Thanks for all the replies.
Yes, the PIRs will be fed from the same circuit. The plan is to wire a phot
osensor trigger, whose output goes live in darkness, to a relay, such that
I get a "on" switch in daylight only. The two PIRs will both be supplied by
the same output of that relay so that they are active in daylight only (wh
ich is what I need). Both PIR outputs will be connected to the same power t
erminals of the single device that I intend to have them control, which, in
turn, ought to keep herons away from my pond! Lol.