Each Summer Butterfly Conservation, in association with Marks and Spencer, organises "The Big Butterfly Count" - a nationwide butterfly survey. This year its being held between 20th July and 11th August and all you have to do is spend 15 minutes in your garden, or park, or woodland etc., and count the butterflies or certain species of day flying moths that you see in a fifteen minute period.
The survey was launched in 2010 and last year 27,000 people participated spotting 223,000 butterflies. Butterflies react quickly to environmental changes and are, therefore, excellent biodiversity indicators and can provide a warning also of other possible wildlife losses. The survey will also help the charity to spot butterfly trends and identify any declining species.
(Thanks to Tony Philp for copying this to me)