John Reilly 2018. The Ascent of Birds. How modern science is revealing their story. Pelagic Publishing: Exeter, 340 pp.
At once a thorough literature review of recent advances in ornithology and especially on phylogenetic relationships of and within a great many bird groups. Very readable introductions to many concepts in evolutionary biology (allopatry & sympatry, vicariance & dispersal, the nature of molecular data … ). Especially interesting was discussion using sparrows as the example, of the possible role of hybridisation (introgression) in speciation, with gene swapping through these back-crosses perhaps being significant more often than currently recognised and accelerating rates of genetic change. (In Homo too?)
Very extensively referenced with many footnotes plus a short bibliography with lots of titles to seek out. A reference book to current systematic research across a diversity of bird groups. No loons/divers though.