In the state I reside in there are some types of birds (i.e. roseate spoonbills and white ibises) who show up in the late summer months, particularly July and August and then they apparently migrate back south again. This raises many questions I now have. Like did they migrate north after the breeding season to escape the heat? Are they lost? Why do they head north of their breeding season instead of spending the rest of their time down south before fall migration?
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I’m not sure what state you are in, but in north Georgia we get White Ibis, Roseate Spoonbills, Wood Storks and other waders with a higher relative frequency in the early fall. Most of these are juveniles.
This article may help answer your question in more detail: Why Have Roseate Spoonbills Invaded the North This Summer?, but in short, this is a normal and natural occurrence.
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The term most often applied to the movements you’ve described is “post-breeding dispersal” rather than “migration” as such. (It is a “migration” in the more general sense that birds are moving, but not a true temperate zone seasonal north-south migratory event.)
That said, the reasons for such movements are probably multiple. Commonly, the majority of dispersing birds are young-of-the-year. This probably derives from a long-term evolutionary strategy of dispersal almost universal in higher plants and animals–offering the extremely slim chance to colonize new suitable habitat patches, should they find any. Most often they don’t, and seasonal weather changes either force the birds back south or the young birds die.
There may also being regional and seasonal differences in habitat productivity that either (a) force/prompt birds to depart their breeding range, or (b) offer seasonally beneficial destinations for growth and survival prior to returning south as weather pattens change. And of course, the reasons each species undertakes these movements may vary slightly.
I love the old adage: “Nature is not just more complex than we think, it is more complex than we can think.”
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Oh ok. Thanks for clarifying that for me.
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I have seen Wood Storks in south Louisiana and southeast Texas from June-October. They travel northeast from Mexico to get here. More info: https://txtbba.tamu.edu/species-accounts/wood-stork/
One year a Jabiru traveled with a group of Wood Storks to south Louisiana. https://www.houmatoday.com/story/news/2008/08/07/ever-seen-a-jabiru-rare-sighting-reported-in-la/26778583007/ There have been sightings of this species in the US a few other times.
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