Scent Marking Research Articles

Group size and social status affect scent marking in dispersing female meerkats

Abstract Many animal species use scent marks such as feces, urine, and glandular secretions to find mates, advertise their reproductive status, and defend an exclusive territory. Scent marking may be particularly important during dispersal, when individuals emigrate from their natal territory searching for mates and a new territory to settle and reproduce. In this study, we investigated the scent-marking behavior of 30 dispersing female meerkats (Suricata suricatta) during the three consecutive stages of dispersal—emigration, transience, and settlement. We expected marking patterns to differ between dispersal stages, depending on social circumstances such as presence of unrelated mates and social status of the individuals within each dispersing coalition and also to be influenced by water and food availability. We showed that defecation probability increased with group size during the settlement stage, when newly formed groups are expected to signal their presence to other resident groups. Urination probability was higher in subordinate than in dominant individuals during each of the three dispersal stages and it decreased overall as the dispersal process progressed. Urine may, thus, be linked to advertisement of the social status within a coalition. Anal marking probability did not change across dispersal stages but increased with the presence of unrelated males and was higher in dominants than in subordinates. We did not detect any effect of rain or foraging success on defecation and urination probability. Our results suggest that feces, urine, and anal markings serve different communication purposes (e.g., within and between-group communication) during the dispersal process.

P-Mail: The Information Highway of Nocturnal, but Not Diurnal or Cathemeral, Strepsirrhines

Scent marking is a well-established, but highly variable, mode of communication among strepsirrhine primates. We begin by reviewing this literature, focusing on nocturnal species. Our understanding about the information content of scent signals and the factors driving species diversity remains incomplete, owing to difficulties in acquiring comparative chemical data. We therefore re-examine such a data set, representing the richness and relative abundance of volatile organic compounds (VOCs) in the urine of 12 species (from Galagidae, Lorisidae, Daubentoniidae, Cheirogaleidae, Indriidae, and Lemuridae), to explore differences between nocturnal, diurnal and cathemeral species. As predicted by the variable importance of urine marking across species, the urine of nocturnal strepsirrhines contained the most VOCs and putative semiochemicals, differed significantly in composition from that of diurnal and cathemeral species and showed the strongest species scent “signatures.” Relevant to retracing the evolutionary trajectory of cathemeral strepsirrhines, nocturnal and diurnal species were most differentiated in their VOCs, with cathemeral species being intermediary, but more closely aligned with diurnal species. These data support cathemerality as an ancient expansion of diurnal animals into a nocturnal niche. Consideration of the traits and variables associated with olfactory communication offers a profitable new way for examining species diversity and patterns of evolutionary change.

Cryptic Communication in a Montane Nocturnal Haplorhine, Tarsius pumilus

Crypsis, including visual and auditory concealment, usually manifests in primates as an antipredator strategy. Other factors may also influence cryptic communication style, including habitat structure and phylogenetic history. Compared to less cryptic lowland Sulawesian tarsiers, montane pygmy tarsiers (Tarsius pumilus) exhibit a communication style that lacks scent marks and lower-frequency vocalisations. This study examines why auditory crypsis occurs in montane tarsiers more so than in larger tarsier species and presents the only known spectrograms of T. pumilus in the field. T. pumilus regularly exhibited calls with a dominant frequency of 60–80 kHz (n = 4) in both social situations (duet calls) and stressed contexts. These results indicate that highland, smaller-bodied tarsiers habitually communicate at high frequencies in contexts where Sulawesian and Philippine tarsiers use lower frequencies. While predation threats and habitat acoustics may influence the use of high-frequency vocalisations, this study found that T. pumilus shows an expected relationship between vocal frequency and body mass. These traits may represent a retention of primitive haplorhine traits rather than derived adaptations to a montane environment.

Evolutionary patterns of major urinary protein scent signals in house mice and relatives.

