I live in a place that can see snow on the ground 7 months of the year. What we call "spring", people in more southerly latitudes would consider to be winter. All this means that our opportunities for observing plants, animals, birds and insects as we usually think of them - growing, active, colorful- are limited to a very short portion if the year.
Unless, that is, we learn to look in winter. This guide is a great introduction to identifying plants, animals, and insects - yes, insects - in the snowy season. Broader in scope but less in depth and a bit drier than Heinrich's Winter World I think it makes a great companion to that book for anyone interested in getting out there and observing nature in the snow.
One sad note - the book was written in the mid 70's, so some of the info is dated. Stokes is describing a world where Elms are still dying of Dutch Elm disease and the fungi that break them down are flourishing. Those elm are now largely gone. He is describing a world where emerald ash borer has not yet arrived and insect populations have not yet crashed. The information in the books is still accurate and great, but you will keenly notice the absences where he saw abundance once you start to observe.