Procyon lotor (raccoon)

P. lotor is a medium-sized carnivore species with the most widespread distribution among the Procyonidae. Its opportunism and flexible behavioural traits result in omnivory and a wide ecological niche, with few natural predators. In addition, P. lotor has physical and physiological traits that allow it to colonize a wide range of habitats and climates. It has continued to expand its native, North American range northward through the southern provinces of Canada, in addition to arid regions of the southwestern United States. Where conditions are favourable, colonization following introduction can be rapid. The species has been introduced to some islands off the coasts of Canada and Alaska, and in the Caribbean, and is considered invasive in some cases. It is expanding its range as an alien species following introductions in western Europe, and Japan. Further intentional introductions at the international scale are unlikely; however, the species may be introduced accidentally (it is common in the pet trade) or through range expansion.

Most early references recognize 18 species for the family Procyonidae (Wozencraft, 1993), which includes the following genera: olingos (Bassaricyon sp.) and kinkajous (Potos sp.) of Central and South America, ringtails (Bassariscus sp.) and raccoons (Procyon sp.) of North and Central America, and coatis (Nasua sp., Nasuella sp.) of North, Central, and South America. Traditionally, the genus Procyon has consisted of 7 species; however, 5 of these (P. minor, P. maynardi, P. insularis, P. gloveralleni, P. pygmaeus) are insular and may simply be variations of introduced P. lotor (Corbet and Hill, 1986; Helgen and Wilson, 2003; Helgen et al., 2008) or may be extinct and replaced by P. lotor (Lotze and Anderson, 1979; Hall, 1981; Pons et al., 1999), with the exception of P. pygmaeus located on Cozumel Island, Mexico (Cuarón et al., 2004). The other continental congeneric is the crab-eating raccoon, P. cancrivorus, which occurs in South and Central America (Goldman, 1950).

P. lotor is a medium-sized member of the order Carnivora, with a stocky torso and short limbs. The pelage coloration, with the striking black mask and ringed tail, makes the raccoon easily recognizable. The spine is curved posteriorly, giving the animal a roundish appearance similar to a bear. The black mask usually extends from slightly above the eyes to the base of the snout and flares out along the cheeks. It is accentuated by white lines immediately above and below the mask, and the mask is often broken down the middle by a brown bar. As a raccoon ages the mask tends to fade. The anterior side of the ear is entirely white; the posterior side has a black base that extends to nearly half the ear. The top of the nose and forehead are greyish or reddish brown. Pelage color on the shoulders and back is dominated by reddish-brown guard hairs. However, variations on this color scheme are common, including nearly black, orange, or cinnamon variants, and geographic variation in pelage color occurs (Goldman, 1950; Stains, 1956; Johnson, 1970; Lotze and Anderson, 1979; Gehrt, 2003). The ventral side is lighter, usually a light brown, with sparse guard hairs. The hair on each foot is short and whitish-gray. Four to seven blackish rings and a dark tip characterize the tail. The feet are plantigrade with naked footpads. Front and back feet are pentadactyl with no webbing between the toes, and each toe has a sharp, curved, nonretractile claw. The tracks resemble human prints, with the long toes of the front foot resembling fingers and the shorter toes of the back foot, with its longer foot pad, resembling human toes. The pinnae are relatively small compared to those of canids or felids, and the snout is medium length and pointed. Cheek tufts that flare to the sides give the impression of a broad head when seen from the front. There are no pelage differences between males and females; however, males are larger than females in body measurements and weight. Adult body weights usually range from 4 to 9 kg, with regional variations in size across North America, and body weights may change seasonally at northern latitudes. The smallest individuals occur in South Florida (Goldman, 1950); with mean winter body weights of 2.4 and 2.0 kg for adult males and females, respectively. Mean body weights for adults at northern latitudes range from 6.9 - 10.4 kg during the winter, and body weights in South Texas average 9.0 and 6.7 kg for males and females, respectively (Gehrt and Fritzell, 1999). Adult raccoons have 40 teeth, with a dental formula: i3/3; c1/1; p4/4; m2/2 (Gehrt, 2003). The dentition reflects the omnivorous habits of this species, with sharp incisors and canines suitable for cutting or tearing, contrasting with square-shaped molars and 4^th upper premolars with small, rounded cusps, suited for grinding plant material. Morphological characteristics of P. lotor in Germany appear to be similar to those of North America (Lutz, 1995). 