Scent marks are important mediators of territorial behaviour and sexual selection, especially among mammals. The evolution of compounds used in scent marks has the potential to inform our understanding of signal evolution in relation to social and sexual selection. A major challenge in studies of chemical communication is that the link between semiochemical compounds and genetic changes is often unclear. The major urinary proteins (MUPs) of house mice provide information on sex, status and individual identity. Importantly, MUPs are a direct protein product of genes, providing a clear link between genotype and phenotype. Here, we examine the evolution of urinary protein signals among house mice and relatives by examining the sequences and patterns of mRNA expression of Mup genes related to urinary scent marks. MUP patterns have evolved among mouse species both by gene duplication and variation in expression. Notably, protein scent signals that are male specific in well-studied inbred laboratory strains vary in sex-specificity among species. Our data reveal that individual identity signals in MUPs evolved prior to 0.35million years ago and have rapidly diversified through recombining a modest number of amino acid variants. Amino acid variants are much more common on the exterior of the protein where they could interact with vomeronasal receptors, suggesting that chemosensory perception may have played a major role in shaping MUP diversity. These data highlight diverse processes and pressures shaping scent signals, and suggest new avenues for using wild mice to probe the evolution of signals and signal processing.

Behavioral Response of the Mammalian Community to River Otter Latrine Activity

Mammals commonly use latrines to communicate with each other via behaviors, such as scent marking and defecation. Olfactory cues resulting from these behaviors may influence the behavior of other species in and around latrines. The North American river otter (Lontra canadensis) is well known for its conspicuous use of latrines. We investigated whether latrine behavior of otters affected the behavior of other mammalian species. We used remote cameras to record activity patterns, visitation rates, and species richness at nine otter latrines located at five study sites across northern Indiana. We predicted the use of latrines by otters would result in the avoidance of latrines by other mammals in these riparian systems. Monthly mean species richness was lower at control sites than at latrine sites. Coyotes visited latrine sites more often than control sites, but all other species visited latrines and controls equally. Analysis of activity patterns revealed only white-tailed deer (Odocoileus virginiana) changed activity from primarily nocturnal at latrines to primarily diurnal activity at control sites. Our findings suggest otter latrine activity has minimal effect on the behavior of most other mammals. Therefore, surveying otter latrines with remote cameras may simultaneously provide unbiased estimates about the diversity of the riparian mammal community given mammals tended to visit latrine and control sites equally.

Ecological context influences scent‐marking behavior in the giant panda

AbstractSignal detection theory predicts that animals should select scent‐marking sites in a way that maximizes their probability of detection by target receivers. Many studies have been conducted with a focus on signaling behavior and function. Yet, the role of the environment in structuring scent‐mark patterns is poorly known. We studied the giant panda, a solitary species that relies heavily on chemosignaling for communication through depositing urine and anogential gland secretions (AGS) on trees, to determine how environmental factors influence scent deposition strategies. Using a combination of sign surveys, camera trapping, and gas chromatography mass spectrometry analysis, we conducted a comparative study of giant panda scent marking in two reserves, Wanglang and Foping, in China. The two reserves differed with regard to prevalence of tree species that differed in bark roughness, diameter at breast height (DBH), and moss status. For urine‐marking pandas selected large, mossy trees with very rough bark trees, whereas AGS marking was used preferentially on rough‐barked moss‐free trees in both reserves. Both AGS and urine contained more volatile than nonvolatile constituents and urine had higher relative abundance of volatiles than AGS, indicating urine likely has a larger signal range and shorter signal persistence than AGS. Urine marking was significantly more prevalent in Wanglang, which contains more rough‐barked, moss covered, and higher DBH trees favored for urine marking, than in Foping. Thus, habitat features appear to constrain pandas’ use of different types of marking, potentially altering how the communication system functions in different ecological contexts. Our study underscores the importance of future study evaluating environmental influences on chemosignaling behavior.

