Blue foxes’ (Vulpes lagopus) motivation to gain access and interact with various resources

https://doi.org/10.1016/j.applanim.2016.01.012Get rights and content

Highlights

  • When accessed, blue foxes interact urgently with a sand enrichment.

  • Nest box is used as an observation and resting site more than as a hiding place.

  • Blue foxes experienced with various enrichments do not interact much with platform.

  • Blue foxes may divide up their area for different activities when possible.

Abstract

We analysed the willingness of blue foxes (Vulpes lagopus) to work for and utilise five resources: a platform, wooden block, sand floor, nest box and empty space. Ten juvenile blue fox males were housed singly in apparatus consisting of three cages connected with one-way doors through the walls in between the cages and subjected to work for each of the five resources, one at a time. The resource was placed in one of the outermost cages of the apparatus. Force needed to open the door leading to the resource cage was increased daily by 0.25 or 0.5 kg. The number of daily entries, visit durations and interaction with the resource were recorded on workloads of 0, 0.5, 1.5, 2.5, 3.5, 5, 6.5, and 8 kg of extra weight. The latency to start interacting with the resource after entering the resource cage was measured on a workload of 3.5 kg. The mean number of daily entries in the resource and the other outermost, i.e. control cage varied from 7 to 28 and from 17 to 44, respectively. The increasing workload decreased the number of entries in the resource cage, increased those in the control cage (Linear Mixed Model: F1,638 = 79.5, P < 0.001) and lengthened the visit durations in both cages (F1,642 = 7.2, P < 0.01). The foxes made most (F4,643 = 9.0, P < 0.001) and shortest (F4,641 = 2.8, P < 0.05) visits to the outermost cages when the available resource was either a platform or empty space. The visit durations were longest when the available resource was a nest box. The foxes interacted regularly with the wooden block, but five foxes were not observed interacting with the platform. The nest box was utilised approximately 50% of the time spent in the resource cage, while the platform was utilised only 1–6% and wooden block 2–17% of the time. The mean latency to start interacting with the resource after entering the resource cage was shortest for the sand floor (8 s) and longest for the platform (113 s, F3,335 = 26.3, P < 0.001). The results show that the foxes re-scheduled their activities on increasing workloads in the apparatus. Based on the number of entries and visit durations, blue foxes valued the wooden block, nest box and sand floor more than the platform or an empty cage. After entering the resource cage, the foxes started interacting fastest with the sand floor, showing high motivation to interact. After entering the resource cage, the foxes make use of the roof of the nest box more urgently than the interior of the nest box. Long bouts in the cage with nest box indicate resting behaviour.

Introduction

The welfare of blue foxes (Vulpes lagopus) is a significant issue. Annually, approximately two million blue foxes are farmed for their fur on commercial fur farms in Europe (Fur Europe, 2015). The housing conditions of blue foxes consist of mesh cages in outdoor sheds. According to European recommendations, the cages must be furnished with a platform for surveillance of the surroundings and an object for oral activities and play (European Convention, 1999). Due to continuous debate on the welfare of farmed foxes in the current housing conditions (e.g. Nimon and Broom, 2001, Akre et al., 2008), various enrichment items, e.g. year-round nest box (Korhonen et al., 2006), sand floor (Koistinen et al., 2008), straw (Korhonen et al., 2002), dog toys (Pedersen, 2004) and scratching plate (Korhonen and Huuki, 2011) have been introduced to fox cages in scientific studies. These resources were designed to promote variable behavioural repertoire in the cage housing and to meet the potential behavioural needs of this species, since these factors are crucial in ensuring animal welfare.