P. lotor is considered a native of Central and North America, and it has the most widespread distribution of the Procyonidae, extending from Panama into Canada and Alaska (Glanz, 1991; Gehrt, 2003). Historically, it was rare in southern Canada and in parts of the Rocky Mountains and western deserts, especially the Great Basin region (Kaufmann, 1982; Sanderson, 1987). Today it is found throughout Utah and Nevada, probably in response to agricultural irrigation and urbanization (Kamler et al., 2003). Likewise, it has expanded its range northward and is currently found in Canada from central British Columbia, across the prairie provinces up to the edge of the boreal forest, and across to Nova Scotia (Larivière, 2004). It occurs, as a result of introductions, on islands off the coast of British Columbia (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014; Bartoszewicz, 2011); MacDonald and Cook (1996) considered raccoons introduced to Alaskan islands to have been extirpated, but there are reports of their continuing presence (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014). It was brought to Prince Edward Island, Canada, in the early 20^th century to keep in fur farms, but escapes have resulted in the species now occurring throughout the island (PEI Fisheries, Aquaculture and Environment, 2000). It has been introduced to some Caribbean islands (the presence of the species on Puerto Rico is possible but unverified -- S. Roy, FERA, Sand Hutton, UK, personal communication, 2014). Introduced populations of P. lotor occur in Eastern and Western Europe, and also in parts of Japan. Following accidental releases and abandonment, it is established in 42 of 47 prefectures in Japan (Ikeda et al., 2004). It is currently found free-ranging in Germany, the Netherlands, Luxembourg, Belgium, France, Switzerland, Austria, the Czech Republic, Slovakia, Hungary, Poland, Denmark, Belarus, Slovenia, and the former Yugoslavia (Serbia) (Cirovic and Milenkovic, 2003; Frantz et al., 2005). There are reports of its presence in Sweden and Finland (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014), but according to Bartoszewicz (2011) it is not present in Finland and in Sweden (and Norway) there have been only occasional escaped individuals.

P. lotor dramatically increased in abundance across North America beginning in the 1940s, with a concomitant increase in distribution. From 1920 to 1987, the total estimated geographic range in North America increased from 6.6 million km² to 8.8 million km² (Sanderson, 1987). Sanderson (1987) estimated there were 15-20 times as many raccoons in North America during the 1980s as there were in the 1930s. With recent declines in pelt value and a concomitant reduction in harvest, raccoons may have experienced another significant population increase and North American range expansion during the 1990s (Gehrt et al., 2002). Some range extensions were the result of introductions, such as islands off the coast of southeastern Alaska (Scheffer, 1947) and the Queen Charlotte Islands of British Columbia (Hartman and Eastman, 1999). P. lotor was rarely observed in the prairie provinces of Canada until the 1960s and 1970s, when it expanded northward (Larivière, 2004). Larivière (2004) suggested that the northward expansion of the range may be a result of agriculture and a warming climate, although accidental transport of animals by people may also have played a role.   Island populations from the West Indies previously considered endemic insular species are now considered introduced, invasive populations of P. lotor (Helgen and Wilson, 2003; Helgen et al., 2008). P. lotor was likely introduced to Barbados between 1650-1680, to Providence Island in the Bahamas sometime prior to 1784 and Grand Providence in 1932-1933, and to Guadeloupe sometime prior to 1886 (Helgen and Wilson, 2002). It was eradicated from Barbados by 1972, but still survives on Providence Island and Guadeloupe (Helgen and Wilson, 2002). A report of P. lotor on Jamaica is questionable, and there is no evidence of the species currently on the island (Helgen and Wilson, 2002). It is likely that these introductions were facilitated by people.

