Yudakov, A. G. and I. G. Nikolaev, The Ecology of the Amur Tiger [Chapter 2].

Chapter 2

The Distribution and Population Size of Tigers in the Primorskii Region ("Primorskii Krai") at the Beginning of the 1970s.

Selection of an Area for Long-Term Observations

The results of a census of the tiger (species) that was carried out by us throughout the entire area of the Primorskii Krai in 1969-1970 were published at that time (Yudakov & Nikolaev, 1973). Data from later census work in 1978-1979 were also published in the literature (Pikunov et al., 1983; Pikunov, Bazyl'nikov & Rybachuk 1985). A return to the examination of information that is 15-years-old is now necessary in order to characterize the status of the population of this species in the Far East of the USSR in the winter season, directly prior to investigations on permanent plots. Moreover, only this information will allow the possibility of judging what place the general area of our investigations occupied in the overall picture of the distribution of tigers in Primorskii Krai, for which reason precisely this sector was chosen for more in-depth studies.

It is necessary to briefly characterize both the changes in the distribution and in the population size of the Amur tiger in a historical perspective. Until 1900, these animals were encountered throughout practically the entire territory of the present-day Primorskii Krai. The density of the population was high in places. E. Ya. Tereshenkov (1959) reported that until 1884 the tiger was found in Vladivostok1. At that time, they were frequently encountered in the valley of the Ussuri River, near Lake Khanka, and on the shores of the Sea of Japan from Pos'et Bay to Ol'ga Bay. In the northern part of Primor'e, tigers went far beyond its borders, inhabiting the Tumnin River area (Przheval'skii 1870). During the period from 1900-1906, a significant number of tigers was noted by V. K. Arsen'ev (1947a,b, 1948) in the Przheval'skii Mountains and on the eastern slopes of the Sikhote-Alin (Mountains) in the valley of the Avvakumovka River.

From approximately the beginning of the present century, an intensive extermination of tigers, caused by the pursuit of hunting trophies, began everywhere in the Far East. In the period from 1900-1906, up to 60 tigers were taken annually in the Ussuri Krai [Arsen'ev 1948]. In these years, these animals were almost entirely extirpated by humans from the southern part of the Prikhanka lowlands (around Lake Khanka), from the area around Nikol'sk (the present Ussuriisk), Vladivostok, and Pos'et (Baikov 1925). Later, from 1920-1945, encounters with tigers on the territory of Primorskii Krai became very rare events. At this time, the species continued to exist in isolated "tiger" sectors in remote places: in the watershed of the plateau of the upper reaches of the Ilistaya, Arsen'evka, Partizanskaya and Artemovka Rivers, in the Partizanskii range (ridge), in the watershed of the Milogradovka and Chernaya Rivers, on the plateau between the Zhuravlevka, Malinovka, Kabarga and Krylovka Rivers, and in the upper reaches of the Bolshaya Ussurka River and its tributaries, the Dal'nyaya, Armu and Kolumbe Rivers (Fig. 3) (Yudakov 1971).

The critical problems of a census and the necessity of the tiger's conservation during the period 1939-1941 were raised by L. G. Kaplanov (1948) with regard to the rapid destruction of the natural habitat of the tiger. He undertook a series of winter trips through the territory of the Sikhote-Alin State Nature Reserve ("zapovednik") with the goal of determining the population size of the tigers. Information (obtained by questioning people) was collected for other parts of the Primorskii Krai. The information that he obtained showed that not more than 20-30 animals inhabited the Primorskii Krai in 1940. The data of L. G. Kaplanov also served as the main reason for a complete ban on the hunting of tigers that began in 1947 in both the Primorskii Krai and in the Khabarovsk Krai due to the initiative of the well-known Far Eastern hunting guide and nature conservationist K. G. Abramov.

Thus, the threat of the extirpation of the tiger as a species in the Far East of the USSR was avoided, but a limited capture of tiger cubs nevertheless continued. For example, during the period from 1947-1955, 32 tiger cubs were caught (Abramov 1956). Because of this, the size of the population grew slowly, and the capture of living tigers was forbidden for 5 years.

1Repeated entries of tigers into Vladivostok were noted during the winter of 1985-1986, i.e., a century later.

