Семенов-Тян-Шанский О.И. Экология тетеревиных птиц. Москва, 1959.

31. Arctous alpina — the «Thunder-berry» in Lapp. 32. Dryas punctata — the «Ptarmigan grass» in Russian. 33. Evaluation of Tetraonids principal food plants in annual aspect. Names of food plants listed (from above) are: Pinus silvestris, Junipe- rus sibirica (dotted), Salix sp. sp., Betula pubescens and B. verrucosa (horizontal hatched), Alnus borealis (cross hatched), Betula nana ( verti cal h a t c h e d ) , Em p e t r um n i g r um ( b l a ckened) , A r c t o u s alpina, Vaccinium vitis idaea, Vaccinium uliginosum (circles), Vaccinium myrt ill us, o t h e r pl ant s (wh i t e ) . 34. Skulls of Lagopus lagopus (above) and Lagopus mutus (below), in comparison. 35. Daily and seasonal changes in crop contents of Tetrao uroga- llus. Explications: day and twilight period (white), dark period (hatched), weight of crop contents (dotted). 36. Daily and seasonal changes in crop contents of Lagopus lagopus. For explications — see above, fig. 35. 37. Grit contents in stomachs of Tetrao urogallus and Lagopus lagopus; above — weight ratio per mille, below — average weight of one stone. 38. Comparison of intestine parts in some Gallinaceous birds; all measures calculated for 1000 g body weight. From above: Tetrao urogallus, Lyrurus tetrix, Tetrastes bonasia, Lagopus lagopus, L. mutus, L. scoticus, Phasianus mongolicus, Alectoris graeca. 39. Digestive tract of Tetrao urogallus female, from abdominal side (left) and from back side (right). 40. Growth of Tetrao urogallus juv.; xx — males, oo — females. 41. Growth of Tetrastes bonasia juveniles; for explications — see fig. 40. 42. Growth of Lagopus lagopus juveniles; for explications — see fig. 40. 43. Growth of Lagopus mutus juveniles; for explications — see fig. 40. 44 .Distribution of Tetrao urogallus body weights; dash line — females, dash-and dot-line — immature males, solid line — adult males. 45. Distribution of Tetrastes bonasia body weights; dash line — females, solid line — males. 46. Distribution of Lagopus lagopus body weights; for explica­ tion s— see fig. 45. 47. Distribution of Lagopus mutus body weights; for explica­ tion s— see fig. 45. 48. Seasonal alternations of Tetrao urogallus body weights. Figu­ res indicate number of specimens used for building the line. 49. Age difference of Capercaillie males weight in spring. Expli­ cations: figures below the columns indicate the quantity of specimens, figures above — addition in weight in kg. 306