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ISSN 0869-4362
Русский орнитологический журнал 2005, Том 14, Экспресс-выпуск 296: 723-741
Genus Lyrurus Swainson, 1831 (Black Grouse): taxonomic position, composition, distribution, phylogenetic relationship and origin
R.L.Potapov
Zoological Museum, Russian Academy of Sciences, St.-Petersburg, 199034, Russia Поступила в редакцию 24 August 2005
The taxonomic status of the black grouses is one of the most important topics of this paper. Linnaeus described all tetraonid birds that he knew under a single generic name Tetrao (Linnaeus, 1758). Later, different authors not only ranked them to the family Tetraonidae, but distinguished several genera among them. Only the capercaillies preserved its original generic name Tetrao. The genus Lyrurus was described as the monotypic genus with the type species Lyrurus tetrix (Swainson, 1831) because of the unique shape of the male’s tail and tail feathers. This new genus was accepted by European ornithologists significantly later. The Caucasian Black grouse, discovered in 1875, was described as Tetrao mlokosiewiczi (Tachanowsky, 1875) and later was attributed to the genus Lyrurus (Ogilvie-Grant 1893, Satunin 1907; Nesterov 1911; and others) without additional arguments: the close relationship of these 2 species was clear enough.
The originality of the genus Lyrurus
Most of the well known taxonomists of the 20th century accepted the generic status of Lyrurus without discussion (Hartert 1922; Steg-mann 1932; Peters 1934; Sushkin 1938; Buturlin, Dementiev 1936; Vaurie 1963 and others). Subsequently, some authors reestablished the previous taxonomic nomenclature and included black grouses to the genus Tetrao again without any argumentation. We must not forget that taxonomic hierarchy must reflect the level of the divergence between different taxa. The criteria of establishing the taxa of the same rank, in our case the genera, must be equal at last inside the larger taxon (in case of the genera, the family).
Despite of this evident procedure, the uniting of two genera in one was disputed in brief only in a single publication (Short 1963)*. L.Short argued the uniting of capercaillies and black grouses in one genus because of
* In this paper, publications based on the results of the study of the mitochondrial DNA sequences and other molecular biology methods are not concerned. These studies demonstrate the close relationship between the capercaillies and black grouses (Ellsworth et aZ.1996) and, by the way, between all genera of the monophyletic family Tetraonidae. I am sure that a lot of surprising things are hidden in the genotype of all the tetraonid species. But, being the zoologist, I study the definite results of the tetraonid’s evolution. I am ready to discuss my results only in this field.
similarities (as he mentioned) of size and color, prominent dimorphism, feathering of the tarsi and toys, the length of tail feathers and the color of eggs and nestlings. All these details have no taxonomic value at the generic level and do not reflect the specificity of the genus. At the same time so prominent and important generic characters as the unique skull in capercaillie males and the shape and length of the male’s tail and tail feathers in black grouses together with many other characters strongly differing in these birds, were ignored by the author. The detailed investigation of all the original characters specific of the both genera, performed by me, demonstrated the existence of significant differences between capercaillies and black grouses, making the uniting of these species in a single genus impossible (Potapov 1985). This monograph was published in Russian and, therefore, I think it necessary to repeat briefly the arguments confirming the independence of these bird genera and incompetence of L. Short’s argumentation.
1. The well expressed sexual dimorphism: the same degree of sexual dimorphism is typical of the genus Centrocercus and, to a lesser extent, to the genera Falcipennis and Dendragapus.
2. The feathering of tarsi is virtually the same not only in Tetrao and Lyrurus, but also in Falcipennis, Dendragapus, Centrocercus, Lagopus and partly in Tympanuchus (the subgenus Pedioecetes). The same concerns of the feathering on the base of the central toe. In general, the intensity of the tarsi feathering depends rather from the severity of climate, than from taxonomic position and may be different in different populations of the same species.
3. Long tail feathers are typical of males of some other species, not only of capercaillies and black grouses. For example, males of sage grouses possess the longest tail feathers among all the tetraonid birds (103% of wing length). The length of male’s tail in relation to the wing length varies from 77.5% to 100.5% in capercaillies (T. urogallus karelicus and T. uro-galloides urogalloides respectively) and, in black grouses, from 71% to 95.7% (Lyrurus t. tetrix and L. mlokosiewiczi respectively). The same tail length ratio was found in males of the ruffed grouse (83%), the Severzov’s hazel grouse (71.1%), and the dusky grouse Dendragapus obscurus (7280% in different subspecies). In any case, the length of the male’s tail cannot be used as the taxonomic character, because it strongly depends on the sexual selection in every species and subspecies, besides from bird age and individual and geographical variations. The same is true for the number of tail feathers. Together with capercaillies and black grouses, Bonasa umbellus, some subspecies of Dendragapus and all species of Tympanuchus possess 18 tail feathers. Moreover, in some species this number varies individually from 14 to 24! I think that similar variations will be found in all other grouse species.
