Some personal statistical nonsense...... (1 Viewer)

Guys, I've been ''moth-ing'' now for seven years, mostly running the MV, not so much for it being a ''Big-Hitter'', more to do with if I oversleep, I can do so with a relative conscience, knowing that the birds, will not attempt to access the trap with the heat of the MV...keeping them out!

In this time I've trapped circa 200 species (a conservative estimate, to include some of the larger Micro species e.g Small Magpie, Brown China-mark, Mother of Pearl etc.).

Going through my list to date, I find that I've trapped just 5...'single occurence' species, which Include, one national rarity, one scarce out of habitat species, one not so scarce out of habitat species, and two nationally regular. Certainly a mixed bunch, the five equate to 2.5% of my approximate total.

I was wondering how my single occurrence percentage incidence compares nationally. Am aware that the dynamics of each ''moth-ers'' situation would be extreme, ie. trapping frequency/location etc. I thought perhaps a mean average might be of interest to others ? Cheers

I've been trapping for 9 years and have caught 347 Macros, 97 Micros (444 total), mostly from the previous and current garden. I have caught/seen 109 Macros on one occasion only. Although most of these are from visits to Dungeness or Durlston, but for the gardens (old and new) it is just 62/347 macros on one occasion only.

For any stats that is 17.9% across the garden traps. I think counting the visits to Dunge and Durlston skews the figures as I am bound to see different species less frequently as I don't trap there often, unlike the garden.

Andy M.

Andy1979 said:

I've been trapping for 9 years and have caught 347 Macros, 97 Micros (444 total), mostly from the previous and current garden. I have caught/seen 109 Macros on one occasion only. Although most of these are from visits to Dungeness or Durlston, but for the gardens (old and new) it is just 62/347 macros on one occasion only.

For any stats that is 17.9% across the garden traps. I think counting the visits to Dunge and Durlston skews the figures as I am bound to see different species less frequently as I don't trap there often, unlike the garden.

Andy M.

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Clearly you're a more fastidious moth-er than I Andy, and you've got a commendable list to date.

Just to confirm..17.9% represents all your ''single occurrence garden moths'' collectively over 9 years? Cheers

Yes, if by "single occurance" you mean I've only caught it once.

I don't keep separate garden records as such concentrating on my overall patch records. It's a pretty large area bordered by the River Yeo to the south, the River Avon to the north, the Bristol Channel to the west and the M5 to the east.

As a result, there is a nice mix of habitats - some mixed woodland, calcareous grassland, acidic damp grassland, ‎birch woodland, reedbeds, coastal saltmarsh, quarries and a limited rocky coastline. The macro total is currently about 440 species. My 'single occurrence' percentage is about 6% - around 20 species.

I would say even on macros:-
1. Gardens in very close proximity - less than a mile apart - can have very different lists on the wanderers as a result of which wind directions and weather conditions are favoured by their aspects and the positioning of their traps. I'm lucky that my garden and the other most trapped garden are complimentary. Other gardens that ran for a few years still have 'one offs' that have not been repeated on the patch eg Netted Pug and Golden Plusia.
2. It is possible to have breeding species (on even quite limited sites) that do not wander and can only be caught infrequently in very localised parts of those sites‎ - I have caught Reddish Light Arches twice in say 8 years on one site at a trap in exactly the same place and White-lined Snout four times to a trap in almost exactly the same place but both never anywhere else on the site and White-lined Snout never elsewhere on the patch. This is despite running multiple traps on the nights in question and many other times during the flight periods. I suspect both breed at the location. I have also recorded first patch records at sites that I have trapped dozens of times already by placing a trap specifically for a particular species eg my first patch Bordered White and our 'one off' Annulet. Before those records I had trapped within a few hundred yards of the locations where I eventually caught the species on multiple occasions.
3. Some species do not wander very much at all - I suspect that this is particularly the case with those that are unlikely to find suitable habitat elsewhere by wandering randomly eg Dark Spinach twice to a trap on saltmarsh at the same location and nowhere else on the patch and Crescent Striped once at the same place. Indeed Suspected is regular at a patch of birches in the centre of the Gordano Valley but I have never recorded it away from there.
4. Some will be genuine 'one offs' - I doubt I'll have another Silver-striped Hawk-moth or Scarce Merveille du Jour on the patch. A few will arrive and then continue to be recorded - Small Ranunculus and Brown-tail for us - and I expect the next Jersey Tiger (one record currently) any day with colonisation in due course. I suspect some of our wanderers and 'one offs' are from across the Bristol Channel - Glaucous Shears and Northern Spinach spring to mind.
5. There are species which are very common at some sites only a couple of miles off patch for which we have only a handful of records eg Blomer's Rivulet and Clouded Magpie and a single 'one off' in Satin Lutestring. I wonder if the M5 is a barrier for those species.

The single occurrence percentage would be exacerbated even further by micros – the majority of which I normally find in close proximity to the foodplant.

Of course, the more limited the location and the shorter the duration over which it is judged the higher the percentage that can be expected.

I have been recording in the garden for over 12 years and mobile on the patch for over a decade.

All the best

Very basic statistics, but since June 2011 I have had 286 macros in the garden, some of which would be either local or rare for Herts e.g. Jersey tiger in Aug 2012 was only the 2nd one for Herts (1st in 1930's) but are now more frequent, although it remains a single occurance for me. Only have county stats to 2006. However, 16 have only been trapped once, or 5.59% of my total. Note that 5 of the 16 have been my NFM's this year i.e. pine beauty, shark, chocolate tip, maple pug and small phoenix, so this also skews the figures.
Cheers,
Jono

Interesting that Paul and Jono have an average of c6% single occurrence records and Andy 18%, with self now on 2.5% (error with my previous stats...should have been 3.5%!) . My ''nationally not uncommon'' single occurences are...Puss Moth, Leopard Moth and Antler Moth with the rarer Marsh Carpet and Crimson Speckled being the rest (the latter being an immigrant could feasibly occur almost anywhere), however the Marsh Carpet appearing to be very much out of habitat (living adjacent horse-ride, deciduous woodland edge with stream), being the odd one out!

Since the thread was put up, I've added 3 more lifers which have been quickly relegated by more occurences!
Wave Black, Phoenix, and Kent Black Arches, also two second and third occurences...Dusky Sallow and Jersey Tiger.

Meaningless nonsense!...however quite interesting the relative increased incidence of three of the species mentioned, being regarded as nationally scarce and still holding a B rating?

Cheers

Personally I think that my biggest problem with moths is overlooking stuff either in, around or near the trap or amongst commoner species. The luxury of the time to go through things properly is rarely available.

All the bes

Paul Chapman said:

Personally I think that my biggest problem with moths is overlooking stuff either in, around or near the trap or amongst commoner species. The luxury of the time to go through things properly is rarely available.

All the bes

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Certainly agree with the loss of moths that ''rocket'' out passed your elbows whilst your focused on something that looks more ''interesting''.

I'd have thought nigh on impossible to quantify, but surely the traps contents, will always be a small percentage of moths attracted to the light, compared to the majority that are attracted momentarily, then disappear, or ''drop down'' in a gradated radius, away from the light source.

Cheers