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Measuring fecal glucocorticoid metabolites (fGCMs) is a widely used, non-invasive method for studies of stress in vertebrates. To study physiological responses in wild Arctic foxes (Vulpes lagopus) to perceived stressors such as fluctuating food availability, occurrence of competitors and predators and disturbance from human activities, a species-specific physiological validation of a method to evaluate adrenocortical activity is needed. Here we used 15 captive Arctic foxes (both males and females and juveniles and adults) to investigate fGCM concentrations following ACTH injection (physiological validation), or handling alone and compared them with their respective baseline concentrations prior to the treatments. A 5α-pregnane-3ß,11ß,21-triol-20-one enzyme immunoassay measured significant fGCM increases following both treatments. The time lags to reach peak fGCM values were 9.3 ± 1.3 h and 12.8 ± 1.7 h for ACTH and handling treatment, respectively. Concentrations of fGCMs varied a lot between individuals, but not attributed to sex nor age of the foxes. However, we found a negative relationship between boldness and fGCM concentrations. Faecal glucocorticoid metabolites concentrations did not change significantly over a period of 48 h in samples kept at temperatures reflecting winter and summer means. This would allow the collection of samples up to two days old in the wild regardless of the season. We conclude that our successfully validated method for measuring fGCMs can be used as a non-invasive tool for studies exploring various stressors both in wild and captive Arctic foxes.

Providing captive foxes with relevant enrichment objects may support their ability to cope with barren housing systems and thus have positive welfare effects. The relevance of enrichment objects is, among others, related to animals’ preference that should be examined prior to supplementing their housing environment. In this study, we assessed 30 juvenile, singly housed silver foxes’ short-term preference for five different oral enrichment objects based on their immediate use of the objects when they were given simultaneous access after one week of deprivation. Also, wear and tear after one week of continuous access was assessed as a measure of use and to estimate the robustness and durability of various objects. A cattle femur bone was clearly the first ranked object (P ≤ 0.05), followed by a rawhide bone, a mutual pulling device mounted between neighbouring cages, and straw and a plastic cube as the least used objects. All of the objects were, to a various degree, gnawed by the foxes. After one week of use, about 30% of the cattle bone mass was consumed, compared to about 88% of the rawhide bone mass. Although the plastic cubes were almost indestructible and therefore durable objects their low ranking do not necessarily make them good enrichment objects for foxes. Offering meat bones to captive foxes provide the animals with biologically relevant stimuli that elicit oral manipulation and play, behaviours with potential rewarding effects to the animals.

In order to understand the impact of different experimental and husbandry procedures on fish, and ensure that the behavioural and physiological needs of fish used in research are met, it is necessary to have detailed knowledge of their behaviour. This knowledge is largely lacking for Atlantic salmon. Results from behavioural studies of rainbow trout are often extrapolated to Atlantic salmon even though this may not be correct. Pre-smolt Atlantic salmon show diurnal variation in behaviour in the wild, but there are no published descriptions of behaviour during the dark hours for salmon held in the laboratory. Thus, the first aim of this paper was to describe the time budget of singly-held salmon both during the light and dark hours on the first and seventh day after introduction to a new environment. Statistical differences in time budget between morning, afternoon and night are described. In addition, three environmental enrichments were provided, and the time spent using each resource was scored. In general, no behaviours differed in frequency between morning and afternoon registrations, but there were significant differences in the time-budget between day and night and also between day 1 and 7. Fish hid less and displayed more behaviours during the night than during the day, and also after 7 days in the tank compared to at the first day. The exceptions were bottom behaviours which were displayed with the same frequency during day and night and during day 1 and day 7, and hovering, which was unchanged at night from day 1 to day 7. Thus, different behaviours seem to be influenced by light and by the novelty of the surroundings to different degrees. Of the three enrichments included in the study, the hiding place and the inlet current were used most frequently. As far as the authors know, this is the first paper describing the daytime and night time behaviour of parr Atlantic salmon in a research facility in detail.

