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ISSN 0869-4362
Русский орнитологический журнал 2003, Экспресс-выпуск 225: 630-636
New data on winter life of the Grey Partridge Perdix perdix in Leningrad Province
R.L.Potapov
Zoological Institute, Russian Academy of Sciences, St.-Petersburg, 199034, Russia Received 2 April 2003
The Grey Partridge Perdix perdix (L.) inhabits the Leningrad Province, reaching there its northernmost range limits. Populations of the Grey Partridge in the Province fluctuate from presumably high level in 1930s down to total local extinction observed upon several years following severe winters of 1901-1902, 1939-1941, and 1955-1956 (Malchevsky, Pukinsky 1983). In all the northern part of its European range Grey Partridge is closely associated with agricultural landscapes, especially arable fields and pastures. The species life style strongly depends on human agricultural activities (Potts 1986). In Leningrad Province, I have observed a gradual decrease in the number of Grey Partridges in the second half of the XX century. The decline was caused by cardinal changes in the agriculture, namely, by the replacement of cereal fields with vegetable ones (Malchevsky, Pukinsky 1983). On the contrary, the Pskov Province, adjoining Leningrad Province from the southwest, is more favorable for grey partridges. In this Province, winter is shorter and less severe, and the snow cover is finer. This area is hilly with steep and often snow-free slopes and cereal fields alternating with pastures and small woods are abundant. Grey partridges have never disappeared completely from this region, even during severe decrease in abundance observed elsewhere (Kalinin, Potapov 1993).
The low density of the Grey Partridge population in the Leningrad Province, permanent fluctuations of this density and local extinction of birds in many places hampered examination of this species. The information on the ecology of this species in Leningrad Province is very scarce; hence, any detailed data on reproduction or winter life of the Grey Partridge in Leningrad Province is very important. The only fact known on the species from the Province was the following: in 1930s, these birds roosted under the snow in snowy winters in some places (Malchevsky, Pukinsky 1983). Prof. A.S.Malchevsky flashed up partridges regularly from the shelters under the snow in the end of the January 1933, when the frosts reached —25°C. Unfortunately, no data about the design of such shelters are available till present.
New data about winter ecology of Grey Partridge in Ogorelie environs
In the winter of 1995/1996, the Zoological Museum of the Zoological Institute has received the license from the Province Game Management Authority to procure 5 specimens of Grey Partridge for a new museum exposition. The team of the museum employees (V.S.Ivanov, S.O.Mamonov, and S.I.Fokin) visited Ogorelie settlement (59°01'N, 30°57'E) in the beginning of February 1996. There, a number of partridges were seen every winter for at last 3 previous years.
The team collected 4 specimens and followed by my instructions, obtained some additional data on the winter ecology of partridges in this area. The stuffed skins of these birds are displayed as a biological group exhibit at the Zoological Museum "Winter life of the Grey partridge in Leningrad Province".
Ogorelie is a little settlement surrounded by arable fields now abandoned. The fields were overgrown by weeds after the devastating decline of agricultural activity that occurred there several years ago. This new vegetation consists mainly of several weed species, mainly Atriplex sp., Chenopodium sp., Carduus sp., etc., that form sick and tall (up to 1.5 m) thickets, mainly along the edges of the fields. These fields look like little islands of exposed habitats (total area less than 6 km2) amongst boggy forests, thickets and sphagnum bogs.
The winter of 1995/1996 was comparatively soft, without strong frost (-25°C or higher) and with moderate snow cover (up to 45 cm). During the visit, the weather was sunny with temperature of about -10°C at noon. Little groups consisting of 6-12 partridges spent the day at feeding places along thick grows of weeds and changed their feeding places only when disturbed. If not, they spent all night close to the feeding place.
