While examining tide gauge records from Atlantic City's Steel Pier, Mr. Galvin discovered a remarkable effect apparently caused by spectators who came to watch horse-diving between 1929 and 1978. From old photographs, it was estimated that there must have been about 4,000 spectators who would come to watch. Given that this crowd probably weighed about 150 tons, the pier was subject to significant loading and unloading cycles. The initial 1912-1928 data showed the sea level rising at a rate of 0.12 inches per year. The rate tripled around 1929 when the horses began diving. When the shows were suspended from 1945 to 1953, sea level fell at a rate of 0.06 inches per year. When the diving resumed, the sea level rose again at a rate of 0.16 inches per year.
Horses produce various things: in this case sea level change. It occurs to me that there are a lot of Chicken Little's that are full of something else horses produce.