The earliest feathered dinosaur fossils date from the early Cretaceous, but the ancestry of birds goes further back to Jurassic theropod dinosaurs, which shared a common ancestor with the crocodilians. Well known theropod groups include the tyrannosaurs, allosaurs, and other carnivores. Of surviving bird groups, the most ancient are the ratites (ostriches, rheas, tinamous, moas, kiwis, cassowaries, and emus), followed in evolutionary order by the waterfowl (ducks, geese and swans) and then the land fowl (chickens, turkeys, pheasants and their kin). Heene cemetery’s most ancient bird visitors are the woodpigeons. Strictly, therefore, we ought to refer to birds as dinosaurs, for they are direct descendants. The RSPB would be more accurately restyled as the RSPD. Where known, the conservation status of each bird is given as red, amber, or green, according to its survival potential based on 2016 populations and recent population trends.
Birds are warm-blooded, and have feathers, toothless, beaked jaws, and a strong, lightweight skeleton. They lay hard-shelled eggs. Their hearts have four chambers, and their metabolic rate is high. Although most are adapted for flight, many can also run, jump, swim and dive. Flightless birds retain vestigial wings. Brown, green, and grey are the commonest bird colours, for camouflage.
