Sir David Attenborough visited WWT Wetland Centre to launch world’s biggest butterfly survey.

The naturalist was at the WWT London Wetland Centre on Friday, July 15 to begin the Big Butterfly Count.

The butterfly counting survey lasts from July 15 to August 7, and Sir David encouraged residents to get involved.

Sir David said: “It doesn’t matter how many times you do it, we are grateful for any observation.

“You can do it day after day if you wish for three weeks but even just one would be valuable.”

Counting butterflies can be a lot of fun and is a great excuse to get outside in the summer months, he said, but there is also a purpose to it.

By looking at the different butterfly species in our environment, experts can determine how other species are being affected by climate change.

Counting butterflies also makes it easier to identify if a particular species is becoming endangered, and means action can be taken to prevent its extinction.

Last year’s Big Butterfly Count was the biggest ever, with 52,000 people taking part.

If you want to get involved in this year’s Big Butterfly count, visit butterfly-conservation.org