Birder Robert (Bobby) Irwin found a Neotropic Cormorant (just assigned to a new genus, and now Nannopterum brasilianum) off Humbug Island at the Detroit River International Wildlife Refuge on 28 June 2021. The eBird checklist with photos is here. As of 30 August 2021, it was still being seen, at least sporadically.
This identification is not an easy call. I happened to have visited the Refuge the previous day, one of the first times I have returned after spending years doing bird and insect surveys for the USFWS prior to the Refuge opening to the public. Various habitat modifications have resulted in a nesting colony of Double-crested Cormorants just north of the new fishing pier, with nearly 30 nests that I could see. Most of the young have fledged, so there were dozens of cormorants in the trees, flying around, and in the water, all in various plumages. Neotropic Cormorants are smaller than Double-cresteds, have longer tails, and different plumage on the face, but these differences are not always obvious, especially when the birds are moving around or distant. Kudos to Bobby for picking this one out.
As you can see from the range map, this bird is well out of range. However, they are known to wander a lot, and there are a number of Michigan records, mostly from the past few years. In fact, there is a pair nesting at Lake St. Clair Metropark in Macomb County right now!
I have maintained a comprehensive Wayne County checklist, including historical records, for many years. By my accounting, this makes species #352 for the county, of which 9 are extirpated/extinct, hypothetical, or not "countable."