Yes, the British did try to train seagulls to attack or locate U-boats. The first, supposed, such initiative has been described as the brainchild of Admiral Sir Frederick Inglefield. Inglefield had, at the start of the war, been placed in command of the Motor-Boat Reserve. This was an auxiliary coastal patrol, set up using motorboats and yachts requisitioned from civilian owners. As Britain's anti-submarine defences in 1914 were almost non-existent, the Motor-Boat Reserve was an important force for patrolling Britain's coastline against submarine attacks. Unfortunately, few of the craft were armed, and they had no way of detecting a submerged submarine. Supposedly, Inglefield attempted to compensate for this using seagulls. A testing-range was set up in Poole Harbour, using dummy periscopes in an attempt to train the seagulls. However, there are no reports of this in archival sources, nor amongst Inglefield's own papers.

A better-attested case comes from the Board of Invention and Resarch (BIR). This was set up in 1915, as a civilian organisation directing research and development for the Royal Navy. Led by Admiral Jacky Fisher, it drew from a wide variety of expertise. The BIR's Section II was to investigate new anti-submarine weapons and techniques, and would recieve the greatest funding from the government and Admiralty. The BIR drew in suggestions from the Admiralty, from serving naval officers, and from the public at large. It then winnowed through these, discarding those that were unworkable, and testing those that might be practical. Most of those drawn from the general public fell into the former category - for example, a proposal to reduce the danger on moonlit nights by dimming the moon using spotlights casting 'dark-tinted rays'. The idea of using gulls was a repeated suggestion from the public, and was actually tested.

The first such suggestions had come in 1915, but were overlooked by the committee. The idea was taken further in 1916, when it was referred to Admiral Duff, the head of the Royal Navy's Anti-Submarine Division. The idea in question called for merchants to tow dummy periscopes that dispensed food at intervals, training the birds to associate periscopes with food. They would then, hopefully, flock to any periscope they spotted, providing a much more obvious indication of the presence of a submarine. A number of members of the BIR were strongly in favour, especially Dr Chalmers Mitchell, secretary of the Zoological Society of London, but Duff thought it frivolous. There were a number of problems with the idea - it might be difficult to mimic the movement of a periscope, it might lull merchant captains into a false sense of security, and gulls were rarely found out at sea, where the danger was greatest. Despite these objections, the BIR decided to take it to the trial stages.

The Admiralty offered the old submarine B3 for the tests in May-June 1917. A number of well-respected ornithologists were invited to take part in the experimental program, and work began in the Firth of Forth. To counter the lack of gulls at sea, the possibility of using other birds was mentioned - hawks and pigeons in particular. Discussions with experts proved this to be unworkable. Meanwhile, the tests were going nowhere. B3 was the test submarine for the hydrophone establishment at Hawkcraig Point. This was a much more promising line of research. Complaints from Hawkcraig and the submarine's commander, led to the abandonment of the trials, before they had really gone anywhere.

In 1917, the idea was resurrected by Thomas Mills, an English-born Australian entrepreneur who had made his fortune in gold mining. In a letter of February 1917, Mills again suggested to the BIR the use of a dummy periscope towed behind merchant ships. The concept was discussed, and Mills was informed that similar ideas had been investigated and discarded. Mills was not disheartened, producing and patenting his own decoy submarine. Built to be towed behind a motorboat, it used a clockwork mechanism to dispense food. Mills attempted to persuade the Admiralty to use it, but was rebuffed after it was pointed out that the gulls wouldn't be able to distinguish between Allied and German submarines. In September, he returned to the BIR, who again rejected it. Mills then procured a patent for his device, and set about testing it at Exmouth. He continued trials, despite difficulty procuring bait for the device and petrol for his motorboat, until the end of the war. Despite frequent attempts, he never received official sanction for his research. However, he did receive a write-up in the local newspaper, as well as Popular Science Monthly, plus an oblique mention in an article on the topic in the San Francisco Chronicle.