www.ukbutterflies.co.uk

A Great Spotted Cuckoo is visiting the Glanville Fritillary sites on the IOW, and is eating many larvae an hour, it has been at Bonchurch and Wheeler's Bay, the one year we get a mild winter and a warm February & March this happpens, with the loss of most of the mainland colonies one of our rarest butterflies is in danger again. Hopefully the National Trust are taking some measures to protect at least some of the larvae.

http://blackaudibirding.blogspot.com/20 ... wight.html

Frustrating, but I guess that's nature. With any luck, the corvids will continue to harass it until it moves on.

Nothing much one can do, like David said it's the game of nature. Great Spotted Cuckoos feed mainly on hairy caterpillars but I doubt this bird will eat all of the caterpillars. Even if this has an impact on the population of the Glanville I don't think it will decimate it to the point of extinction. I would be more concerned if the habitat was under threat by some building projects.
Sylvie