I'm a new member of RSPB and would like to know what benefits there are besides entry and a magazine. Does membership include access to the international organization to which RSPB belongs? Discounts in the cafés?
First, a warm welcome to the RSPB Community.
Depending on what type of membership you've signed up for, have a look at the RSPB Membership pages online, or if you have your membership welcome pack, have a read through that.
I'm not aware of any discounts in the cafe's or for any other services, apart from access and parking charges which you'll be exempt from upon presenting your membership card to either the site reserve staff or by scanning the barcode on your card at the ticket machine.
https://www.rspb.org.uk/membership
Mike
Flickr: Peak Rambler
I'm referring specifically to the question about whether there is reciprocity with the sister organizations, like the Audubon Society in the U.S., for example.
I'm not aware of any discounts with sister organisations globally, and I know there isn't any within the main UK conservation organisations. If anyone else knows different, then please share that knowledge here.
What I can tell you is, some outdoor clothing retailers will offer discount on clothing and various gear on productions of a valid membership card. This is not a link with the RSPB, but an internal idea within the retailer themselves to help generate sales, and in many instances, help us the customer, to enjoy a good day out in comfort. But you would need to speak to the retailer to see what discounts or offers they have individually.