Measuring glucocorticoid metabolites in faeces has proven a useful, non-invasive method to monitor adrenocortical activity in several farm and wild species. Unlike plasma cortisol, whose sampling requires restraint and blood draws, faecal cortisol metabolites (FCM) may be particularly suitable for farmed silver foxes as these animals are sensitive to handling by humans. Prior to using FCM as a potential indicator of stress in silver foxes, however, a proper physiological and/or biological validation is required. Here, we determined FCM concentrations in 30 silver foxes (10 adult vixens, 10 juvenile females and 10 juvenile males) every alternate hour for 24 h after 1) an increase in cortisol induced by injection with synthetic ACTH (hereafter ACTH), and 2) a 2 min period of handling and restraint. Baseline FCM values, recorded every fourth hour for 24 h before the ACTH and handling treatments, served as controls. FCM values increased significantly following ACTH injection (P = 0.0001) and handling (P

Non-random association of females has been reported in many social species, with kinship being the main mechanism in shaping these associations. Understanding the patterns of association during rut is particularly important in polygynous animals, as this may have implications for inbreeding vulnerability and genetic structuring of populations. However, these patterns are highly dynamic and may be influenced by the population sex ratio and male age structure. We examined females' association in reindeer (Rangifer tarandus), a highly polygynous ungulate, to determine whether genetically related females associate more often than non-kin during rut and whether this association was influenced by the aforementioned factors. During three rutting seasons the male age structure and the sex ratio of the herd was manipulated: two extremely female biased sex ratios, one with only adult males and one with only young males, whereas the third being closer to a more even sex ratio and male age structure. We found that genetic relatedness influenced female association in the mixed male age group, but not in the adult and young male age groups. Highly related females (relatedness ∼0.5) associated more closely than unrelated females. Further, period of the rut as well as male age structure and sex ratio had a significant effect on female association. Our study suggests that the female reindeer association during rut is not only influenced by preference for kin but also by male–male competition and male age as well.

The flexible social organisation in red foxes ( Vulpes vulpes ) suggests that social contact could enrich the housing of silver fox vixens (a selected line of red foxes) farmed for their fur. To investigate their social motivation, adult vixens housed in an operant apparatus were allowed to pull a loop for full physical contact with a same-aged vixen. The access cost was increased daily and their maximum price paid (MPP) measured. Five test and five stimulus animals were pair housed long-term in separate apparatuses over 5 weeks in November/December wherein each pair could have 12 h daily physical contact in a shared compartment. Prior to the operant trials, two food competition tests were completed to establish dominance relations within pairs. To examine vixens’ motives for contact, social behaviour during interaction was also recorded. Subsequently, the test foxes’ MPP for a comparator resource, food, was also measured and their relative price paid (RPP, %) for contact calculated. When access to the resource cage was free (FR1), at the start and end of the experiment, time spent in contact averaged approximately 1/6 (2 h) of the available time; this was stable between these periods. Neither visit rate to nor time spent in the shared compartment differed between the start and the end of the trial, indicating that the test subjects’ social motivation remained stable during the experimental period. The MPP (mean ± SE) for social contact averaged at 560 ± 160.6 pulls; this was significantly lower ( P = 0.015) than the MPP for food (2108 ± 526.6 pulls), representing a RPP of 24.8 ± 3.36%. During social interaction agonistic gaping signals occurred (though never serious fights requiring intervention), but there were also bouts of play, social exploration and high levels of synchronous resting. Aggressive behaviour during the second food test predicted the levels of aggression during operant trials. RPP positively correlated with the total time spent together ( r = 0.87, P = 0.054), and with the time spent resting together ( r = 0.89, P = 0.046). Differences in RPPs for contact and levels of agonism between pairs illustrate that social contact between adult vixens is enriching for some, but may put welfare at risk for others, especially if they have no opportunity to retreat from aggression. However, levels of agonistic behaviour during, e.g. food competition tests may be a possible indicator of the compatibility between potential cage mates. Due to the low number of animals the result must now be replicated with further animals.

Usually, farmed silver foxes are housed singly throughout adulthood. Due to the flexible social nature of wild foxes social grouping may act as an alternative housing procedure for adult vixens. However, sociality may involve increased levels of aggression during competition for e.g. dominance with negative impact on foxes’ welfare and future reproduction, in particular for subordinate individuals. In this study we examined consequences of housing adult vixens in triplets for 13 weeks from September to December on their body weight development, occurrence of wounds and future reproduction. To evaluate effects of social competition dominance relations were recorded. Three-hundred-and-fifty-eight one to four year old silver fox vixens housed in six different commercial farms participated in the study. In each farm half of the vixens were housed in single cages as controls whereas the other half were housed in triplets in three connected cages consisting of one one-year-old, one two-year-old and one three- or four-year-old vixen. After the triplets were separated in December all animals were housed singly until they were mated in February and throughout the breeding period. Socially housed vixens gained more weight compared to the singly housed controls during the group housing period, however, the lowest ranked vixen were significantly lighter (7.0 ± 0.11 kg) compared to the second ranked vixens (7.4 ± 0.11 kg), indicating possible food competition. Yet, the body weight of subordinate vixens was not below that of singly housed controls (6.9 ± 0.05 kg) at the end of the group housing period. Thirty-six % of the group housed vixens had scabs or injuries 3 weeks following the start of the experiment whereas this was 2.3% in the controls. 1.7% ( N = 6) of the group housed vixens were excluded from the experiment due to infectious bite wounds. Damaging aggression seemed to decrease with succeeding time as 6.7% of the group housed vixens had injuries at the end of the experiment. There were no effects of social housing on the vixens reproductive output apart from heat development that occurred on average two days earlier in group housed vixens. Dominant vixens weaned approximately one more cub (4.3 ± 0.33) compared to the lower ranked vixens (3.2 ± 0.34, P = 0.036). To conclude, aggression during social housing in autumn may jeopardize foxes’ welfare and have negative consequences for future reproduction in subordinate vixens. Future studies are needed to clarify how various housing procedures affect social dynamics in group housed foxes.

