Procyon lotor (Linnaeus, 1758)
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11. View Plate 30
French: Raton laveur / German: \Waschbar / Spanish: Mapache comun
Taxonomy. Ursus lotor Linnaeus, 1758 ,
Historically, more than 50 types of Northern Raccoons have been named. However, more recent work has shown this species to have a high degree of morphological plasticity in the face of environmental variation. Caribbean forms were recently shown to be recent introductions from the east USA and are no longer considered unique species. The taxonomy of inland forms has not yet been revised with modern methods, so the twenty recognized subspecies remain poorly defined.
Subspecies and Distribution.
P.l. lotor Linnaeus, 1758 — NE USA.
P.l. auspicatus Nelson, 1930 — SE USA (Central Florida Keys).
P. l. elucus Bangs, 1898 — SE USA (Florida).
P. l. excelsus Nelson & Goldman, 1930 — NW USA (in and near Idaho).
P.l. fuscipes Mearns, 1914 —S USA (Texas) and NE Mexico (Tamaulipas, Coahuila).
P.l. grinnelli Nelson & Goldman, 1930 — Mexico (S Baja California).
P. l. hernandezii Wagler, 1831 — Mexico.
P.l. hirtus Nelson & Goldman, 1930 — Central Plains of USA and Canada.
P. l. incautus Nelson, 1930 — SE USA (W Florida Keys).
P. l. inesperatus Nelson, 1930 — SE USA (E Florida Keys).
P. l. insularis Merriam, 1898 — W Mexico (Maria Madre I).
P.l. litoreus Nelson & Goldman, 1930 — E USA (coastal Georgia).
P. l. marinus Nelson, 1930 — SE USA (Florida Everglades).
P. l. megalodous Lowery, 1943 — S USA (coastal Louisiana).
P.l. pacificus Merriam, 1899 — NW USA.
P. l. pallidus Merriam, 1900 — SW USA.
P. l. psora Gray, 1842 — SW USA (California).
P.l. pumilus G.S. Miller, 1911 — Central America.
P. l. simus Gidley, 1906 — W USA (N California).
Descriptive notes. Head-body 44-62 cm, tail 19-36 cm; weight 2:7-10. 4 kg. Northern Raccoons have relatively short ringed tails and striking black masks. Their body fur is grizzled gray, and often long. There may be some reddish color on the nape of the neck. Animals in arid areas are lighter in color, whereas those in humid forests are darker. The largest raccoons are in the north-west USA and the smallest are in the south-east.
Habitat. Raccoons use a variety of habitat types, preferring waterways such as streams, rivers, lake shores, and wetlands. The have adapted well to urban habitats.
Food and Feeding. Northern Raccoons are among the most omnivorous mammals on Earth. They will take advantage of any locally abundant food source they can get their hands on, including fruits, nuts, grains, invertebrates, fish, and small terrestrial vertebrates. A variety of plant products make up a majority of their diet in all seasons. In urban areas raccoons are famous for ingenious ways of procuring garbage, and in rural areas, for raiding crops. In natural settings raccoons are typically tied to aquatic habitats, and aquatic invertebrates such as crabs and crayfish often make up a substantial portion of their diet. They occasionally catch frogs, lizards, snakes, and other terrestrial vertebrates, although these are rare in their diet compared with invertebrate prey. Raccoons are reported to be able to detect a single acorn buried under 5 cm of sand, and much of their animal food comes not after dramatic chases but from using their keen sense of smell to locate nests and predate eggs or nestlings. This can be a problem for the egg-layers in areas where raccoon density is elevated because of human subsidization. Nest predation has been implicated in reducing the population size of turtles, green iguanas, and some low-nesting bird species. The Raccoon’s keen nose also makes it a good scavenger, able to detect fresh carcasses. Competition with other omnivores is not obvious. Opossums did not change population parameters, diet, or habitat use in an area where raccoons had been removed. Food passes through the raccoon digestive system in 9-14 hours, long enough to make it probable that they function as important seed dispersers for the fruit plants they feed on. Northern Raccoons received their species name, lotor , meaning “the washer”, because they are thought to wash their food before eating it. They are fond of dunking their food, although there is no indication this has any washing function, since they submerge both clean and dirty foods. One alternative hypothesis is that getting their hands wet increases the pliability of the skin on their fingers, thus increasing theirtactile sensitivity. Indeed, raccoons use their dexterous hands to procure much of their food, prying under rock on stream bottoms or into garbage cans.
