Prioksko-Terrasny Nature Reserve covering 4945 ha, 134 species of birds from 14 orders (Ciconiiformes, Anseriformes, Falconiformes, Galliformes, Gruiformes, Charadriiformes, Columbiformes, Cuculiformes, Strigiformes, Caprimulgiformes, Apodiformes, Coraciiformes, Piciformes, Passeriformes) had been registered by 1991. Later 5 more species were observed here. Thus, by the present time, the list of species of birds registered in the Reserve numbers 139 species. About 55% from them are Passerines. Most of birds of the Reserve belong to migratory breeding species or to nomadic breeding species. Some species are vagrants in the Reserve and in the Moscow Region (nutcracker Nicifraga caryocatactes (L.), etc.). Birds, nesting in central parts of Russia
The Origin of Birds exquisite detail the fossil remains of several extinct birds, including "Hesperornis", "Ichthyornis", "Archaeopteryx", and ""Archaeornis"", the name used commonly at the time for the Berlin specimen, which was then thought to represent a separate genus. Throughout this section are many finely detailed and labeled renderings of different parts of the skeletal anatomy of these birds, as well as other groups of extinct reptiles and some modern birds. Heilmann's attention to detail in his artwork is inspired at least in part by his dissatisfaction with anatomical renderings of these animals in scholarly works of the time, which he deemed as "unsatisfactory"