4. The development of the intensive black color in males with the violet luster on the breast is typical only of Lyrurus species. In the genus Tetrao, only a single species, T. urogalloides possesses this completely black color with white spots and violet luster on the breast. Two of three subspecies demonstrate this type of coloration. In males of T. urogallus only frontal and central parts of the belly are black and its black tail has white spots. The breast plastron is green or violet with metallic glance.
5. The size of the capercaillies and black grouses is large indeed, but the differences in the size between these two groups are significant. About what similarity it is possible to speak, if the body size of capercaillie males (body length with tail is 955-992 mm and body weight 4000-6500 g) is nearly twice as long and four times as heavy as that of black grouse ones (body length 585-595 mm; body weight 1100-1650 g). These differences are significantly stronger than those between spruce grouses and blue grouses, where all attempts to unite them in a single genus Dendra-gapus failed.
6. The color of the eggs. There is only one type of the egg’s coloration in tetraonid birds — the numerous brown spots, from dots to little patches in size, are arranged on the yellow-brown background. Only the number of spots and intensity of their coloration vary, together with the color of background (from very pale, almost white to brownish rufous). Variations in color of the background and spots are great even in the same species. For example, the background color of freshly laid eggs depends on the current diet of the hen (it was proved experimentally). It is obvious that egg’s color in grouses cannot be used as the specific generic character. The same is true for color patterns of nestlings, mainly the head pattern The brown «cap» with black border is the basic, may be the most ancient color pattern. It is well developed in all species of the genera Lagopus and Falcipennis, and also in Tetrao urogalloides, Lyrurus mlokosiewiczi and eastern subspecies of Lyrurus tetrix. In all other species this «cap» pattern is reduced to the different degree, up to a single small brown spot in the occipit and some black little marks in the top of the head.
There are all six arguments that allowed L.Short to unite capercaillies and black grouses in the single genus. At the same time, such prominent and specific character of the genus Tetrao, as its unique skull, or such a remarkable feature of the genus Lyrurus as the unusual shape of male’s tail and tail feathers, were ignored.
The detailed study of morphology, ecology and ethology of these birds demonstrates great differences between capercaillies and black grouses. Many of these differences have the taxonomic significance in the generic level and are not shared by other genera of the tetraonid birds.
The skull of capercaillies is unusual not only because of its large size, but because of its triangle shape too. The skull looks like a narrow wedge in horizontal protection and is compressed in dorsal-ventral direction. The ratio of the skull height to its width is only 55-59%, instead of 76-86% in other tetraonid birds. The skull width constitutes 41.7-42.8% of its length (in other tetraonid birds, more than 55%). There are some other structural characters of the capercaillie’s skull that are absent in other tetraonid birds. However, even the mentioned remarkable character is significant enough for distinguishing these birds as the independent genus. Other morphological peculiarities of capercaillies include elongated trachea that form the loop at the base. Another important detail is the great width of the pelvis, like in species of genera Bonasa, Falcipennis and Lagopus (84-85% of its length), whereas in black grouses the pelvis noticeably narrower (76-78%), as in species of the genera Dendragapus, Centrocercus and Tympanuchus.
On the other side, the black grouses also have some prominent features that separate them from other tetraonid birds. First of all it is the specific lyre-shaped black tail of males with curved and elongated outer retrices. Even in females the gray tail is distinctly bifurcated. Another important character of black grouses is the specific structure of «eyebrows» in the Caucasian black grouse. In this relation it is useful to mention, that «eyebrows», i.e. stripes of the naked skin above the eyes, are characteristic of all the tetraonid birds. In males, these eyebrows are rich of blood vessels and covered by a complicated mosaic of knobs, protuberances, tubercles. During the mating season eyebrows are filled by blood and strictly increase in size. The color of eyebrows is red or yellow.
The eyebrows of tetraonid males include 2 types. The eyebrow of the first type is flat, covered with flat knobs, and possesses the high crest along the upper margin. In calm conditions, the crest is hanged down, covering the eyebrow. This type is typical of species of the genera Centrocercus, Tympanuchus and Lagopus. The eyebrow of the second type is convex with high knobs, protuberances and tubercles. This type of eyebrows is typical of species of the genera Bonasa, Falcipennis, Dendragapus and Tetrao (Potapov 1985). Only one single genus, Lyrurus, is unique in this respect. One of its two species, L. tetrix, possesses the eyebrows of the second type, while another, species, L. mlokosiewiczi, of the first type (Potapov 1978). This structure of the eyebrow in L. mlokosiewiczi which is similar to that of the ptarmigans, may be considered as the plesiomorphic character and the evidence of close relationship between the ancestors of Lagopus and Lyrurus.
