Article

A critical re-examination of food “washing” behaviour in the raccoon (Procyon lotor Linn.)

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Abstract

An objective study of the so-called “washing” behaviour of the raccoon is carried out on ten captive animals in order to determine the true causal nature of the response. The activity is described in detail and an analysis of the food objects which most readily release the response is made. Those factors of the water site which influence the frequency of the response are also examined in detail. The importance of the response as a functional cleansing or moistening action is discussed and it is suggested that, in order to avoid confusion, the behaviour should be described as “dousing”. The ontogeny of the response is studied in five young raccoons and a possible explanation for the behaviour is put forward.

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... In this case, the disruption likely leads to anxiety and the repeated, almost compulsive dousing, may be an attempt to mitigate this anxiety generated from the artificial environment of captivity and re-establish neurobiological homeostasis. In fact, one report of a raccoon in the London Zoo in the 1960s indicated that a maternal raccoon doused her newborns so often that she drowned them (Lydall-Watson, 1963). Although this captivity-induced behavior may be a better model for obsessive-compulsive disorder than depression, both disorders involve disruptions in movement patterns and are influenced by stress and anxiety. ...
... Whether or not this area is close in proximity to the actual cause/s of depression is arguable, but there is considerable evidence pointing to other areas that should be investigated as well-we now know that other neurochemicals such as dopamine, noradrenaline, and glucocorticoids also seem to play either direct or indirect roles in the onset of depression. Additionally, neurotrophic factors, such as brain-derived neurotrophic factor (BDNF) may be most closely related to the onset or delay of depressive symptomology (Lydall-Watson, 1963;Lang et al., 2004). Antidepressant drugs have been shown to modify BDNF and the BDNF receptor, tyrosine kinase receptor B (TrkB), in the nucleus accumbens, and has an anti-anxiety effect in the forced swim test (Nibuya et al., 1995;Eisch et al., 2003). ...
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Despite the existence of a vastly improved health care system and a multi-billion dollar antidepressant industry, the rates of depression in the US remain alarmingly high. An exploration of lifestyle changes over the past century suggests that the level of physical activity necessary to provide life's basic resources, referred to as effort-based rewards, has diminished in our industrialized, technologically advanced, service-oriented society. The evolution of the accumbens-striatal-cortical circuitry and its modulating neurochemicals in our ancestors played a significant role in sustaining the continued effort critical for the acquisition of resources such as food, water and shelter; consequently, vast reductions in the degree of physical activity required to obtain necessary resources in today's society likely lead to reduced activation of brain areas essential for reward/pleasure, motivation, problem-solving, and effective coping strategies (i.e. depressive symptomology). Comparative cultural and gender analyses reinforce the significant role of effort-based rewards in mood regulation, suggesting that minimal engagement in such endeavors leads to compromised resilience upon exposure to life's stressful challenges. If physical activity is indeed important in the maintenance of mental health, increased emphasis on behavioral and behavioral/cognitive preventative life strategies, as opposed to an emphasis on psychopharmacological strategies directed at very specific neurochemicals after the onset of depression, should be adopted as protective measures against the onset of depressive symptomology. Thus, strategies that include more global neurobiological activation in the relevant context of directed efforts provide a fresh perspective for depression research.
... Male raccoons and opossums often have larger territories than females (Holmes and Sanderson, 1965;Lotze and Anderson, 1979;Gehrt and Fritzell, 1998) and could be foraging more broadly across the landscape. Finally, the relationship between raccoons and water is supported by the documented behavior of raccoons utilizing water sources to ''wash'' their prey, resulting in raccoons at water sources and in proximity to amphibian populations and potential predation of amphibians (Lyall-Watson, 1963;Lotze and Anderson, 1979). ...
