I have heard the lot, crossed knives, throwing salt over you r shoulder etc. When you see a magpie you should say, three times, good morning mr magpie (two) add good morning mrs magpie the you are supposed to spit on the cat. If you see a magpie in the afternoon its bad luck.
Crows are supposed to bring death. We have lots of crows and they line up on the chimney pots sqwawking but a solitary one sitting on the chimney pot is supposed to be bad.
As for gulls dropping their load, that is supposed to be good luck, s...t for luck they say.
Also breaking a mirror is supposed to be 7 years bad luck but if you bury the bits in your garden then your lover will be faithful for 7 years, assuming your lover has looked in it. Tried this and my lover was very vain so when I broke the mirror I buried it but he was unfaithful anyway do I dumped him.