One of the more unusual ideas proposed by the BIR [British Board of Invention and Research] involved dragging a dummy periscope behind a ship while food was discharged nearby. The aim was to attract a flock of seagulls to the periscope and, following repeated runs, condition the birds to associate periscopes with a good meal. Ergo, anytime a periscope popped above the surface, a flock of seagulls would beeline towards it giving the game away.
Physics World
Variations of this claim can also be found on Explain XKCD; BirdNote; Audubon; and Today I Found Out. I didn't find evidence to support the claim on any of these sites.
Question: In WWI, did the British Board of Invention and Research propose conditioning seagulls to associate a submarine's periscope with food?