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The prevalence and diversity of parasitic nematodes in wildlife have been well studied for certain species, yet for others considerable gaps in knowledge exist. The parasitic nematode Dracunculus insignis infects North American wildlife, and past research on this species has led to an increased understanding of the potential host diversity and transmission of the closely related human Guinea worm, Dracunculus medinensis (which is currently the focus of a global eradication program). Many definitive hosts have been documented for D. insignis; however, the life cycle has been studied only in laboratories, and only a single phylogenetic study has been conducted on D. insignis (from Canada). The goals of the present study were to investigate the prevalence of infections with Dracunculus species among wildlife at a single site (Di-Lane plantation) in the southeastern United States, evaluate the genetic diversity of parasites at this site, and investigate potential paratenic hosts that may be involved in transmission. Over 3 yr, we sampled 228 meso-mammals, reporting an overall prevalence of infection with Dracunculus insignis of 20% (46/228). Amphibians and fish were sampled in the same geographic area as infected meso-mammals. Dracunculus insignis third-stage larvae were recovered from 2 different species of amphibians, but all fish sampled were negative. Phylogenetic analysis of the partial cytochrome c oxidase I (COI) gene showed very little diversity of Dracunculus at Di-Lane; however, we did recover a single nematode from a Virginia opossum (Didelphis virginiana) that falls outside of the D. insignis clade, more closely aligns with Dracunculus lutrae, and may represent an undescribed species. This work documents the occurrence of D. insignis in frogs, a potential transmission pathway for D. insignis at a single geographic site in nature. When applied to the global Guinea Worm Eradication Program, and Chad, Africa, in particular, this work increases our knowledge of the potential role of aquatic animals in the transmission of Dracunculus species and informs on potential intervention strategies that may be applied to the eradication of Guinea worm in Africa.
... However, experiments suggest that washing may not always be the primary function of this behaviour. For example, Carib grackles seem to be moistening, rather than washing, their food (Morand-Ferron et al. 2004), while racoon ''washing'' may actually be a natural riverbank foraging technique, unrelated to cleaning (Lyall-Watson 1963). Unambiguous washing involves transporting food deliberately to a water source and a distinction between items that do and do not need cleaning (Kawai 1965;Visalberghi and Fragaszy 1990;Nakamichi et al. 1998;Allritz et al. 2013). ...
Article
Carrying food to water and either dunking or manipulating it before consumption has been observed in various taxa including birds, racoons and primates. Some animals seem to be simply moistening their food. However, true washing aims to remove unpleasant surface substrates such as grit and sand and requires a distinction between items that do and do not need cleaning as well as deliberate transportation of food to a water source. We provide the first evidence for food washing in suids, based on an incidental observation with follow-up experiments on European wild boar (Sus scrofa) kept at Basel Zoo, Switzerland. Here, all adult pigs and some juveniles of a newly formed group carried apple halves soiled with sand to the edge of a creek running through their enclosure where they put the fruits in the water and pushed them to and fro with their snouts before eating. Clean apple halves were never washed. This indicates that pigs can discriminate between soiled and unsoiled foods and that they are able to delay gratification for long enough to transport and wash the items. However, we were unable to ascertain to which degree individual and/or social learning brought this behaviour about.
... Although some influenza A viruses can replicate in the intestinal tissues of some mammal species [28], Hall and others [1] noted a very small quantity of viral RNA on a single rectal swab following experimental infections of raccoons with a human H3N2 influenza A virus. The frequency which raccoons ''wash'' their food is debatable [29], and some have argued that ''dousing'' may be a more appropriate term for this behavior [30]. In addition, differences in this type of behavior among captive versus wild-caught raccoons have been suggested [31]. ...
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Background Wild raccoons have been shown to be naturally exposed to avian influenza viruses (AIV). However, the mechanisms associated with these natural exposures are not well-understood. Methodology/Principal Findings We experimentally tested three alternative routes (water, eggs, and scavenged waterfowl carcasses) of AIV transmission that may explain how raccoons in the wild are exposed to AIV. Raccoons were exposed to 1) water and 2) eggs spiked with an AIV (H4N6), as well as 3) mallard carcasses experimentally inoculated with the same virus. Three of four raccoons exposed to the high dose water treatment yielded apparent nasal shedding of >102.0 PCR EID50 equivalent/mL. Little to no shedding was observed from the fecal route. The only animals yielding evidence of serologic activity during the study period were three animals associated with the high dose water treatment. Conclusions/Significance Overall, our results indicate that virus-laden water could provide a natural exposure route of AIV for raccoons and possibly other mammals associated with aquatic environments. However, this association appears to be related to AIV concentration in the water, which would constitute an infective dose. In addition, strong evidence of infection was only detected in three of four animals exposed to a high dose (e.g., 105.0 EID50/mL) of AIV in water. As such, water-borne transmission to raccoons may require repeated exposures to water with high concentrations of virus.
