Is Behavioural Enrichment Always a Success? Comparing Food
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RVC OPEN ACCESS REPOSITORY – COPYRIGHT NOTICE This is the peer-reviewed, manuscript version of the following article: Januszczak, I. S., Bryant, Z., Tapley, B., Gill, I., Harding, L. and Michaels, C. J. (2016) 'Is behavioural enrichment always a success? Comparing food presentation strategies in an insectivorous lizard (Plica plica)', Applied Animal Behaviour Science, 183, 95-103. The final version is available online: http://dx.doi.org/10.1016/j.applanim.2016.07.009. © 2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/. The full details of the published version of the article are as follows: TITLE: Is behavioural enrichment always a success? Comparing food presentation strategies in an insectivorous lizard (Plica plica) AUTHORS: Januszczak, I. S., Bryant, Z., Tapley, B., Gill, I., Harding, L. and Michaels, C. J. JOURNAL: Applied Animal Behaviour Science PUBLISHER: Elsevier PUBLICATION DATE: October 2016 DOI: 10.1016/j.applanim.2016.07.009 1 Is behavioural enrichment always a success? Comparing food presentation strategies 2 in an insectivorous lizard (Plica plica) 3 4 Authors: Inez Sukuna Januszczak1, Zoe Bryant2, Benjamin Tapley2, Iri Gill2, Luke Harding2, 5 Christopher John Michaels2 6 7 1. Royal Veterinary College, 4 Royal College Street, London, NW1 0TU, United Kingdom 8 2. Zoological Society of London, Regent’s Park, London, NW1 4RY, United Kingdom 9 10 Corresponding author: Inez Sukuna Januszczak 11 Mobile: 07796848758 12 Email: [email protected] 13 [email protected] 14 15 16 17 18 19 20 21 22 1 23 Abstract 24 Staggering food availability through a delivery device is a common way of providing 25 behavioural enrichment as it is usually thought to increase the amount of natural behaviour 26 due to the unpredictability of the food source. Tree-runner lizards (Plica plica) are a 27 Neotropical, scansorial, insectivorous species. We provided these lizards with an enrichment 28 device that slowly released insect prey and tested its effect on the activity and frequency of a 29 number of behaviours in comparison with a scatter control (where prey items were broadcast 30 in the enclosure; standard food presentation for captive insectivorous lizards) and a non- 31 feeding control. Both types of food increased activity and counts of several behaviours in 32 comparison with the non-feeding control. However, we found the provision of the behavioural 33 enrichment device led to a significantly lower frequency of almost all analysed behaviours in 34 comparison with scatter control trials, mainly in behaviours associated with activity 35 (unsuccessful strikes (= unsuccessful capture of prey) (p=0.004), locomotion (p=0.004), 36 alertness (p=0.004) and the number of times a boundary in the enclosure was crossed ie. 37 activity (p=<0.001)). The frequencies significantly increased in the enrichment trials (relative 38 to the scatter control) were the number of successful strikes (= successful capture of prey; 39 p=<0.001) and targeting prey (p=<0.001). There was no significant difference in latency to 40 first strike (p=0.24), duration of hunting activity (p=0.83) or enclosure use (p>0.05) between 41 scatter and enriched trials. The relative success of the scatter feed in promoting activity and 42 increasing hunting difficulty was likely partly due to the enclosure design, where the complex 43 physical environment contributed to the difficultly in catching the prey. However, when the 44 feeding duration and enclosure use was analysed there was no significant difference 45 between the scatter control and enrichment trails. The results from this study highlight the 46 importance of evaluating enrichment strategies, and the role of complex enclosure design in 47 creating effective enrichment for insectivores, which can contribute to their welfare in 48 captivity. 49 Keywords: enrichment; behaviour; reptiles; lizards; activity; Plica plica 2 50 1.Introduction 51 Enrichment is an aspect of animal husbandry that is designed to promote natural behaviours 52 and improved welfare and to reduce atypical behaviours or stereotypies in captive animals, 53 often by mimicking an animal’s natural environment and increasing its surrounding stimuli 54 (Mason, 1991; Passos et al., 2014). Enrichment can be divided into environmental, 55 behavioural and social categories, depending on whether an intervention targets an 56 individual’s physiological needs (environmental), or is intended to elicit natural behaviours 57 either from individuals (behavioural) or between conspecifics (social) (Shepherdson, 1994; 58 1998). This can be achieved by increasing the ‘behavioural repertoire’ of an animal in 59 captivity (Dawkins, 2006; Michaels et al., 2014). 