Where oh where have all the Migrants gone?

At the beginning of May all the state's most ardent birders start heading for known hotspots, looking for the annual spring migrants. Many of them are near the shoreline, like Hammonasset, East Rock park, Greenwich Point, and a bit later, River Road in Kent. But by the end of the month most of the migrants have passed through, and except for residents and a few birds that make those places their summer home, the woods, fields and marshes are relatively quiet. And certainly it's true, many of our spring visitors barely pause before continuing north, sometimes far into Canada.
But there are quite few species whose breeding grounds are in New England, just a bit north of Connecticut. There are a few spots in northern Ct that are cool and forested enough to be very similar to the places  those birds are looking for, and a small number of them stay. Most of those locations are in hilly, remote locations in northwestern Ct. As an example,I know there is a breeding population of Dark-eyed Juncos on the Canaan Mountain plateau in Canaan, North Canaan and Norfolk.
But in eastern Ct, similar conditions exist in the Yale Forest area of Ashford and Union, and I assume, up to the Ct line in  Bigelow Hollow SP and the Nipmuck Forest  to the north. It's not as high, but still relatively cool and damp, with large tracts of deep old woods. As an example, a couple of years ago I visited Boston Hollow in late June when the forecast was for temps in the 90's, but when I left there about 1 PM my car thermometer still only said 76*. I went directly to Willimantic, perhaps 15 miles south, and when I got there the temperature was 93.
In a nutshell, that's why, when the migration hotspots grow quiet, the Yale Forest area is still hopping. In fact, it's just getting started. The breeding season for most species is mid-May through June, and depending on the species and size of the birds it may be the end of July before some are fully fledged (out of the nest on their own). The bottom line is, any migrant bird that's still there after early June is almost certainly going to nest there.
I'm going to try to make a list of the birds I'm almost certain breed in or near the Yale Forest, but I know I'll forget some, and there are other possibles that I'm not sure of:

Turkey Vulture, Red-tailed Hawk, Broad-winged Hawk, Northern Goshawk, Barred Owl, Mourning Dove, Ruby-throated Hummingbird, Yellow-bellied Sapsucker, Downy Woodpecker, Hairy Woodpecker, Pileated Woodpecker, Northern Flicker, Eastern Wood-pewee, Acadian Flycatcher, Least Flycatcher, Great Crested Flycatcher, Blue-headed Vireo, Red-eyed Vireo, Blue Jay, American Crow, Common Raven, Tree Swallow, Black-capped Chickadee, Tufted Titmouse, Red-breasted Nuthatch, White-breasted Nuthatch, Brown Creeper, Winter Wren, Blue-gray Gnatcatcher, Eastern Bluebird, Veery, Hermit Thrush, American Robin, Gray Catbird, Cedar Waxwing, Ovenbird, Louisiana Waterthrush, Northern Waterthrush, Blue-winged Warbler, Black-and-white Warbler, Common Yellowthroat, American Redstart, Magnolia Warbler, Blackburnian Warbler, Yellow Warbler, Chestnut-sided Warbler, Black-throated Blue Warbler, Pine Warbler, Yellow-rumped Warbler, Black-throated Green Warbler, Canada Warbler, Eastern Towhee, Chipping Sparrow, Song Sparrow, Scarlet Tanager, Northern Cardinal, Red-winged Blackbird, Brown-headed Cowbird, Baltimore Oriole, Purple Finch, American Goldfinch.

That's a total of 61 species if I counted right. In addition, I know that Coopers Hawk nests in Bigelow Hollow, just a few miles to the north, and I often see Osprey, so I assume there is a nest somewhere in the area. I probably missed a few others.
There may only be a few pairs of some of these species, but for some, Boston Hollow et al is a major and very important breeding area. For a few it may be the only area in Ct with a significant breeding population.
Of course there are pockets of breeding birds elsewhere in the state, but very few can match the number of different species seen in the Ashford/Union area. And there are certainly other species that nest in the state, but not in that area, primarily because of the habitat they require. Some of the most notable spots are along the shoreline, such as Hammonasset and the major salt water marshes, and major fresh-water marshes in the state.
So it's really no mystery why the Union/Ashford area is still alive with birds, long after the spring hotspots have gone quiet. A combination of a cool climate and large tracts of ideal habitat are a magnet that some birds just can't resist. In fact, from early June until the end of July, the population probably actually increases as more and more nestlings fledge. Eventualy the frequency and volume of song will decrease, but the birds will still mostly be there until it's time to head for their wintering grounds.
There is a sharp contrast, however, in winter. My experience with Boston Hollow is that it's like a tomb in cold, snowy weather. It's easy to make a tour through the area and not hear or see a single bird. Of course there will be some hardy souls that stay around, but they are few and quiet. I believe that even birds that largely don't migrate out of the state head out of the Hollow in search of more temperate climate and more productive feeding locations. For example, Red-breasted Nuthatches often winter on the shoreline. I'm not sure I have ever seen a Chickadee or Titmouse near Boston Hollow in winter, even when they are all over my yard, 18 miles away. But after the first of April they slowly begin to come home from their winter vacations.