Fox Urine Research Articles

Erysipelothrix anatis sp. nov., Erysipelothrix aquatica sp. nov. and Erysipelothrix urinaevulpis sp. nov., three novel species of the genus, and emended description of Erysipelothrix.

Seven genotypically distinct strains assigned to the genus Erysipelothrix were isolated in different laboratories from several animal sources. Strain D17_0559-3-2-1T and three further strains were isolated from samples of duck, pig and goose. The strains had >99 % 16S rRNA gene sequence similarity to each other and to strain VA92-K48T and two further strains isolated from samples of medical leech and a turtle. The closest related type strains to the seven strains were those of Erysipelothrix inopinata (96.74 %) and Erysipelothrix rhusiopathiae (95.93 %). Average nucleotide identity, amino acid identity and in silico DNA-DNA hybridization results showed that the strains represented two separate novel species. One further phylogenetically distinct strain (165301687T) was isolated from fox urine. The strain had highest 16S rRNA gene sequence similarity to the type strains of Erysipelothrix tonsillarum (95.67 %), followed by Erysipelothrix piscisicarius (95.58 %) and Erysipelothrix larvae (94.22 %) and represented a further novel species. Chemotaxonomic and physiological data of the novel strains were assessed, but failed to unequivocally differentiate the novel species from existing members of the genus. MALDI-TOF MS data proved the discrimination of at least strain 165301687T from all currently described species. Based on the presented phylogenomic and physiological data, we propose three novel species, Erysipelothrix anatis sp. nov. with strain D17_0559-3-2-1T (=DSM 111258T= CIP 111884T=CCM 9044T) as type strain, Erysipelothrix aquatica sp. nov. with strain VA92-K48T (=DSM 106012T=LMG 30351T=CIP 111492T) as type strain and Erysipelothrix urinaevulpis sp. nov. with strain 165301687T (=DSM 106013T= LMG 30352T= CIP 111494T) as type strain.

Novel Hendra Virus Variant Circulating in Black Flying Foxes and Grey-Headed Flying Foxes, Australia

A novel Hendra virus variant, genotype 2, was recently discovered in a horse that died after acute illness and in Pteropus flying fox tissues in Australia. We detected the variant in flying fox urine, the pathway relevant for spillover, supporting an expanded geographic range of Hendra virus risk to horses and humans.

Livestock guardian dog protection of free-range poultry from the red fox

Context Predation of layer chickens is a major issue for free-range egg producers. Using livestock guardian dogs (LGD) to protect free-ranging poultry is a possible option for producers, although there is little published literature regarding how the dogs protect chickens. Aims This case study was conducted at a free-range egg production farm in Western Australia, where red foxes (Vulpes vulpes) were a common predator of chickens prior to introducing Maremma LGD. We investigated LGD responses to experimental cues that might indicate fox incursion (fox urine and calls). Methods Four dogs were GPS tracked and monitored using camera traps. Over the first week, experimental fox cues were set out around the paddock boundaries, alternating with ‘non-cue’ experimental control nights. We recorded whether the LGD altered (1) their space use, (2) activity patterns (movement speed), or (3) behaviour in response to these cues. We also recorded (4) distances between LGD from known sightings of foxes. Key results The Maremmas appeared to work independently of each other, covering separate areas. There was no significant difference in overnight home range area by experimental fox cue treatment, but there was a significant (P < 0.001) treatment × dog interaction term for distance moved. Three dogs spent most of their time at night around the chicken shelters and generally increased distances moved on experimental fox cue nights. The fourth dog was more bonded to people and did not alter its movements. Paradoxically, dogs rested more and barked less on experimental fox cue nights; however, we recorded foxes on camera traps placed around the chicken shelters on 17 of the 23 nights of monitoring, and the high background activity level of foxes on this property compromised our experimental control (nights without experimental fox cues). The dogs did not move towards known fox sightings. Conclusions The Maremmas in this trial closely guarded the chicken shelters rather than maintaining the entire paddock as a predator-exclusion zone. Implications Understanding how guardian dogs behave when challenged by potential predators will help increase producers’ confidence in the efficacy of these dogs as a viable method to protect livestock from predation threat.