Due to farmed foxes' ( Vulpes vulpes ) social flexibility and possible motivation for intraspecific contact, group housing may act as an alternative housing procedure. Because initial social contact between silver foxes usually involves agonistic displays as a part of foxes' social dominance assessments and owing to their territorial motivation, the incidence of serious aggression may put foxes' welfare at risk. The aim of this study was to investigate the consequences of housing adult silver fox vixens in triplets of various age compositions on their agonistic behaviour, body weight gain and bite injury level following the first hours and days after mixing in triplets. Ninety 1.5 and 2.5-year old vixens were housed in triplets consisting of four different age compositions ( N =3×6×4=72) and in one singly housed control group ( N =18) in September. Group 112 consisted of two 1.5-year olds and one 2.5-year old; Group 221 of two 2.5-year olds and one 1.5-year old; Group 111 of 1.5-year olds and Group 222 of 2.5-year olds. The triplets were housed in standard wire mesh cages connected with openings and with access to top nest boxes. The foxes' behaviour was recorded continuously the three first hours after mixing, 1h day 2 (26th hour) and 1h day 3 (50th hour) after mixing. One and two weeks following mixing, the number and severity of bite injuries were assessed. There was no overall difference between groups in observed agonistic behaviours. In all experimental groups aggression was most frequent the first hour (chasing=7.7±1.2; physical aggressive signals=2.3±0.32; fights=2.0±0.23). Overall, number of aggressive interactions was reduced with time ( P P =0.03). A negative correlation between weight asymmetry and number of fights was found ( r =−0.57, P

Among mammals, social ranking is generally thought to affect the outcome of disputes over preferred, limited or future resources. Therefore, we should expect individuals' preference for conspecifics to be affected by their own and other individuals' competition capacity. Here, we investigated the social preference and behavioural response in farmed silver fox vixens ( Vulpes vulpes ) towards unfamiliar vixens of different competition capacities, measured by their ability to compete for and defend a limited food resource, in a choice test. We found that low competition capacity vixens spent significantly less time in front of the high competition capacity vixens (2647±600s) compared to the time they spent in front of the low competition capacity vixens (6041±877s, P P =0.03). This suggests that low competition capacity vixens perceive high competition capacity vixens as a greater potential threat than high competition capacity vixens do. Time spent in social exploration, resting, sitting and performing aggressive behaviours in front of a stimulus animal were also affected by competition capacity of the foxes. The vixens were also retreating significantly more from the high competition capacity vixens (2±0.8 times) than from the low competition capacity vixens (0.4±0.4 times, P =0.03), possibly reflecting that the high competition capacity vixens were more offensive than the low competition capacity vixens. Our results contribute to the knowledge of social behaviour in this species, and may have implications for the social housing environment of the farm foxes.