Encounters between pairs of unfamiliar dogs in a dog park

IntroductionThe aim of this study was to explore spontaneous social interactions between dyads of unfamiliar adult dogs. Although intraspecific encounters are frequent events in the life of pet dogs, the factors that might influence encounters, such as sex, dyad composition, reproductive status, age, and state of cohabitation (keeping the dogs singly or in groups), remained unexplored.MethodsIn this study, we assigned unfamiliar, non-aggressive dogs to three types of dyads defined by sex and size. We observed their unrestrained, spontaneous behaviors in an unfamiliar dog park, where only the two dogs, the owners, and experimenter were present.ResultsWe found that the dogs, on average, spent only 17% of the time (less than 1 min) in proximity. Sex, dyad composition, reproductive status, and age influenced different aspects of the interactions in dyads. Female dogs were more likely to initiate the first contact in their dyad but later approached the partner less frequently, were less likely to move apart, and displayed less scent marking. Following and moving apart were more frequent in male-male interactions. Neutered dogs spent more time following the other dog and sniffed other dogs more frequently. The time companion dogs spent in proximity and number of approaches decreased with age.ConclusionThe study provides guidance for dog owners about the outcomes of intraspecific encounters based on the dog’s age, sex, and reproductive status, as well as the sex of the interacting partner.

Do Red Foxes (Vulpes Vulpes) Increase the Detectability of Scent Marks by Selecting Highly Conspicuous Substrates

In mammals, especially those that are nocturnal or crepuscular, chemical marks usually play a significant role as environmental labels. Scent marks in mammals can have many functions, including territorial defense and communication signals in the mating season. Furthermore, animals can increase the detectability of marks by selecting highly conspicuous locations and substrates on which to mark, such as stones and sticks, on or around faeces, other animal carcasses, anthropogenic features, and plants. Human-carnivore interactions can result in a conflict where perceived damage to livelihoods occurs in socio-economically poor areas. In the Shigar Valley, Karakorum Range, Pakistan, subsistence mixed farming is the predominant land use and red foxes (Vulpes vulpes) are widely persecuted. Understanding the effects of human activity and habitat factors on fox behaviors in the region are lacking. We used line transect surveys aided by a domestic dog (Canis familiaris) to detect fox faeces locations and characterize fox den form 2015-16-17. We encountered 467 fox scats by dog assistance. We tested for associations between scent deposition, and environmental variables including vegetation and substrate type, distribution of livestock carcasses and dung, roads and agricultural land at micro-habitat. We found more fox scats on aromatic plants, shrubs, and on or near livestock feaces and carcasses. Fox scent marking site selection varied for forested and shrub areas relative to open grassland or barren ground and vegetation cover and tree density at the microhabitat scale. The findings suggest that foxes do not avoid human activity per se and anthropogenic benefits (road kill, livestock carrion, crop food sources) may outweigh the costs of persecution. Foxes may also provide ecosystem benefits via seed dispersal, carrion removal and regulation of prey populations.

GRAPHICAL REPRESENTATION IN THE FORM OF LABEL MEREK/MARK ETIQUETTE IN RELATION WITH NON-CONVENTIONAL TRADEMARKS REGISTRATION IN INDONESIA

Legal development introduces the new type of trademarks differ to those of the conventional ones. This paper gives an account of non-conventional trademarks categories, particularly sound, scent and taste mark, in terms of their registration. Subsequently, it also further illustrates that graphical representation, as a prerequisite, stifles the registration of non-conventional trademarks through recent studies and cases both in the European Union and United States. European Union, under Trademark Directive 2008, required graphical representation as a requirement which turned out to be the primary problem in terms of registration for non-conventional trademarks. United States, having no such requirement, tend to be more acceptable in registering non-conventional trademarks. This paper also argues that graphical representation is immaterial and its removal from the relevant provision increases the legal certainty and flexibility. Problem of non-conventional trademarks registration incurred by graphical representation requirement is most likely to be faced by Indonesia which tries to encompass the protection of non-conventional trademarks. Indonesian Trademark Law requires Label Merek (a representation form), which in common practice is seen merely as representation form that consists of lines, images and character (graphically represented form), as a minimum requirement for trademark registration. Seeing Label Merek merely as a graphical represented form will stifle the registration of non-conventional trademarks. Therefore, such representation form needs to be construed broadly beyond graphically represented form in order to encompass the protection of non-conventional trademarks.