Volatile scent chemicals in the urine of the red fox, Vulpes vulpes

The red fox is a highly adaptable mammal that has established itself world-wide in many different environments. Contributing to its success is a social structure based on chemical signalling between individuals. Urine scent marking behaviour has long been known in foxes, but there has not been a recent study of the chemical composition of fox urine. We have used solid-phase microextraction and gas chromatography-mass spectrometry to analyze the urinary volatiles in 15 free-ranging wild foxes (2 female) living in farmlands and bush in Victoria, Australia. Foxes here are routinely culled as feral pests, and the urine was collected by bladder puncture soon after death. Compounds were identified from their mass spectra and Kovats retention indices. There were 53 possible endogenous scent compounds, 10 plant-derived compounds and 5 anthropogenic xenobiotics. Among the plant chemicals were several aromatic apocarotenoids previously found in greater abundance in the fox tail gland. They reflect the dietary consumption of carotenoids, essential for optimal health. One third of all the endogenous volatiles were sulfur compounds, a highly odiferous group which included thiols, methylsulfides and polysulfides. Five of the sulfur compounds (3-isopentenyl thiol, 1- and 2-phenylethyl methyl sulfide, octanethiol and benzyl methyl sulfide) have only been found in foxes, and four others (isopentyl methyl sulfide, 3-isopentenyl methyl sulfide, and 1- and 2-phenylethane thiol) only in some canid, mink and skunk species. This indicates that they are not normal mammalian metabolites and have evolved to serve a specific role. This role is for defence in musteloids and most likely for chemical communication in canids. The total production of sulfur compounds varied greatly between foxes (median 1.2, range 0.4-32.3 μg 'acetophenone equivalents'/mg creatinine) as did the relative abundance of different chemical types. The urinary scent chemistry may represent a highly evolved system of semiochemicals for communication between foxes.

Physiological response to the odorant TMT in fully fed and calorically restricted laboratory mice.

2,3,5-trimethyl-3-thiazoline (TMT) is a chemical compound that is extracted from red fox urine and can be used to artificially simulate the presence of a predator. The purpose of this study was to test the hypothesis that TMT would block entry into torpor in the calorically restricted C57Bl/6 mouse. We first demonstrated that TMT induced fear in the mouse. Exposure to TMT induced an acute freeze response (67.2±6.7% of time), as compared to 6.7±1.7% when exposed to water. Further, exposure to TMT for 30min led to elevated circulating corticosterone levels, 377±33ng/ml, as compared to 29±4ng/ml when exposed to water. When mice were exposed to TMT during the dark or light phase, body temperature (Tb) dropped by 1.7±0.9°C and 0.7±1.1°C, respectively, over the first 110min after exposure. To determine whether TMT influences daily torpor, mice were calorically restricted and exposed to either water or TMT. Mice were exposed 30min before the start of torpor, determined by the bout of the previous day. Exposure to TMT significantly (p<0.01) blunted the fall in the minimum Tb from 28.8±0.3°C (water) to 30.1±0.6°C (TMT) and significantly (p<0.05) decreased the amount of time Tb was under 32°C, from 431±48min (water) to 292±78min (TMT). These results establish that mice perceived the scent of TMT as a physiologically stressful stimulus and that Tb response is modestly blunted in the presence of that stressor. Our experiment highlights the intricate interplay between predation risk and energy conservation.

