Position of operant cost affects blue foxes’ time budget between sand floor and mesh floor

The aim of the study was to assess whether positioning of the operant cost would affect blue foxes’ (Vulpes lagopus) behaviour and time budget between a mesh floor and sand floor. We built fourteen test apparatuses, six consisting of two fox cages with a mesh floor in both cages and eight with a mesh floor in one cage and a sand floor in the other cage. A cost could be imposed to pass through one-way doors between the cages. The effect of changing the cost to move from the mesh floor to the sand floor or from the sand floor to the mesh floor or between the two mesh floors was examined in 28 juvenile male blue foxes. The foxes’ time allocation between the cages was recorded for four different costs. The foxes’ behaviour was analysed in more detail at the lowest and highest costs. The visit duration increased considerably when leaving the cage became costly, but did not markedly change when entering was costly. The foxes spent less time on the sand floor than on the mesh floor. The foxes preferred to rest on the mesh floor, but rested also on the sand floor when there was a cost associated with leaving the sand floor. The sand floor stimulated digging, rooting and play. In conclusion, both positioning of the cost and the floor material affected blue foxes’ time budget between the two cages.     

Preferences of farmed blue foxes for different floor types

In the first experiment, farmed blue foxes were allowed to choose for 1 week between four standard farm cages equipped with different floor materials: plastic-coated wire mesh, dry wood, dry sand and wet (summer) or icy (winter) sand. Resting consisted of 10-15 separate bouts/day occupying 50-60% of the total 24-h. There were no other differences in the use of the cages except that the time spent on, and the duration and number of resting bouts were lower on wet or icy sand, resting periods being more affected than activity. In the second experiment, two cages were connected with a 1.2 m tunnel. One cage was always elevated (50 cm) compared to that one which was lower. One cage of each pair had a wire floor whereas the other cage either had sand or wire floor. Sand floor was preferred for active behaviours and wire floor for resting if these were on elevated level. Of two identical wire-floored cages, the elevated one had the priority. Foxes preferred to rest on the same floor where they had finished their previous resting bout, often exclusively and independently of floor material or floor level.     

Complex housing environment for farmed blue foxes (Vulpes lagopus): use of various resources

The present study was designed to measure the use of various, simultaneously available resources in a complex housing environment in juvenile blue foxes. Twelve blue fox sibling (male–female) pairs were housed in two-section experimental cages from the age of 8 weeks until the age of 7 months (from June to December). Each experimental cage was furnished with two platforms, a nest box, a sand box and a wooden block. This housing set-up provided the foxes with social contact, and an opportunity for oral manipulation, scratching and nesting, as well as the choice of staying on a solid floor material or on an elevated location. The foxes’ behaviour was recorded at three time points during autumn (September, November and December). The foxes used all available resources. The most utilised resource was the nest box, possibly because it could be utilised in several ways (as a shelter, an elevated location, an object for scratching and for oral manipulation). The foxes also stayed more in the cage section containing the nest box than in the cage section containing a sand box. The foxes rested much on the cage floor, but they also used the interior of the nest box and elevated locations for resting. Social contact often occurred during resting. Thus, the nest box and elevated location, in conjunction with social contact seem to be valuable while resting. While active, the foxes utilised the cage floor and roof of the nest box instead of the platforms. Scratching, digging and an interaction with the wooden block were seldom observed. Activity occurred mainly on the ‘empty’ cage area. In conclusion, all studied resources provided blue foxes with a distinct value, as they all were used in the complex housing environment. The nest box is used most and for most variable behaviours.     

Trade-off between floor level and floor material in farmed silver foxes

Farmed silver foxes (Vulpes vulpes) were allowed to balance their known preference for an elevated floor against their presumed preference for a sand floor. In Experiment 1, foxes had to choose between two identical cages, connected with an opening. One cage had a wire floor and the other had a sand floor, but the cages either were on the same (low or elevated) or on different levels (one cage 40 cm higher than the other). In Experiment 2, the cage pairs were connected with a 1.2 m long wire-mesh tunnel, one cage was always on a higher level (50 cm) than the other. In Experiment 1, foxes always preferred the sand floor during their active time. They also preferred the sand floor for resting, if it was on the same level as wire floor, but did not show any genuine preference if the floors were on different levels. In Experiment 2, foxes never preferred the lower floor. They preferred the elevated sand floor for activity and the elevated wire floor for lying. When two floors were identical they preferred the elevated one. Their rest consisted of 11-22 bouts, a major part of these being spent in the preferred cage. They also preferred a previous lying site to a new one, often exclusively and independently of floor material. In Experiment 1 foxes preferred the sand floor whereas in Experiment 2 they preferred the elevated floor indicating that the ability of a trade-off situation to rank resources depends on the method it is inflicted.     