Research on housing conditions show that individual resources may serve several functions (Koistinen and Korhonen, 2013). In such cases, the welfare effects of any single resource remain slightly ambiguous. Nest boxes can be used as a secluded resting area, observation place (roof), defecation/marking site, medium for scratching and gnawing (Korhonen et al., 2006, Koistinen and Korhonen, 2013) 20–30% of daily time (Mononen et al., 1996, Koistinen and Korhonen, 2013). Access to a nest box may increase fearfulness of foxes towards human, but does not affect the prevalence of stereotypic behaviour or adrenal function (Korhonen et al., 2006). A sand floor provides sensory feed-back through the foxes’ paws, an elimination site, a substrate for exploration and digging, and the pebbles can be used for playing (Koistinen, 2009). Blue foxes are willing to work for access to short visits on a sand floor (Koistinen and Mononen, 2008), but a mesh floor is highly preferred in the daily time-budget (Koistinen et al., 2008). Access to a sand floor decreases occurrence of stereotypic behaviour (Koistinen et al., 2008), but no consistent effect to the blood parameters or adrenal function has been detected (review in Koistinen, 2009). Interaction with the platform varies considerably between individuals, from 0 to 60% of day (Mononen et al., 1996, Koistinen et al., 2008, Koistinen et al., 2009a), and does not reveal consistent positive effect to welfare of foxes in the means of stereotypic behaviour or adrenal function (review in Mononen et al., 2012). Instead, the wooden block (Korhonen and Niemelä, 2000) bone (Koistinen et al., 2009a) and probably also some other small objects can be used for gnawing, carrying, play, poking and such short-duration activities, for up to 77 times a day (Korhonen and Niemelä, 2000). Access to these objects decrease occurrence of stereotypic behaviour (Korhonen et al., 2002, Koistinen et al., 2009a) and improve dental health, but do not clearly affect adrenal function (Korhonen et al., 2002, Ahola et al., 2010). Thus, the interaction with these resources and their welfare effects remain somewhat unclear.

In the present study we concentrate on the interaction of blue foxes with a platform, wooden block, nest box, sand floor and empty space. In our earlier study, time-budget calculations revealed that juvenile blue foxes continued interacting with all these resources when they were simultaneously available in a complex housing environment (Koistinen and Korhonen, 2013). An animal’s time-budget provides important information of the resource use (Elmore et al., 2012), but one measurement cannot typically reveal all aspects of the interaction with the resources. In order to accomplish the previous knowledge of the foxes’ interaction with these resources, in the present study, we measure the willingness of the foxes to gain access to the resources and the urge to start interacting with the resource. In this design, the foxes have to push through a weighed door to be able to interact with the resource. The number of entries, visit duration and the resource use are typically affected by the increasing cost to the access to the resource (e.g. Cooper and Mason, 2000). It is hypothesised that, the more the animal tries to sustain the resource use against increasing cost, the more the animal is motivated to gain access to the resource. The latency to start interacting with the resource after entering the resource is measured to show the urge of the foxes to interact with the resource.

Section snippets

Material and methods

The present experiment was approved by the Animal Care Committee of MTT Agrifood Research Finland and carried out on the research station of the former MTT Agrifood Research Finland situating in western Finland, in Kannus.

Number of entries and visit duration in the RC and CC

Only three out of 10 foxes passed through the heaviest, 8 kg door for all resources. Six foxes passed through the 8 kg door for 2–4 resources, and one fox never passed through the heaviest 8 kg door, but passed throughout the 7.5 kg door for platform, empty space and nest box. When looking at the number of foxes passing through the heaviest 8 kg door, 7, 4 and 6 foxes, out of 10, passed through the heaviest door in the case of sand floor, platform and empty space, respectively; whereas, 6 out of 8,

Discussion

We succeeded in making the entry through the one-way door to the RC more difficult, as the number of entries to the RC decreased with increasing workload and not all foxes passed through the one-way door loaded with the heaviest, 8 kg of extra weight. However, since adult blue foxes (Koistinen et al., 2009b) and mink (Cooper and Mason, 2000) can pass through one-way doors loaded with a weight close to their own body weight, i.e. 8 kg in foxes with body weight of 9–10 kg and 1 kg in mink with body

Acknowledgements

The authors are grateful to Hanna Huuki, Eija Korpela and Martti Koskinen for practical assistance, Paula Martiskainen for drawing (Fig. 1), to Vesa Kiviniemi for statistical assistance and to Roseanna Avento for language check. The study was financially supported by independent funding from Ministry of Agriculture and Forestry, the former MTT Agrifood Research Finland and Finnish Cultural Foundation North Savo Regional fund.

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