The feeding places, mainly the thick grows of weeds covered with fluffy snow at the height up to 40-50 cm, were trampled by numerous bird's traces and snow was pierced through by many holes, tunnels, and cavities between the weed stems. The tunnels and cavities often reached the ground as a result of digging activity of the feeding and roosting partridges. The study of the feeding places and the contents of crops and gizzards of the birds collected shows that the usual food of partridges consist of the seeds of the lamb's quarters (Chenopodium sp., probably Ch. album) with an addition of a some green leaves of the clover. The dry weight of the crop full of seeds of Chenopodium was 2.7 g as maximum. However, the number of these seeds was impressive! I counted 3156 seeds in the crop and 1011 seeds in the gizzard, but it was only a part of its full content: other seeds were turned into monotonous porridge-like paste due to the grit's work in the stomach. Among all collected specimens, the maximum size of the full crop was 37x27 mm.
All collected specimens possessed fat deposits in regions of feather tracts, along sides of the breast, at the base of the neck and tail, and around the intestines. The presence of that fat deposits and the normal weight of collected specimens (Table 1) is the evidence of good nutritional conditions for partridges in this area, despite of the full absence of the cereals.
Table 1. Weight (g) and dimensions (in mm) of the Grey Partridge specimens from Ogorelie, Leningrad Province, 4 February 1996
№ Sex Age Weight Wing Tail Length of intestines Length of guts
Small Large "neck" "Container"
1 Male ad 363 595 85 735 78 46; 50 138; 141
2 Female ad 387 560 75 717 72 45; 46 138; 140
3 Female sad 405 600 75 685 70 46; 46 114; 120
4 Female ad 397 551 81 723 76 45; 50 140; 140
In this period of winter, partridges spent nights under the snow. For roosting, birds used the cameras they dug under the snow, or natural shelters like numerous cavities in the snow covering the weeds tickets. Formation of such cavities depends on the weed vegetation density. Many intersecting stems and twigs of the plants form a kind of a roof, preventing snow from reaching soil during snowfalls. During examination of these places, a lot of fresh and old partridge's footprints (fresh snowfall occurred only several days ago) did not allow to distinguish the roosts of solitary birds from such of groups. However, in some cases, the existence of collective and solitary roosts was evident. For example, in one roosting place, the bottom of the refuge of the collective roost (a stamped oval snow platform 42x32 cm covered by little heaps of droppings, situated along the margins of the platform) was preserved, but the snow roof above the shelter was destroyed when partridges left it. The distance between the bottom of the shelter and snow surface was 22 cm. At distances of 145 and 130 cm from this place, two round holes were found; these were made by 2 partridges which had put their heads from under the snow to look round in order to find a way to the place of collective roost. The size of these holes was 6x7 cm. Another roosting place under the snow was somewhat smaller: the bottom (38x21 cm) was situated at a distance of 28 cm from snow surface and was only sufficient for 2 birds (for comparison, the snow hole's bottom formed by the Hazel Grouse, a bird of the same size, is only half as wide: 19x11 cm — Potapov 1985). In the places of feeding, birds' snow tracks were 15-20 mm deep.
Fig. 1. Winter excrements: 1 - Perdix perdix; 2 - Bonasa bonasia. Рис. 1. Зимние экскременты: 1 - Perdix perdix\ 2 - Bonasa bonasia.