In nature, the way essential resources are distributed is recognized as a potentially important factor influencing the frequency of aggressive interactions between animals. This knowledge is rarely taken into consideration when designing housing environments for social groups of farm animals. Adult farmed silver foxes (Vulpes vulpes) are often housed singly, but previous studies have demonstrated that vixens show a motivation for social contact in particular periods of the year and housing in social groups may therefore act as an alternative housing procedure for foxes. However, grouping unfamiliar animals may result in elevated levels of aggression due to competition for resources and thus affect welfare negatively. In the present study we investigated how housing environments with the same space and resources, but with different resource distributions affected the behaviour of adult vixens housed in pairs. A total of 40 vixens were housed in pairs in two coupled cages (2.00 m × 1.10 m × 0.75 m) with either two nest boxes and two food trays (treatment 1) or one nest box and one food tray (treatment 2) from 18 months of age. The occurrence of aggressive behaviour, play behaviour and synchronous resting was recorded throughout the day (i.e. every third hour for 15 min during 24 h) on day 1, day 5, day 19 and day 33 after mixing. In addition, the frequency of physical aggression was recorded for 75 min around feeding time. Body weight gain and wounds were also recorded on day 25 after mixing. The results showed that there had been more severe aggression in treatment 2 during the days after mixing due to higher frequency of physical aggression around feeding time (treatment 1: 0.6 ± 0.21 times, treatment 2: 2.9 ± 0.99 times, P = 0.06), more wounds (treatment 1: 3 of 10 pairs, treatment 2: 8 of 10 pairs, P = 0.03) and less body weight gain (P = 0.03) compared to treatment 1. The observed aggression levels throughout the day decreased with subsequent observations days for both aggressive displays (P < 0.01) and chase behaviour (P = 0.04), indicating that it takes between 5 and 19 days to establish a stabile social relationship within a vixen pair. There was an increase in social (P = 0.09) and locomotor play (P = 0.03) as well as synchronous resting (P < 0.001) with subsequent days after mixing, suggesting that the stress by being mixed with an unfamiliar conspecific is decreasing with time. In both treatments, there was a decrease in object play (P < 0.001) with subsequent days after mixing, however vixens in treatment 2 showed in general more object play than vixens in treatment 1 (4.3 ± 0.60 scores vs. 2.5 ± 0.47 scores respectively). To conclude, we found that different resource distributions affected wounds, body weight gain and physical aggression during feeding in pair housed silver fox vixens. The elevated aggression levels the first days after mixing may affect vixens’ welfare negatively, however, the increase of social play after mixing suggests that social housing also have positive effects on welfare. The resource distribution of highly valued resources should be taken into account when designing the future social housing system for farmed foxes.

Determining foxes’ social preference, and how this influences their social behaviour towards different conspecifics at different ages may give us a better understanding of how to prevent foxes from exposure of possible social stressors when housed in groups. Here, we investigated the effect of familiarity on social preferences in silver fox females and their motives for seeking social contact at two different ages. Fourteen silver fox females conducted two preference tests, first at the age of 9 weeks and the second at the age of 24 weeks, where they could choose between an empty cage, a familiar female or an unfamiliar female at their own age. The position and behaviour of the females were recorded using instantaneous sampling every tenth minute for 26 h. There was a clear preference to seek contact with a conspecific at 9 weeks of age (p 0.05), however there was a tendency to play more in front of the unfamiliar stimulus animal (p = 0.07). No preference was seen for either the familiar, unfamiliar or empty cage stimulus when the females were 24 weeks old (p > 0.05), however they were more aggressive towards the unfamiliar stimulus animal (p < 0.01). Thus, there was no effect of familiarity in time spent with a social stimulus at either age, however these results suggest that the motives for seeking contact as cubs were non-aggressive and possibly play related, whereas the aggressive behaviour displayed by juveniles towards the unfamiliar female indicates an increased competitive motivation.

To investigate the strength of social motivation and the motives underlying social contact in farmed silver foxes ( Vulpes vulpes ), we housed six young vixens continuously in a closed economy operant apparatus and measured their ‘maximum price paid’ when required to perform a task to obtain unrestricted social contact or food (a ‘yardstick’ resource). In the former trials, vixens of the same-age and origin acted as stimulus animals ( N = 6), and both test and stimulus foxes could decide their own visit durations to a shared compartment. Their motives for visiting this ‘social compartment’ were examined by recording their behaviour during social contact. When access was almost free (a baseline fixed ratio schedule of 1) the test vixens visited the stimulus fox 30.3 ± 4.3 times and spent 45% of the time together per 24 h. The stimulus foxes spent on average 80% per 24 h in the shared compartment and visited this cage 40.7 ± 9.6 times per 24 h. When higher costs were imposed, the test vixens proved willing to pay to access the stimulus vixens and the average maximum price paid for contact was 38.3 ± 8.3% of the price paid for food when hungry. During the time spent together, the stimulus foxes made use of their opportunity to leave the cage, on average 1.43 ± 0.20 times per visit. The behaviour recordings showed that during initial encounters the vixens would fight to establish dominance, and in four of the pairs the test subject emerged as the dominant individual. However, during subsequent interactions, no serious aggression was recorded and social behaviour was characterised by higher levels of sniffing and grooming (23.7 ± 4.3 times/h), play signals (10.5 ± 4.1 times/h) and agonistic displays (5.5 ± 2.5 times/h). Not all of the time together was used for social interaction and during the observation period, the vixens allocated 33.1 ± 6.9% of the time to synchronous resting. We conclude that young silver fox vixens were motivated for social contact, and that this contact was beneficial for welfare due to the low level of aggression and the occurrence of grooming and play.

