July 22, 1847: The first Mormons arrive in the Salt Lake Valley. In the next couple weeks they planted crops, which was a very late growing season.
Winter 1847-1848: A fairly mild winter.
Spring 1848: A late frost ensures some crops don’t survive, but many do. Seeds from 1847’s crop are gathered and planted.
Late May 1848: Mormon Cricket swarms show up, devastating a lot of the crops. It was likened into Egypt’s 8th plague. There was seemingly no way to stop them.
June 9, 1848: The gulls, which were native to the valley, showed up. They gorge themselves on the crickets. They often ate so much they threw up, only to go eat even more. They continued this for 2 weeks till the population had died down.
Post-1848: This event went on to be immortalized. It was paraded as a miracle sent from God to ensure his chosen people were safe, but also as a show of power from God. It was retold many times and had such an impact that the seagull became Utah’s state bird.
I would not call this a miracle. This was the first time that Mormons had experienced this cycle, and they mistook it for a miracle from God to sustain his chosen people. In reality, this same cycle happened for hundreds of years before Mormons got to the Salt Lake Valley.
However, I think this is definitely a notable event in Mormon history. It illustrates how scared and unknowledgeable Mormons were about their new surroundings in Utah. It shows how the Mormons developed the land and the struggles they had doing so.