Extent of digging and its possible underlying causal factors in penned blue foxes

A recent European animal welfare recommendation stresses the importance of studying digging behaviour in farm-born blue foxes (Alopex lagopus). The current study was conducted (1) to clarify the extent of digging and (2) to evaluate factors that motivate digging. In experiment 1, six juvenile male blue foxes were housed together from August to the following June in an earthen enclosure. Experiment 2 was conducted from July to December, using ten enclosures each containing two juvenile male blue foxes. Behaviour was monitored by 24-h video recordings and visual observations. Progress of digging was also followed by making scale drawings of all digging marks on paper. As early as the first study day, clear signs of digging were observed. Digging sites were concentrated below and close to nestboxes and pen walls. Maximally about 20% of the total enclosure area was affected. The total surface area of digging sites did not increase from late summer onwards because foxes tended simultaneously to cover part of the old sites when digging new ones. Motivational tendency to dig varied with time. Digging activity decreased during autumn and almost totally ceased during winter. In May, foxes resumed digging activity. Digging motivation was evaluated by two means: (1) by analyzing digging purpose (experiments 1 and 2), and (2) by the damming-up test (experiment 1), that is, after 10 months foxes that had been exposed to the earthen floor were transferred for 12 days into wire-mesh cages with no possibility to dig in the ground. Thereafter, foxes were transferred back into the earthen enclosure to measure the rebound of digging following deprivation. Foxes were observed to dig for the following reasons: (1) to make a hole or a resting site, (2) to locate an escape route, (3) to cache food, faeces, or sticks, (4) in response to a novel object (new nestbox, replacement of nestbox), and (5) displacement without any clear goal. Daily time spent digging averaged 7 min and 17 min per fox in Exps. 1 and 2, respectively. A clear rebound effect for digging was not identified. It can be concluded that digging is a complex behavioural pattern caused by a variety of motivations that can vary over time. The present study was unable to show unambiguously that digging is an important need for farmed foxes. Received: 28 February 2000 / Received in revised form: 6 June 2000 / Accepted: 20 June 2000     

Effect of space allowance and earthen flooring on behaviour of farmed blue foxes

This study sought to evaluate the effect of cage space and earthen flooring on the behaviour of individually caged, farmed blue foxes (Alopex lagopus). Three different cage sizes [80 cm long (CL80), 120 cm long (CL120), 240 cm long (CL240); each 105 cm wide×70 cm high] with wire-mesh flooring, and one two-level cage (CL240E) with both wire-mesh (240 cm long×105 cm wide×70 cm high) and earthen flooring (80 cm long×105 cm wide×70 cm high) were employed. Quantitative ethograms were obtained from ten males in each group by videotaping the animals for 144 h monthly from August through November. Altogether 30 different behaviours were described. These were rather similar in all study groups. Examples of behavioural differences included pacing around with a neighbour and the incidence of scratching, which both declined with increasing cage space. Only the foxes in the cage with an earthen flooring (CL240E) exhibited digging behaviour, which averaged 11 min/24 h. The wire-mesh section was distinctly preferred to the earthen-floor section for most behaviours. Foxes in all groups were at their most active from 0800 to 1600 hours. Total activity, including several separate behaviours, declined as winter approached. Locomotor and oral stereotypies were infrequent, and no significant differences were found between the various cage options. For several hours before feeding, the foxes showed increasing levels of stereotypies, but afterwards, stereotypies abruptly declined. Received in revised form: 28 March 2001 Electronic Publication     

Social preferences in farmed silver fox females (Vulpes vulpes): Does it change with age?

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 < 0.01). The cubs did not differentiate between a familiar or unfamiliar stimulus animal (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.     