60 It is now commonplace for behavioural enrichment to be provided to some taxa of captive 61 animals, particularly mammals and birds (de Azevedo et al., 2007). However, there has been 62 little research on the effects of enrichment on reptiles (Manrod et al., 2008; Burghardt, 2013; 63 Michaels et al., 2014). It has only recently become possible to properly cater to basic reptile 64 needs in captivity, due to progression in heat-and light-generating technology and a further 65 understanding of the environmental requirements for reptile health (Divers and Mader, 66 2005). This historic absence of appropriate husbandry is perhaps one reason for the relative 67 lack of interest in enriching reptiles (Rosier et al., 2011), as well as a relative lack of human 68 empathy for this group alongside a common perception reptiles are too neurologically simple 69 to suffer (Burghardt, 2013). This is despite the fact that more ‘sophisticated’ behaviours have 70 been recognised in reptiles, such as long lasting parental care in crocodilians (Garrick et al., 71 1977), spatial learning in Eastern water skinks (Eulamprus quoyii; Noble et al., 2012), and 72 parental care and sociality in Australian skinks (Egernia whitii, While et al., (2009) and E. 73 kingi, Master and Shine (2002), respectively). 74 This deficiency in empirical data means that the husbandry of captive reptiles is either 75 frequently based on anecdotal reports or human intuition, which can be particularly 3 76 unreliable when applied to animals that are so phylogenetically different from ourselves 77 (Langkilde and Shine, 2006). There is, however, a limited literature on the benefits of 78 enrichment for a small number of reptile species: box turtles (Terrapene) were found to have 79 a preference for an enriched environment over a ‘barren’ one (Case et al., 2005) and sea 80 turtles displayed fewer stereotypic behaviours when they were provided with novel objects 81 (Therrien et al., 2007). Among lizards, the Varanidae (Monitor lizard family) is known to show 82 various behavioural characteristics that are usually attributed to ‘higher’ vertebrates, such as 83 counting (Pianka et al., 2003) and problem solving (Manrod et al., 2008) and respond well to 84 both environmental and behavioural enrichment as a part of their husbandry (Manrod 2008; 85 Burghardt, 2013; Michaels et al., 2014). Conversely, one study suggests that for the eastern 86 fence lizard (Sceloporus undulatus), a non-varanid species, environmental enrichment does 87 not have a measurable effect on behaviour and corticosteroid levels (Rosier et al., 2011); 88 this study has been the centre of some controversy, however; see Burghardt (2013) for a 89 discussion. There is not yet sufficient evidence to draw general conclusions or identify 90 patterns about the effects of enrichment on reptiles,, and more research is required to 91 broaden the variety of ecotypes and phylogenetic groups studied. 92 In captivity, insectivorous lizards are typically ‘broadcast’ or ‘scatter’ fed, whereby multiple 93 prey insects are distributed around the enclosure at one time. Altering the way in which food 94 is presented can be used to provide behavioural enrichment for captive insectivores (Hurme 95 et al., 2003) by increasing physical activity and exploration of space and by eliciting a larger 96 frequency and variety of behaviours; thus reducing the risk of psychological or physical 97 diseases (mainly obesity, which can commonly occur in captive reptiles, (Dinse, 2004; 98 Donoghue, 2006)). 99 100 We used tree-runner lizards (Plica plica) to provide information on enrichment in a group of 101 lizards (Tropiduridae) that has not been studied previously. For our study, we assessed the 4 102 impact of a feeding enrichment device on their behaviour and enclosure use in comparison 103 with standard food presentation method (scatter or broadcast feeding) and a non-feeding 104 control. Although the activity budget of tree-runners in the wild is currently unknown, the 105 small size and relative simplicity of a typical captive environment means under stimulation is 106 likely to cause problems with captive animal welfare. 107 Increased activity in captivity when engaged in natural behaviours is likely to suggest 108 improved mental stimulation and will also contribute to the physical fitness of animals. 109 Increased activity levels and movement in the enclosure while engaged in natural 110 behaviours was therefore considered a desired outcome of enrichment, and that was what 111 we were assessing in our experiment. 112 113 2.Materials and Methods 114 Ethics statement: all experiments were non-invasive, with all treatments falling within the 115 scope of normal zoo husbandry, and did not compromise the welfare of the lizards. The 116 study was approved by the Zoological Society of London (ZSL) zoo research coordinators 117 before commencement. 118 2.1. Study animals 119 The study was conducted with five juvenile tree-runner lizards (Plica plica) at ZSL London 120 Zoo, England. All animals were captive-bred and full siblings. Tree-runner lizards are found 121 in rainforests in South America, in countries east of the Andes (i.e. Bolivia, Brazil and 122 Colombia) and are scansorial, climbing on vertical rocks and smooth-barked tree trunks (Vitt, 123 1991; Murphjy and Jowers, 2013).