The differences in ecology of capercaillies and black grouses are not less important. Capercaillies are the birds of the coniferous taiga forests and inhabit the entire taiga zone of the Eurasia from Atlantic to Pacific
coasts. Parts of the coniferous trees, such as needles of pines and spruces and buds and twigs of larches constitute the main winter food of capercaillies. This moment is very important, because it was shown (Potapov 1974, 1985) that nutritional specialization in tetraonid birds concerns first of all the winter diet, while summer diets are more or less similar. Black grouses are birds of semi-exposed habitats, avoid dense forests and find the optimal life conditions in the forest-steppe zone, in marginal parts of forests in the lowlands and in the subalpine belt. Its range also covers large parts of the taiga zone and the forest-steppe zone in Eurasia from Atlantic to Pacific regions, but, in contrary to the capercaillies, does not reach the Pacific coast. The winter food of black grouses consists mainly of deciduous trees, first of all, of catkins, buds and twigs of birches. Black grouse don’t penetrate to the larch taiga of the eastern Siberia, despite of the possibility to feed by larch buds and twigs in winter (Lyrurus tetrix in upper parts of the forest belt in Alps).
Capercaillies and Black grouses have the collective leks indeed, but there are many differences between them in this respect. The leks of black grouses are placed in open habitats, e.g., bogs, meadows, glades, clearings, even in lake’s ice, but not far from the forest edge. This feature, i.e. leks in exposed habitats, relates black grouses to species of genera Tympanu-chus and Centrocercus. By contrast, the capercaillies place their leks only in the forests. Collective leks of forest grouses are characteristic not only of these birds. Recently, the evidence appeared that collective leks are also typical of the Siberian spruce grouse Falcipennis falcipennis (Pukinsky 2003).
Another important ethological difference between the capercaillies and black grouses concerns the main nuptial posture of the males. The main nuptial posture of the capercaillie male is the «upright» posture, whereas black grouse male have «forward» one, low-neck posture when the head and neck are drew out ahead, in parallel to the substrate, like in Tympanuchus species. Only the Caucasian black grouse have very specific main nuptial posture, resembling the posture of the inflatable pigeon that resembles such kind of posture in the blue grouse and the sage grouse. Generally speaking, the courtship displays of capercaillies and black grouses are quite different in most of details.
All this arguments demonstrate basic differences between capercaillies and black grouses. Therefore, uniting of these species in the single genus is a glaring taxonomic error.
The composition of the genus Lyrurus Swainson, 1831
and its distribution.
The genus Lyrurus includes only 2 species, the Black Grouse Lyrurus tetrix and the Caucasian Black Grouse L. mlokosiewiczi. The range of
the black grouse is well known, but I want to point out several important peculiarities of it. First of all, this species do not penetrate in the eastern Siberian taiga zone, where larches are completely dominant species. That is why black grouse is absent in the eastern part of the taiga zone to the east of the Lena river and to the north of the mountain ridges that separate the Amur Basin from the north. Dense taiga forests with spruces, firs, larches, Manjurian pines and dense tickets of creep pines above the timberline, that covers the mountains around the Amur Basin and along the Pacific coast (Sikhote Alin etc.) are very unsuitable for this species and prevent their distribution in the Pacific coast. As a result, in the easternmost part of its range, the black grouse populates mainly open habitats in the valleys of the rivers. It seems that the eastern limits of the species area ancient enough. In any case there are no palaeontological finds of the black grouse in Holocene deposits in Sakhalin, where the bones of some other tetraonid birds were discovered (Tetrao urogalloides, Bonasa bonasia, Falcipennis falcipennis, Lagopus lagopus).
The absence of the black grouse in the vast area of larch taiga is a result of super severe winter climatic conditions, for which this species is not adapted. Special experimental investigation of the energetic possibilities of this species shows that its heat conductivity is more than twice exceed the theoretically expected value (1.151 kilo-joule/°C/hour, Hissa et al. 1982). Because of this during the frosty weather (-20°C and more low) the black grouse spend practically all the day in its snow hollow and can to spend for the foraging not more than a half an hour (Potapov 1982).
Concerning the southern border of black grouse range there are no doubts that it fluctuated significantly during Pleistocene cold and warm epochs. There is palaeontological evidence on the presence of this species in Pyrenees and Crimea mountains during the cold Wurmian epoch nearly 20000 years ago. Even a hundred years ago, in Eastern Europe the range of the black grouse reached the coasts of the Black and Azov Seas and the Kuban river basin. Black grouse disappeared from all these parts because of human agricultural activity and its southern border stepped back to the north as far as 500-700 km. In the Asian part of the range, the southern border also stepped back to the north, although to shorter distances, only in Northern Kazakhstan and Western Siberia, but not in mountain forest of the Southern Siberia and Tien Shan.
The second species, Caucasian black grouse L. mlokosiewiczi occupies a very small mountain area, the Caucasus, and some adjacent mountains. The ranges of both black grouses are not connected and, moreover, are divided by the nearly 1000 km of territory, uninhabited by black grouses. Meanwhile, only a hundred years ago, when the black grouse was distributed to the south up to the Kuban river basin, both Lyrurus species were divided only by comparatively narrow belt of dense virgin forests, that
covered northern foothills and slopes of the Great Caucasian Mountain Ridge. The Caucasian species, that inhabits only subalpine belt and adjacent parts of the forest and alpine belts, preserved its range during last century without significant changes. It is necessary to point out, that the range of this species is not enough clear. First of all, it concerns the distribution of this species in Turkey (it is only well known that it populates the Pontian Mountain Ridge westward to 39°37' W) and in Azerbaijan (Minor Caucasus, i.e. Karabach Mountains, where it is known from two main mountain ridges: Murovdag and Dalidag). The distribution of this bird in Dagestan needs more precise definition too.
