The Rare Vertebrates of Connecticut, out of print for 40 years and not otherwise available on the internet, is now accessible via Bird Conservation Research, Inc. Much has changed since this volume was released. Species thought to be rare in the 1970s, like the Cooper's Hawk, Pine Warbler, Yellow-bellied Sapsucker and Red-bellied Woodpecker, have undergone explosive population growth and are now regular Connecticut residents. Others, like the Ruffed Grouse and White-throated Sparrow, have declined and still others, like the Common Raven, had yet to colonize the state.
Thinking concerning the meaning of terms like State rare and State endangered has, as a consequence, evolved (see, for example, this). An important conclusion to be drawn from the extent of population change observed over time is that wildlife communities are dynamic rather than static assemblages (see this). This conclusion affects how conservation concern is evaluated and requires us to develop a more sophisticated notion of how we view rarity at the local level. See this page and click on the PowerPoint presentation Global vs. Local Perspective on Endangerment for a more-in-depth analysis of this issue.
The Rare Vertebrates of Connecticut provides us with a useful perspective on some of the earliest thinking concerning conservation of rare species at the local level. It is available here.