Spillover of bat borne Rubulavirus in Australian horses – Horses as sentinels for emerging infectious diseases

Background: Over 1000 horses are investigated annually for Hendra virus (HeV)-like illness, of which very few (<1%) test HeV positive. In Australia, in addition to HeV, other zoonotic viruses have affected horses including Australian bat lyssavirus, West Nile Virus (Kunjin), Murray Valley encephalitis virus and Ross River virus. In 1997, Menangle virus (MenPV), family Paramyxovirus, genus Rubulavirus, caused severe reproductive failure in pigs and influenza-like illness with rash in two piggery staff. MenPV has been isolated from Australian flying fox urine along with novel related rubulaviruses and HeV. We describe evidence of natural exposure to bat-borne rubulaviruses in Australian horses as well as seroconversion suggesting causality of severe respiratory illness. Methods and materials: Three-hundred-and-seventy-four horses were tested by a multiplex microsphere-based immunoassay (MIA) for IgG against MenPV nucleocapsid (N) protein and a subset also against Tioman virus (TioPV) N protein and MenPV hemagglutinin-neuraminidase (HN) protein. Confirmatory testing comprised immunofluorescence assay (IFA) on Vero cells infected with MenPV and related rubulaviruses. Results: Median fluorescence intensities (MFI) against MenPV N and a prior prevalence estimate of 20% were used in a Bayesian latent class model to determine appropriate cut-offs for positive test classification. Assay sensitivity was estimated assuming a specificity of both 95% and 99%. MFI reflecting potentially significant IgG to MenPV N protein was demonstrated in 34% (94/274) of horses with high perceived flying fox exposure (29% in QLD and 32% in NSW) whereas horses without plausible exposure recorded insignificant MFI. IFA confirmed antibodies to three of five related flying fox rubulaviruses tested (MenPV, Yeppoon virus and Grove virus). Case presentations: Two young-adult geldings developed severe acute respiratory illness in 2016 featuring obtunded demeanour, tachypnoea, tachycardia, congested/ hyperaemic mucous membranes, pyrexia and serous nasal discharge. Convalescent sera revealed a greater-than 10-fold increase in MFI to MenPV N (965 to 12,886). IFA confirmed antibodies to MenPV present in convalescent sera only. Conclusion: We highlight the potential of optimised syndromic surveillance for emerging zoonoses and One Health benefit of horses as sentinels of emerging infectious disease. Future research should determine the significance of rubulavirus spillover to horses and any associated human health risks.

Spillover of bat borne rubulavirus in Australian horses – Horses as sentinels for emerging infectious diseases

Background: Over 1000 horses are investigated annually for Hendra virus (HeV)-like illness, of which very few (<1%) test HeV positive. In Australia, in addition to HeV, other zoonotic viruses have affected horses including Australian bat lyssavirus, West Nile Virus (Kunjin), Murray Valley encephalitis virus and Ross River virus. In 1997, Menangle virus (MenPV), family Paramyxovirus, genus Rubulavirus, caused severe reproductive failure in pigs and influenza-like illness with rash in two piggery staff. MenPV has been isolated from Australian flying fox urine along with novel related rubulaviruses and HeV. We describe evidence of natural exposure to bat-borne rubulaviruses in Australian horses as well as seroconversion suggesting causality of severe respiratory illness. Methods and materials: Three-hundred-and-seventy-four horses were tested by a multiplex microsphere-based immunoassay (MIA) for IgG against MenPV nucleocapsid (N) protein and a subset also against Tioman virus (TioPV) N protein and MenPV hemagglutinin-neuraminidase (HN) protein. Confirmatory testing comprised immunofluorescence assay (IFA) on Vero cells infected with MenPV and related rubulaviruses. Results: Median fluorescence intensities (MFI) against MenPV N and a prior prevalence estimate of 20% were used in a Bayesian latent class model to determine appropriate cut-offs for positive test classification. Assay sensitivity was estimated assuming a specificity of both 95% and 99%. MFI reflecting potentially significant IgG to MenPV N protein was demonstrated in 34% (94/274) of horses with high perceived flying fox exposure (29% in QLD and 32% in NSW) whereas horses without plausible exposure recorded insignificant MFI. IFA confirmed antibodies to three of five related flying fox rubulaviruses tested (MenPV, Yeppoon virus and Grove virus). Case presentations: Two young-adult geldings developed severe acute respiratory illness in 2016 featuring obtunded demeanour, tachypnoea, tachycardia, congested/ hyperaemic mucous membranes, pyrexia and serous nasal discharge. Convalescent sera revealed a greater-than 10-fold increase in MFI to MenPV N (965 to 12,886). IFA confirmed antibodies to MenPV present in convalescent sera only. Conclusion: We highlight the potential of optimised syndromic surveillance for emerging zoonoses and One Health benefit of horses as sentinels of emerging infectious disease. Future research should determine the significance of rubulavirus spillover to horses and any associated human health risks.

