Can an intermittent presentation method reduce habituation to olfactory enrichment?
Using the Bolivian squirrel monkey in two European Zoos.


137 Seiten

Department of Biology, University of Copenhagen
Section of Ecology and Evolution, Professor MSO Torben Dabelsteen
Zoo Salzburg


Environmental enrichment is an animal husbandry procedure that attempts to enhance the quality of care and well-being of captive animals by providing stimuli necessary for optimal welfare. Most enrichment objects are implemented with the aim of generating some change in the behaviour of the study animal, and these changes often include stimulation or prevention of specific behaviours that are thought to be connected to improved fitness and welfare. Traditional methods of environmental enrichment have mainly focused on changing feeding regimes, providing manipulable objects, and implementations of cognitive challenges. More recently, the focus have shifted toward the benefits of odours as a form of enrichment. Olfactory enrichment is the application of scent or scented material to an animal’s enclosure. Typical odour used includes food scents, essential oils, herbs, spices, faeces, urine and other scents derived from prey or predator species, and artificial scents. However, a reoccurring obstacle in provision of environmental enrichment is that animals will habituate to the presented stimulus. Thus, investigations of how habituation can be delayed are needed. The Bolivian squirrel monkey (Saimiri boliviensis boliviensis) is a small New World monkey that is broadly distributed in the Amazonian basin and Guiana plateau of South America. Although olfactory behaviours occurs infrequently in the wild, both field and captive research have found that male squirrel monkeys use olfaction to evaluate the receptiveness of females, and that female squirrel monkeys use smell to identify individuals, especially their infants. Squirrel monkeys, furthermore, engage in various scent-marking behaviours and in this species it includes (amongst others) rump rubbing, back rubbing and urine wash. This study attempted to alter the behavioural time budget of two troops of Bolivian squirrel monkeys by introducing sugar-free, pineapple flavoured, diluted fruit juice as a type of olfactory enrichment. Furthermore, it investigated if a reduction in stimulus presentation could decrease the habituation rate towards the juice. Additionally, the effects on the frequency of scent-marking in the troops were investigated. All statistical analyses were based on data collected in two European zoological gardens, Odense Zoo in Denmark and Salzburg Zoo in Austria, in July and September 2013 (Odense) and October-November 2013 and January 2014 (Salzburg). The study resulted in a manuscript called: “Can an intermittent presentation method reduce the habituation to olfactory enrichment? – Using the Bolivian squirrel monkey in two European Zoos.” This manuscript consists of an analysis of changes in frequency of occurrence of 13 behaviours, two analyses of changes in the frequency of enrichment directed behaviours over a five day period in the two presentation methods, and analyses of the changes in type and frequency of nine different scent-marking behaviours. Data was collected using personalized check-sheets and a combination of instantaneous scan – and one/zero sampling with a two minute sample interval. Behavioural observations were done twice a day. The aim of this enrichment study was to gain knowledge about the efficacy and effect of pineapple juice as an olfactory enrichment stimulus and whether previous findings on repeated enrichment presentation and habituation could be applied to this New World monkey, and whether scent application affected the frequency of scent-marking behaviours. The results of the statistical analyses indicates that pineapple juice appears to cause few alterations to the daily time budget of captive squirrel monkeys and likewise had no apparent effect on the occurrence of scent-marking. Conversely, changing the frequency of enrichment presentations appears to reduce the rate of habituation. Leaving gabs between presentations session resulted in a recover in the interest towards the olfactory enrichment.



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