Most Baltimore Orioles spend the winter in Florida as well as Central and South America. Their journey north begins at the end of April. They usually hit my mid-Michigan feeder at the beginning of May with a big song and dance. I have my feeder on the window at the East Lansing Wild Birds Unlimited store and he'll sing right to the customers when he's happy and give me the look if I haven't had a chance to fill his jelly feeder.
Then in June his visits are less frequent as he's busy incubating eggs and then sourcing out bugs for his babies and only stops by occasionally for a quick bite. Last year I put out mealworms in June and he continued to feed regularly. Then he brought up all his babies to feed right out side my window.
|baby oriole waiting for a mealworm treat|
Besides molting, birds also have to fatten up before they leave and wait for just the right weather conditions. Birds have internal barometers and can actually feel changes in air pressure in their inner ear. When a storm approaches, the air pressure goes down and the birds eat a lot more in anticipating of bad weather. Then these smart birds will take advantage of the strong tailwinds for the long journey south.
October through February most orioles hang out in the tropics. In March and April some orioles begin moving north again. On average, they probably travel about 150 miles each night in flocks, flying at about 20 miles per hour. If the weather is favorable, it will take an oriole about 2-3 weeks to complete his migration north to reach my window again by May.