I know that Denso Martin Reserve has been around a while but we (family) have just discovered it. It's on the Otley road about 1/3 mile past the Baildon turn off.
It's a little gem with a well organised info centre and resident warden - Stephen. Situated next to the River Aire there are lots of birds including 4 chiff chaffs already in. We saw goldcrest, LT tits and a kingfisher flashed by on the river. Link