The role of vole populations in prevalence of the parasite (Echinococcus multilocularis) in foxes

Effects of population fluctuation of the gray-sided vole(Clethrionomys rufocanus) on the prevalence (infection rates) of the parasiteEchinococcus multilocularis in red fox(Vulpes vulpes) populations was investigated from 1985 to 1992 in eastern Hokkaido (Abashiri, Nemuro, and Kushiro area), Japan. This parasite needs two hosts to complete its life cycle; the gray-sided vole as its intermediate host and the red fox as its final host. We found that: (1) Infection rates in foxes depended on the current-year abundance of voles in all three study areas, particularly in Abashiri. (2) In addition to this direct density-dependence, delayed density-dependence between the infection rate and the prior-year abundance of voles was detected in Nemuro and in Kushiro. (3) The regional differences in density-dependence pattern were related to regional differences in the winter food habits of red foxes: in Abashiri the proportion of voles in the fox’s diet greatly decreases in winter, while the proportion remains high in winter in Nemuro and in Kushiro, probably because of shallower snowpack. These results suggest that infection rates in foxes in Abashiri were less influenced by the prior-year prevalence, since the infection cycle might be interrupted in winter, when voles became less important in fox’s diet. In contrast, the state of the prevalence may carry over from year to year in Nemuro and in Kushiro, because red foxes continue to eat a considerable amount of voles throughout year. The regionally contrasted results for the relationship between infection rate in foxes and vole abundance were parallel to the regional difference in fluctuation pattern of vole populations, which are highly variable in Abashiri area, but less variable in Kushiro-Nemuro area. Drastic change in vole populations appears to affect the host-parasite system.     

Variation in the diet composition of a generalist predator, the red fox, in relation to season and density of main prey

Diet composition of a generalist predator, the red fox (Vulpes vulpes) in relation to season (winter or summer) and abundance of multi-annually cyclic voles was studied in western Finland from 1983 to 1995. The proportion of scats (PS; a total of 58 scats) including each food category was calculated for each prey group. Microtus voles (the field vole M. agrestis and the sibling vole M. rossiaemeridionalis) were the main prey group of foxes (PS = 0.55) and they frequently occurred in the scats both in the winter and summer (PSs 0.50 and 0.62, respectively). There was a positive correlation between the PSs of Microtus voles in the winter diet of foxes and the density indices of these voles in the previous autumn. Other microtine rodents (the bank vole Clethrionomys glareolus, the water vole Arvicola terrestris and the muskrat Ondatra zibethicus) were consumed more in winter than in summer. The unusually high small mustelid predation by red foxes (PS = approx. 0.10) in our study area gives qualitative support for the hypothesis on the limiting impact of mammalian predators on least weasel and stoat populations. None of the important prey groups was preyed upon more at low than at high densities of main prey (Microtus voles). This is consistent with the notion that red foxes are generalist predators that tend to opportunistically subsist on many prey groups. Among these prey groups, particularly hares and birds (including grouse), were frequently used as food by foxes.     

Inferring the Distribution and Demography of an Invasive Species from Sighting Data: The Red Fox Incursion into Tasmania

A recent study has inferred that the red fox (Vulpes vulpes) is now widespread in Tasmania as of 2010, based on the extraction of fox DNA from predator scats. Heuristically, this inference appears at first glance to be at odds with the lack of recent confirmed discoveries of either road-killed foxes—the last of which occurred in 2006, or hunter killed foxes—the most recent in 2001. This paper demonstrates a method to codify this heuristic analysis and produce inferences consistent with assumptions and data. It does this by formalising the analysis in a transparent and repeatable manner to make inference on the past, present and future distribution of an invasive species. It utilizes Approximate Bayesian Computation to make inferences. Importantly, the method is able to inform management of invasive species within realistic time frames, and can be applied widely. We illustrate the technique using the Tasmanian fox data. Based on the pattern of carcass discoveries of foxes in Tasmania, we infer that the population of foxes in Tasmania is most likely extinct, or restricted in distribution and demographically weak as of 2013. It is possible, though unlikely, that that population is widespread and/or demographically robust. This inference is largely at odds with the inference from the predator scat survey data. Our results suggest the chances of successfully eradicating the introduced red fox population in Tasmania may be significantly higher than previously thought.