Motivational factors underlying aversive Pavlovian-instrumental transfer.

While interest in active avoidance has recently been resurgent, many concerns relating to the nature of this form of learning remain unresolved. By separating stimulus and response acquisition, aversive Pavlovian-instrumental transfer can be used to measure the effect of avoidance learning on threat processing with more control than typical avoidance procedures. However, the motivational substrates that contribute to the aversive transfer effect have not been thoroughly examined. In three studies using rodents, the impact of a variety of aversive signals on shock-avoidance responding (i.e., two-way shuttling) was evaluated. Fox urine, as well as a tone paired with the delivery of the predator odor were insufficient modulatory stimuli for the avoidance response. Similarly, a signal for the absence of food did not generate appropriate aversive motivation to enhance shuttling. Only conditioned Pavlovian stimuli that had been paired with unconditioned threats were capable of augmenting shock-avoidance responding. This was true whether the signaled outcome was the same (e.g., shock) or different (e.g., klaxon) from the avoidance outcome (i.e., shock). These findings help to characterize the aversive transfer effect and provide a more thorough analysis of its generalization to warning signals for different kinds of threats. This feature of aversive motivation has not been demonstrated using conventional avoidance procedures and could be potentially useful for applying avoidance in treatment settings.

The effects of red fox scent on winter activity patterns of suburban wildlife: evaluating predator-prey interactions and the importance of groundhog burrows in promoting biodiversity

During winter, prey species in suburban areas of the northeastern United States must consider trade-offs in maximizing survival while they are simultaneously constrained by predators and climatic conditions associated with winter such as snow and low temperatures. Many mammalian prey mitigate the physiological stress from the cold by taking refuge in burrows. Some have also developed olfactory sensitivity to predator scent cues as they attempt to avoid predation in the landscape of fear and co-evolutionary arms race between predators and prey. The Eastern cottontail (Sylvilagus floridanus) is one of these species that both uses burrows in winter and is sensitive to scents. However, despite the importance of cottontails in the diet of Red foxes (Vulpes vulpes), one of their major predators, little is known about scent cues that cottontails use to detect foxes. Eastern cottontails and other suburban wildlife that occupied burrows dug by Groundhogs near Ithaca, New York, USA were exposed to scent wicks treated with Red fox urine during the winter of 2017–2018 to determine if the frequency of burrow use would decrease because of a perceived heightened risk of predation. We observed no response to the predator odor by cottontails and the other burrow-utilizing species. This lack of a behavioral response by prey may be due to the attenuation of fear in suburban environments. A surprising variety of mammalian and avian taxa (n = 22) were recorded at burrows, including Striped skunks, mice, Domestic cats, Virginia opossums, Bobcats, White-tailed deer, Weasels, a Coyote, and a Gray fox. Surprisingly we did not observe a single Red fox, for whom intraspecific scent cues are also important. We also documented daily patterns of activity around burrows of the five most commonly observed taxa. Our investigation reveals that Groundhogs are notable ecosystem engineers whose burrows function as important landscape features and local hotspots of biodiversity during the winter in a suburban ecosystem.

