Should it read..
'Marconi ponds are regularly visited by Kingfishers, Herons' etc

or 'Marconi Ponds is regularly visited by Kingfishers and Herons' etc.

Both versions are correct.

Marconi ponds are...[okay]
Marconi Ponds is...[okay]

The capital letters on kingfishers and herons need changing though. (I would classify those as common nouns.)