The winter droppings of the Grey Partridge differ significantly from that of the grouse (Fig. 1). These droppings are never cylindrical, being of the same shape in winter and in summer. They look like twirled spiral cones 23.5-28 mm long and 8-11 mm wide (as maximum). For comparison, the droppings of the Hazel Grouse (the bird of the same size) are 17.2-24 mm long and 5.7-7.3 mm wide (Potapov 1985). Excrements from the guts, so specific for tetraonid birds, were absent. It is not surprising. The winter excrements of these birds are the result of complicated work of its specific digestive tract. The ability to survive during all winter on the plant food of low nutritional value, but abundant and less time and energy consuming is one of the main diagnostic features for all species of the family Tetraonidae (Potapov 1974, 1982, 1985, 1992). In its turn, this ability is based on the presence of well developed guts accumulating the liquid digestive extract (chyme) containing the main nutritionally valuable sub-
stances. In the guts, the extract undergoes treatment for 24 h or more (usually about 48 h per portion), thus, significantly prolonging the digestive process. So, the guts are a special kind of reactor working uninterruptedly throughout the winter to provide the bird with a constant supply of energy and nutrients. The guts in the intestinal tract of tetraonid birds are never empty in every moment of the winter season. On the contrary, in all species of the family Phasianidae the guts are developed to a significantly less degree and do not play an important role in the daily digestive process during the winter. Our work with the wintering Grey Partridge gave us one more possibility to check the intestinal tract in all specimens collected. The size of the guts and all intestines was usual for this species (Table 1) and similar in autumn and winter. The construction of the gut was also usual for all partridge species. It consists of two large accepting capsules, followed by a very thin "neck" connecting these capsules with the main part of the gut — the so called "container" (Fig. 2). The frontal part of the. container is the widest (26 mm in circumference); its medium and caudal parts are half as wide. In grouse species, the inner surface of the containers bears distinct ridges covered by well developed absorbent epithelium. In the Grey Partridge, these ridges are small, interconnecting in many places and resembling a net instead of the 7-9 straight ridges typical of Tetraonidae. In the middle of winter, when the guts of tetraonid species are most active and are permanently filled with the digestive extract, the guts of Grey Partridges are nearly empty. By now, we have no reasons to deny the role of the Grey Partridge's guts in the digestive process during winter, but it is possible to assume that it is insignificant.
Fig. 2. The guts of Perdix perdix in winter: 1 - Large intestine; 2 - small intestine; 3 - accepted capsule;
4 - the "neck";
5 - the "container".
Рис. 2. Слепые кишки серой куропатки зимой: 1 - прямая кишка; 2 - тонкий кишечник; 3 - приёмная капсула; 4 - "шейка"; 5 - "баллон".
Discussion
All above-described details of the winter ecology of Grey partridges from Leningrad Province are very similar to that of partridges from the Canadian prairie (Westerskov 1965), Finland (Pulliainen 1984) and Belarus (Nikiforov 1988), i.e. from areas with snowy and frosty winters. Of all the regions mentioned, the climate of the south-eastern part of Leningrad Province (the examined area) is most similar to that in Canadian prairies; in both areas, the snow is soft and loose, but sometimes becomes more compact because of thaws. In this connection, it is necessary to bear in mind that alternation of thaws and frosts is most unfavorable for partridges: the snow cover becomes so hard that it becomes difficult for a bird to get the food from under the snow. In addition, during the thaw, the bird's feathers become wet while contacting with the melting snow;
hence, their thermo-insulation ability dangerously decreases. More snow means more dangerous conditions for partridges during thaws. In this respect, the examined area at the southeastern part of Leningrad Province is more favorable to partridges than that situated closer to the seashore, where the thaws are more frequent.
The winter diet of partridges in the examined area is more similar to that of the introduced partridges in the Canadian prairies: in both cases, weed seeds prevail in the diet (Westerskov 1965, 1966). In Belarus or Finland, main components of winter diet include the green leaves of winter crops and cereal grain. It is interesting to notice, that after the crash of the collective farm system of agriculture, typical of the former USSR, with its vast areas of mono-cultures, abundant and uncontrolled use of chemicals etc., many agricultural fields became empty and were later occupied by weed thickets. It was found, that this vegetation is very suitable for Grey Partridges. New populations of these birds began to reappear in some districts of Leningrad Province. In any case, the present study shows that this species can exist without any agricultural cereals as it is usually understood. By the way, in Canada prairies, despite of the abundance of cereals, the weed seeds are the second important group after the waste grain, constituting as much as 40% of the partridge's winter diet (Westerskov 1966).