... They also douse nonfood items. 27 Similar to coatis, raccoons also carry out rolling behavior, although this is often performed in water. The rolling behavior seems to enable raccoons to feed on toxic amphibians irrespective of prey size, because it is sufficient to stimulate noxious and toxic secretions and Nutrition and Behavior of Coatis and Raccoons eventually reduces the amount of secretion by the prey item, thus limiting the prey's defensive capabilities. ...
Raccoons and coatis are inquisitive members of the Procyonidae family, commonly found in zoos, treated in wildlife rehabilitation centers, and increasing in popularity as pets. Compared with other carnivores, both species have unique adaptations and behaviors associated with their omnivorous lifestyles. It is therefore important for clinicians to have an appreciation of their natural history, diet, and behavior to aid in the formulation of captive diets and feeding strategies to mitigate potential nutritional or behavioral pathologies.
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Contrafreeloading is the choice to perform a physical task to access food over freely available food, a behavior pattern contrary to the predictions of both optimal foraging and learning theories. This study examined the presence and degree of contrafreeloading in Grey parrots (Psittacus erithacus) and the possible interpretation of such behavior in the context of play. Experiment 1 presented 4 subjects, Griffin, Athena, Franco and Pepper, with container pairs holding more- or less-preferred free or enclosed food items. Degrees of contrafreeloading were classified as follows: calculated contrafreeloading (working to access preferred food over less-preferred, freely available food); classic contrafreeloading (working to access food equal in value to freely available food); and super contrafreeloading (working to access a less-preferred food over preferred, freely available food). Of these three, Griffin significantly preferred classic and calculated contrafreeloading; Athena, Pepper, and Franco significantly preferred calculated contrafreeloading. Experiment 2 examined a more ecologically relevant contrafreeloading task in 5 parrots, Griffin, Athena, Lucci, Pepper, and Franco, using shelled and unshelled nuts. Athena and Franco significantly preferred cracking the shell to obtain the nut (contrafreeloading); Griffin and Lucci did not; Pepper chose at chance. We examine numerous possible explanations for their behavior and suggest that individual differences in contrafreeloading among the Grey parrots could relate to which task each considers some form of play. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
Article
Species that scavenge on dead animals are exposed to enhanced disease risks. Eight hypotheses have been suggested to explain how scavengers avoid becoming sick from their diet. We conducted a systematic review of the literature and found correlative support for four of the eight hypotheses but limited evidence of systematic studies of the hypotheses. We found no support that using urine to sterilize carcasses, having bald heads, eating rapidly, or food-washing behavior reduced disease risk in carrion eaters. With the exception of food washing, none of these hypotheses have been properly evaluated as an adaptation to avoid sickness from carrion. There is some support for having a specialized microbiome, having enhanced immunologic defenses, avoiding rotten food, and maintaining a low gastric pH to eliminate pathogens. Specialized immunologic defenses and having a low pH have the most support, but the diversity of mechanisms suggests that there is a great opportunity for even more detailed study. Increased knowledge in these mechanisms may provide biomimetic insights to help combat foodborne illnesses and enhance health.
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Introduction Methods Results Discussion Acknowledgments References
Article
Electrophysiological recordings were made at a large number of sites in the primary somatosensory cortex of six anesthetized raccoons. A high density of penetrations (110-229 per animal), within or near the representation of the fourth digit, allowed identification of three cortical regions with different physiological properties: a glabrous zone, containing a highly detailed, somatotopically ordered representation of the glabrous surface of the digit; rostral to this a claw-dominant zone, in which the neurons at most penetrations respond to stimulation of the claw of the fourth digit, but may also receive input from the hairy skin or surrounding glabrous skin; and a more rostral multidigit zone, in which the neurons respond to stimulation of two to five digits, with the dominant digit usually being the one represented caudally (i.e., the fourth digit at most of the sites sampled here). Claw-dominant zones with receptive fields restricted to digit three or five are also found rostral to the representations of the glabrous skin of the corresponding digit. The glabrous and claw-dominant zones constitute a complete map of the fourth digit. The multidigit region presumably is a separate map, since its neurons have different spatial convergence, higher thresholds, and a lower incidence of slowly adapting inputs than those in the claw-dominant and glabrous zones. A comparison between animals with lesions of the basal forebrain and intact animals found no differences in the organization of these zones or in the responses to peripheral input, suggesting that cholinergic inputs to the cortex are not essential to these properties. The detailed description of these regions and the proposed terminology should resolve some inconsistencies in the use of the term "heterogeneous zone" in this species.