The functional role of scent marking in the social organization of large sympatric neotropical felids

Communication is an integral part of animal behavior, impacting population structure and individual fitness and regulating spatial distributions. Scent marking is common among solitary, low-density, and wide-ranging carnivores, such as felids. Understanding the functional role of scent marking will inform our understanding of the behavioral ecology of carnivores. We investigated patterns of scent marking by pumas (Puma concolor) and jaguars (Panthera onca) via weekly surveys of trails for scrapes and documenting scent-marking behaviors and responses using motion-triggered video cameras. Jaguars mainly sprayed vegetation, whereas pumas mainly scraped the ground. Only a subset of individuals for both pumas and jaguars were responsible for the majority of scent-marking activity. On average, male pumas scraped more frequently (scrapes/km) than male jaguars, and the scrape rate of male pumas increased following the presence of potential mates and competitors. Male pumas returned to trails more quickly following the presence of conspecifics (potential competitors or mates) than in their absence, however, visitation by male jaguars increased in response to competitors only. A male puma detected travelling with three different females on separate occasions scraped more frequently than males who were not detected with females. This study suggests that jaguars and pumas are constantly assessing, and reacting to, the presence and marks of competitors and potential mates, facilitating the maintenance of complex social structures. La comunicación es una parte integral del comportamiento animal; la cual impacta la estructura de la población, la aptitud de adaptación individual y regula la distribución espacial. La marcación olfativa es común entre los carnívoros solitarios, de baja densidad y amplia distribución, como los felinos. El entender el papel funcional de la marcación con olores, informa nuestra comprensión de la ecología del comportamiento de los carnívoros. Investigamos los patrones de marcación de olor por pumas (Puma concolor) y jaguares (Panthera onca) a través de muestreos semanales de senderos con rastros de rasguños, documentando los comportamientos y respuestas de marcación de olor utilizando cámaras de video activadas por movimiento. Los jaguares rociaban principalmente la vegetación, mientras que los pumas predominantemente hicieron rasguños en el suelo. Solo un subconjunto de individuos, tanto de pumas como de jaguares, fueron responsables de la mayoría de la actividad de marcación de olores. En promedio, los pumas machos rasguñaron con mayor frecuencia (rasguños /km) que los jaguares machos, y la tasa de rasguñar se incrementó luego de la presencia de parejas potenciales y de competidores. Los pumas machos regresaron a los senderos más rápidamente siguiendo la presencia de con-específicos (potenciales parejas o competidores) que en su ausencia; sin embargo, la visita de jaguares machos se incrementó sólo en respuesta a los competidores. Un puma macho que se detectó viajando con tres hembras diferentes en distintas ocasiones, rasguñaba con mayor frecuencia que los machos que no fueron detectados con hembras. Este estudio sugiere que jaguares y pumas, constantemente están evaluando y reaccionando, a la presencia y las marcas de las potenciales parejas y competidores, facilitando el mantenimiento de estructuras sociales complejas.

Using GPS collars to investigate the frequency and behavioural outcomes of intraspecific interactions among carnivores: A case study of male cheetahs in the Maasai Mara, Kenya.

Intraspecific interactions between individuals or groups of individuals of the same species are an important component of population dynamics. Interactions can be static, such as spatial overlap, or dynamic based on the interactions of movements, and can be mediated through communication, such as the deployment of scent marks. Interactions and their behavioural outcomes can be difficult to determine, especially for species that live at low densities. With the use of GPS collars we quantify both static and dynamic interactions between male cheetahs (Acinonyx jubatus) and the behavioural outcomes. The 99% home-ranges of males overlapped significantly while there was little overlap of the 50% home-ranges. Despite this overlap, male cheetahs rarely came into close proximity of one another, possibly because presence was communicated through frequent visits to marking posts. The minimum distance between individuals in a dyad ranged from 89m to 196m but the average proximity between individuals ranged from 17,145 ± 6,865m to 26,367 ± 11,288m. Possible interactions took place more frequently at night than by day and occurred mostly in the 50% home-range of one individual of a dyad or where cores of both individuals overlapped. After a possible encounter male cheetahs stayed in close proximity to each other for up to 6 hours, which could be the result of a territory defence strategy or the presence of a receptive female. We believe that one of the encounters between a singleton and a 5-male coalition resulted in the death of the singleton. Our results give new insights into cheetah interactions, which could help our understanding of ecological processes such as disease transmission.

