N. procyonoides is considered invasive in its introduced range in Europe, because it has spread fast (about 40 km, and up to 120 km, per year) from the places of introduction (...
Adult Raccoon dog; pictured via camera-trap in November 2004 in a secondary forest in Ibaraki Prefecture, Japan.
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Midori Saeki
Adult
Adult Raccoon dog; pictured via camera-trap in November 2004 in a secondary forest in Ibaraki Prefecture, Japan.
Midori Saeki
Title
Adult
Caption
Adult Raccoon dog; picture via camera-trap in December 2005 in an afforested, but not managed area in Ibaraki Prefecture, Japan.
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Midori Saeki
Adult
Adult Raccoon dog; picture via camera-trap in December 2005 in an afforested, but not managed area in Ibaraki Prefecture, Japan.
Midori Saeki
Title
A pair of Raccoon dogs
Caption
A pair of Raccoon dogs; picture via camera-trap in November 2004, in a mature forest in Ibaraki Prefecture, Japan.
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Midori Saeki
A pair of Raccoon dogs
A pair of Raccoon dogs; picture via camera-trap in November 2004, in a mature forest in Ibaraki Prefecture, Japan.
Midori Saeki
Title
Immature raccoon dogs
Caption
Immature raccoon dogs; picture via camera-trap in September 2005, on a forest ridge in Ybaraki Prefecture, Japan. These animlas are probably siblings (about 4-5 month old) with similar appearance.
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Midori Saeki
Immature raccoon dogs
Immature raccoon dogs; picture via camera-trap in September 2005, on a forest ridge in Ybaraki Prefecture, Japan. These animlas are probably siblings (about 4-5 month old) with similar appearance.
Midori Saeki
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Pregnant female with researcher
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Researcher, Midori Saeki, with pregnant Raccoon dog in the month of June. Notice her submissive and 'tamed' attitude.
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Midori Saeki
Pregnant female with researcher
Researcher, Midori Saeki, with pregnant Raccoon dog in the month of June. Notice her submissive and 'tamed' attitude.
Midori Saeki
Title
Young cub
Caption
A very young female cub, named 'Poko'; she was raised in captivity; after she matured, a wild male frequented her and cubs were born, of which the picture is one.
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Midori Saeki
Young cub
A very young female cub, named 'Poko'; she was raised in captivity; after she matured, a wild male frequented her and cubs were born, of which the picture is one.
N. procyonoides is considered invasive in its introduced range in Europe, because it has spread fast (about 40 km, and up to 120 km, per year) from the places of introduction (Lavrov, 1971), and is still spreading towards the west and south (Kauhala and Kowalczyk, 2011). It may also spread further north to Finnish and Swedish Lapland due to global warming. It is suspected to be harmful (due to predation) to native birds and frogs, but firm evidence of this is lacking. It is also an important vector of rabies and some parasites, such as Echinococcus multilocularis (Holmala and Kauhala, 2006; Romig, 2006; Kauhala and Kowalczyk, 2011).
N. procyonoides ussuriensis: Originally in southeastern Siberia (Amur, Sungari and Ussuri river valleys) and eastern China (Manchuria). This subspecies was introduced to other parts of the former Soviet Union between 1929 and 1955 (Lavrov, 1971) and is now widespread in Europe.
N. procyonoides procyonoides: China and northern Indochina
N. procyonoides orestes: southwestern China
N. procyonoides koreensis: Korean Peninsula
N. procyonoides viverrinus: Japan (except Hokkaido)
N. procyonoides has a black facial mask, small rounded ears, a pointed muzzle and long hair on the cheeks. The body colour varies from yellow to grey or reddish. There are black hairs on the back and shoulders and also dorsally on the tail. The legs, feet and chest are dark. Small pups are almost black. Underhair is usually grey. 'Samson' individuals have no guard-hairs and their underfur is reddish. The tail is fairly short and is covered with thick hair. In summer the fur is thin and fat reserves are small, so the animal looks much slimmer than in autumn. In autumn and winter, the animal is very fat and has thick fur, giving an impression of a round animal with short thin legs. The dental formula is 3/3-1/1-4/4-2/3, with lower m3 sometimes missing (Kauhala and Saeki, 2004a).
