Procyon lotor - Raccoon

Skull Pictures:       
Dorsal      Posterior mandible
Lateral     Ventral
Mandible     

Description:

Earliest scientific name was Vulpi affinis Americana was published by John Ray who believed it had affinity to fox. Todays scientific name was published by Carolus Linnaeus in 1758. (Schwartz, 1981) Procyon means “before the dog” and lotor means “a washer” because of their behavior seen in captivity of dipping their food in water (Zelveloff, 2002). The common name raccoon was derived from the Native American tribe, Algonquin, and means he who scratches with his hands. Another common name uses is the coon which was named for describing clothing made from Procyon lotor such as coonskins. The last common name used for Procyon lotor, ringtail, was derived from one of its relatives Bassariscus astutus (Schwartz 1981).

The subgenus Procyon has many distinguishing characters when comparing it to the other subgenus Euprocyon; such characters as long pelage, presence of under fur along with grayish out surface of the forearms and thighs (Goldman 1950). Other characters have also been used to distinguish between the two subspecies like narrower, sharper claws and tending to be stronger allowing them to be an arboreal species. Also, the molarform teeth are not as adapted for crushing, compared to Euprocyon (Goldman 1950).

Within the subgenus Procyon 25 species have been recognized by Hall and Kelson with changes made in 1963 by Paradiso. These different species are difficult to distinguish without knowing local populations of the species in question (Lotze 1978).

General Characteristics:

 A black mask stretches across the eyes through the check region and tapers around the underside of the throat. Above the sharp black band a white dusking leads into a mixture of grays and blacks up to the top of the cranium. Their short prominent pointed ears tend to be grayish leading to black at the base. A white outline typically surrounds the ears and can be prominent. A pointed muzzle ends in a black naked, wet nose, broadening across their jowls (Schwartz 1981).

Throughout the rest of the body pelage tends to be a mixture of black and white, some having describing the upper pelage as a grizzled brown black with a strong washed yellow. The sides of the body are grey with the under part a dull brownish with a yellowish grey wash. Pelage tends to be course in texture on the outer surface and softer on the underside. Pelages are not dynamic with seasons of year or sexes (Schwartz 1981). Abnormal color variation occurs and albinism is often documented (Johnson 170; Whitney and Underwood 1952a).

They have four long feet with naked soles each containing five toes with short curved claws. Claws are not retractable and/or feet are not webbed between the digits. Usually plantigrade to semiplantigrade gait types are seen. Hands are well developed for manipulation of objects while the feet support the body (Lotze 1979).

Along with the black mask another prominent feature is a heavily furred ring tail, usually about one half the length of the body. It alternates rings of black and white in 4 to 7 rings with the rings closer to the body are usually the most pronounced (Schwartz 1981).

Male’s length: 634-1,050 mm

Female’s length: 600-909 mm

Male’s weight: 8-25 lbs

Female’s weight: 6 ¾ -17 ½ lbs

Record weight: 49 lbs

Morphological Characteristics:

Tooth formula for most adults is 3/3 1/1 4/4 2/2 totaling 40 teeth. The formula is usually a sufficient diagnosis for raccoons (Schwartz, 1981). Teeth also tend to be heavy but not sharply cusped (Schwartz, 1981). First premolars may be absent and extra teeth have been documented (Lotze 1979).

Eyes tend to be round in shape to facilitate night vision.  Eyes are large and convex, which allows for bright images to project into the retina. The retina contains fewer cones therefore raccoons tend to be color blindness or possibly have “color weak” vision. It may be difficult to detect colors but they can detect a difference in brightness. Eyes have also been described as extremely piercing because of red tinge they can contain. Binocular vision is possible since the eyes are positioned forward on the cranium but they have poor distance vision (Zelveloff 2002).

Skull is broad and round in shape. The sagittal crest varies in size and can be absent. The auditory bullea tend to be highly inflated on the inner sides and are laterally compressed (Zelveloff 2002).

Ears have the capability to hear high auditory ranges from 50 kHz to 85 kHz. Noises also have the ability to make raccoons immobile, therefore it is known as their protective sense (Zelveloff 2002). 

