Sunday, March 14, 2021

Not yet...

 Lets have a little talk about migration! We are getting reports of ospreys seen in MN and tho several of us have been out checking ( I checked about a dozen nests today) no ospreys have been seen. Yes the weather has been warm but we must remember that Minnesota Ospreys migrate to south and central america for the winter. They are not watching weather reports in MN before they head north! They are hard wired to begin their migration as a response to the amount of daylight, the length of the day. And each Osprey is a little different, but we often see the same ospreys returning early to their nests, and the same ones are late every year! So we are often not surprised by which nests are occupied first. There can be changes when a long time breeding bird does not survive and a new one takes over the territory. At any rate, when they start their move northward is a hormonal reaction to the changes in daylight and doesnt change that much from year to year....but when they start to get closer to their territory they may slow down if they start encountering frozen lakes. Since ospreys are primarily fish eaters, they need a food source to depend upon when they return. So return dates may be altered slightly if lakes are open early, or remain frozen until later than usual. That last push of their migration may be effected by the weather in that regard.....will there be food or not? But generally they do not return until, at the earliest the last week of March, and at the latest, mid April. New younger ospreys may return even later than that to find a mate and a territory.

So when lakes remain frozen later than normal, the ospreys may congregate south of here....Missouri, Kansas etc.....and then we get a lot of them at once when the weather changes. We must also remember that Ospreys are not dumb. Migrating takes a lot of energy, so they prefer to fly when winds are coming from the south, to carry them home easily. They usually wont fly in to a strong north wind. Again, they may hunker down and wait. So perhaps that gives you some idea of what conditions may affect their return dates. As of now, none of my experienced volunteers or I have seen any Ospreys. Keep watching those lakes! And those winds!

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