Activity patterns. Raccoons are primarily nocturnal, with activity peaking slightly before midnight. However, they will venture out in daylight to take advantage of food sources, for example, to forage at low tide. In cold areas raccoons may enter a dormant period during winter, spending weeks or months in a den. This is not hibernation, as their heart rate and body temperature do not decrease. Instead, they burn through stored body fat to maintain themselves over this period, sometimes losing more than 50% of their mass during winter.
Movements, Home range and Social organization. Raccoon populations have increased and spread substantially over the past century. Their numbers were at an alltime low in the 1920s and 1930s following severe persecution for the fur trade. Game management regulations allowed them to begin their recovery in the 1940s, and by the 1980s their populations were estimated to be twenty times larger than in the 1930s.
Their range expanded, too, and they are now found in nearly all of the lower 48 states, including deserts and mountain regions where they had previously been rare or absent. The spread of agriculture and concurrent decline of the Gray Wolf and Puma were probably both important factors in the increase and spread of the raccoon. The raccoon is one of the most successful native species at adapting to urban and rural environments, but raccoons also occur in wilderness. Densities in natural areas have been estimated as 0-5—4 ind/km? in northern prairies and 3-5-6 ind/km* in hardwood forests. Their populations increase where they can find anthropogenic food sources. These subsidized densities range from 1-27 ind/km? for rural areas and 50-100 ind/ km? in cities. Some estimates from urban parks are as high as 333 ind/km?, although these calculations do not take into account the area used by raccoons outside of the park. In Chicago, densities were typically one third higher in the autumn than in the spring, reflecting the litters born in the summer and mortalities that occurred during the winter. The higher densities in urban areas are caused by a combination of demographic factors, including increased survival, higher annual recruitment, and increased site fidelity. These factors are all encouraged by the raccoon’s ability to learn how to take advantage of abundant anthropogenic food, and apparently also by high levels of intraspecific tolerance. Most individuals in a population are under two years old, and few reach as old as seven years. Some trapping studies found a male-biased sex ratio, but subsequent research suggests that this result may have occurred because the males were more trappable, and females actually outnumber males in most populations. Corresponding with their higher densities, urban raccoons typically use smaller home ranges than rural animals: 5-79 ha compared to 50-300 ha, often focusing their activities around a few select sources of anthropogenic food. Wilderness animals use even larger home ranges, averaging between 800-2500 ha in North Dakota, where individuals were recorded travelling as far as 14 km in one night. Typical nocturnal movements cover less ground and consist of a few periods of rapid movement between den and feeding sites, followed by more lengthy periods of small, localized movements at foraging sites. Patterns of home range overlap and social organization in raccoons vary predictably with density and available resources. Female raccoons appear to space themselves out according to the available food, and sometimes water, resources. Where food is rare or scattered females are more solitary. Where food is more abundant, and many individuals are able to share space without competing for food, related females may overlap more in home range and occasionally interact during nocturnal foraging or in diurnal resting dens. Males adopt strategies that allow them to maximize their individual fitness, given this distribution of females. In low densities, males will set up territories and defend them against other males, attempting to gain exclusive access to the female (s) they spatially overlap. In areas with medium densities of females, males cannot defend a territory alone, and they share space with other males. One study found that 3-4 of these overlapping males formed stable bonds that lasted for several years. These male groups frequently travelled and denned together, overlapping many different females, but no other males. The raccoon mating system appears to vary across these situations, between polygyny in low density areas and promiscuity in higher density areas. In the polygynous systems males compete for access to estrous females within a predictable dominance hierarchy related to body weight and canine width. In promiscuous systems females mate with multiple males, and most litters (88% in one study) have multiple paternities. The primary predators of adult raccoons were probably Gray Wolves and Pumas. The extinction of these large predators from many areas, especially in urban or rural areas, probably freed raccoons from substantial predation risk throughout much oftheir range. Raccoons and Coyotes are sympatric over much of their ranges, but the nature of interactions appears to be variable. In Kansas, 40% of raccoon mortalities came from Coyote predation, and raccoons make up a substantial portion of the diet of Coyotes in some parts of