The introduced range of N. procyonoides covers north-western Russia, Finland, Sweden (Norbotten province), the Baltic States, Poland, Germany, the Czech Republic, Slovakia, Hungary, Belarus, Ukraine, Moldova, Romania, Bulgaria and Serbia. The species is occasionally seen in Norway, Denmark, Austria, Italy, the Netherlands, France, Switzerland, Slovenia and Bosnia (Mitchell-Jones et al., 1999; Kauhala and Kowalczyk, 2011); there have been media reports of small numbers being present in the wild in the UK (Butler, 2017; Sawer, 2017) but as yet there do not appear to be any official or peer-reviewed reports, apart from the mention of one confirmed sighting in 2005 by Marchant (2012).
The northern limit of distribution lies in areas where the mean temperature over the year is just above 0°C, the thickness of snow cover is about 80 cm, the snow cover lasts about 175 days and the length of the growing season for plants is 135 days. When the climate warms and winters are milder and shorter, N. procyonoides will most probably widen its distribution area northwards. Now the northern limit of permanent distribution lies at the Arctic Circle (in Finland). In the south, the species has managed to cross the Alps – two specimens were photographed in northern Italy in 2005 (P. Genovesi, INFS - Italian Wildlife Institute, Ozzano Emilia, Italy, personal communication, 2005).
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Numbers have increased rapidly during the last decade. 398 raccoon dogs were killed in 1995 and 4325 were killed in 2001/2002 in Brandenburg. First report in east Germany 1961
Russians introduced N. procyonoides from southeastern Siberia to several places, first in the Asian part, and later mainly in the European part, of the former Soviet Union, between 1929 and 1955 (Lavrov, 1971). Altogether they introduced about 9100 individuals. They first bred the animals in farms and then released them into the wild in order to get a new valuable fur animal. In many areas the population remained small, especially in Asia, because most released individuals died. The first introduction was made to Transcaucasia, Abkhazia, southern Ossetia and Karatalinia (Lever, 1985).
The introductions to the European part of the country were more successful. N. procyonoides was introduced, for example, to the Leningrad and Novgorod areas (100 individuals in 1935-1936), Pihkova (80 individuals in 1947), the Karelian isthmus (82 individuals in 1953), Estonia (1950), Murmansk (1935-1936), Archangel (several introductions in the early 1950s) and the Kalinin area (1934) (Lavrov, 1971; Lever, 1985). Some introductions were made also to the Tatar, Bashkir, Mari, Chuvash and Mordvinian republics (Lever, 1985). N. procyonoides was also released in the North Caucasus (where 1947 pregnant females were released in 1934), Ukraine (1936), Astrakhan (1936-1939), Moldavia (1949-1954), Kirgizia (78 individuals in 1934) and Belarus (100 individuals in 1963) (Lever, 1985).
N. procyonoides spread fast from the places of introduction. For instance, in Estonia the species spread at a rate of 120 km per year and it was observed all over the country as early as 1954 (Lavrov, 1971). It reached Lithuania from Belarus. The first observation in Lithuania is from 1948 and by 1959 the species was found all over the country (Lavrov, 1971). In Latvia, there were about 1000 individuals as early as 1951.
In the Novgorod and Leningrad areas N. procyonoides spread at a rate of 40 km per year. Soon it also invaded Finland along the Karelian Isthmus, and the first individuals were observed in Finland in 1935 (Siivonen, 1958). During the 1950s the population started to increase in Finland, and southern and central Finland were colonised by the mid-1970s (Helle and Kauhala, 1991). Although the first individuals were seen in Sweden in 1945 (Niethammer, 1963), the population remained scarce until it started to increase a few years ago (F Dahl, Swedish University of Agricultural Sciences, Umeå, Sweden, personal communication, 2009). The first individuals were seen in northern Norway (Finnmark) in 1983 (Wikan, 1983) but there has been no permanent population in Norway. However, during winter 2007/2008 a few were shot in mid-Norway (R Andersen, Norwegian University of Science and Technology, Trondheim, Norway, personal communication, 2008). Most probably they invaded there from Sweden.