Aliev and Sanderson (1966) reported at least 26 intentional releases of P. lotor, from 1936 to 1958, across parts of the former USSR, involving 1243 individuals. Release sites were focused in the Caucasus region (504 individuals), Azerbaijan area (120 individuals), Belarus (130 individuals), and the Dal’niy Vostok region (Primorsky Krai, Russian Far East; 489 individuals). Introduction stock was acquired from facilities and zoos in Germany and Russia, as well as wild-caught individuals from the Azerbaijan area following releases there. These releases of P. lotor were part of a national program to enhance fur production. By 1964, the authors estimated a self-sustaining population of 40,000-45,000.     The western European range of P. lotor is primarily the result of three introduction events. P. lotor was first intentionally introduced in Germany in 1934, apparently successfully. A second release near Berlin in 1945 was accidental, when a breeding facility was damaged during the war (Lutz, 1995). A third release occurred in western France in 1966, when raccoons were intentionally released by U.S. military personnel (Leger, 1999). Following these releases, P. lotor has increased in number and invaded 13 adjacent countries.   Ikeda et al. (2004) described three primary introduction events in Japan, each accidental, although there have likely been multiple incidental releases. The first invasion occurred in 1962 in Aichi Prefecture, when some individuals escaped from a zoo; others were abandoned by a breeder in Gifu Prefecture in 1982. Similarly, notable escapes were recorded in 1979 in Eniwa City, Hokkaido Prefecture and in Kamakura City in 1988. Multiple escapes and releases have occurred in Hokkaido and elsewhere since then. Following introduction, P. lotor rapidly colonized and is currently the most abundant medium-sized carnivore on the island of Hokkaido (Suzuki et al., 2003). Colonization in Japan has been most rapid in areas marked by agricultural and urban development. P. lotor doubled its range over a 3-year period (2001-2003) in Kanagawa Prefecture, Japan (Hayama et al., 2006). Since its initial release in 1988 in Kamakua City, P. lotor is now established throughout the city (Ikeda et al., 2004). 

The broad ecological niche of P. lotor allows it to exploit a wide range of habitats, and largely explains the success of its colonization as an alien species. Its value as a furbearer prompted introductions to the former Soviet Union, and the establishment of fur farms from which releases occurred in western Europe. However, P. lotor can exert ecological impacts on local fauna through predation, competition, or disease transmission.  These ecological risks associated with the species exceed the economic value from the fur; intentional introduction programs at the international level are discouraged, and have not occurred since the 1960s. Nevertheless, accidental releases of captive individuals from zoos or breeding facilities may still occur, such as in Japan. The species is common in the pet trade, which increases the risk of accidental introduction (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014). Where P. lotor becomes established, it can have economic impacts on agricultural production through crop and fowl depredation, and it can have health and economic implications through its role as host to various zoonoses, some of which are lethal to humans. 

Natal dispersal usually takes place during the autumn by raccoons at 0.5 or 1.5 years of age, and sometimes during the spring at approximately 1 year of age (Stuewer, 1943; Urban, 1970; Gehrt and Fritzell, 1998). At more northern latitudes, natal dispersal takes place after the first winter (Schneider et al., 1971; Fritzell, 1977). However, at southern latitudes dispersal may take place at any time and individual differences in sexual maturation may explain variations in the timing of dispersal (Gehrt and Fritzell, 1998). Male-biased dispersal has been reported for most studies (reviewed by Gehrt, 2003), although female dispersal also may occur occasionally. Dispersal distances are difficult to determine, and may be underestimated in many studies. Distances up to 33 km have been reported from multiple mark-recapture and radiotelemetry studies (Stuewer, 1943; Fritzell, 1977; Clark et al., 1989; Gehrt and Fritzell, 1998), and Seidensticker et al. (1998) reported a maximum dispersal distance of 10.9 km during their study. An exceptional distance of 275 km was reported for 2 males on separate occasions (Priewert, 1961; Lynch, 1967). 

P. lotor closely resembles its congener P. cancrivorus, but differs in having relatively slightly shorter features, such as a shorter snout and legs in proportion to the body, and the species are sympatric only in Panama and Costa Rica (Hall, 1981). In eastern Europe and Japan, P. lotor may co-occur with Nyctereutes procyonoides, a member of the Canidae that also possesses a black mask and a body type similar to P. lotor. However, N. procyonoides has the characteristic four-toed digitigrade footprint and does not have a ringed tail. 

P. lotor occurs in a wide range of habitats; however, those associated with water are always important (Kaufmann, 1982). It exhibits a strong affinity for woodlands near water or wetlands (Gehrt, 2003), and woodlots are used heavily in all types of landscapes. Upland habitats, such as pastures and grasslands, are typically avoided, but P. lotor will use linear features such as fence rows, shelter belts, and roads as travel lanes (Fritzell, 1978; Glueck et al., 1988). It is a regular inhabitant of urban landscapes, and densities can reach overabundant levels where anthropogenic resources are available (Gehrt, 2004).

