One of the interesting features of birds is how many of them change with the season.
Merely consider two raptors: the Osprey and the Rough-legged Hawk. These two species might well never meet. The osprey spends the summer here, but winters in Central America. The Rough-legged Hawk spends the winter here, but summers in the arctic tundra. Even if they were to overlap briefly, they occupy different local niches: the Osprey captures fish in the Lake and the Rough-legged Hawk captures rodents in fields.
In honour of the seasonal return of the Rough-legged, I show composite images of each bird as it flew past me.
This is a composite image of a single osprey flying past at the end of July.
And this is one of a Rough-legged Hawk seen earlier this week.