After 1940, work on a census of tigers in the region was not carried out until 1957. On the basis of data from questionnaires that were received from the Directorate of the Hunting Industry, K. G. Abramov (1960) approximated the population size of tigers in the Primorskii Krai at 35 individuals. Later (1958-1959), a special census was carried out, on the basis of which the population size was then estimated at 55-56 individuals (Abramov 1961a). In 1965, (according to data obtained from questioning people, which was gathered by the Directorate of the Hunting Industry under the auspices of the Primorskii Regional Executive Committee), 70 tigers inhabited the territory of the region (Kudzin 1966). For this same year, A.A. Sludskii (1966) cited an approximate number of 120 individuals for the entire south of the Far East of the USSR. S. P. Kucherenko (1970) determined the number of tigers in the Primorskii Krai in 1968-1969 to be 110-134 individuals. Such was the information on the population size of tigers in the Primorskii Krai toward the beginning of 1969.

Data characterizing the population size of tigers during the period from 1920-1970 in each of the six traditionally-accepted districts ["raion", (mentioned above)] are presented below (cf. Fig. 3):

The South-West Census District: This district included the right tributaries of the Razdol'naya River (the Kazachka, Borisovka, Nezhinka, and Anan'evka Rivers) as well as the Amba, Barabashevka, Poima, Ryazanovka, Narva, Gladkaya, and Tsukanovka Rivers that flow directly into the sea. The data in the literature concerning the presence of tigers in this district are somewhat contradictory. Thus, K. G. Abramov (1960) in one instance reported an absence of tigers here, and on another occasion reported the presence of two individuals (Abramov 1961a). N. N. Rukovskii (1961) distinguished the western border section of the region as one of the central areas inhabited by tigers. N. V. Rakov (1965) said the same thing.

We succeeded in clarifying the fact that the tigers' population has remained stable in the South-West District during the last twenty years (1950-1970), since significant changes in their numbers were not observed. The sites inhabited by them coincided with the upper reaches of the Borisovka, Nezhinka, Anan'evka, Amba, Narva and Ryazanovka Rivers. In the more southerly sectors, tigers came from Chinese territory, penetrating into our territory for a distance of 5-10 km. During the winter of 1969-1970 three tigers were counted on the upper reaches of the rivers mentioned: two large males and a solitary cub (cf., Fig. 3).

The Western Census District: This district includes the basins of the Komissarovka and Mel'gunovka Rivers that flow into Lake Khanka. In 1920-1950, no tiger tracks were observed in this district at all. Tracks were noted for the first time in 1950 in the upper reaches of the Komissarovka River above the settlement of Reshetnikovo. Then tracks appeared along the central course of the Komissarovka River. From 1960 on they occurred along the entire basin of this river and also along the upper course of the Mel'gunovka River (the Studenaya and Nesterovka Rivers) and in the Sinii mountain range (the divide between the Komissarovka and Mel'gunovka Rivers). The greatest number of tigers was observed in this district during the period from 1961-1967. For example, on December 12, 1967, two groups (of six and three individuals, oral communication from N. M. Gorelenko) were encountered near the road at the source of the Komissarovka River. In this same period, frequent instances of attacks by tigers on domestic animals were recorded. During the winter of 1968-1969, ten tigers continuously inhabited this region.

Figure 3. The distribution of tigers in the territory of the Primorskii Krai in 1970.
This map was prepared with in Free Software GIS GRASS and is based on the original map.
Legend:

1. Borders of the census districts

2. Geographic distribution of the tiger in the Primorskii Krai in 1970

3. "Centers" (refugia) where tigers were preserved in the period from 1920-1940

4. Adult male

5. Adult female

6. Female with cubs

7. Adult tiger of undetermined sex

In the winter season of 1969-1970, tigers were found by the authors in the region indicated only in the upper reaches of the Komissarovka River (where four individuals were constantly present: a male, a female, and two cubs that were transitioning to an independent way of life). The sector that was constantly inhabited by them was located between the courses of the Cheremukhovaya and Talochkinaya Rivers and the border with China (cf., Fig. 3). On the remaining territory of the census region, the tracks of one tiger were noted, an individual that during the middle of winter went from the border of the People's Republic of China across the Komissarovka River to the Sinii Mountains and soon returned to its original location.

The Southern Census District: This district encompasses the basins of the Artemovka, Partizanskaya, Kievka, and Chernaya Rivers (all of which flow into the Sea of Japan), the Mel'niki and Muraveika Rivers (tributaries of the Arsen'evka River), the Ilistaya River, the Komarovka River, and a series of small left tributaries of the Razdol'naya River. At the end of the 19th century, tigers were continuously encountered in this district, and their numbers were relatively high.