Isoflurane and Carbon Dioxide Elicit Similar Behavioral Responses in Rats.

Euthanasia in rodents is an ongoing topic of debate due to concerns regarding the aversive nature of gases with anesthetic properties such as carbon dioxide (CO2) and isoflurane. The aim of this study was to expand upon previously published work evaluating the aversiveness of CO2 by introducing an isoflurane treatment group in parallel. Aversion was tested using a forced exposure setup and an aversion-avoidance setup. In the first part of the study, 12 naïve female Sprague-Dawley rats were exposed during four consecutive days, once to each of four treatments: isoflurane, fox urine, oxygen, and CO2. In the second part of the study, 24 naïve female Sprague-Dawley rats and 12 rats from the first experiment were exposed to CO2, isoflurane, or both gases. In the forced exposure study, there were no significant differences between CO2 and isoflurane treatments except in line crosses. Overall, rats were more active in the isoflurane and CO2 treatments compared to the control groups, suggesting that isoflurane and CO2 are similarly aversive. In the aversion-avoidance study, rats previously exposed to isoflurane left the dark chamber significantly earlier compared to naïve rats during exposure to isoflurane. We also show that learned aversion to isoflurane is sustained for at least 15 days after initial exposure. Given this result, we suggest that CO2 is superior to isoflurane when euthanizing rodents with prior exposure to isoflurane. Overall, these results confirm previous studies which suggest that care should be taken when considering the serial use of isoflurane as an anesthetic.

Exposure of Mice to the Scent of a Predator Blunts, but Does Not Block Torpor

2,3,5‐trimethyl‐3‐thiazoline (TMT) is a chemical compound extracted from red fox urine and can be used to artificially simulate the presence of a predator. The purpose of this study was to test the hypothesis that TMT would block entry into torpor in the lab mouse. We first demonstrated that TMT induces fear in the mouse. Exposure to TMT induced a freeze response (67.2 ± 6.7% of time without movement over 10 minutes), as compared to 6.7 ± 1.7% without movement when exposed to water. When fed mice were exposed to TMT during the dark or light phase, body temperature dropped by 1.4 ± 0.2°C and 1.0 ± 0.2°C, respectively, over the first hour after exposure. Exposure to TMT for 30 minutes increased circulating corticosterone, 377 ± 33 ng/ml, as compared to 29 ± 4 ng/ml when exposed to water. To determine whether TMT influences daily torpor, mice were calorically restricted and exposed to either water or TMT. Mice were exposed one hour before the start of torpor, determined by the bout of the previous day. Exposure to TMT blunted torpor by increasing the minimum body temperature from 29.2 ± 0.3°C (water) to 30.1 ± 0.6°C (TMT) and by decreasing the amount of time the mice spent under 32°C from 431 ± 48 minutes (water) to 292 ± 78 minutes (TMT). These results establish that mice perceived the scent of TMT as a physiologically stressful stimulus and that torpor is blunted but not blocked in the presence of that stressor.

Pre‐autonomic corticotropin‐releasing hormone neurons in the paraventricular nucleus of the hypothalamus may contribute to chronic unpredictable stress‐induced blood pressure hyperreactivity

