Many years ago, a group of Dearborn birders and RRBO banders submitted lists of the five bird species they thought might be the next to land on the Dearborn bird checklist*. I don't even need to dig it out to know that American White Pelican (Pelecanus erythrorhynchos) was not on that list.
On the evening of 16 October 2020, Mike O'Leary happened to be outside when 12 pelicans flew south over his yard. The Dearborn checklist now is now 266 species (which includes two extirpated and two hypothetical species).
Perhaps if we were compiling that list today, one of us might have thought to add pelican. This species has undergone a remarkable expansion in the Great Lakes over the past decade or so. Take a look at these two maps from eBird, showing reports from southern Michigan. The first map has all the sightings from 1900-2000 and the second just the past 20 years (with the caveat that eBird only launched in 2002, although many historical sightings have been added).
The expansion of breeding populations is well-documented in the two best small society journals in this region: the Passenger Pigeon, the journal of the Wisconsin Society for Ornithology (2014 article here); and Ontario Birds, the journal of the Ontario Field Ornithologists (2019 article here, and summarized in this article).
Keep looking up!
*As a reminder, you can download the most recent (2019) annotated
Dearborn checklist for $5. Applicable for most species for all of
southeast Michigan, it gives residency status, relative abundance, and
dates of occurrence for over 260 species. You can read the details about
how the data were collected and what is presented in this blog post.
You can go to the download page here. You will find the 2019 version as well as the 2007 version, which contains maps, some photos and illustrations, and other material. A description for each is available by clicking on the titles; there is also an option to purchase both for a discounted price.