Senses:

Most important to raccoons are their sense of smell and their sense of touch. Their sense of smell is accentuated by the rhinarium shape of their nose’s shallow pads and their lack of phitrum. Their keen sense of smell can be demonstrated by their ability to detect acorns up to 2 inches under sand. However, their scents are not fully understood but like other mammals, they mark their home range with their scent. They also have paired anal sent glands and they seem to deposit their scent by rubbing this region on various items.  Anal sniffing has also been observed along with communal defecation sites in places like logs and stumps usually near trails. Their sense of touch is their most conspicuous sense seen in with their ability to gripe and manipulate objects. Raccoons are very dexterous, demonstrated when they catch insects. They also possess tactile discrimination; they can differentiate objects without seeing them. This may be possible because of their enlarged tactile receiving area in the brain where groves that correspond to parts of forearm receive specific signals form specific fingers, equaling a large number of brain cells responding to forepaw stimulation (Zelveloff 2002).

Distribution:

Raccoons are found from Southern Canada throughout the USA, except in parts of the Rocky Mountains, Mexico and Central America to Central Panama. They have also been introduced to France, Germany and other republics of the former USSR (Smithsonian National Museum of Natural History). Raccoons can be found throughout Wisconsin but tend to a  more dense population in the southern 2/3 of the state and occur at small densities in the northern part of the state (Zelveloff  2002).

The earliest known Procyon was from the upper Pliocene of North America (Simpson 1945). Some post-Pleistocene remains of raccoons from central Texas resemble living P. lotor form the northern USA, indicating that earlier they had a much wider range (Wright and Lundelius 1963).

Habitat:

Raccoons need only a permanent source of water, a den and an average amount of food. Dens tend to be hollow trees usually large and dry but they don’t add nesting material. Dens are typically made in maple or elm trees of 2-20 meters in size (Zelveloff 2002). They can also habit in attics and chimneys of abandoned farm houses or even occupied houses. Food is the least important part of equation to live. They also have the advantage to live in rural and urban areas, since they have adapted to survive in close proximity with humans (Hoffmeister 1989).

Ontogeny and Reproduction:

Breeding season has been established from December to August with most females matting in March resulting in approximately half the births in May (McKeever 1958). Depending on where the raccoons are geographically located this will change the duration of the mating season; therefore this information is very variable within the literature. Duration of the breeding season has been estimated by techniques such as the degree of ovarian development, the weight of the testes, smears from the tail of the epididymides and also vaginal smears (Wood 1955).

Raccoons have a polygnnous or promiscuous based sexual dimorphism in physical characteristics or spatial patterns of home ranges during matting season (Gehrt and Fritzell 1998). Male raccoons may breed in their first year or they may wait until their second year (Wood 1955). This is the same for female raccoons (Wood 1955). Female raccoons have the ability to have a second estrus after failing to produce a litter the first time, this usually results outside their normal breeding season (Gehrt and Fritzell 1998). However, in Wisconsin the survival of this juvenile is unlikely due to the extreme winters (Zelveloff 2002).

Onset of breeding season in raccoons is possibly linked to the length of photoperiod (Lotze 1978). Some others have linked it to increasing temperatures (Sanderson and Nalbandov 1973). Most agree that a raccoon’s gestation period is approximately 63 days.

Ovulation most likely occurs after copulation (Llewellyn and Enders 1954). The number of males that found females has been found to be positively correlated to copulation (Gehrt and Fritzell 1998). During estrus females typically reduced their movements at night and subsequently adult males moved near the females (Gehrt and Fritzell 1998). This is likely due to the fact that female is only receptive for short periods of time, usually only 3 days (Gehrt and Fritzell 1998). Dominate males would be expected to sequester an estrous female in absence of other estrous females; they also take advantage of these females. Female raccoons may also mate with multiple males which increase genetic heterogeneity (Gehrt and Fritzell 1999).

Litter sizes have been determined by counting embryos or placental scars (Sanderson and Nalbandov 1973). Larger litter sizes tend to occur more in the northern parts of their range, this seen in Wisconsin. Large litter sizes may be an adaptation to the high mortality rate that also occurs in these regions (Sanderson 1973).

Raccoons can be weaned sometime between month 4 and a month 7 (Montgomery, 1969). Dispersal of the males does not tend to happen until month 9. Until dispersal it has been described that young raccoons run ahead or behind their mother, prior to being weaned. Closer to month 9 such behaviors have been described: relationships of sibling becoming more independent just before winter and young raccoons eventually begin to den without the presence of their mother. However it has also been noted that closer to winter they will den together especially as the winter becomes more severe (Montgomery 1969).

Many aspects of ontogenetic development can be studied in raccoons such as tooth eruption in preweaned raccoons, suture closure between the bones of the skull, eye lenses growth rates, fetal growth rate and ossification of the baculum (Sanderson 1950). Dental cementum can also be used instead of these above characters (Johnson 1970).