Exposure to chronic unpredictable stress (CUS) has been shown to augment the pressor response to novel stress. The neural circuits mediating the CUS induced blood pressure hyperreactivity are not fully understood. Exposure to CUS is known to increase the production of corticotropin‐releasing hormone (CRH) in the paraventricular nucleus of the hypothalamus (PVN). A subpopulation of PVN CRH neurons project to the rostroventral medulla (RVLM), a key nucleus regulating sympathetic outflow and blood pressure. To study how CUS exposure affect RVLM‐projecting CRH neurons in the PVN, we injected retrograde AAV expressing Cre‐inducible mCherry into the RVLM of CRH‐Cre mice. We then exposed mice to the a CUS paradigm. The CUS paradigm included the following stressors: hot air stream (10 min), cold temperature (4°C, 1h), fox urine exposure (10 min), hypoxia (10% oxygen, 20 min), shaker (100 oscillations/min, 1h), forced swimming (10 min). These stressors were randomly assigned to the mice twice daily for 14 days. We found that mice exposed to the CUS had significantly increased number of RVLM‐projecting CRH neurons in the PVN compared to mice that were not exposed to the CUS (CON, 32 ± 4 vs CUS 81 ± 9; p = 0.003). To study whether RVLM‐projecting CRH neurons in the PVN regulates blood pressure, we expressed Channelrhodopsin 2 (ChR2) specifically into the PVN CRH neurons by injecting AAV expressing Cre‐inducible ChR2 into the PVN of CRH‐Cre mice. Optogenetic activation of CRH fibers in the RVLM significantly increased blood pressure (7 ± 1 mmHg). These results indicate that CUS can induce CRH production in a large population of PVN preautonomic neurons that do not produce CRH in basal condition. This population of plastic RVLM‐projecting CRH neurons in the PVN may contribute to CUS induced blood pressure hyperreactivity.Support or Funding InformationThis work was supported by American Heart Association Postdoctoral Fellowship 18POST34050013 and National Heart, Lung, and Blood Institute PO1 Grant HL‐088052.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Habenula and interpeduncular nucleus differentially modulate predator odor-induced innate fear behavior in rats.

Fear is an important behavioral system helping humans and animals to survive potentially dangerous situations. Fear can be innate or learned. Whereas the neural circuits underlying learned fear are already well investigated, the knowledge about the circuits mediating innate fear is still limited. We here used a novel, unbiased approach to image in vivo the spatial patterns of neural activity in odor-induced innate fear behavior in rats. We intravenously injected awake unrestrained rats with a 99m-technetium labeled blood flow tracer (99mTc-HMPAO) during ongoing exposure to fox urine or water as control, and mapped the brain distribution of the trapped tracer using single-photon emission computed tomography (SPECT). Upon fox urine exposure blood flow increased in a number of brain regions previously associated with odor-induced innate fear such as the amygdala, ventromedial hypothalamus and dorsolateral periaqueductal grey, but, unexpectedly, decreased at higher significance levels in the interpeduncular nucleus (IPN). Significant flow changes were found in regions monosynaptically connected to the IPN. Flow decreased in the dorsal tegmentum and entorhinal cortex. Flow increased in the habenula (Hb) and correlated with odor effects on behavioral defensive strategy. Hb lesions reduced avoidance of but increased approach to the fox urine while IPN lesions only reduced avoidance behavior without approach behavior. Our study identifies a new component, the IPN, of the neural circuit mediating odor-induced innate fear behavior in mammals and suggests that the evolutionarily conserved Hb-IPN system, which has recently been implicated in cued fear, also forms an integral part of the innate fear circuitry.

Risk Mitigation of Emerging Zoonoses: Hendra Virus and Non-Vaccinating Horse Owners.

Hendra virus was identified in horses and humans in 1994, in Queensland, Australia. Flying foxes are the natural host. Horses are thought to acquire infection by direct or indirect contact with infected flying fox urine. Humans are infected from close contact with infected horses. To reduce risk of infection in horses and humans, Australian horse owners are encouraged to vaccinate horses against the virus and adopt property risk mitigation practices that focus on reducing flying fox horse contact and contamination of horses' environment with flying fox bodily fluids. This study investigates uptake of four Hendra virus risk mitigation practices in a sample of non- and partially vaccinating horse owners living close to previous Hendra virus cases. Protection motivation theory was used to develop a conceptual model to investigate risk perception and coping factors associated with uptake of risk mitigation practices. An online survey was administered via Facebook pages of veterinary clinics close to previous Hendra virus cases. Factors associated with uptake of risk mitigation practices were investigated using univariate and multivariate binary logistic regression. Belief that a risk mitigation practice would be effective in reducing Hendra virus risk was significantly associated with the uptake of that practice. Issues around the practicality of implementing risk mitigation practices were found to be the greatest barrier to uptake. Factors that relate to risk immediacy, such as nearby infection, were identified as more likely to trigger uptake of risk mitigation practices. The role of veterinarians in supporting Hendra risk mitigation was identified as more influential than that of respected others or friends. Findings from this study are being used to assist stakeholders in Australia responsible for promotion of risk mitigation practice in identifying additional pathways and reliable influencing factors that could be utilized for engaging and communicating with horse owners to promote Hendra virus risk mitigation behaviour.

