Our survey work and methods of recording Glow Worms at Clipstone Old Quarter in Nottinghamshire, is regarded as being some of the most thorough, but it was impractical to expect Jenni to mark each female in the way we do, as part of the methodology we employ at Clipstone Old Quarter.

For the aims of this particular research, female marking/labelling etc was not required anyway. All that was needed was the total number of females within a given area, on every night throughout the entire season.

Habitat extremes - a brief introduction to two very different Glow Worm habitats

The right and upper right photographs, show part of Jenni's recording area on the Great Orme, with our own recording area of Clipstone Old Quarter in the two photographs below.

Jenni's Glow Worm study site is on the north-west coast of Wales on the Great Orme at Llandudno, Conwy and ours at Clipstone Old Quarter, an area of commercial forestry within Sherwood Forest, Nottinghamshire. Due to the expanse of the Great Orme, Jenni worked a much smaller area of the site each night (the comparison area), which she was able to cover easily.

Both sites also show huge differences in their respective Glow Worm populations. Whilst we are confident that Clipstone Old Quarter is one of the best inland colonies (its certainly the most consistantly recorded colony in the UK) our record single count of females is still below 100. Over the past few years, counts of many hundreds of female Glow Worms have been recorded by Jenni on the Great Orme and Robin Scagell of the UK Glow Worm Survey also counted over a hundred females on his visit there last year.

The resulting data proved to be especially interesting. Immediately obvious from the two graphs produced below, is the huge difference in the numbers of Glow Worms between the sites. Because of the higher Glow Worm numbers at the Great Orme, rises and falls are more evident in Fig 02. Rises in numbers are of course, caused by the sudden emergences of females. Falls are due to numbers of females being mated the night before, following a large emergence of males and females subsequently not glowing again.

At a glance, there may seem to be no comparison in the data at all, but there were five key points of rise and fall in numbers during the course of the season. Ignore the number of dates between the key points in Fig 01 and Fig 02, as for this study we were looking for the peaks and not the length of time between them.

The number of males at the Great Orme was astonishing and reached three figure counts on six occasions. Because of the sheer number of female Glow Worms on site, Jenni rarely had the opportunity to check for males with females. Instead, the extraordinarily high numbers of males, were largely to be found on the pavement below street lighting, situated at the end of Marine Drive near West Shore. Peak male numbers, interestingly occurred just after the peak numbers of females.

As far as we are aware, the number of times a male can successfully mate is still unknown. Possibly these are males that have already mated with females and are now largely spent. But could previously mated males be out-competed by freshly emerged, more vigorous males?, or is the attraction is just down to street lighting?

Fig 03 shows the seasonal site counts and male Glow Worm emergence and numbers at the Great Orme in 2013. We have superimposed the five key points of female emergence/peaks from Fig 01 and Fig 02, against the number of males each night on the Great Orme.

This proved interesting, as it showed that the peak number of males under street lighting, actually occurred just after the high seasonal peak numbers of females.

There is a small peak which coincided with peak numbers of females (key point 3) so does this mean that males were successfully finding and mating with females, then more greatly attracted to the street lights on the nights following mating? This could account for the slightly later peak in the number of males.

Although the number of males recorded at Clipstone Old Quarter never got near double figures, it was obvious through the high percentage of 'one night' females shown in Table 01, that male numbers were particularly high in 2013. Going purely by male counts, the peak dates for males at Jenni's Great Orme site was between June 3rd and 8th, with a maximum of 268 males on June 7th. Peak numbers of males at Clipstone Old Quarter came a few days earlier, between June 23rd and 29th.

It would help if similar comparisons between Clipstone Old Quarter and the Great Orme, possibly incorporating Glow Worm sites in the south of the UK or Scotland, could be made in the coming years. There's plenty of possible research options, as it is becoming clear to us, that we still actually know very little about the intricacies of Glow Worm biology.