A Birder, the problem you might find with your proposal is that you have suggested a "private hire" arrangement, which is not something that a PPL holder can accomodate, as we are holders of Private Pilots Licences, as opposed to Comercial Pilots Licences. The operators of aircraft for hire with a pilot, is the province of commercial outfits with AOC's and aircraft flown by CPL's.
However, if what you are suggesting is a cost sharing arrangement with a pilot, you may find that this works, but any ppl sharing with you will need to be very careful as to what basis they are undertaking these flights.
Good luck with the rare birds!