Song structure and sex-specific features in the indris

In the dense tropical rainforests of Madagascar, visual communication is impeded by obstacles. Lemurs use scent marking to communicate at a short distance and loud calls to communicate at a long range. The Indri (Indri indri) is a diurnal primate that emits choruses of three distinct types. The song types are essential in advertising position within the group territory, in deciding the sorts of aggressive group encounters, and in maintaining cohesion between animals dispersed during feeding. A detailed examination of the advertisement songs showed that three main parts constitute them. The last, most consistent of these parts, showed phrases consisting of units emitted with a descending frequency. The rhythm of these units changed significantly between phrases of different durations and the sexes. We also found that the unit structure may provide conspecifics with information on the individual identity of the emitter and that male songs, but not female’s, are more similar to those of their parent of the same sex than to other indris. The song of the indris is an effective way to transfer information at a long distance and may transmit sex and individual identity information.In the dense tropical rainforests of Madagascar, visual communication is impeded by obstacles. Lemurs use scent marking to communicate at a short distance and loud calls to communicate at a long range. The Indri (Indri indri) is a diurnal primate that emits choruses of three distinct types. The song types are essential in advertising position within the group territory, in deciding the sorts of aggressive group encounters, and in maintaining cohesion between animals dispersed during feeding. A detailed examination of the advertisement songs showed that three main parts constitute them. The last, most consistent of these parts, showed phrases consisting of units emitted with a descending frequency. The rhythm of these units changed significantly between phrases of different durations and the sexes. We also found that the unit structure may provide conspecifics with information on the individual identity of the emitter and that male songs, but not female’s, are more similar to those of their parent of the s...

Common feline problem behaviors: Urine spraying

Urine spraying (synonymous terms include urine marking or scent marking) is commonly described as urine deposited on vertical surfaces while the cat is in a standing position. With the increasing trend of keeping cats indoors in some countries and the potential resultant increase in frustration-related behaviors, urine spraying may occur in the home. Although also a normal feline behavior, it is usually not deemed acceptable when the cat targets household possessions. Urine spraying is a common behavioral complaint that practitioners receive from cat owners and has the potential to disrupt the human-cat bond. In fact, feline elimination issues are a frequent reason cited by owners when they relinquish their cats to shelters and rescue organizations. While the location of the deposited urine should be diagnostic, this is not always the case. Urine marking can occur on horizontal surfaces, thus complicating the diagnosis. Urine spraying by intact males and females is used to signal availability for mating but the behaviour can also be exhibited by neutered animals. Multiple factors including medical problems can trigger the onset and maintenance of urine spraying, and correct identification of these is necessary for treatment to be most successful. This review draws on information from multiple studies that have been published on the normal aspects of urine spraying in cats, the frequency as reported by owners, the relationship of urine spraying to intercat aggression and various treatment options including behavior modification, pheromone therapy and use of psychoactive medication.

Scent marks of rodents can provide information to conspecifics.

For a scent mark to be informative it must provide a reliable, honest signal that allows individuals that detect it to predict fitness tradeoffs if they choose or not choose to respond to it. I argue that scent marks provide a great deal of information about the sender to receivers. The manner in which an animal uses this information to make decisions will depend on the context and manner in which it encounters these scent marks. Receivers can use the information found in the scent marks and odors to locate the donor, learn its identity, determine the donor's phenotype or genotype, and assess whether the scent marks were encountered earlier by conspecifics. For receivers to make potentially informed decisions, when they encounter the scent marks of conspecifics with whom they have had different experiences across a variety of contexts higher level cognitive processing involving procedural memory, episodic memory, autobiographical memory and making judgements of numerical discrimination would be required. Senders should have some insight into the receivers to increase the likelihood that the targets respond appropriately to the scent mark by reducing uncertainty. The sender's state or the current state of the environment and the context will affect when and where the scent marks were deposited. Decisions to deposit scent marks and respond to them must represent a tradeoff in the benefits and costs to the sender and receivers in terms of their fitness and survival. The actual tradeoff should be context dependent and reflect the experience, physiology, and life history constraints affecting the receiver. Calculating these tradeoffs likely involves some cognitive processing and requires some sort of information transfer between the sender and the receiver.