Food is frequently used as a ‘yardstick’ in operant experiments. However, previous work on silver foxes had suggested that how food is presented can affect how they respond to it, with excess food leading to variable consumption rates, and cages containing food being avoided over control cages except while eating. Our first experiment therefore examined foxes’ consumption of excess food in more detail by comparing their daily intakes with foxes fed a control diet for 4 weeks. Eighteen silver fox vixens were assigned to one of two groups in which the experimental group ( N = 9) was feed 2.5 times that of control ( N = 9). Although appetite, measured as the amount of food consumed, tended to fluctuate none of the overly fed foxes stopped eating during the experimental period. On average, the excessive fed group consumed more food (317 ± 18 g/day) compared to the controls (273 ± 12 g/day). In Experiment 2 we aimed to test whether the presence of excess food affected the foxes’ use of the cage. Five silver fox males were housed in separate multi-compartment apparatuses and the position of a food bowl was randomly switched between two cages for 18 days. The subjects had to perform one operant response to enter each cage and time inside the compartments was calculated. The foxes spent significantly less time in the food compartment (4 h 13 min), compared to the empty cage (12 h 12 min) and as expected by random (8 h) ( P

To measure farmed foxes' motivations for full, naturalistic social contact, we constructed an apparatus where they could perform an operant to access stimuli, but then leave freely and thence determine their own bout lengths. Motivational measures based on demand curves can be invalid in such set-ups, and we therefore sought to validate the measure ‘maximum price paid'. This was achieved by measuring six silver fox males' maximum operant responding for access or proximity to three resources differing in biological significance: food, vixens in oestrus and males. We predicted that if valid, maximum price paid would be highest for food and vixens. Maximum price were 970±399 (S.E.) for food, 677±173 (S.E.) for vixens and 389±101 (S.E.) for other males ( P

This is about the two big "guys", Spot and Mika, and their endeavour to propagate their genes during the mating season 2007. They were 6 and 5 years old weighting 172 and 141 kg before rut, respectively. Together with 23 other males (one 5 yrs, two 4 yrs, three 3 yrs, six 2 yrs and eleven 1 yr old) they roamed within a ~15 km2 fenced area competing for access to 87 females. Indeed, the competition was intense and all males present contributed to the dynamic observed. Especially Hot, the heaviest 4 yrs old male weighing 155 kg before rut, played a prominent role - in addition to Spot and Mika, their mating tactics being highly dynamic. However there is no short cut to success - strength have to be coupled with smartness - but shit happens - as we'll see.

The authors regret that some errors arose in the results section of their paper. The errors consist of invalid numbers and proportions that are reported in the results section, a total of five occasions here calculations are incorrect. In general, these errors are based on using the wrong numbers as basis for computation f percentages. The errors are not of such a character that they affect the statistics, and the mistakes do not influence the ontent of the discussion, the general conclusions of the study or the content and text of the abstract. The errors are listed elow. The authors apologise for any inconvenience. Page 134, Section 3.3, lines 10–13 should read: The proportion of vixens that was not mated did not differ between the treatments ( 2 =0.304, P=0.582; group housed: .8% (8/165); singly housed: 6.2% (11/177)). Page 134, Section 3.3, lines 13–17 should read: Likewise, theproportionofmatedvixens thatdidnotdeliveror lost their cubs immediately afterbirthwasnot significantly ifferent between group housed (17.3% (27/156)) or singly housed vixens (15.6% (25/160)) ( 2 =0.163, P=0.687). Page 135, Section 3.4, lines 9–12 should read: Therewere not significantlymore high ranked vixenswith injuries (No injuries/Injured:N=31/23) compared to the lower anked vixens (Rank 2: N=32/23 and Rank 3: N=37/19; 2 =1.1, N=165, df = 2, P=0.586). Page 135, Section 3.5, lines 1 and 2 should read: In 32 of 55 triplets (58.2%) the dominance ranking changed between October and December. Page 136, Section 3.7, lines 7–12 should read: In total, the proportions of animals that were barren or lost their cubs at birth were 11.3% (6/53) for the highest ranked ixens, 21.6% (11/51) for the medium ranked and 19.2% (10/52) for the low ranked vixens; however, this differences were ot statistically significant ( 2 =2.11, N=156, df = 2, P=0.348). Page 137, Section 4, lines 14–17 should read: The dominance relations changed from October until December in 58% of the triplets, however, on average, 69% of the rst ranked vixens maintained their rank during the course of the study.