The first N. procyonoides were noticed in Poland in 1955 and in East Germany in 1961 (Nowak and Pielowski, 1964). In Poland, the population increased and the species is today among the most common carnivores in the country (Jedrzejewska and Jedrzejewski, 1998; Kauhala and Kowalczyk 2011). The population remained sparse in Germany until it started to increase rapidly in the 1990s, first in eastern Germany (Ansorge and Stiebling, 2001). The hunting bag increased rapidly between 1995 (398) and 2001/2002 (4325; Weber, 2004). The species has also spread to Denmark (Jutland and the island of Fyn) from Germany, and 25 observations were made between 1995 and 2003 (Baagøe and Jensen, 2007).
The first observations of N. procyonoides were made in France in 1979 (Artois and Duchêne, 1982), in Austria in 1962 (Lever, 1985) and in Switzerland in 1997 (Weber, 2004). One was seen in central Switzerland 1570 m above sea level in 2003 (Weber, 2004) and a pair was photographed in northern Italy in 2005 (P. Genovesi, INFS - Italian Wildlife Institute, Ozzano Emilia, Italy, personal communication, 2005). It thus seems that the species has crossed the Alps. It was seen in Hungary as early as 1962 and in Romania in 1951 (Nowak and Pielowski, 1964). Today it is widespread also in the Czech Republic and in Slovakia (Mitchell-Jones et al., 1999). It is also found in Bosnia, Moldova, Serbia and Slovenia (Kauhala and Kowalczyk 2011).
In Japan, where N. procyonoides is native in most large islands except the Okinawa Islands, it was introduced to Chiburi-jima island in 1941 and Yaku-shima island in the 1980s (Saeki, 2009). It appears that this species can survive and sustain high density on small islands (Ikeda et al., 1979), although the population originated from a small number of individuals (possibly only one mated pair).
N. procyonoides is very adaptable, it is omnivorous, it has a high reproductive potential, and it has a tendency to wander long distances, so it can easily spread to new areas. It seems that it has found a vacant niche at least in northern Europe (there is no proof that native carnivore populations have decreased after it colonised the area, with the possible exception of Belarus – see ‘Impact on biodiversity’ section). It has probably benefited from bait vaccinations against rabies in Europe, and it will also benefit from global warming, because severe winters set a limit to its distribution area.
N. procyonoides favours open landscape, especially damp meadows with abundant undergrowth, marshes and river shores, but avoids large coniferous forests and other woodlands with a thick canopy (Novikov, 1962; Stroganov, 1969; Yudin, 1977; Nasimovich, 1985; K Kauhala, Finnish Game and Fisheries Research Institute, Turku, Finland, and M Auttila, University of Joensuu, Joensuu, Finland, unpublished data). It also favours small deciduous and mixed forests and deforested areas (Barbu, 1972; Nasimovich, 1985; Woloch and Roženko, 2007). It needs dense undergrowth, which provides shelter and food. It does not thrive in barren areas with scarce undergrowth.
Habitat preferences of the species differ somewhat between seasons. Lake and river shores are favoured especially in early summer, when there are many frogs and much other food available (Kauhala, 1996). N. procyonoides is an excellent swimmer and often escapes into water when chased. In late summer and autumn it favours moist woodlands with abundant berries, such as bilberries. It also visits gardens where it can find fruit and berries.
In Japan, N. procyonoides in the countryside has similar habitat preferences as on the continent (Saeki et al., 2007). However, it is also found in very urban areas, such as Tokyo Metropolitan wards, requiring minimum vegetation cover of 5-15% (Yamamoto et al., 1995) and using gutters and underground drains for movement and resting sites (Yamaguchi, 1987; Kaneshiro et al., 2000).
The habitat use of the species is thus affected by the availability of food, shelter and also suitable den sites. Dens are often under big rocks, in tree trunks or under outbuildings. Old badger setts can also be used, even at the same time as badgers (Kauhala and Holmala, 2006; Kowalczyk et al., 2008; Kowalczyk and Zalewski, 2011). Winter dens are usually located in the usual home range but if suitable dens are not available in the home range, the winter den may be outside it (Kauhala et al., 1993).
