Another county tick

Not sure why birding is this way, but like shooting a basketball or playing a slot machine, the hits often come in bursts. (Is this not the true definition of mathematical chaos?). But after a several month drought of new county birds from May through October, I have now hit upon my 2nd county tick in 10 days. This time, I was out checking the ag fields of far NE Kent Co. for American Golden-Plover habitat, when I came upon a field freshly covered in manure and containing 6-10 inch high corn stubble. This field was absolutely awash in the standard open country species such as American Pipit, Killdeer, and Horned Lark. Mixed in were smaller #s of Snow Bunting and Lapland Longspur, and it really felt like an overall good spot for American Golden-Plover. But amongst the 20 or so Canada Geese were 5 swans. Now, swans in a muddy ag field are, in my experience, guaranteed to be Tundra Swans. And we have just now begun to enter the migration period for this species in Kent Co. So I assumed the birds would be so. But upon my first glances I noticed they were in fact a family group of Trumpeter Swans (!), 2 adults and 3 juveniles. This is the first observation of this species away from water and perched on the ground that I have ever made. Realizing the strangeness of the sighting I took extra steps to photograph and videotape the birds, and here they are:

A good Kent Co tick, and not the age class I expected

Got a call from J Lau (aka Jonathan Lautenbach) yesterday morning which I knew was going to be a rare bird. Indeed, he reported 2 White-rumped Sandpipers at Millenium Park. This is a long-awaited county tick for me, so I shot down and was fortunate to find the birds with his help. First the location:


The birds frequented these 3 locations throughout our visit.
Here are the best photos I could manage of them:The big issue of course is not ID, but age. At this late date, i assumed theses birds would be automatic juveniles. However, I was struck by the lack of obvious juvenal markings on the tertials and wing coverts. Furthermore, when I got close looks, I realized that the terts and especially the wing coverts were heavily abraded. Juvenile White-rumpeds begin the preformative molt in November (Pyle Guide Part II), and even if they hadn't replaced their juvenal tertials and wing coverts by now they would be much much fresher and less abraded than those of this bird. Here is an example of a young bird from 19 Nov 2009 at Muskegon Wastewater. Note the juvenal patterning and broad, rounded edges (unabraded) of the already 5 month old juvenal terts and wing coverts.

So, I believe these two birds have to be adults. I would love to know when is "too late" for this age class at such a northerly latitude. I would expect adults to clear out of Michigan by mid September at the latest, but perhaps I need to rewrite my expectations. Thoughts on ageing and molt timing would be appreciated.

Kent co. tick 238! Looking forward to moving into the 240s sometime soon...