Species reported as potential predators of P. lotor include coyotes (Canis latrans), bobcats (Lynx rufus), red foxes (Vulpes vulpes), owls (multiple species), alligators (Alligator mississippiensis), pumas (Felis concolor) (Stains, 1956; Johnson, 1970; Kaufmann, 1982; Shoop and Ruckdeschel, 1990; Gehrt, 2003), wolves (Canis lupus) and bears (Ursus spp.) (S. Roy, FERA, Sand Hutton, UK, personal communcation, 2014). Predation by red foxes and owls is probably restricted to young raccoons. However, predation is probably not an important cause of mortality in most raccoon populations (Gehrt, 2003), and no studies have identified predation as a controlling mechanism for P. lotor populations. P. lotor hosts a variety of ecto- and endoparasites, and their relative importance in the ecology of the species probably depends on geographical location, season, and the age and sex of the host. At least 10 species of fleas (Siphonaptera), 1 species of sucking louse (Anoplura), 6 species of chewing lice (Mallophaga), and 14 species of ticks and mites (Acari) have been reported for P. lotor (summarized in Stains, 1956). At least 56 species of endoparasites have been identified in P. lotor (Stains, 1956; Johnson, 1970), including Protozoa (4 species), flatworms (Platyhelminthes; 22 species), Nematoda (27 species), and spiny-headed worms (Acanthocephala; 3 species). The list of viruses and bacteria associated with the species is long, and continues to grow (reviewed by Stains, 1956; Johnson, 1970; and Gehrt, 2003); however, notable epizootics that impact population numbers are most often associated with canine distemper virus (Roscoe, 1993; Schubert et al., 1998; Mitchell et al., 1999) and raccoon strain rabies (Rosatte et al., 2006).

P. lotor represents an important economic cost around the world as a host of disease, particularly rabies, as a nuisance species in urban areas, and as a pest in agricultural systems. 

The raccoon rabies outbreak in the eastern United States has had substantial economic consequences. For example, costs associated with raccoon rabies in 2 counties in New Jersey were $405,565 per 100,000 human population during the pre-epizootic period, and $979,027 per 100,000 population during the epizootic period (Uhaa et al., 1992). Cost of rabies control in these counties increased by $1.2 million from 1988 (prior to raccoon rabies) to 1990 when raccoon rabies was introduced to the area. In the state of Connecticut, the estimated number of people receiving a post-exposure prophylaxis following exposure to the virus increased from 41 in 1990 to 887 in 1994. The median cost of these treatments was $1500 per person (Nelson et al., 1996). Similarly, expenditures associated with raccoon rabies in New York increased 4000% during the outbreak from 1989 to 1993 (Wyatt et al., 1999).   Because of its ubiquitous distribution and adaptability to human-dominated landscapes, P. lotor is a frequently reported nuisance species in urbanized areas (de Almeida, 1987) and represents a significant cost to homeowners when it causes damage to structures (Gehrt, 2004). For example, Gehrt (2003) estimated the economic costs of raccoons in the greater Chicago metropolitan area in the United States to be over $1,000,000 in 1999.    P. lotor is an important cause of crop losses, and is the primary cause of damage to corn crops (maize – Zea mays) in most regions of North America (DeVault et al., 2007). Significant agricultural damage from P. lotor also is reported from Japan (Kotani et al., 2009) and parts of Europe (Bartoszewicz et al., 2008).

In areas where P. lotor becomes overabundant, such as urban parks or woodlots, predation on a wide range of vertebrate prey may be quite high (Robinson et al., 1995). Ground-nesting birds, such as waterfowl, may be particularly vulnerable (Greenwood et al., 1990; Garrettson and Rohwer, 2001); hole-nesting species can also suffer competition for nest sites (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014). P. lotor may impact other species through the transmission of certain diseases, such as canine distemper or raccoon roundworm (Baylisascaris procyonis). A wide range of avian and mammalian species have been documented as potentially affected by B. procyonis (Kazacos and Boyce, 1989; Page et al., 1998).

P. lotor is susceptible to a number of diseases which have public health consequences for humans and their pets. Among the primary concerns for humans or domestic animals are rabies, raccoon roundworm (Baylisascaris procyonis), leptospirosis (Kazacos and Boyce, 1989; Jenkins et al., 1988; Wandeler et al., 2000; Rosatte, 2000; Rosatte et al., 2006; Rosatte et al., 2007b) and echinococcosis (S. Roy, FERA, Sand Hutton, UK, personal communication, 2014).

It can also act as a nuisance species, for example causing damage to structures -- see Economic Impact section.

Little information is available on the current distribution and abundance of P. lotor in some parts of eastern Europe and especially areas adjacent to the Caucasus region. Likewise, there is virtually no information on the ecological impacts of P. lotor on native wildlife in Europe or Japan. As P. lotor populations continue to increase, it is likely that a variety of prey species will be negatively affected (Hayama et al., 2006).