From the beginning of the 20th century, this part of Sikhote-Alin was intensively developed by settlers, which led to a sharp decrease in the numbers of tigers. After 1920, tigers were almost never encountered on the territory between the railroad and the basins of the Ilistaya and Artemovka Rivers up until the end of the 1960s. Their disappearance was facilitated by the almost complete deforestation of this entire sector during 1910-1920 (in addition to the intensive hunting of tigers during the period from 1900-1910). Tigers once again appeared here only beginning in 1960, and during the period from 1967-1968, seven tiger cubs had already been caught. In the upper reaches of the Ilistaya River and, in particular along the Arsen'evka River, tigers were found as single individuals even during the period from 1920-1945, and after 1950, they were constantly encountered.

Tigers were everywhere and in large numbers in the basin of the Partizanskaya River during the period from 1902-1905. Then, as a result of the settlement of the territory and the extirpation of the sika deer (Cervus nippon), their numbers sharply decreased. Tiger tracks were no longer regularly encountered after 1922. Later, solitary individuals periodically appeared, coming from the upper reaches of the Arsenev'ka River. And, in 1938, many tiger tracks were discovered in the valley of the Alekseevka River (a tributary of the Partizanskaya River). Apparently, tigers appeared in this sector while following herds of wild boar that were passing through.

In the period from 1951-1953, the first attacks by tigers on domestic animals were noted in this census district (near the settlements of Molchanovka and Monakino). And, during 1967-1968, attacks on domestic animals became frequent in the district that includes the settlements of Brovnichi, Tigrovaya, Serebryanaya, and Aleksandrovka.

It is possible to judge the changes in the numbers of tigers in the basin of the Kievka River using information from the Chronicles of Nature of the Lazov (formerly, the Sudzukhin) State Nature Reserve. In 1960, tracks of tigers were only encountered in the eastern part of the Nature Reserve, where a female with two cubs was constantly present. In 1962, solitary incursions of tigers into the Nature Reserve were recorded; one of the tigers among this group was killed near the settlement of Kishinevka in December. The tracks of two tigers were noted in the Nature Reserve in 1963, mainly in its eastern part. In 1966, four adult tigers and one tiger cub were already present, and during the period from 1967-1968, tiger tracks were noted in large numbers throughout the entire territory of the Nature Reserve.

Tigers' tracks were also periodically noted in the basin of the Chernaya River even during the period from 1920-1940. Since 1958, they have been encountered more frequently: the transits of tigers across the Chernaya River into the Lazov Nature Reserve were recorded. They began to live continuously near the Kamenka River from this time. No fewer than five tigers lived along the left tributaries of the Chernaya River in 1967. In September of that year, a professional hunter from the Lazov Nature Reserve encountered five tigers around a Manchurian red deer (Cervus elaphus xanthopygos) that they had brought down near the source of the Sychev River (a left tributary of the Chernaya River).

Twelve tigers were counted in the basin of the Artemovka River and on the upper reaches of the Arsen'evka, Ilistaya, Rakovka and Komarovka Rivers at the beginning of 1970: Nine tigers were counted in the basins of the Partizanskaya, Litovka, Sukhodol and Shkotovka Rivers, and there were 11 tigers in the basins of the Chernaya and Kievka Rivers (including 6 tigers on the territory of the Lazov Nature Reserve). For the entire Southern Census District, 32 tigers were counted in the winter of 1969-1970. Among them were: 6 males, 10 females, 15 tiger cubs, and the sex of one tiger was impossible to determine) [cf., Fig. 3].

The Central Census District: This district is the largest both in area and in the number of tigers. It includes the basins of the Milogradovka, Margaritovka, Avvakumovka, Zerkal'naya, and Rudnaya Rivers (all of which flow into the Sea of Japan), and part of the basin of the Ussuri River (above the Sungacha River) with its tributaries, the Kabarga, Krylovka, Otkochnaya, Zhuravlevka, Dorozhnaya, Pavlovka and Arsen'evka Rivers. Tigers were numerous in this district at the end of the 19th century. During the period from 1910-1945, they became rare, and in the majority of sites disappeared altogether. The first signs of an increase in the population size were noted in 1945-1947. And after 1960, and particularly during the period from 1964-1965, tigers began to be encountered everywhere in the district, even where they had not been seen since the end of the 19th century.