Lyrurus tetrix is the polyphyletic species. Its huge range covers the territories with very distinct landscapes and natural conditions. It is naturally, that different populations were adapted to different natural conditions during the long span of its sedentary life. At present the taxonomists recognize 8 subspecies: (from east to west) L. t. ussuriensis, L. t. baikalensis, L. t. jenisseensis, L. t. mongolicus, L. t. viridanus, L. t. tetrix, L. t. juniperorum and L. t. britannicus. These subspecies differ mainly in the coloration of adult males and females. Males differ in the width of the white band («mirror») at the wing, in the degree of the development of black coloration and in the duration of such development (from 2 to 4 years), in the color of the metallic glance at the breast (violet, green) and in some other details. Females differ in the coloration of the underparts of the body: from five main colored zones to the monotonous cross-stripy, gray-rufous coloration. Due to the types of coloration all subspecies of the Black grouse must be divided for two groups: the western (tetrix, juniperorus, britannicus) and the eastern (viridanus, mongolicus, jenisseen-sis, baikalensis, ussuriensis) groups (Fig. 1).
In the eastern group the forest-steppe black grouse, L. t. viridanus, that inhabits the forest-steppe zone from the Volga to Ob rivers (central part of the species range), possess the most ancestral features in coloration. Males of this subspecies have unclear black throat patch with white bordering (the ancestral feature) in its first adult plumage (Fig. 2), the white «mirror» at the wing is developed to the maximum extent. They retain the gray-brown vermiculation of the upper pats of the body, especially of the upper wing-coverts (another ancestral feature), during all its life. In other subspecies this character is well developed usually only in the first adult plumage. In other words, males of this subspecies never possess full black color, which is characteristic of males of other subspecies. Females of this subspecies also possess the ancestral character of coloration: the underpart of the body has five zones colored differently: whitish throat, vermiculated gray-rufous neck, rufoust breast, blackish belly and white under tail cover feathers. Other subspecies of this group populate areas to the east of L. t. viridanus range (mongolicus, jenisseensis, baica-
Fig.1. Range of Lyrurus tetrix (after Potapov 1985).
Subspecies: I — L. t. britannicus, II — L. t. tetrix, III — L. t. juniperorum,
IV — L. t. viridanus, V — L. t. mongolicus, VI — L. t. jenisseensis, VII — L. t. baicalensis, VIII — L. t. ussuriensis. Shaded — eastern group of subspecies.
lensis, ussuriensis). They have many similarities with viridanus and differ only by some details. The color of males becomes darker eastwards, and coloration of females becomes more monotonous. All males have the green metallic brilliance in the breast and rump and develop full black coloration of the third adult plumage. The size of the white band on the wing is the same and only in the mountain form mongolicus it is little smaller. The rufous color of the breast in females expressed to a lesser extent or is entirely absent in many specimens of mongolicus and jenisseensis; it is completely absent in ussuriensis. The females of the latter subspecies are the darkest among all the representatives of this group and possess a rufous tint.
In contrary, the subspecies spread to the west and to the north from L. t. viridanus (tetrix, juniperorum and britanicus) differ more clearly in the full development of black with the violet metallic glance coloration of the breast and upper body parts in males, and in monotonous coloration of lower body parts in females. This group of subspecies inhabits the western and northern parts of the species range. Males of this group demonstrate extensive black coloration with violet metallic brilliance at the breast, head and upper parts of the body in the first, second or third (as a rule, in the first or second) adult plumage, and comparatively narrow
white band («mirror») on the wing. Female also possess dark coloration, formed of dark gray patterns and rufous narrow stripes across the body. The British subspecies, L. t. britannicus is the most advanced in coloration: males possess entirely black coloration virtually in the first adult plumage and have the smallest white «mirror» on the wing. Females also have the darkest coloration among all the subspecies, with reddish hue on the rump and tail upper coverts. This is the single subspecies with reduced feathering of the central toe, as the result of the long existence in warm climate.
A propos, this is the single subspecies that is completely isolated from other subspecies. All other subspecies are not divided by natural barriers and contact with each other. In the area of each such contact there is a transitional zone with mixed populations. The width of such zones varies from several dozens to hundred km, in dependence of the degree of differences between the landscape characters and environmental conditions in territories populated by different subspecies.
In most subspecies of both groups, the size of the birds is approximately the same. Only the Baikal black grouse is distinguished by its large body size. The length of the wing of this form is 275-296 mm in males and 237-250 mm in females, instead of 262-289 and 232-238 mm in other subspecies. This large size may be explained by climatic conditions in the area that possesses the most continental climate with the lowest winter temperatures down to -50oC.