N. procyonoides ussuriensis has 54 chromosomes, whereas N. procyonoides viverrinus and N. procyonoides albus have only 38 chromosomes (Mäkinen et al., 1986; Ward et al., 1987). The total number of euchromatic chromosome arms in the female (the nombre fondamental) is, however, 66 in all subspecies. The difference in chromosome number is probably due to Robertsonian translocations (centric fusions), which often occur during speciation. Japanese animals have thus adapted to a mild marine climate and are probably on the road to speciation (Kauhala and Saeki, 2004b).
A study of epigenetic variability in N. procyonoides skulls indicated that the populations in Europe differ clearly from the population in the Russian Far East (Ansorge et al., 2009), reflecting the 60-year isolation between the populations. There are also differences between European populations: animals in Finland and eastern Poland seem to form one group, which differs from those in Germany. This indicates that there were different dispersal routes and animals did not wander to Germany from eastern Poland.
Genetic variability of raccoon dogs in Europe results from the the combination of factors including multiple translocations with use of individuals from different geographical areas, secondary contact, and admixture of two co-occurring separate maternal lineages with divergent evolutionary histories (Pitra et al., 2010).
Reproductive Biology
Mating occurs (in southern Finland) usually in late February or March, depending on the weather (Helle and Kauhala, 1995). Females ovulate earlier in southwestern Finland than in eastern Finland, which reflects the impact of climate on reproduction: the length of winter determines the time of ovulation. Also young of the previous year may come to oestrus later in spring than older females.
The parents settle in a den about a week before the pups are born after a gestation period of 9 weeks. Young are thus usually born in April or May. The mean litter size is 9-10 in areas with favourable conditions, whereas in areas with a harsh climate it may be 6-7 (Morozov, 1953; Popov, 1956; Prusaite, 1961; Yudin, 1977; Helle and Kauhala, 1995; Kowalczyk et al. 2009). Middle-aged females (3-5 years old) have the largest litters. The abundance of food, such as wild berries, may affect the litter size: when berries are abundant in autumn, females are in good condition the following spring and produce large litters.
N. procyonoides is monogamous and the male participates in pup-rearing by warming and guarding the pups when the female is foraging (Kauhala et al., 1998a; Drygala et al., 2008). Because they mainly catch small food items, such as voles, frogs and insects, food is not carried to the den. Because young pups are fed entirely on milk, the energy needs of nursing females are high and they forage during both day and night. The pups first emerge from the den when they are about three weeks old. They are weaned at the age of three months, but can catch small prey, such as insects, before they are entirely weaned.
The later the oestrus, the later the pups are born, and the shorter is the time for pups to grow and gather fat reserves before winter. When spring comes late, the young can accumulate only small fat reserves before winter sleep and many of them do not reproduce the following spring. The productivity of the population is thus lower in areas with harsh and long winters than in areas with a milder climate.
The home ranges of different pairs do not (at least in Finland) usually overlap during the breeding season (Kauhala et al., 1993).
Physiology and Phenology
N. procyonoides is the only canid which hibernates in areas where winters are harsh. Winter lethargy usually lasts from November until March (in Finland) but when the winter is mild, they may be active even in mid-winter. They usually sleep when the air temperature is <-10°C, snow depth >35 cm and day length <7 h (Kauhala et al., 2007). Most animals are active when the temperature is above zero, there is no snow and day length is >10 hours.
N. procyonoides has adapted to winter sleep by accumulating large fat reserves during autumn: it almost doubles its body weight (Kauhala, 1993; Mustonen et al., 2007). The average body temperature is 38°C during the snow-free period but is 1.4-2.1°C lower during winter. In winter, animals are hypothermic for 5 h in the morning, whereas their body temperature is highest in the evening. Thyroid hormone levels are also low during winter and the animal thus adapts its general metabolism to the availability of and requirements for energy (Korhonen, 1987). Animals in a fur farm lost their appetite when the air temperature decreased to -5°C, which indicates an endogenous behavioural pattern: when it is too cold the animals hibernates and does not eat.
