Although the piece functions effectively as an exercise in playing couplets, the title and the performance note refer to the common UK superstition surrounding the song of the curlew as a portent of imminent doom.
[Fishermen] deprecate the cry of the "Seven Whistlers"... and consider it a death-warning.
"I heard 'em one dark night last winter... They come over our heads all of a sudden singing 'ewe, ewe,' and the men in the boat wanted to go back. It came on to rain and blow soon afterwards, and was an awful night, Sir; and sure enough before morning a boat was upset, and seven poor fellows drowned. I know what makes the noise, Sir; it's them long-billed curlews, but I never likes to hear them."
Folk-Lore of the Northern Counties of England and the Boarders (1879)
While fear of this particular omen was common amongst fisherfolk around the UK, a similar superstition peculiar to Seaton Snook also existed around the cry of Jacob Cox's Horse.