Test of four hypotheses to explain the function of overmarking in foals of four equid species.

Overmarking occurs when one individual places its scent mark directly on top of the scent mark of another individual. Although it is almost ubiquitous among terrestrial mammals, we know little about the function of overmarking. In addition, almost all studies on mammalian overmarking behaviour dealt with adult individuals. Reports on this behaviour in juveniles are extremely rare, yet may elucidate the function of this behaviour. We tested four mutually non-exclusive hypotheses which might explain this behaviour in juveniles: (1) conceal the individual's scent identity, (2) announcement of association with other group members, especially the mother-i.e., sharing identity with the mother, (3) to prevent the next conception of the mother, i.e., parent-offspring conflict, and (4) an early expression of male sexual behaviour. We observed 43 foals (out of 108 individuals) from all African equid species (Equus africanus, E. grevyi, E. quagga, E. zebra) in five zoos. In total, we recorded 3340 eliminations; 260 of these events were overmarked by 38 individual foals representing all species. This represents one of the highest rates of overmarking ever recorded by mammalian juveniles. Foals of all species except African wild ass overmarked the mother more often than another herdmate: with male foals overmarked at a higher rate than female foals. Mothers preferred to overmark foals, but not exclusively their own foal. Our results provide support for the hypotheses that overmarking serves to share identity between foal and mother, and that it is an early expression of male sexual behaviour.

Prey density determines the faecal-marking behaviour of a solitary predator, the Iberian lynx (Lynx pardinus)

Scent-marking is a common behaviour among mammals with different functions including territory marking. However, this behaviour has high energy costs and thus a territory owner must select the most strategic sites to place its scent marks. We hypothesised that the scent-marking behaviour of the Iberian lynx (Lynx pardinus), an endangered feline and a food specialist, is positively related to the abundance and distribution of its main prey, the European wild rabbit (Oryctolagus cuniculus). We predicted that the distribution of rabbits as a staple food resource could determine the patterns of scent-marking by the lynx using communication signals. We selected two areas of Sierra Morena (Andalucia, Spain) with different densities of rabbits. The most intensively used faecal-marking locations by the lynx were those of a high rabbit density (Χ2 = 16.54, df = 1, P < 0.0001). Conversely, the lynx marked in other locations not associated with rabbit presence such as crossroads and sheltered locations dominated by shrubs and rocks wherever the rabbit was not a limiting resource and was distributed homogeneously. This behaviour suggests scent-marking might have other alternative functions such as increasing the likelihood of detection or marking key resources.

Communal breeding affects offspring behaviours associated with a competitive social environment

Communal breeding is characterised by shared care of offspring produced by more than one female, and can affect the behavioural development of young. The decision to care communally can vary according to local conditions, and has been hypothesised to occur more frequently when social competition is intense. However, it is unknown whether communal rearing of young influences adult behaviours likely to be adaptive under competitive conditions. Here, using a controlled experimental approach, we investigate effects of communal rearing on competitive and exploratory behaviours of adult male house mice. In tests of competitive scent marking, only communally-reared subjects discriminated between related and unrelated rivals, depositing more scent marks in close proximity to unrelated males. Communally-reared subjects also displayed higher exploratory tendencies, with an increased probability of crossing a water barrier, while not exhibiting higher activity levels in an open field test. Since exploration tendencies and discrimination between kin and non-kin are likely to be advantageous when dispersing from the natal territory or in a high density population, our findings suggest that communal rearing prepares male house mice for a competitive social environment. Our results add to growing evidence that the early social environment influences development of important behavioural competences to cope with social challenges later in life.