Can Cage-Trap Performance in Capturing Red Foxes Be Improved by Using Different Baits and Scent Attractants?

Cage-trapping is one of the control methods frequently used by hunters to remove red foxes (Vulpes vulpes) in Spain, although its low efficiency and selectivity have been frequently reported. We tested the effect of the combinations of two bait types (live/ dead) and two scent attractants (fox urine/valerian extract) in order to improve the efficiency and selectivity of cage traps in central Spain. The combination of live bait and fox urine increased the efficiency of cage traps to capture red foxes in comparison with live bait alone. None of the experimental treatments led to a significant reduction in the capture rate of non-target species, selectivity levels were always low (0%–21%) and non-target species were captured. In view of that, the burden of releasing captured non-target animals depends ultimately on the trapper. For this reason, the use of cage traps is still questionable for managing foxes in Spain.

Lack of Response to Olfactory Lures Among Mammals in Riparian Habitat in Southern Wisconsin

Non-invasive mammal surveys often employ olfactory stimuli on the assumption that they will attract mammals and increase the success of monitoring projects. However, information on the effectiveness of scent lures is variable and often relies on data generated from mammal tracks or sign, which can be challenging to quantify. Therefore, we sought to determine whether certain olfactory stimuli are more effective than others at eliciting a response from mammals along riparian corridors in Southern Wisconsin, using camera traps to monitor response to four scents and a control of de-ionized water. We recorded the number of times each species responded as well as the length of time spent investigating scents (Muskrat gland, mink gland, Red fox urine, crayfish oil) and the control. We recorded 2812 passes by 16 mammal species during our 12-month study, with Virginia Opossum (Didelphis virginiana), Woodchuck (Marmota monax), Eastern Gray Squirrel (Sciurus carolinensis), Eastern Fox Squirrel (Sciurus niger), Raccoon (Procyon lotor), Coyote (Canis latrans), and White-tailed Deer (Odocoileus virginianus)observed on cameras most frequently. However, 72% of observations involved mammals passing through without investigating any scents or the control, and among the 28% of observations where mammals did investigate, we found no significant differences in their response to specific scents or the control or in response by season. Further analysis revealed no significant differences in the time mammals spent investigating individual scents or the control. The lack of response suggests that factors other than scent may have attracted wildlife to our stations. Although under some circumstances olfactory attractants may increase the level of response to monitoring stations, we suggest that attraction to our stations was largely a behavioural response to novel stimuli in the environment.

Predator odor exposure increases food-carrying behavior in rats

To cover their energy demands, prey animals are forced to search for food. However, during foraging they also expose themselves to the risk of becoming the prey of predators. Consequently, in order to increase their fitness foraging animals have to trade-off efficiency of foraging against the avoidance of predation risk. For example, the decision on whether a found food piece should be eaten at the food source or whether it should be carried to a protective site such as the nest (food-carrying behavior), is strongly dependent on different incentive factors (e.g., hunger level, food size, distance to the nest). It has been shown that food-carrying behavior increases the more risky the foraging situation becomes. Since predator odors are clearly fear-inducing in rats, we ask here whether the detection of predator odors in close proximity to the food source modulates food-carrying behavior. In the present study, the food-carrying behavior of rats for six different food pellet sizes was measured in a “low risk” and a “high risk” testing condition by presenting water or a fox urine sample, respectively, next to the food source. For both testing conditions, food-carrying behavior of rats increased with increasing food pellet weight. Importantly, the proportion of food-carrying rats was significantly higher during exposure to fox urine (“high risk”) than when rats were tested with the water control (“low risk”). Taken together, these results demonstrate that food-carrying behavior of rats is increased by the detection of a predator odor. Our data also support the idea that such food-carrying behavior can be considered as a pre-encounter defensive response.