Longevity records for free roaming wild population ranges between 7 to 12 years (Lotze 1978) with other sources stating less than 5 years (Schwartz 1981). Captive animals live much longer lives, usually up to 17 years (Schwartz 1981).

Ecology:

Raccoons eat a very wide variety of both plants and animal matter, usually selective when food is abundant but when food is scarce they eat whatever is available. Their tendencies are to be omnivores. Most important plants to wild raccoons are berries, nuts and seeds from a variety of plants and the most important animal are arthropods (Hamilton 1951). Some other items they have been documented in eating are plums, grapes, corn acorns, snakes, turtles, earthworms, squirrels, duck and muskrats (Schwartz 1981).

Raccoon’s main predator is man. Hunters harvest about 60% of the population in Wisconsin, without a defined hunting season or bag limit (Schwartz 1981). Hounds or dogs are used to hunt raccoons, usually breeds like Black and Tan, Bluetick Redbone and Walker (Schwartz 1981).

Locomotion is well studied in raccoons; however no real data from Wisconsin has been documented. Raccoons are expert climbers and are capable of climbing head or tail first up and down (Schwartz 1981). Along with climbing capabilities they are also swimmers, they can submerge their body about halfway and paddle to move through the water: usually at speeds at about 3 miles per hour (Zelveloff 2002). These two modes of locomotion can be used to escape from danger, since raccoons tend to flee instead of fighting. They will fight if they are cornered but their preference is to escape (Schwartz, 1981).

Raccoon populations fluctuate, usually increasing rapidly and then decreasing. Population densities vary from one raccoon per 5 ha to one per 43 ha, which tends to be more typical (Twitchell and Dil 1949).  Clumped disposition seems due to availability of water, food and den sites. Raccoons can be solitary or in groups from about 9 to 23 individuals of both sexes and mixed ages (Schwartz 1981).

A study done on sexual difference in home range of raccoons conclude that size of home ranges in males didn’t vary much between seasons and males have much larger home ranges when compared to female raccoons. Female raccoons had considerable variation in sizes of their home ranges however like males the size of the home ranges didn’t vary with seasons. Male home ranges are larger based on relationships between body mass and size of home range; a larger male raccoon will have a larger home range. Along with body sizes social behavior plays a role in male home ranges, such as an increase in matting activity increases their home range and males tend to not contact other males, possibly territorial (Gehrt and Fritzell 1999).

Raccoons have been used as an indicator species for monitoring environmental zoonoses and pollutants; important to humans because raccoons have been documented to carry 13 pathogens that can cause disease in humans (Bigler et al. 1975). Direct contact with raccoons or by means of water contaminated with raccoon urine or feces are possible ways to contract these pathogens or diseases (Johnson 1970).Most disease raccoons carry tend to not have an affect on their population except canine distemper (Robinson et al. 1957).

A heath link was posted by the Medical Colleges of Wisconsin on November 2003 about a Baylisascaris procyonis. The release described way the roundworm is spread, signs of Baylisascaris procyonis in humans and who is at the greatest risk. Baylisascaris procyonis is a large roundworm parasite that is present in raccoon’s intestines, that doesn’t harm the raccoon but can cause serious illness to humans. This was reported because about half of the tested raccoons in Wisconsin were infected, but most relevant in the southern half of the state. Children tend to be the greatest risk at attracting this disease along with wildlife rehabilitators, hunters and trappers. Symptoms include nausea, lethargy, liver enlargement, incoordination, and loss of muscle control, coma and blindness (Medical Colleges of Wisconsin 2003).

Heavy metal has been examined in raccoon’s liver, (Sanderson 1950) kidneys and their hair (Bigler et al. 1975). A study done about the concerns of metal accumulation from raccoons across trophic levels stated the characteristics of raccoons that make them an  ideal sentinel species for containment studies: high population level in North America, broad omnivorous, move freely in and out of waste sites and they also travel extended distances between rural and urban areas (Bigler et al. 1975)

Raccoon’s economic importance lies mostly as a fur games species. Their furs are used for coats, collars, muffs and trimmings. Their flesh is roasted and the oil is used with leather work. Also in the earlier days, their baculum was used as tool for tailors (Schwartz 1981).

