from a faith-promoting Mormon's webpage:
The seagull is Utah's state bird. This is because of a miracle that occured in 1848. That spring the crops were invaded by crickets.
After numerous prayers and pleadings to God, the sky was darkened by thousands of seagulls. They came, they ate the crickets, they vomited them up, then they gobbled up more, and the crops were saved. The birds' intention was to kill crickets rather than to feed themselves.
The Seagull Monument in Salt Lake City is an everlasing reminder of these days of darkness and light.
from an internet bulletin board:
Chapter 8 of New Mormon History is entitled: "Mormons, Crickets, and Gulls: a New Look at an Old Story" by William G. Hartley
In this heavily referenced essay, Hartley (a BYU professor of history and church history) makes the following points:
1) The gulls were not strangers to the valley. They are natural enemies to various insects including crickets.
2) Gulls habitually regurgitate the indigestible parts of insects they have swallowed.
3) Gulls did not arrive until after severe cricket damage had already occurred in 1848.
4) In 1848, Mormon crops were seriously damaged by three enemies--frost, crickets, and drought. The Gulls dealt with only one problem and too late at that.
5) The "miraculousness" of the event was not clearly recognized by contemporaries (including newspapers, diaries, and official church correspondence).
6) Since 1848, gulls frequently have been on the wing to feast on crickets and other insects, making the 1848 encounter hardly unique.
Like other popular accounts of important and unusual historical events, over the years the details of the cricket war of 1848 have been oversimplified, improved upon, and been given somewhat legendary characteristics.
It is a good article and clearly shows how a perfectly natural event was made into a myth/miracle to advance the faith of the masses and illustrate how God is taking care of his people.