The presence of 46-48 tigers during the winter of 1969-1970 was established for the territory of the Central Census District. During the period of the census, four of them were killed, and one tiger cub was caught. Among the remaining tigers, there were 6 males, 16 females, 18-20 cubs and one adult tiger whose sex we were unable to determine (cf., Fig. 3).

The North-East Census District: The eastern slopes of the Sikhote-Alin Mountains (from the Rudnaya River to the Samarga River) constituted this census district. Tigers were common in this territory until 1906 along the Serebryanka River, and they were periodically encountered along the Amgu River (Arsen'ev 1947b). From 1909-1912, N. P. Pravdin (1926), having investigated the eastern slopes of the Sikhote-Alin Mountains from the Serebryanka River (to) the Samarga River, noted that tigers were rarely encountered in this district despite an abundance of various wild animals. Utilizing the account by V. K. Arsen'ev, S. I Ognev (1935) drew the northern border of the geographic distribution of tigers along the eastern slopes of the Sikhote-Alin (Mountains) to the north of the Samarga River.

During the winter of 1939-1940, L. G. Kaplanov (1948) established the fact that five tigers inhabited the upper reaches of the Velikaya Kema River. And K. G. Abramov, using data from a census of tigers conducted in 1959, indicated the presence of eight tigers for this sector of Eastern Sikhote-Alin (archives of the Far Eastern Scientific Center of the Academy of Sciences of the USSR).

The population dynamics of tigers in the North-East Census District can be traced using the annual recordings of their tracks that were made by the professional hunters and the scientific workers of the Sikhote-Alin State Nature Reserve. Thus, according to records taken from the Chronicles of Nature, tigers did not continuously inhabit the territory of the nature reserve in the period from 1961-1965; instead, only the tracks of animals passing through the nature reserve were recorded: four in 1961, one in 1962, four in 1963, one in 1964, and one in 1965. Since 1966, tigers have permanently inhabited the territory of the Sikhote-Alin Nature Reserve and, judging by data in the Chronicles of Nature, they numbered eight individuals in 1969. The number of tracks recorded has also sharply increased beginning in 1966: 16 tracks were found in 1966, 80 tracks were found in 1967, 62 tracks were found in 1968, and 85 tracks were discovered in 1969. According to the data of E. N. Matyushkin (1966), tigers were almost absent on the territory of the Nature Reserve in the basins of the Serebryanka and Zabolochennaya Rivers in the period from 1963-1965. But, by 1967, S. P. Kucherenko (1970) had already determined the number of tigers in the census district that includes the nature reserve to be 10-12 individuals. The northern border of the geographic distribution of the tiger on the eastern slope of the Sikhote-Alin mountain range, according to the data of S. P. Kucherenko (1970) ran along the lower course of the Samarga River. However, judging by data obtained by questioning people, tigers were constantly encountered only in the basin of the Maksimovka River, and north of this sector only single, short-term incursions (3-5 cases per decade) have been noted up to the present time.

Therefore, the basin of the Maksimovka River should be considered to be the northernmost district ) on the eastern slopes of the Sikhote Alin Mountains that was constantly inhabited by tigers in 1970.

During the winter of 1969-1970, eight tigers were counted in the North-East Census District: one male, two females, three cubs, and two adult tigers whose sex we were unable to determine (cf., Fig. 3).

The Northern Census District: This district includes the basins of the Bikin River, the Bol'shaya Ussurka River, and the Malinovka River. A sharp decrease in the number of tigers was observed along the basins of the rivers listed above (especially the Bol'shaya Ussurka River) from 1920 to 1940 due to the intensive capture of tiger cubs and the shooting of adult individuals. L. G.

Kaplanov (1948) recorded a total of 10-12 tigers in 1940 in the basins of the Bol'shaya Ussurka River and the Bikin River. In the following years, their numbers gradually began to increase, and, in 1959, K. G. Abramov counted 18 tigers in this area (archives of the Far Eastern Scientific Center of the Academy of Sciences of the USSR). From 1967 to 1969, (the presence of) 12-16 tigers was noted for the basin of the Bikin River, with 14-16 tigers being found along the Bol'shaya Ussurka River (Kucherenko 1970).