When seasonal weight regulation of the species was studied in a fur farm, the plasma leptin and growth hormone levels were found to be low but ghrelin levels high in autumn when the animals were fattening themselves (Nieminen et al., 2002). Leptin and growth hormone levels peaked in October and declined rapidly thereafter during a transition period before winter lethargy. The levels of leptin and growth hormone were high in winter during the period of wintertime catabolism, but the ghrelin-leptin ratio was low. In winter when the animal uses its fat reserves, leptin, ghrelin, and growth hormone may work in synergy to increase lipolysis. Growth hormone may also induce winter sleep. Instead of the amount of fat in the body, the main regulators of the levels of these hormones are presumably seasonal rhythms entrained by melatonin (Nieminen et al., 2002).
In Japan, N. procyonoides albus in Hokkaido decreases its body temperature by 1.3-2.1°C with a transient 18-36% decrease in resting heart rate while maintaining a circadian rhythm in late February (Kitao et al., 2009). N. procyonoides viverrinus in warmer regions remains active throughout winter, although the activity level (mean nightly travelling speed and nightly range span) is lower in cold periods (Saeki, 2001).
Nutrition
N. procyonoides is a true omnivore and eats anything it can catch. The diet varies between areas and seasons (Nasimovich, 1985). In Japan it is dominated by fruit, insects and marine animals and differs considerably from that in the other areas (Ikeda, 1985; Sasaki and Kawabata, 1994; Hirasawa et al., 2006). In most other areas small rodents – voles, mice and shrews – form the bulk of the diet in all seasons (Nasimovich, 1985; Kauhala et al., 1998b). Frogs, lizards, invertebrates, birds and their eggs are also frequently consumed, especially in early summer (Kauhala and Auniola, 2001). Birds are more important when voles are scarce than when voles are abundant (Ivanova, 1962). Berries and fruit are favoured in late summer and autumn and serve as an important food source before entering winter dormancy. Cereal, such as oats or maize, is often found in the stomach in autumn and winter. Carrion and fish are consumed during all seasons if available (Jedrzejewska and Jedrzejewski, 1998; Sidorovich et al., 2000). They are especially important in winter when other food sources are scarce.
Environmental Requirements
The northern limit of N. procyonoides distribution lies in areas where the mean temperature of the year is just above 0°C, the thickness of snow cover is about 80 cm, the snow cover lasts about 175 days and the length of the growing season for plants is 135 days. Optimal conditions for the species are in areas where snow cover is no more than 10-30 cm and lasts less than 160 days (Nasimovich, 1985). In mountainous areas they use the river valleys and do not occur high in the mountains where winters are harsh.
N. procyonoides needs open habitats with abundant undergrowth, which provides shelter and food. It does not thrive in barren forests with thick canopy but scarce undergrowth. It also requires den sites, such as holes under big rocks, in tree trunks or under buildings, or badger setts (Kowalczyk and Zalewski, 2011). See more details under ‘Habitats’.
N. procyonoides juveniles usually disperse during their first autumn. The mean dispersal distances were 14 km for females and 19 km for males in south-east Finland, the mean maximum distances being 48 km and 71 km, respectively (Kauhala et al., 2006). Twenty-one percent of juveniles dispersed farther than 20 km. In a stable population, adults do not usually disperse (Kauhala et al., 1993). However, they too may disperse in a colonising population (Sutor, 2008; Drygala et al., 2010).
Accidental Introduction
N. procyonoides has been bred on fur farms, e.g. in Finland and Russia, and some individuals have certainly escaped from the farms. On Chiburi-jima island in Japan, a pair was given as a gift to the village chief and escaped.
Intentional Introduction
N. procyonoides (9100 individuals) were introduced from south-eastern Siberia to many parts of the former Soviet Union between 1929 and 1955 (Lavrov, 1971). See more details under ‘History of introduction’.
Because the species is an important vector of rabies in northeastern Europe (Holmala and Kauhala, 2006), bait vaccinations are carried out, e.g. in Finland twice each year. The cost of this is considerable. The species is also a vector of Echinococcus multilocularis (Romig et al., 2006), Trichinella spp. (Oivanen et al., 2002), and sarcoptic mange (Shibata and Kawamichi, 1999). Preventive measures against these parasites may become costly.
