Ocean Mist

5 May 2017

New Five Visit Transect Proves Instant Hit

Posted by Jes

A number of Butterfly Conservation Ireland members monitor butterfly populations by carrying out transect walks. These are fixed route walks through butterfly habitats where butterflies are counted according to a standard system to ensure that the results stand up to scrutiny. The butterflies 2.5 m to the right and left of the walker, and within 5 m to the front of the walker are recorded, along with temperature, wind speed and direction, date, start and finish times of the walk and percentage of direct sunlight. The transect route is walked, ideally, once a week, every week from 1 April to 30 September, a total of 26 counts. The data is interesting because it shows the ups and downs in the various species’ fortunes from year to year (you rarely get the same number of each species between one year and the next) and the increases and declines show the impact of weather patterns, climate change, habitat changes, changes in the management of habitats, the effects of parasites, sudden influxes of migrants which may reflect conditions in distant lands as well as a range of factors that may not be known or poorly known. When transects are monitored over a period of several years, the data becomes more valuable, because it provides a means to track long-term trends, giving more definitive information of the health of our environment.

But it’s not just  the hard data that’s valuable. Over time, many transect walkers become deeply attached to the areas monitored, and fiercely protective of their patch and their butterflies. With this grows a desire to care for the area and its wild creatures; the walker knows where every Primrose is, where bees nest in the hedge bank, where they are most likely to spot their first Orange-tip butterfly, or hear their first Willow Warbler sing. And having the information dating back years, the transect walker, now a conservationist, is uniquely placed to justify their site’s protection. The commitment to these sites has already proved important in Butterfly Conservation Ireland’s drive to demand respect for these butterfly-rich places. We have been able to influence management of these sites by those who own/manage the areas and publicise the value of sites under threat of inappropriate development, and avert disaster.

Another benefit of the transect data is that it is sent to a national database, hosted by the National Biodiversity Data Centre in Waterford. This secures the data so that it is not lost, and it can be used to judge the health of our environment across the country, and can be compared with data gathered in Britain and Europe. In short, it contributes to international research and development of conservation plans.

In order to expand the number of transects, the  National Biodiversity Data Centre have devised a transect system that allows the transect walker to monitor a site by walking the fixed route five times a year. Here’s how this reduced effort transect walk works. The route is visited five times. There are two walks, separated by two weeks, in May, (weeks 6-9) and three walks, separated by two weeks, in July and August (weeks 14-22). This has the advantage of enabling one to cover more sites, building up a wider picture of population size, distribution and range, and the health of our broader environment. The results will be used to produce a Butterfly Atlas 2017-2021; this initiative is an all-Ireland project, involving Butterfly Conservation Ireland, our colleagues in Butterfly Conservation UK Northern Ireland branch and the National Biodiversity Data Centre, among others.

A pioneer of this new 5-visit scheme is Butterfly Conservation Ireland member Pat Bell. Pat has completed the first of his May walks, which he carried out along the Barrow Way at Ardreigh, south of Athy, Co. Kildare, grid reference S 692916. The count yielded 1 Brimstone, 3 Large Whites, 3 Small Whites, 34 Green-veined Whites, 14 Orange-tips, 8 Holly Blues , 6 Small Tortoiseshells, 21 Peacocks, 1 Red Admiral, and 3 Speckled Woods, a total of 94 butterflies. A beautiful photograph Pat took of a mating pair of Orange-tip butterflies is featured below.

Please help us to build a picture of how our butterflies are coping in today’s landscape. If you would like to learn about how to set up and monitor butterflies along a favourite route that you enjoy walking, contact the National Biodiversity Data Centre for information on how to get started: http://www.biodiversityireland.ie/contact-us/

If you would like to monitor the butterflies in your garden and receive an annual report on garden butterflies, download Butterfly Conservation Ireland’s garden survey form here:


If you would like to send us records of butterflies you see when out and about, see here for details on how to do this:


Get involved, and build a connection with the natural world and its endless possibilities!

Orange-tips along the Barrow.© Pat Bell.

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