Article
To determine the presence and organization of kinesthetic, as compared with other mechanosensory projection zones in the thalamus of raccoons, unit-cluster responses to mechanical stimulation of the postcranial body were mapped electrophysiologically in the thalami of 14 raccoons anesthetized with Dial-urethane. A distinct zone of kinesthetic projections (from receptive fields in muscles, tendons, and joints) was found in the rostral and dorsal aspects of the mechanosensory projection zone. These projections are somatotopically organized: those from axial structures lie dorsalmost and those from successively more distal limb regions are successively more caudoventral. The kinesthetic forelimb representation is large and lies rostrodorsal to a large central core of cutaneous projections from the forepaw digits. A few scattered kinesthetic projections were found at the caudal edge of the sensory thalamic region. The large, spatially and somatotopically distinct kinesthetic projection zone in the thalamus parallels those seen in the cortex and medulla of raccoons. Similar findings in monkeys, and suggestions from data in cats and humans support the hypothesis of a distinct pathway to the cortex for kinesthetic information in all mammals.
Article
The locations of the cells of origin of the spinocervical tract (SCT) and spinothalamic tract (STT) were examined in relation to the somatotopic and laminar organization of the cervical enlargement of the raccoon dorsal horn (DH). In different animals, either the lateral cervical nucleus or the lateral thalamus was injected with a 2% solution of wheat germ agglutinin-horseradish peroxidase (WGA-HRP). Following 24 h or 4 days, respectively, the animals were sacrificed and both injection and target sites (spinal cord segments C6-T2) were processed using the TMB method. All labelled cells were counted in every fifth 50 microns section. Following injection of WGA-HRP into the lateral cervical nucleus, all labelled SCT cells were located ipsilateral to the injection sites. Most (84%) were in laminae III and IV, laminae known from other studies to contain cells preferentially responsive to light tactile stimulation, with very few (3%) in lamina I. Nearly 50% of labelled cells were located in the medial 1/3 of the DH, the region of representation of the glabrous surfaces of the raccoon forepaw. The mean number of labelled SCT cells per section was 4.19. After tracer injections of the lateral thalamus, more than 75% of STT cells were located contralateral to the injection sites. Forty-three percent were located in lamina I and 24% were in lamina V, laminae whose cells have been shown to be responsive to more intense forms of stimulation, as well as to light touch. Only 22% were located in the medial 1/3 of the DH. The mean number of labelled STT cells per section was 0.83. The results suggest that the SCT may play a more critical role in relaying discriminative light tactile and nociceptive information from the glabrous surfaces of the forepaw, but that there may be a greater role for the STT in relaying nociceptive information from the forelimb as a whole.
Article
The evidence of this study shows that with increasing skin temperature, vibratory thresholds decrease to a minimum, at which point, with further heating, these thresholds rise. The function uniting temperature and vibratory sensitivity is similar to that linking temperature and pressure sensitivity, with the minimal thresholds falling at approximately the same point. With decreasing skin temperature vibratory thresholds show a continuous rise. The effects of warming and cooling the skin are shown to be not due to changes in skin conductivity or to the result of gross vascular action. There is no dependence of temperature function on stimulus frequency. A chemical theory is postulated to explain the results. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Observed the senses and instincts of the raccoon. It was found that the sense of touch was highly developed in the palm of the forepaw and the tip of the nose. This was found to be associated with the instinct of curiosity. They had a liking for sweets and avoided sour food. Hearing was the protective sense of the raccoon. The slightest sound produced immobility and fear. The impulse to suck was present at birth. In a young raccoon, a stage of creeping, characterized by widespread forelimbs and outstretched palms was observed. Climbing involved the sense of support, and was present before the raccoon possessed either the strength or the muscular co-ordination necessary for climbing. An inhibition of one instinct by another, was seen in the impulse to follow in the raccoons. Two characteristic positions of sleeping were observed in raccoons. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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