By contrast to the black grouse, the Caucasian species is monophyletic and till present nobody can find the differences between populations, dwelling in different mountain systems. The main reason of this uniformity is the similarity of basic environmental conditions in the subalpine zone, first of all similarity of climatic conditions. At the same time, there are some sufficient differences between the character of vegetation in northern and southern parts of the species range. For example, birches, mountain ash, bilberry, and rhododendron, so usual in the Great Caucasus, are absent in the subalpine belt of the Minor Caucasus, but dog-rose is present in large numbers. These differences influence on the composition of the food in local populations, especially on the winter diet. These conditions may result in the geographical differences between populations, but only in cases with a strictly settled way of life. The absence of such differences is the evidence of genetic exchange between populations through all the range. Evidently, the main role in this process belongs to males because of their high flying ability (Potapov 2004).
Phylogenetic relationships of the genus Lyrurus
The phylogenetic relationships of the black grouses would become more clear if not only morphology of the adult birds (including coloration) is analyzed, but the development of coloration in junior stages, the first
and the following adult plumages in all subspecies, the coloration of aberrant specimens and androgynous females would also be taken into account. The slow development of the final adult coloration during the several years is the evidence of its primitive character. By contrast, its quick development is the evidence of the more advanced character. As was shown previously, the most primitive adult male’s coloration among the subspecies of L. tetrix is characteristic of the forest-steppe subspecies L. t. viridanus, and the most advanced one, of the British L. t. britannicus. Really, some ancestral features, like the black throat spot with unclear white bordering in the first adult plumage, mentioned above, are present in the first subspecies (Fig. 2). This pattern reflects the certain stage the phylogeny of grouses. It is well developed in adult males of the palae-arctic hazel grouses (subgenus Tetrastes), and in all species of spruce grouses. Its distinct traces are also present in Dendragapus and Centro-cercus males (Potapov 1985).
Fig. 2. The black throat spot of males in: 1 — Bonasa bonasia, 2 — Falcipennis falcipennis, 3 — Dendragapus obscurus fuliginpsus, 4 — Lyrurus tetrix viridanus (subadult) (From Potapov 1985).
It is interesting to note that the coloration of so named androgenous females (females with the insufficient influence of the female’s sexual hormones) in L. tetrix is very dark, but not black, and looks like one-year-old male of L. t. viridanus, but with more ancestral features. The black color with violet glance presents only in the tops of breast and rump feathers. The tail feathers are black with white bases. It is very important evidence, because the type of male’s coloration, hidden in female’s genome, stays out of the pressure of natural selection and, so, preserve many ancestral features.
The aberrant coloration of many specimens in L. tetrix also gives the interesting data about the content of the species genome. 27 variants of such aberrations were described, including 9 aberrations for males and 18 for females (Kots 1937). At the same time, no aberrations were ever found in L. mlokosiewiczi. The most remarkable feature in coloration of all the aberrant males is the development of the depigmentation (white color) of feathers in different parts of the body, expressed to a various degree, and occasionally resulting in the complete albinism. It is wonderful that one of these aberrations, named «marginata» by prof. Kots, suddenly appeared in southern Norway in large number: males of one of local populations had the similar coloration, which strongly differed from the usual one. This population was described as a new subspecies L. t. bjerkreimensis (Schaanning, 1921). Distribution of this mutation was restricted to a small area and its future is unknown. It is important to note that the male coloration in this case have an obvious similarity with the
spring coloration of the males of the willow ptarmigan Lagopus lagopus:
full dark colored head, neck and breast and a lot of white color at the other parts of the body (Fig. 3).
Fig.3. Stuffed black grouses of “subspecies” L. t. bjerkreimensis (from Schaanning 1921).
Among 18 color variations of females one is especially interesting. A.Kots named it «pseudocaucasica» because of close similarity to that of female of the Caucasian black grouse.
The Caucasian black grouse is unique among all other species of tet-raonid birds because of the strong difference between coloration of the first and the subsequent adult plumages of males.
One-year-old males possess the female-like gray-brown coloration without black feathers. It is so unusual that in the first description of this
species L.Taczanowski described a one-year-old male as the female. This mistake was revised twelve years later by T.Lorenz, when he collected a series of males and females of different ages (Lorenz 1887). The strong difference between the first and subsequent coloration of adult males is always present and is maintained undoubtedly by the natural selection. Occasionally, one-year old individuals with single black feathers are found in collections and it seems that this trait could have been more expressed if it was not suppressed by the natural selection, which supports the gray female-like coloration. It is possible that the gray coloration of young males is somehow connected with the fact that they spend their first winter together with females in the upper part of the forest belt and such coloration has the camouflage function. Old black males spend winter in separate flocks mainly above the timberline (Vi-tovich 1986). Another possible reason is that the gray cryptic coloration of young males helps them to escape raptor’s attacks in the leks because they are not enough experienced to avoid such attacks.