Information about the roosting of the Gray Partridge under snow is not new. K.Westerskov (1965) was the first ornithologist who had described roosting of Grey Partridges under the snow in detail. He was well acquainted with traditional roosting of these birds in Europe and Eastern North America, where groups of partridges spend the night in snow sitting closely to each other in order to reduce heat losses. He was surprised when he discovered that in prairies, in frosty weather and dry, fluffy and deep snow, Gray Partridges use snow-hole roosting habits similar to that of the Tetraonid species. Westerskov (1965) mentioned that it happened when the snow was 30 cm or more deep, and described a technique of this process, that was very similar to that of the grouse. However, no detailed description of the construction of such snow refuges was given, and both the quantity and the character of the night excrements were unexamined. The author mentioned that the small hollows, in which birds rest, were situated at a depth of a foot or more under the surface. It is unusual for the Tetraonid birds, because usually they make their roosting hollows so, that it will be possible to stand up and stick out their heads from snow surface to look around when it is needed. That is why the bottom of the hollow of the Hazel Grouse, the bird of the same size, is placed no more than 25 cm under the snow surface, i.e. significantly less, than 1 foot (Potapov 1985). From Westerskov's description, it is not clear, whether birds spent the night under the snow in close contact with each other or separately. I know only one other evidence about the roosting of single partridges under the snow (Malchevsky, Pukinsky 1983), but other cases of group roosting are unknown.
Another interesting detail, not mentioned in literature before, is the use of cavities in snow drifts formed in the process of snowfall on tall and thick weeds for the roosting. In such places, the snow is especially fluffy and easy to dig, to say nothing about the numerous cavities, many of which reach the ground where the green leaves are available for partridges. Such situation is undoubtedly usual for snowy regions used by partridges regularly.
The next problem that is not studied yet enough, it is the role of Grey Partridge guts in the digestive process in winter. I know only one author who has studied the winter life of this species in Belarus, mentioning the active role of the guts (Nikiforov 1988). He also indicated that gut's excrements were found after every night when birds left their roosting places, similarly to Tetraonid birds. In his case, the main food items of Grey Partridges were the green leaves of the cereals and weed grass; no vegetable seeds were mentioned. E.Pulliainen (1984) had studied the chemical composition of the winter food of the Grey Partridge in southwestern Finland and their gut size. He concluded that underdevelopment of the guts and their low digestive ability suggests that the partridge does not need to digest cellulose or to detoxify secondary compounds such as the tannins. He didn't mention anything about the gut's excrements. K.Westerskov (1965, 1966) studied the winter life and nutrition of this species in Canadian prairie and paid special attention to their excrements. However, he also did not mention the presence of the gut's excrements. I have checked hundreds of droppings, collected in the places of feeding and roosting, but could not find any traces of specific excrements from the guts, so usual in the droppings of Tetraonid birds.
Acknowledgments
I am very grateful to my colleagues V.S.Ivanov, S.O.Mamonov, S.I.Fokin who fulfilled my instructions and collected the data in the field, to Drs. N.A.Medvedeva for identification of the plant seeds, and E.R.Potapov and S.A.Leonovich for comments and editing the text.
References
Kalinin M.V., Potapov R.L. 1993. The rise of Grey Partridge Perdix perdix numbers and their expansion in North-Western RussiaIINewsletter WPA Spec. Group on Partridges, Quails andFrancolins. 3: 5. Malchevsky A.S., Pukinsky J.B. 1983 .The Birds of the Leningrad Province and Adjacent Territories.
Leningrad, 1: 1-480 (In Russian). Nikiforov M.E. 1988. Gray Partridge in Belarus, its Ecology, Preservation and Utilization. Ph.D. thesis. Leningrad: 1-20.
Potapov R.L. 1974. Adaptation of the family Tetraonidae to the winter season UProc. Zool. Inst. Ac. Sci.