Scent-marking behavior of the southern giant pouched rat (Cricetomys ansorgei)

Southern giant pouched rats (Cricetomys spp.) are large rodents in the family Nesomyidae, native to sub-Saharan Africa, that are best known for their olfactory abilities. In fact, because of their acute olfactory abilities, they are used to detect explosives such as landmines. Understanding the natural scent-marking behaviors of animals in this family seems particularly relevant considering the olfactory nature of biodetection and the importance of olfactory communication among rodents in general. For many rodent species, individuals use scent marking to communicate social information to conspecifics. Countermarking (i.e., depositing scent marks either on top of or adjacent to preexisting scent marks of conspecifics) is a primary way rodents communicate information to conspecifics, and countermarks can serve as both intra- and intersexual signals. We presented male southern giant pouched rats (Cricetomys ansorgei) with male urine marks in novel and familiar environments to determine how and where these animals might countermark. A subset of male pouched rats used urine, anogenital, or cheek rubbing to mark adjacent to the preexisting mark in the novel environment only. No males marked in a familiar environment. We suggest that males countermark adjacent to existing marks in novel environments to advertise individual identity to conspecifics while preserving the identity of others.

Persistent inflammatory pain alters sexually-motivated behavior in male rats

Urine from pro-œstrus female rodents evokes increased levels of sexually-motivated behaviors in males, including sniffing and scent marking of the urine spot as well as activation of brain reward regions. Stressors such as social defeat can adversely impact urine scent marking behavior in male rodents, an effect that can be mitigated with anti-depressant drugs. Persistent pain is also known to be a potent stressor, producing elevated levels of plasma corticosterone as well as reduced sucrose preference and reduced social interaction. However, the effect of persistent pain on sexually-motivated behavior is unknown. Here, we compared urine scent marking behavior in male rats for up to 3 weeks following intra-articular injection of Complete Freund’s Adjuvant (CFA) or sham injection. CFA-injected rats exhibited profound and ongoing deficits in static weight bearing capacity. CFA-induced persistent inflammatory pain increased plasma corticosterone levels and reduced urine scent marking behavior in male rats. Moreover, while the vast majority of injured rats showed decreased urine scent marking preference for the pro-œstrus female urine spot, male rats with higher baseline scent marking preference also exhibited higher post-injury scent marking preference, more sniffing behavior and lower levels of plasma corticosterone, compared to those with lower baseline scent marking preference. Overall, scent marking behavior may be an ethologically relevant behavioral predictor of persistent pain-induced stress in rats, representing a novel translational approach to understanding chronic pain comorbidities.

Urine marking in male domestic dogs: honest or dishonest?

AbstractScent marking is a common mode of communication in mammals. Such marking is thought to communicate information about the signaler's size and corresponding competitive ability and accurately reflect the signaler's attributes (i.e., an honest signal). However, new data suggest that scent marking can be dishonest in certain circumstances. Via two studies, we tested the hypothesis that urine marking is a dishonest signal in adult male domestic dogs, which raise a hindlimb when marking vertical objects. In Study 1, we tested whether raised‐leg angle (i.e., during a urination, the angle between a dog's raised leg and the axis normal to the ground) is a proxy for urine mark height (n = 15 dogs) and, in Study 2, we tested whether small dogs exhibit larger raised‐leg angles than large dogs (n = 45 dogs). We videotaped urinations of adult male dogs and, afterwards, measured height of urine marks (Study 1) and degree of raised‐leg angles (Studies 1 and 2). In Study 1, we found significant positive relationships between both raised‐leg angle and height of urine mark and body size (using either body mass or height at withers) and height of urine mark; raised‐leg angle was a stronger predictor than either measure of body size. In Study 2, we found a significant negative relationship between body size (using either body mass or height at withers) and average raised‐leg angle. Our findings support raised‐leg angle as a proxy for urine mark height and provide additional evidence that scent marking can be dishonest. Assuming body size is a proxy for competitive ability, small adult male dogs may place urine marks higher, relative to their own body size, than larger adult male dogs to exaggerate their competitive ability. We did not control for over marking, which also may explain our findings.