like it could be an identification or data entry error, but if there is a comment along the lines of "this individual was exceptionally early, but it was checked carefully" that makes it clear that the recorder realised it was something out of the ordinary. See figures 1 and 2.

If you want to get help with identification from a photo you can share it via the Upper Thames Moths blog, the Berks Moth Group email group, or add it to the iSpot wildlife identification site.

What can go wrong?

Everyone makes mistakes sometimes, no matter how 'expert' they are: moths can be difficult to identify, and errors can also occur when writing down records or transcribing them onto a computer. If it is decided that a record is unsafe, it is removed from the county database and archived in a separate spreadsheet, just in case any queries subsequently arise, or further evidence comes to light.

About 1,500 records have been archived off the county database since 2007, which represents just over 1% of the almost 126,000 moth records submitted in that time. The vast majority of these have been as a result of doubt over the correct identification, followed by doubt over the date (i.e. a moth reported at an unusual time of year without supporting evidence), see Figure 3.

Of the 1,000 or so records removed due to identification problems, 618 (60%) resulted from just four common species that mistakenly get recorded at species level when they haven't been dissected:

• Grey Dagger
• Common Rustic
• Marbled Minor
• Lesser Common Rustic

Other species that are problematic and have to be rejected fairly often include:

• Dark Marbled Carpet (confusion with Common Marbled Carpet)
• Copper Underwing (Svensson's Copper Underwing)
• Ingrailed Clay (sometimes reported in late summer, where evidence is available these have proved to be misidentified Small Square-spot)
• Common Swift (sometimes reported in late summer, where evidence is available these have proved to be misidentified Orange Swift)

and among the micros:

• Cnephasia stephensiana (needs dissection to confirm)
• Caloptilia alchimiella / Caloptilia robustella (needs dissection to confirm)
• Pyrausta purpuralis (confusion with Pyrausta aurata)

I'm not going to 'name and shame' any particular recorders for submitting dodgy records! Suffice it to say that there is a correlation between the total number of records made by any one person and the number of errors - in other words most people make the occasional error, and if you record more moths you will make more errors, even though the percentage rate of error is tiny. There are some well-known names in the list of people who have had records removed (and one of those people is the county recorder!).