We can obtain additional information about the appearance of the ancestor of black grouse from the coloration of the hybrids of L. tetrix with other tetraonid species. Together with the well known hybrids with capercaillie, there are descriptions of many hybrids of this species with L. lagopus (including L. l. scoticus), and, less frequently, with L. mutus, Bonasa bonasia, Tetrao urogalloides (a single case) and even with the pheasant Phasianus colchicus and the domestic hen. The most stable features of black grouse hybrids are the following: the bifurcated tail, the white «mirror» at the wing, and the black coloration of the upper parts of the body. At the same time, most feathers possess a white fringe at the apex. It is important to point out that in male hybrids of L. tetrix x L. lagopus the eyebrow have the willow ptarmigan’s type, but under the thick feathering of the toys they preserved the pectinations, so usual for the most of the tetraonid species, including black grouses.
The most prominent morphological feature relating the genera Lyrurus and Lagopus is the type of the eyebrow in the Caucasian black grouse, mentioned before. It is also interesting to note that occasionally rare specimens with slightly bifurcated tails were found among willow ptarmigan females deposited in collections. It is obvious, that this shape of tail appeared as a result of delay of the grow of central tail feathers during autumn moult because of the lack of time to finish the moult completely.
It is interesting to pay attention to close coincidence of the main habitats of black grouses and willow ptarmigans in many parts of their ranges. In the taiga zone there are vast open bogs that serve as breeding sites for willow ptarmigans and the places of the leks for black grouses. In British Isles such places are represented by moors. In the forest-steppe zone of southern Siberia and northern Kazakhstan, these places include virgin or
partly cultivated areas mixed with swampy thickets of willows, meadowsweets etc. and small pine or birch groves. In some regions in northwestern Kazakhstan the southern borders of the ranges of both species coincide completely. In such places both species use different food sources during winter. Black grouses feed at the crowns of the birches, whereas willow ptarmigans find their food in willow shrubs on the ground. In the Amur Basin, at the southeastern limit of the range, L. tetrix spends winter seasons in habitats, typical more of L. lagopus (that is absent here), namely, in willow thickets in wide river valleys, feeding on willow buds and twigs while walking between the shrubs like ptarmigans.
Summarizing all the data, concerning characters, that are, to a lesser or greater degree shared by black grouses Lyrurus with representatives of other genera, it is evident that this genus possesses the closest relationship with the genus Lagopus and more remote relationship with Falcipennis, Bonasa and Tetrao, i.e. virtually with all the palaearctic genera of Tetraonidae. At the same time the role of the esophagus of L. tetrix as a resonator, that amplifies the sounds of the nuptial song by several times, relates the genus Lyrurus to the nearctic genera Dendragapus and Tym-panuchus.
The origin of the genus Lyrurus and the evolutionary history of black grouses
Zoologists usually have three kinds of sources to trace the evolutional history of black grouses: the palaeontological and palinological data, the traces of the ancestral features in ontogenesis, geographical and individual variability, and in hybrids, and the morphological, ecological and other characters that are associated with adaptations to natural conditions typical of this taxon.
The earliest paleontological evidences are known now from southern, central and Western Europe, especially from Balkan Peninsula and Car-patian Mountains Bazin, where the fossils identified as Lyrurus sp. appear from the Pliocene, nearly 1.7 MA (Boev 2002; Mlikovsky 2002). Especially interesting are the finds of fossil bones, which have the specific characters as the black grouse, as the ptarmigan (Boev 2002). The fossils of recent species are known from the middle Pleistocene of France, nearly 550 KA (Mourer-Schauvire 1975 — L. tetrix longipes) and Caucasus (L. mlokosie-wiczi) nearly 350 KA (Potapov 1985). The find of L. tetrix in Pliocene of Mongolia (Rich et al. 1986) is doubtful: the earliest appearance of fossils of all recent tetraonid species that is known nowadays is dated 500-600 KA. It seems that such long duration of the existence of modern galliform species is impossible. In this case we can deal only with one of the ancestral forms of this species or even of the genus Lyrurus.
The analysis of the morphological adaptations and ecology of the black grouses permits to suppose that the ancestral form of this genus populated semi-open landscapes, where its winter foraging activity was closely associated with arboreal and shrub vegetation. Its evolutionary history was similar to that of all other tetraonids and its range was determined by climate and vegetation: climate with cold snowy winter and arboreal and shrub vegetation as the main winter food source. During the Pleistocene, such conditions existed in most parts of the Palaearctic. It is well known that arboreal, and partly shrubby vegetation had a restricted distribution during cold phases (glaciations), but moved far northwards during warm periods (interglaciations). The range of the ancestor of the black grouse changed in accordance with this process.