Temporary inactivation of the anterior part of the bed nucleus of the stria terminalis blocks alarm pheromone-induced defensive behavior in rats.

Rats emit an alarm pheromone in threatening situations. Exposure of rats to this alarm pheromone induces defensive behaviors, such as head out behavior, and increases c-Fos expression in brain areas involved in the mediation of defensive behaviors. One of these brain areas is the anterior bed nucleus of the stria terminalis (aBNST). The goal of the present study was to investigate if pharmacological inactivation of the aBNST by local microinjections of the GABAA receptor-agonist muscimol modulates alarm pheromone-induced defensive behaviors. We first established the behavioral paradigm of alarm pheromone-induced defensive behaviors in Sprague-Dawley rats in our laboratory. In a second experiment, we inactivated the aBNST, then exposed rats to one of four different odors (neck odor, female urine, alarm pheromone, fox urine) and tested the effects of the aBNST inactivation on the behavior in response to these odors. Our data show that temporary inactivation of the aBNST blocked head out behavior in response to the alarm pheromone. This indicates that the aBNST plays an important role in the mediation of the alarm pheromone-induced defensive behavior in rats.

Exploratory behavior is associated with plasma carotenoid accumulation in two congeneric species of waterfowl

Recently, carotenoid pigments have received considerable attention as modulators of animal health and performance. While studies show that elevated carotenoid intake and accumulation can influence activities like parental care and escape-flight performance, little is known of how carotenoid status influences the expression of animal personality traits, which can be energy-demanding and entail survival costs but also rewarding in the context of foraging and mating. We experimentally investigated the effects of carotenoid availability on exploratory behavior and activity level, using adult males and females of two species of waterfowl: mallard (Anas platyrhynchos) and northern pintail (Anas acuta). We assessed behavior using a novel-environment test designed to measure an individual’s response to novel objects and a potential predator threat (fox urine scent). We found that carotenoid availability was positively associated with some aspects of exploratory behavior: birds with higher concentrations of circulating carotenoids entered the test arena sooner and approached and entered predator-scented bedding material more frequently than birds with low carotenoid concentrations. These results suggest that the availability of carotenoid resources can influence personality traits in waterfowl, and we discuss putative physiological mechanisms underlying this effect.

Fox urine exposure induces avoidance behavior in rats and activates the amygdalar olfactory cortex

Predator odors represent a group of biologically-relevant chemosignals called kairomones. Kairomones enable prey animals to recognize potential predatory threats in their environment and to initiate appropriate defensive responses. Although the behavioral repertoire of anti-predatory responses (e.g. avoidance, freezing, risk assessment) has been investigated extensively, our knowledge about the neural network mediating these innate fear responses is rather limited. In the present study, the GABAA agonist muscimol was bilaterally injected (2.6nmol/0.3μl) into the amygdalar olfactory cortex (AOC), a brain area that receives massive olfactory input from both olfactory systems and is strongly interconnected with the medial hypothalamic defense circuit. Temporary inactivation of the AOC substantially disrupted avoidance behavior of rats to fox urine that is strongly avoided under control conditions (saline injections). Taken together, these results demonstrate that the AOC is critically involved in fox urine-induced fear behavior. This suggests that the AOC is part of a brain fear circuit that mediates innate fear responses toward predatory odors.