During the winter of 1969-1970, 13 tigers were counted in the basin of the Bikin River, 17 tigers were counted along the Bol'shaya Ussurka River, and 11 tigers were counted along the Malinovka River. In all, 41 animals were recorded as inhabiting this district: 13 males, 17 females, 10 cubs, and one young tiger whose sex we were unable to determine (cf., Fig. 3).

In total, no fewer than 130 tigers were counted in the Primorskii Krai in the winter of 1969-1970. This number included 29 males, 46 females, approximately 50 cubs and 7 individuals of undetermined sex.

Thus, as a result of both a prohibition on tiger hunting (in 1947) and a ban on the capture of tiger cubs (during 1956-1960), followed later by a strict regulation of their capture, the numbers of tigers in the Primorskii Krai increased from 20-30 to 130 individuals over the period from 1940-19701. A particularly rapid restoration of their numbers occurred from 1960-1970. At the present time, tigers occupy almost all the forest area that is suitable for them in the Primorskii Krai.

A definite numerical excess of females over males can be traced in the adult population of Amur tigers. This is especially clearly expressed in the Central Sikhote-Alin district, where the largest number of illegal shootings has been recorded (Figs. 3 & 4). The index of the number of cubs per adult female is variable for different parts of the Krai. Thus, it is equal to 0.6 for the basins of the Bol'shaya Ussurka River and the Bikin River, in contrast to a figure of 1.4 for the remainder of the region1.

The highest population density of tigers in 1970 was noted on the eastern slopes of the Sikhote-Alin Mountains between the Partizanskaya and the Zerkal'naya Rivers, on the territory of the Sikhote-Alin Nature Reserve, in the upper reaches of the Arsen'evka and the Malinovka Rivers, and along the tributaries of the upper and middle courses of the Bol'shaya Ussurka and Bikin Rivers.

Let us now turn to a slightly more detailed analysis of the information for the Malinovka River basin, where we later conducted long-term studies. This territory is close to the core area of the present distribution of the Amur tiger in the Far East of the USSR (Kucherenko 1985). In 1970, 11 tigers were counted here: 3 males, 6 females, and 2 cubs (another cub was captured)2. They inhabited an area of approximately 4,500 km2 and were distributed on it as described below. Two adult females inhabited the lower course of the Malinovka River [along the upper reaches of its left tributaries (the Kedrovka, Lazarevka, and Titovka Rivers)]. A male entered this same area from the upper courses of the Tamga and Kabarga Rivers (right tributaries of the Ussuri River). A female with a cub was noted in the upper reaches of the Dobryshanka River (a right tributary of the Malinovka River). The tracks of this same female were encountered on the Zavitaya river basin of the Naumovka River. A male and a female with a litter of two cubs [one of which (the female) was captured by tiger hunters in 1970] inhabited the basins of the Kostyukovka and Bystraya Rivers. In an area where we later carried out tracking, four tigers were counted: a male and a female tiger in the upper reaches of the Malinovka River, and a male with a female that stayed around the basins of the Gornaya and Orekhovka Rivers. Incursions into the upper courses of the Orekhovka Rivers by a female with two cubs [which were coming from the basin of the Pereval'naya River (which flows into the Bol'shaya Ussurka River)] were repeatedly noted.

Sets of densely crowded data points are evident on the schematic map of the census data for the basins of the central section of the Bol'shaya Ussurka River and the upper section of the Malinovka River; it is precisely here that cases involving the death of tigers were relatively frequent (Figs. 3 & 4). According to all the data that we have, the area selected for long-term study was characterized by a high and relatively stable number of tigers. That is also the state of affairs at the present time. The conditions of this region are typical of the habitat of the animals on the western macro-slope of the Central Sikhote Alin mountain range.

¹ By 1978-1979, the population size of the tiger in Primor'e had increased still further relative to that of 1969-1970 (almost by a factor of 1.5, to 172-195 animals) [Pikunov et al. 1983]. The increase in the North-East and the Northern Census Districts (including the basin of the Malinovka River) was the most noticeable.
² Only those individuals whose home ranges lay primarily in the Malinovka River Basin are indicated.

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Figure 4. Tiger shootings in the Primorskii Krai that occurred during the period from 1950-1970.
This map was prepared in Free Software GIS GRASS and is based on the original map.
Legend:
1. 1951-1960

2. 1961-1965

3. 1966-1970

4. The area selected for long-term studies

Copyright � A. G. Yudakov,I. G. Nikolaev

Copyright � K. Lofdahl, A. Shevlakov, 2004 (English translation)