The important crucial point in the evolution of the ancestor of the black grouse was the bifurcation of two lineages that led to the recent species of the genus. The time of this event is unknown. It could happen long before the middle Pleistocene, because the earliest fossil remnants of both species, as mentioned before, are dated by 550-350 KA. In the case of the Caucasian black grouse — 350 KA (oxygene isotope stage 10), i.e. by beginning of the Rissian glaciation (Kudaro cave, Central Caucasus: Potapov 1985), a long time period was necessary for developing of such deep adaptation for the life in the highland, that we see in this species. We have all reasons to believe that his ancestor was a mountain bird. If so, it could reach the Caucasus only from the Balkan mountains, via the mountain ridges of Anatolia (Potapov 1978, 2004). As I mentioned above, the earliest fossils of black grouses were found in Balkan Mts. They belong to an epoch before the Pleistocene. I am not sure that these fossils belong to the representatives of the genus Lyrurus because of the very warm, nearly subtropical climate characteristic of this area in that period. But, undoubtedly, representatives of the genus were present in these mountains from the beginning of the first cold epoch of the Pleistocene. It is well known that the great climatic changes strongly affected the vegetation of the southern mountains of the Palaearctic during the Pleistocene. Forests repeatedly appeared and disappeared here and their distribution fluctuated. Occasionally, the forest belt had only moved up or down slopes, changing altitude above the sea level in accordance with the climate of the next epoch. The Pleistocene populations of the ancestral black grouse in mountains (like modern populations of L. tetrix in Alps or Carpathians) and plains were repeatedly isolated and joined again, in accordance with the appearance and disappearance of the forest belt. One can assume that during one of these cold epochs the ancestral population of the Caucasian black grouse that dwelled around the timberline in the Balkan Mts, got a possibility to expand eastward along mountain ranges of the Asia Minor peninsula, up to Caucasian mountains. It is the only possible scenario, if only
we accept the hypothesis on the origin of the Caucasian black grouse from the mountain ancestor. Penetration of the ancestor of this species in Caucasian mountains from northern plains is less probable. In this case we must accept the origin of this species from lowland ancestral populations. The ancestor of this species had to reach the Caucasus through the open steppe lowland at the time no later than the Mindel-Riss interglacial period. Until present, there is no data about animal life and vegetation in this area during the first half of the Pleistocene epoch.
Moreover, great transgressions took place in the interglacial periods, when waters covered the entire territory between the Black and Caspian Seas north of Caucasian Mountains, interrupting any connections between terrestrial faunas of European steppe zone and Caucasus. The fossil remnants of tetraonid birds were not recorded from the Ukrainian and southern Russian steppe zone till the cold Upper Wurm epoch (nearly 7020 KA). Only in that time, the willow grouse appeared there in large numbers and the black grouse reached Crimean Mountains. Apparently, it could happen because the arboreal vegetation developed in the steppe zone, especially in the river valleys, during the short interglacials (45-30 KA). Later, closely to the recent time period, in the Holocene wet Atlantic period (5-7 KA) the black grouse reached even the northern foothills of the Caucasian Mountains and was stopped by powerful large forests that covered the northern foothills of these mountains. Only a hundred years ago, populations of two species of Lyrurus were separated by these forests by the distance of 120-150 km and by nearly 1200 m altitude.
At last, the black grouse L. tetrix was distributed from southern Europe eastward to the Baikal region during the second half of the Pleistocene. Its range expanded to the north during warm interglacial periods and retreated back at the cold glacial times. The difference between western and eastern populations could appear even in the late Pleistocene times, when climatic and vegetation differences between European and Asiatic parts of the species range arose significantly. In Europe climate became milder being influenced by sea waters, whereas in the Asiatic part of the range, the climate preserved its strongly continental character. As for the habitats of the subspecies L. t. viridanus that preserved the most ancestral features, the mixed forest-steppe landscape could be the optimal habitat of the black grouse at last during the final stage of the Pleistocene. It is well known that such kind of landscapes prevailed in the southern parts of the Palaearctic during the last glacial epochs, bordering vast areas of tudra-steppes from the south. In the Holocene, eastern populations continued dwelling in the ancestral types of landscape (forest-steppe and fragmented mountain forests) in stable continental climate conditions. At the same time western populations obtained more dark coloration under the influence of milder and warmer climate and began to
spread northward in the end of the Pleistocene epoch together with the arboreal vegetation (Fig. 1). These populations reached the British Isles (at that time connected with the continent), occupied the entire Europe to Scandinavia and, after that, colonized the newly appeared zone of taiga forests eastward as far as to the Lena river basin. This does not mean that the black grouse adapted to life in dense taiga forests. Populations of black grouse penetrated in the taiga zone via open habitats like river and lake valleys, burnt out places, etc., and especially large bogs. Later, these natural open habitats were supplemented by artificial habitats, created by humans (pastures, agricultural field, clearings, etc.). In fact, the entire taiga zone is populated by a single subspecies, L. t. tetrix, possibly the youngest among all the subspecies of black grouse. It cannot be older, than the modern taiga zone, which appeared during the Holocene. It is necessary to underline, that along the northern border of its range, this species do not penetrate northward of the taiga zone, to the forest-tundra habitats.
Conclusion
The genus Lyrurus, includes 2 species, L. tetrix and L. mlokosiewiczi, that are very similar in the appearance, coloration and ecology. Both species distinctly differ from capercaillies Tetrao and demonstrate closer morphological, ecological, and ethological similarity with the genera La-gopus, Falcipennis and Bonasa. Both species avoid dense forests, prefer semi-open habitats, and are closely associated with the arboreal vegetation as the main winter food source, and also with open meadows with shrubs and trees as places for brood rearing.
