Your post makes me wonder if the fledging and maturation of Merlins is predicated on the migration cycles and arrivals of the shorebirds they prey on?
I had always assumed that the Merlin's bred farther north and they actually migrated south every year following the shorebirds. To expand that thought I thought that most of the raptors did this just going to the northland to hunt the taiga and boreal forests to breed in the spring burst, hunt the young and then come south to new prey country as the season progressed towards winter.
So this merlin nesting has me slightly perplexed. It is so far south that the vast majority of shorebirds are far to the north. Secondly the hatchlings must then hunt more mature hardened prey. Also I have to ask if the birds only migrated to the southern end of Lake Michigan then why are they hatched and maturing only now. I have seen young kestrels learning to hunt with mom in mid May here in Alpena county.
I swear you guys on Lake Michigan get so much better birding than us over here on the sunrise side. Pout goes here.......................................end of pout.
Bringing the wife back from her mom's in Connecticut stopped in Ottawa and Shiawassee NWR's. Ottawa still a bit slow but interesting in SNWR. Facebook blog cites dickcissels at Bishop road platform so I stopped there. So two dozen birds fly up out of the weeds (mostly goldenrod, Queen Annes Lace and knotweed asters) and I think man, what a lot of them have flocked together. They flew up three times and never really got a good look at them other than they were greenish yellower than I expected and the flashes of black were not always on as a bib. So I get home and am tired and log it all including some pectoral sandpipers, common moorhens, great egrets, dunlins and others. Did not get either pharlarope nor a Baird's at Shiawassee as I had hoped. Dozed off and then went into the books noting on shorebirds when I started to think on birds you see only a few of at time and then flock up in fall and you can see a lot such as Brewers and rusty bb, some ducks, snow birds and horned larks. Then got on the net and looked and found out that Bobolinks also do it. Had to change my birds lists and lost the dickcissels making them into bobolink's.
Congrats on the find. Very interesting. I think that birding is being advanced a lot by the work citizen scientist like you and Russ do. To me it is much more interesting than some grad student measuring pin feathers at a banding station to see if the fall molt of killdeer begins the second or third week of September. I think that common folks will only do that which is significant while the specialist get off in the weeds of insignificance too easily.