Behavior:

Raccoons are best known for their washing behavior that is commonly observed in zoos but is not as common in wild free ranging raccoons. This behavior is better described as a “feeler” instead of a “washer”, because they will rub dry and wet food together and also observed rubbing their hands together without food present (Whitney 1933). Other sources state that the wetter the food the more sensitive their forepaws are, therefore that is why they tend to dip their food in water (Schwartz 1981).

Raccoon behavior has also been studied in laboratories to demonstrate raccoons learning ability. Their ability was shown to be comparable to cats but inferior to primates (Schwartz 1981). Other researchers have noted that raccoons can detect small differences in brightness and could also visually discriminate all test objects within the special limits (Johnson 1970).

Raccoons have a variety of noises that they make related to feelings; when a raccoon chuckle it is usually annoyed at the some behavior, snarl or growl or hiss demonstrates fright and dominance, and low snort demonstrates an unsocial individual has been recognized. A typical call made to their young resembles a low, grumble or purr and the return call young make to their mother is very similar to a tree frog call. Intra-species communications resembles a screech owl in a shrill or whistle (Schwartz 1981).

Literature Cited:

Boring, S.C. et al. 2002. Using Raccoons as an Indicator Species for Metal Accumulation Across Trophic Levels: A Stable Isotope Approach. Journal of Wildlife Management. 66:811-818.

Goldman, E.A. 1913. Descriptions of new mammals from Panama and Mexico. Smithsonian Misc. Coll. 60922):1-20.

Goldman, E.A. 1950. Raccoons of North and Middle America. N. American Fauna 60:1-153.

Gehrt, S.D. and Fritzell, E.K. 1999. Behavioral aspects of the raccoon mating system: Determinants of consortship success. Animal Behaviour. 57:593-599.

Gehrt, S.D. and Fritzell, E.K. 1997. Sexual Differences in Home Ranges of Raccoons. Journal of Mammalogy. 78(3): 921-930.

Hoffmeister, D.F. 1989. Mammals of Illinois: Raccoons. University of Illinois Press, Urbana, IL. USA.

Johnson, A. S. 1970. Biology of raccoons in Alabama. Agric. Ezp. Stat. Auburn Univ. Bull. 402:vi = 1-148.

Lotze, J.H. and Fleischman, A.I. 1978. The raccoons on St. Catherines Island. Georgia. Biochemical parameters by livetrapping and radiotracking. Amer. Mus. Novitiates. In press.

McKeever.S. 1958. Reproduction in the raccoons n the southeastern Iowa. Journal of Wildlife Management. 22:211.

Medical College of Wisconsin. Baylisascaris procyonis. <http://healthlink.mcw.edu/article/954973916.html>.  Accessed 21, November, 2003.

Montgomery, G.G. 1969. Weaning of captive raccoons. Journal of Wildlife Management. 33:154-159.

Robinson, V.B., J. W. Newbeme, and D. M Brooks. 1957. Distemper in the American raccoon (Procyon lotor). Journal of American Veterinary Medicine Association. 131:276-278.

Sanderson, G.C. and Nalbandov, N.J. 1973. The reproductive cycles of the raccoons in Illinois. Illinois Nat. Hist. Surv. Bull. 31:25-85.

Schwartz, C.W. and Schwartz, E.R. 1981. The Wild Mammals of Missouri: Raccoons.  University of Missouri Press and Missouri Department of Conservation, Columbia, USA.

Simpson, G.G. 1945. The principles of classification and a classification of mammals. Bull. Amer. Mus. Hist. 85:1-350.

Smithsonian National Museum of Natural History. Mammal Species of the World: Procyon lotor. <http://www.nmnh.si.edu/cgi-bin/wdb/msw/names/query/12366>.  Accessed 30, November 2003.

Twitchell., A.R. and Dill, H.H. 1949. One hundred raccoons from one hundred and two acres. Journal of Wildlife Management. 30:130-133.

Whitney, L.F. and Underwood, A.B. 1952a. The raccoon. Practical Science Publ. Co., Orange, Connecticut, 177pp.

Wood, J.E. 1955. Noteson reproduction and rate of increase of raccoons in the Post Oak  Region of Texas. Journal of Wildlife Management. 19:409-410.

Wright, T. and Lundelius. E. 1963. Post-Pleistocene raccoons from central Texas and their zoogeographic significance. Pearce-Sellards Ser. Texas. Mem. Mus. 2:1-21.

Zelveloff, S.L. 2002. Raccoons: A Natural History. Smithsonian Institution Press, Washington D.C., USA.

 

Reference written by, Biol 378: Edited by Chris Yahnke. Page last updated4-29-04.