Transects - Herts & Middx Butterfly Conservation

Hertfordshire & Middlesex Transects

Over 75 transects were walked in Hertfordshire and Middlesex in 2023

Transects are the main method of measuring how butterfly populations change with time. The technique is simple, involving walking the same set route every week in good weather throughout the summer months, and noting down the numbers of each species seen within about 5 metres. The method is described under BUTTERFLY TRANSECT MONITORING

The transects walked in Hertfordshire and Middlesex since 1978 are listed here - some have been walked for over 25 years which enables us to understand the long-term population changes in butterflies. Please note that some transects have not been walked continuously.

If you would like to start walking a transect, do look at this list to see whether there is one near to where you live which is no longer regularly walked first.

Case Study
In 2018 the branch gave habitat advice to the site managers of Chorleywood Common. Several changes were made to the way the site was managed which included light grazing and creating clearings in the woodland areas. A transect was set up and this report clearly shows how important transect monitoring is, and how the improvements that were made increased the butterfly numbers. Chorleywood Common 2018 - 2023

Link sections on this page . . . Transect recording information and instructions

Name Grid Ref First walked Last walked
Abney ParkTQ336868?2016
Aldbury N1SP94913820162023
Aldbury NowersSP95215919922023
Alexandra ParkTQ30290320192023
Balls WoodTL34410619952023
Bardon ClumpsTL31815520132023
Batford SpringsTL14515020152019
Beane HillTQ19987319882023
Belmont RailwayTQ161897?2018
Bencroft FieldTL33006220132023
Bencroft WoodTL33506520182023
Bishops Stortford Southern Country ParkTL47319320042023
Bovingdon BrickworksTL00702920222023
Bricket Wood CommonTL13100919972023
Broxbourne West RideTL32507020182023
Butterfly WorldTL12704320092016
Camley Street Natural ParkTQ299834?2017
Chadwell BankTL34913620232023
Chorleywood CommonTQ02995820192023
Cranford Park SouthTQ10177919962021
Danemead Nature ReserveTL34607920182023
Danesbury ParkTL23017019962022
Fir and Pond WoodsTL277006?2015
Fryent Country ParkTQ19587619862023
Gladstone ParkTQ22385720222023
Gravel HillTL21617020132023
Great AshbyTL267269?2014
Greater Stanmore ParkTQ17193220212023
Greenwood ParkTL13905120192023
Gunnersbury TriangleTQ20178619992023
Gutteridge WoodTQ09184319902023
Halsey FieldTL04208820152023
Hampstead HeathTQ27086319782023
Harmondsworth MoorTQ050775?2016
Harpenden CommonTL13713420112023
Heartwood ForestTL16310920102023
Heartwood Forest 2TL17112320102023
Hedgeswood Common to Hoo WoodTL03113120162023
Highgate Cemetery EastTQ28686920212023
Highgate Cemetery WestTQ28686920212023
Horsenden Hill EastTQ16284320032023
Horsenden Hill WestTQ16384420032023
Hounslow HeathTQ12174920102013
Kempton Nature ReserveTQ11770920212023
Kenwood 2023TQ27087320232023
Knebworth WoodsTL22722720172023
Lake Farm Country ParkTQ09080420112022
Lakeside NRSP92212420112021
Lee Valley TurnfordTL368043?2017
Lemsford SpringsTL22312119992023
London Zoo Car ParkTQ28383620162023
London ZooTQ28183420152019
London Zoo amended 2021TQ28183420212023
Mardley HeathTL24818420062023
Marshalls HeathTL16114919892023
Minet Country ParkTQ109802?2018
Miswell LaneSP91411719992023
Norton Common LGCTL21833320112019
Norwood Green Meadows to Long WoodTQ15179220232023
Osterley ParkTQ15179220182023
Panshanger Park - Brocket HillTL283132720222023
Panshanger Park - Chisel ShelfTL29412120152023
Panshanger Park - Cole GreenTL28012220222023
Panshanger Park - Lady Hughes WoodTL30012520152023
Panshanger Park - Rifle ButtsTL29912220152023
Parkland Walk SouthTQ28987920122018
Patmore HeathTL44225719962023
Perivale WoodTQ15983720052023
Pinn MeadowTQ094880?2015
Pryor's WoodTL26526520002022
Railway FieldsTQ31788119972023
Roughdown Common (Lower)TL04805520122023
Roxbourne RoughTQ12087519992023
Sherrardspark (Red Lion to Reddings)TL224140?2016
Sherrardspark (Reddings) - 2010 routeTL230135?2016
Sherrardspark (Sixways Mid Section)TL230134?2016
Sherrardspark (Templewood Vale - Muddy Bottom to Pentley Park Entrance)TL235142?2015
Sherrardspark (Templewood Vale - new)TL23514320072023
Sherrardspark Wood - SeftonTL228138?2016
Shrubhill CommonTL03607220012023
St James Park/Green ParkTQ29579820132023
St Mary's Standon churchyardTL39622220232023
Stockers Lake 2012TQ04593520122023
The WarrenTL20405319952023
Therfield Heath (Base of Church Hill)TL33339520012023
Therfield Heath (Church Hill)TL33339619992023
Therfield Heath (Lankester Hill)TL35340420012023
Therfield Heath (Rifle Range)TL34840119992023
Therfield Heath (Top of Rifle Range)TL34939820012023
Thorley WashTL48918120142021
Tottenham Wildmarsh WestTQ35190520142023
Totteridge FieldsTQ22294020132023
Tower Hamlets Cemetery ParkTQ36682319992023
Trent Park Country ParkTQ28596519982019
Tring Park (9 sections)SP92710020112023
Walpole ParkTQ17380220132018
Ware ParkTL34714319962023
Waterford Heath NorthTL31515220002023
Waterford Heath SouthTL31714920082023
Westbrook Hay FieldsTL03005820222023
Wolf FieldsTQ128786?2017
Wood Lane PirtonTL14331220052023
Wormwood ScrubsTQ22381720222023