Two species of black grouses differ significantly in the range area and the degree of the geographical variability. The Caucasian black grouse L. mlokosiewiczi occupies a comparatively small range, restricted to subal-pine and alpine belts of Caucasian Mountains and adjacent mountain ranges situated in Turkey and Iran. This species has no signs of the geographical variability. The black grouse L. tetrix, by contrast, possesses the large range, that occupies the forest and forest-steppe zones of Eurasia, and demonstrates the intensive geographical variability (8 subspecies are distinguished now, mainly due to the differences in coloration). These differences are giving additional information, that help to restore the last stages of the evolutional history of this species. At the same time the sources that contain information about the early stages of the evolution of both species, its common ancestor, and origin (fossil remains and palino-logical data) are scarce. The earliest finds of fossils, that belong to the representatives of this genus are dated as early as the upper Miocene (Boev 2002, Mlikovsky 2002), whereas the fossils of the modern species appear in the middle Pleistocene, nearly 2 million years late
(Mourer-Chauvire 1975). According to the hypothesis, offered by the author (Potapov 1978, 1985, 2004), the Caucasian black grouse had originated from the ancestral form of the genus Lyrurus. Populations of this form, dwelled in the mountain area of the south-eastern Europe (mountains of the Balkan Peninsula) and adapted to life in mountain conditions, like the modern populations of L. tetrix that inhabit the timberline in Alps, Makedonia or Carpatian Mts. Afterwards, they spread eastwards through the mountains of the Anatolian Peninsula to Caucasus Mts during one of the cold epochs of the Pleistocene (presumably during the Rissian Glacial epoch). The earliest find of L. mlokosiewiczi in Caucasus is nearly 350 KA and L. tetrix in France — 550 KA. It means that the split of the ancestor form into two lineages that led to the modern species took place within the Mindel-Riss interglacial epoch at the latest. The black grouse, L. tetrix, probably, began its independent evolution in the western part of its recent range. In any case, fossils of this species are more frequently found in the western (European) part and become more and more rare eastwards. The more ancient character of the coloration of the eastern subspecies is explained by more continental climate that was usual in the native land in the middle Pleistocene in all Europe.
As for the territory of the genesis of Lyrurus ancestors, dwelling of both two species in western Palaearctic together with paleontological data, point to this area as the native land of the genus. I hope that subsequent paleontological investigations and pollen analyses data will help to detect the native land of black grouses more precisely.
This paper was meant to be presented at the International Black Grouse conference, Ruthin, North Wales, March 2005, which I was not able to attend, and I am obliged very much to the Editor-in-Chief of this Journal, Dr. A.Bardin for the ability to publish my manuscript. I am deeply thankful for Dr. E.Potapov for the help in preparing the English variant of this article.
References
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Род Lyrurus Swainson, 1831 (Тетерев): таксономическое положение, состав, распространение, филогенетические связи и происхождение
Р. Л. Потапов
Данное сообщение подготовлено мной в качестве доклада для Международного симпозиума по тетереву в Уэльсе, Великобритания, прошедшего в конце марта 2005 г. Целью этого доклада было ознакомление специалистов, занимающихся изучением обыкновенного тетерева Lyrurus tetrix, с систематическим положением тетеревов (род Lyrurus) в системе семейства тетеревиных птиц (Tetraonidae) и ошибочностью представления о том, что тетерева и глухари относятся к одному и тому же роду — Tetrao. Должен повторить, что нет ни одной работы, детально аргументировавшей такое объединение, за исключением краткой, поверхностной и во многом ошибочной статьи Шорта (Short 1967). По этой причине мною приводится развернутая аргументация, свидетельствующая о родовой самостоятельности глухарей и тетеревов, опубликованная мною ранее на русском языке (Потапов 1978, 1982, 1985). Более детально здесь анализируются признаки, сближающие роды Lyrurus и Lagopus, а также причины, обусловившие наличие особого первого годового наряда у кавказского тетерева L. mlokosiewiczi и отсутствие у него географической изменчивости.
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ISSN 0869-4362
Русский орнитологический журнал 2005, Том 14, Экспресс-выпуск 296: 741-743
К экологии серой неясыти Strix aluco в период гнездования
И. В. Прокофьева
Российский государственный педагогический университет,
Набережная реки Мойки, д. 48, Санкт-Петербург, 191186, Россия
Поступила в редакцию 4 сентября 2005
В Ленинградской области серая неясыть Strix aluco обычна лишь на юге, а именно, в Лужском районе (Мальчевский, Пукинский 1983). При этом и там многочисленной её назвать нельзя. Под натиском цивилизации эти птицы, как и другие совы и многие дневные хищники, повсеместно сокращаются в числе (Нанкинов 1971). Поэтому сведений об их образе жизни в условиях Ленинградской области очень мало. Исходя их этого, мы приводим результаты наших наблюдений за гнездованием четырёх пар серой неясыти. Работу проводили в Лужском
