Finding out what people thought about their own mothing year is always a fascinating exercise. Around this time in December I try and present a few statistics on what the year has been like for moths in my garden in the hope that others may by now have had time to do something similar. In fact the numbers for Westcott are very much provisional at the moment because many of the dissections needed to complete the data for 2021 have yet to be carried out, but there is still sufficient information to give an idea of what the results were like.
Just to be clear, it is the comparison with previous years at a particular site which brings out important information, not the comparison between here and other sites in the same year. Different sites will always produce different results and I'm well aware of how lucky I am to be trapping in this particular edge-of-village garden, surrounded by a reasonable amount of decent habitat.
Number of nights the traps were run (1st Jan to 30th Nov): 303, of which 158 were with a single trap (twin-30wt actinic) and 145 were with two traps (actinic and 125wt MV). The overall number of nights was fairly typical (300 in 2019, 317 in 2020, again to the end of November) but there was a significant reduction in two-trap nights thanks mainly to dismal weather in April and the first half of May.
Number of species caught: at least 650 (circa 330 macros) but will be higher when dissections are complete. That compares very well with totals achieved over the previous five years, from which the average is 670.
Nights with 100+ species: 13, all in July and using both traps (up very slightly from 11 the previous year but still well down on the 26 of 2018 and 19 in 2019).
Best night for moth numbers: 18th July, 821 moths of 165 species. The best night would normally see a count above 1,000 individuals. However, although provisional (depends on dissection results), the species total of 165 currently equals the highest ever recorded here on a single night.
Highest overall counts for a single species: Common Footman (2,029), Setaceous Hebrew Character (1,624) & Common Wainscot (1,060) for macros, Chrysoteuchia culmella (716), Acentria ephemerella (524) & Agriphila tristella (310) for micros. Those three macro species were the only moths to score above 1,000 individuals in 2021, the results for Large Yellow Underwing, Heart and Dart, Square-spot Rustic, Dark Arches etc being quite poor. However, Setaceous Hebrew Character bounced back after a very poor showing the previous year so it is probably all swings and roundabouts.
New for the site in 2021: Six macros and at least nine micros. The new macros were Balsam Carpet & Cypress Carpet (both spreading), Beautiful Marbled (migrant), Red Sword-grass (probable migrant) & Radford's Flame Shoulder (migrant), as well as the Japanese Silk Moth Antheraea yamamai which was obviously a local release or escapee.
Total number of moths caught in the garden (1st Jan to 30th Nov): circa 29,000 which is a very disappointing total, down by 25% on the count for 2020 and by almost 50% on the record count for 2019.
In summary then, moth diversity was at expected levels but moth abundance was much reduced, due at least in part to poor weather during the early part of the season.
Dave Wilton Westcott, Bucks
I don't do an analysis to anything like that depth but in terms of numbers of moths I was well down this year. This included even common moths like all the grass veneers, Beautiful Plume. In terms of numbers of species I was well up, even accounting for the pheremone lures which I used for the first time this year. Overall the theme was of reduced abundance, increased variety.
ReplyDeleteAlways interesting to see your annual summary Dave. I have yet to get my Mapmate entries up-to-date, but the number of species caught in the garden this year is currently 315. This is slightly better than last year, but nowhere near the 395 achieved in 2018.
ReplyDeleteMy most numerous species for the year was the Garden Grass-veneer Chrysoteuchia culmella, while the top 3 macros were Heart & Dart, White-point and Common Footman. White-point seems to have done particularly well this year in my area.
Amongst the many moths I haven't seen this year was Hummingbird Hawk-moth, and I don't recall anybody mentioning it on this blog this year. Has it been a bit scarce in 2021?
Thanks, Steve. I saw a Hummingbird Hawk-moth working its way around one of our buddleias on 3rd August and that same night another one (or more likely the same individual) came to the actinic trap. They were my only sightings of 2021 so I'd have to agree with you that the species had a very poor year.
ReplyDeleteThere were a few moth species which put in their best ever counts here during the year, including December Moth, Poplar Hawk-moth, Blood-vein, Barred Straw, Common Marbled Carpet, Willow Beauty, Light Emerald, Pale Prominent, Snout & Poplar Grey. However, I did have some surprising no-shows too, of which the most odd was Engrailed which has never failed to appear here in any other year. Further species which didn't turn up at all included Frosted Green, Spruce Carpet, Oak Processionary, Dusky Brocade, Nutmeg, Dot Moth & Double Dart.
Just two records for Humming-bird Hawk-moth here (Loosley Row, Bucks) this year. 22th June and 9th September.
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