USSR 55::207-251 (in Russian, Engl. Summary). Potapov R.L. 1982. Bioenergetics of Tetraonids during winter season IIPros. Zool. Inst. Ac. Sci. USSR
113::57-67 (in Russian, Engl, summary). Potapov R.L. 1985. The family Tetraonidae II Fauna of the USSR. New Series. 133: 1-637 (in Russian). Potapov R.L. 1987. The Grey Partridge IIBirds of the USSR: Galliformes, Gruiformes / R.L.Potapov,
V.E.Flint (eds.). Leningrad: 24-38. Potapov R.L. 1992. Systematic position and taxonomic level of Grouse in the order Galliformes IIBull.
Brit. Orn. Club, Centenary volume. 112a: :251-260. Potts D. 1986. The Partridge. Collins: 1-274.
Pulliainen E. 1984. On the gut size and chemical composition of the food of the partridge (Perdix perdix)
in Finland HSuomen Riista 31: 13-18 (in Finnish, Engl. Summary). Westerskov K. 1995. Winter ecology of the partridge (Perdix perdix) in the Canadian Prairie UProc. N. Z. Ecol. Soc. 12: 23-30.
Westerskov K. 1966. Winter food and feeding habits of the partridge (Perdix perdix) in the Canadian prairie // Can. J. Zool. 44: 303-322.
Новые данные о зимовке серых куропаток РегсИх регсИх
в Ленинградской области
Р.Л.Потапов
В феврале 1996, в процессе сбора материала для создания в Зоологическом музее Зоологического института РАН новой биогруппы "Зимняя жизнь серых куропаток", группой сотрудников Музея (В.С.Иванов, С.О.Мамонов, С.И.Фокин) были собраны материалы по зимнему образу жизни и питанию серой куропатки РегсИх регсИх и добыты 4 экземпляра (табл. 1) на юге Ленинградской области (ст. Огорелье). Здесь на заброшенных и заросших бурьяном сельскохозяйственных полях в течение нескольких лет обитала устойчивая популяция серых куропаток общей численностью более полусотни особей, которые на зиму оставались на месте. Во время проведения работ в начале февраля, при ясной погоде, умеренном морозе (около -10°С) и глубине снежного покрова до 35 см, птицы держались здесь на кормёжках небольшими группами по 6-12 особей по краям зарослей бурьяна, где преобладали марь, лебеда, репейник и другие сорняки. Изучение мест кормёжки и содержимого зобов и желудков показало, что основным кормом были семена мари СИепо-росИит ер. (более 4000 семян в зобу и желудке одной птицы) и небольшое количество зелёных листьев клевера и других травянистых растений. Упитанность добытых птиц была хорошей, о чём свидетельствовали и их вес, и наличие отложений жира (в подкожных жировых депо вокруг основания шеи и хвоста по сторонам груди, по основаниям перьев на птерилиях, а также в полости тела вокруг кишечника).
Места ночёвок располагались в тех же зарослях бурьяна. Снежный покров здесь был особенно рыхлым и изобиловал пустотами, нередко достигавшими земли. Эти пустоты, возникавшие во время снегопадов из-за густоты зарослей, явно привлекали птиц как для кормёжки (позволяя добраться до зелёных листьев на земле), так и для устройства подснежных ночлежных камер. Судя по размерам таких камер и наличию в них кучек экскрементов, в них могли ночевать от одной до 4 птиц.
Тщательный просмотр экскрементов серых куропаток опять не обнаружил экскрементов слепых кишок, столь характерных для тетеревиных птиц в зимний сезон. Поэтому свидетельство М.Е.Никифорова (1988) о нахождении таких экскрементов в Белорусии остается единственным. Они не найдены при изучении жизни серых куропаток в условиях морозных и снежных зим ни в Канаде, ни в Финляндии. У добытых в Огорелье экземпляров слепые кишки (рис. 2) были практически пусты и содержали небольшое количество однородной черноватой жидкости.
Изучение зимней жизни серых куропаток на юге Ленинградской области впервые показало возможность успешной зимовки серых куропаток в условиях умеренно морозной и снежной зимы без наличия посевов зерновых и кормовых трав.
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