Monday 1 October 2018

Gatwick's first butterfly transects

Clouded Yellow Colias croceus f. helice, North West Zone 
(Photo by Vince Massimo)

This was our first year of conducting a butterfly transect in the North West Zone (NWZ). I had expected it to be at times quite trying and physically demanding... and THEN we had the heat wave!

Our NWZ transect is 2.5km in length, which comprises of a route along the River Mole corridor, over the large clay mound (where a colony of Long-horned Bees reside) and the edge of Brockley Wood. We completed 26 weeks of surveys and the almost-constant sun allowed us to easily fit in surveys during the optimum weather conditions.

The UK BMS website has a useful reporting feature, which makes it quick to work out a few simple stats:
We recorded 2,885 butterflies over 26 weeks
The highest count of the year was 509 butterflies on July 8th.
The average temperature for the walks was 20 degrees and level of sunlight was 82%

Peak counts for the top 5 species in NWZ:
  • Meadow Brown peaked at 197 species (June 17th)
  • Gatekeeper was next at 157 (July 8th)
  • Small Skipper at 129 (July 1st)
  • Ringlet 115 at (June 24th)
  • Common Blue peaked at 42 on June 3rd then had a resurgence on July 22nd, reflecting two main flight periods

Low abundance species (single records):
  • Green Hairstreak
  • Clouded Yellow
  • Painted Lady
We had only two records for Small Tortoiseshell, both occurring in April.

With a regular group of volunteers the transect progressed well, so we decided to set up a second transect in the Land East of the Railway Line (LERL). We only began this about midway through the season, it doesn't result in a full year's worth of data, but still good to have it up and running.

A few highlights via photos taken by Vince...

Marbled White Melanargia galathea

Purple Hairstreak Favonius quercus

Clouded Yellow Colias croceus f. helice

Ringlet Aphantopus hyperantus 

A huge thank you to all the surveyors who volunteered their time for butterfly recording at Gatwick: Vince, Peter, Sue, Abigail, Tara, Yasmin, Emily and Ryan. I can't wait now until spring... only 27 weeks to go!

The 2018 species list:

Common Name
Species name
Small Skipper
Thymelicus sylvestris
Essex Skipper
Thymelicus lineola
Clouded Yellow
Colias croceus

Large Skipper
Ochlodes sylvanus
Dingy Skipper
Erynnis tages
Large White
Pieris brassicae
Small White
Pieris rapae
Green-veined White
Pieris napi
Orange Tip
Anthocharis cardamines
Green Hairstreak
Callophrys rubi
Brown Hairstreak
Thecla betulae
Purple Hairstreak
Favonius quercus
Small Copper
Lycaena phlaeas
Brown Argus
Aricia agestis
Common Blue
Polyommatus icarus
Holly Blue
Celastrina argiolus
Red Admiral
Vanessa atalanta
Painted Lady
Vanessa (Cynthia) cardui
Small Tortoiseshell
Aglais urticae
Inachis io
Polygonia c-album
Silver-washed Fritillary
Argynnis paphia
Speckled Wood
Pararge aegeria
Marbled White
Melanargia galathea
Pyronia tithonus
Meadow Brown
Maniola jurtina
Small Heath
Coenonympha pamphilus
Aphantopus hyperantus
Gonepteryx rhamni

Total no. species = 29 NWZ    19 LERL

Previously recorded but missing from our transects in 2018:
Grizzled Skipper - NWZ
Purple Emperor - NWZ
White-letter Hairstreak - NWZ & LERL
White Admiral - NWZ & LERL

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