This is a controversial question. Many people consider N. procyonoides harmful for bird populations, but there is no firm evidence of this. Birds occur in its diet but usually they constitute only a minority of the diet (e.g. Nasimovich, 1985). The species is an omnivorous gatherer rather than a skilful predator. It has short legs, small teeth, and a long intestine, and it is fairly clumsy and slow. Its morphology reveals that it is an omnivore (Lavrov, 1971; Kauhala et al., 1998c). It may eat eggs or catch chicks, but it is unlikely that it can catch many adult birds. When the diets of N. procyonoides, red foxes (Vulpes vulpes) and badgers in early summer were compared in southern Finland, the diet of N. procyonoides was the most diverse, and they consumed game animals less frequently than foxes.
In a predator removal study in Finland N. procyonoides was not observed to cause harm for waterfowl or grouse (Kauhala et al., 2000; Kauhala, 2004). In a nest predation study in Latvia, they destroyed only 0.6% of the nests destroyed by predators (0.3% of all nests) (Opermanis et al., 2001).
Frog populations have declined in many areas and N. procyonoides has been suspected to be responsible for this. Frogs have indeed disappeared from some islands in the Finnish archipelago after the species invaded in the area. Frogs and tadpoles are very easy to catch and N. procyonoides may eat large quantities of them in early summer (e.g. Barbu, 1972; Jedrzejewska and Jedrzejewski, 1998; Kauhala and Auniola, 2001; Woloch and Roženko, 2007).
There is no proof that native carnivore populations in northern Europe decreased after colonisation by this species the area; the exception may be Belarus where many carnivore populations have decreased during the past few decades (Sidorovich et al., 2000).
N. procyonoides was introduced to European Russia because Russians wanted a new valuable fur animal in the wild. The fur is of some economic importance but most pelts are today produced in fur farms, and pelts from wild animals are of little value. One can buy Chinese N. procyonoides fur via the Internet ($70 per skin). It is said that 1.5 – 4 million animals are kept in fur farms in China. In Japan, the guard hairs are used for calligraphy brushes, and the fat used until the 1950s to be used for medicinal purposes. Also, Chinese wet (live animal) markets sell live animals, possibly for meat (Guan et al., 2003; Webster, 2004). The species is rarely eaten in Japan.
Social Benefit
N. procyonoides offers an opportunity for sport hunting. For instance in Finland, some hunters like to catch them at night with dogs (Finnish spitz).
Because N. procyonoides is mainly nocturnal and rather secretive in nature, it is not always easy to detect that it lives in an area, but when the population is increasing, people certainly see some tracks, typical latrines and carcasses on the roads, because many are killed by cars. They can, however, be confused with badgers or raccoons, if one does not stop the car and inspect the carcass. Camera trapping (using and automatic camera with infrared sensor) may be useful.
The facial mask resembles that of the raccoon (Procyon lotor). Carcasses seen along the roads can be confused with those of badgers (Meles meles), if one does not stop and look at the carcass carefully. For instance, many people in Sweden have reported N. procyonoides carcasses on the roads, but when these were checked, they were usually badgers (P-A Åhlen, Swedish University of Agricultural Sciences, Umeå, Sweden, personal communicaiton, 2009).
It is very difficult to prevent N. procyonoides from spreading, because it has the tendency to wander long distances, it has a very high reproductive potential, it is an omnivore and it is very adaptable to different environments.
We cannot prevent the species from spreading but we must and can carry out preventive measures, such as bait vaccinations, against rabies, which is the worst threat connected to this invasive species.
Eradication and control
N. procyonoides is almost impossible to eradicate when it has colonised an area. It has a tendency to increase its litter size (up to 16; Helle and Kauhala, 1995) when the population is under heavy hunting pressure. Furthermore, if the hunting pressure is high in one area and the population temporarily declines, juveniles will wander into the area from adjacent areas and the population will recover within a few months. Locally, some eradication may be conducted to decrease impact of raccoon dogs on native fauna.
More information about the dispersal distances and dispersal routes of juveniles is needed, because dispersing juveniles pose the greatest risk regarding the spread of rabies and dangerous parasites, such as Echinococcus multilocularis.
Drygala F, Zoller H, Stier N, Mix HM, Roth M, 2008. Ranging and parental care of the raccoon dog Nyctereutes procyonoides during pup rearing. Acta Theriologica, 53:111-119.