Ohio and Maine (some of this may be scavenging on roadkill). However, most studies of Coyote diet find little evidence of raccoon predation, and other studies of raccoon mortality have found no Coyote predation. One detailed study of raccoon and Coyote movements in Illinois found no avoidance by raccoons ofareas preferred by Coyotes, or of their scent marks. In some areas, humans have replaced other predators as the major cause of death, either through directed hunting, or accidental deaths such as road kills. Disease has also been found to be important in a number of raccoon populations. Diseases spread more easily between individuals living at high density,so it is not surprising that disease can spread rapidly in urban raccoon populations. Raccoon rabies has been one of the most dramatic examples of wildlife disease in North America. From the 1950s to 1970s a strain of raccoon rabies spread slowly northward out of Florida into Georgia. In 1980, an illegal translocation of 3500 raccoons from Florida to Virginia for hunting purposes set off an epidemic. Apparently at least one of these animals was harboring the rabies virus, and an outbreak spread at a rate of 40km /year up the Atlantic coast, north into Ontario and west into Ohio and Pennsylvania. This epidemic has caused high mortality in urban raccoons, noticeably reducing their populations in some areas, and also spilled over to impact other wildlife, pets, and humans. Another species that suffers from parasite spillover from superabundant raccoons has been the Allegheny Woodrat (Neotoma magister). Woodrats suffer high mortality from infections of raccoon roundworm parasites, which have little effect on the raccoons themselves. Woodrats pick up the parasites while feeding on seeds from raccoon latrines. Raccoons do not habitually sing or call out, but do have a variety of vocalizations that occur during close-range social interactions, including a twittering used by females to encourage their young to follow them away from the den. Scent marking is probably the most important means of communication. Raccoons have paired anal scent glands for this purpose, but also use feces, urine, and other specialized skin glands. In some areas raccoons defecate in habitual latrines, although it is unclear if these serve a social function or are just a by-product of high raccoon density.
Breeding. Northern Raccoons are spontaneous ovulators. Mating typically occurs in February and March, although being consummate opportunists, litters can also be conceived outside of this period. In Texas many females with litters that failed in the spring came into a second estrus later in the year, resulting in a second, but smaller, breeding pulse in the population. Mating appears to be the only time males and females associate. Males consort with females over a period of 1-3 days, with females serially visiting and copulating with more than one male during this time. Gestation averages 63 days (range 54-70) and mostlitters have 3—4 cubs,typically from multiple fathers. Newborns eat solid food at nine weeks but nursing continues until 16 weeks. Cubsfirst leave the nest at 6-7 weeks and often spend much of their first autumn travelling alone. Many juveniles return to mom for winter denning, ultimately dispersing when she comes into estrus the following spring. Males disperse to new areas, covering distances averaging 11 km, although distances up to 275 km have been reported. Females often stick close to home, overlapping in some or all of their home ranges, and sometimes reuniting in winter to form extensive communal dens.
Status and Conservation. Raccoons are considered Least Concern by The [UCN Red List since they are among the most abundant medium-sized mammals in their range. Because of their abundance they have been one of the most economically important furbearers in North America, with fur harvests in 1930s and 1940s ranging between 0-4-2 million skins annually and reaching an all-time high of 5-1 million in 1979/80. However, because of their high reproductive potential and ability to exploit human settlements they saw no obvious broad scale population reductions from this harvest. The fur trade has declined in the last two decades and raccoons are now widely viewed as urban pests, potentially dangerous because of rabies. Their subsidized populations near human settlements may cause conservation problems for other species due to disease spillover or nest predation. Through breeding for the fur trade they have become established as an invasive species in Europe, Russia, and Japan. They are also an introduced species on some Caribbean islands, where they endanger native island fauna not adapted to dealing with a mammalian predator with a keen sense of smell.
Bibliography. Chamberlain et al. (1999), DeVault et al. (2004), Gehrt (2003, 2004), Gehrt & Clark (2003), Gehrt & Fritzell (1996a, 1996b, 1997, 1998a, 1998b, 1999a, 1999b), Gehrt & Prange (2007), Helgen & Wilson (2003), Helgen, Maldonado et al. (2008), Ikeda et al. (2004), Kamler & Gipson (2004), Kasparian, Hellgren & Ginger (2002), Kasparian, Hellgren, Ginger, Levesque et al. (2004), Kennedy & Lindsay (1984), LoGiudice (2006), Nielsen & Nielsen (2007), Prange et al. (2004), Ratnayeke et al. (2002), Rogers & Caro (1998), Schmidt (2003), Smith et al. (2006), Zeveloff (2002).
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