UK Butterfly Monitoring Scheme (UKBMS)
Transect Walkers help to monitor all the butterflies in selected sites throughout the summer. This provides information on changes in the abundance and status of butterflies throughout the UK and also helps guide the management of many nature reserves, not only our own but those of the National Trust, the Wildlife Trusts, the Woodland Trust, RSPB and others.
Butterflies are recorded along a fixed route (a transect) on a weekly basis from the beginning of April until the end of September. Transects are typically about 2 to 4 km long, taking between 45 minutes and two hours to walk. They have to be visited between 10.45am and 3.45pm and only when weather conditions are suitable for butterfly activity.
Due to the vagaries of the weather, it is rare in practice to achieve a full set of 26 weekly counts even if you have no other commitments and can visit the transect at any time in the week It is best to take on a transect as part of a team of several people. In fact, it may best to begin by helping an existing team, so as to learn the methods and develop the field skills required.
The UK Butterfly Monitoring Scheme is organised and funded by Butterfly Conservation (BC), the UK Centre for Ecology and Hydrology (CEH), the British Trust for Ornithology (BTO), and the Joint Nature Conservation Committee (JNCC)
Our Branch Transect Coordinator (Peter Bright) can be contacted by email (click here) if you have any questions or are interested in walking a Transect.
Single species transect surveys
Single species transect surveys are especially useful on nature reserves with one or more uncommon species that are the direct object of management.
The transect must follow the standard method and be carried out at least once a week throughout the flight period and more frequently if possible. The focus on a single species of course reduces both the time required to walk the transect and, more significantly, the number of weekly counts that are needed.
Timed Count Monitoring
Unlike transects, timed counts need only be carried out once a year at a site to provide meaningful results which makes then a useful ‘reduced effort’ method for monitoring rare butterflies, especially those whose distributions change over time across large sites.
The count must be done as near as possible to the peak flight period of the species in question. As with transect walking, timed counts should ideally be made between 10:45 and 15:45 and suitable weather is essential.
First, quickly walk the site to identify the extent of the adult flight area. If adults are patchily spread over a large area, it is better to identify sub-populations and survey them separately. Then count adults by walking the site, either in a series of parallel lines or in a zigzag path, covering the flight area as thoroughly and evenly as possible. This usually takes between 5 and 60 minutes depending on the size of the colony area.
It is important the walk passes through areas of high and low adult density: If only the best patches are visited, analysis may over-estimate abundance.
Please contact Peter, our Branch Transect Coordinator if you have any questions about Transects or other surveys mentioned on this page (click to email)