Juvenile ruby-throated hummingbirds are all out of their nests this time of summer, joined by migrants from the north. All are all feeding heavily to prepare for their long flights to Mexico and Central America.

Last year, Kim and Laurie Mackenthun, who live near Waconia, reported that the hummingbird "feeding frenzy" began Aug. 21. They define the feeding frenzy as the period when they have to fill several of their 12 sugar-water feeders two or more times daily to keep up with the numerous hungry hummers, no doubt numbering well more than 100.

Most ruby-throated hummingbirds leave northern Minnesota by Sept. 12 and southern parts by Sept. 25, so we have plenty of time to watch this marvel of the bird world.

These flying jewels are easily attracted to feeders with red parts if there are flower gardens or wildflowers nearby. They quickly become accustomed to human presence. Fill feeders with a mixture of one part granulated white sugar dissolved in four parts water. Do not add food coloring. A major portion of their diet is sugar from flower nectar and pollen, and tree sap.

The 11th annual Henderson (Minn.) Hummingbird Hurrah begins at 9 a.m. Saturday, celebrating Minnesota's tiniest bird. Find more information about the event online at hendersonhummingbirdhurrah.com.