SIR - Having seen the clip for the forthcoming David Attenborough series about endangered species (Planet Earth, Sunday, 7pm, BBC1), it brought me up short and made me think what on earth are we doing to this planet?' What are we doing to these magnificent animals - tigers, polar bears, orang-utans, etc?

We may think there's no point - we're one in a billion - but if ten, 100, 1,000, 10,000, or 1,000,000 did it, then each small contribution could be like a snowball in the end.

I'm sure I speak for many when I say, we can't let these beautiful creatures disappear, only to be found recorded in encyclopaedias in years to come.

Recycle, give to WWF. Just do something little, but necessary and effective, to stop this happening.

M Byrne, Clover Street, Little Horton, Bradford