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Food choice in fallow deer – experimental studies of selectivity
Stockholm University, Faculty of Science, Department of Zoology.
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, I experimentally investigate feeding selectivity in fallow deer (Dama dama), with respect to plant secondary compounds, especially tannins, which can decrease the quality of foods. I found that fallow deer avoided foods with higher amounts of tannic acid and Quebracho tannin, even though the deer ate some high-tannin food. The food choice was strongly dependent on the context in which the food was presented, so that the food choice in relation to tannin content was relative rather than absolute. When high-tannin food occurred at low frequency, the deer ate proportionally less from this type of food, at least when the difference in tannin content between the two foods was large. A basic implication is that an unpalatable plant type could benefit from its unpalatability, especially when occurring at low frequency. In experiments with two patches, the finding of a stronger within- than between-patch selectivity was mirrored in associational effects. First, low-tannin, palatable food was more eaten when occurring in a high-tannin patch, which corresponds to neighbour contrast susceptibility. Second, high-tannin, unpalatable food in a less defended patch was less eaten, which corresponds to neighbour contrast defence. A proximate cause of the associational effects can be the presence of a simultaneous negative contrast, which was experimentally demonstrated in an additional study. Individual differences in selectivity were present early in life and were consistent over five years, and selectivity was correlated with foraging exploratory behaviour. The results from this thesis suggest that fallow deer are selective in their food choice with respect to tannins from the beginning, and that the frequency of occurrence of different foods, but also the distance between foods and the complexity of presentation, influence the food choice. It is also suggested that a foraging behavioural syndrome is present in mammalian herbivores.

Place, publisher, year, edition, pages
Stockholm: Zoologiska institutionen , 2007. , 114 p.
Keyword [en]
behavioural syndrome, neighbour contrast defence, neighbour contrast susceptibility, simultaneous negative contrast, plant secondary compounds, tannins
National Category
Ecology
Research subject
Ethology
Identifiers
URN: urn:nbn:se:su:diva-6789ISBN: 91-7155-408-4 (print)OAI: oai:DiVA.org:su-6789DiVA: diva2:197053
Public defence
2007-05-25, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00
Opponent
Supervisors
Available from: 2007-05-04 Created: 2007-04-20Bibliographically approved
List of papers
1. The effect of food quality and relative abundance on food choice in fallow deer
Open this publication in new window or tab >>The effect of food quality and relative abundance on food choice in fallow deer
2002 In: Animal Behaviour, ISSN 0003-3472, Vol. 64, no 3, 439-445 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24223 (URN)
Note
Part of urn:nbn:se:su:diva-6789Available from: 2007-05-04 Created: 2007-04-20Bibliographically approved
2. Plant secondary compounds and the frequency of food types affect food choice by mammalian herbivores
Open this publication in new window or tab >>Plant secondary compounds and the frequency of food types affect food choice by mammalian herbivores
2005 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 86, no 9, 2450-2460 p.Article in journal (Refereed) Published
Abstract [en]

We have investigated food choice in individual fallow deer (Dama dama) encountering different relative frequencies of food types in the form of bowls containing pellets with either high or low concentrations of hydrolyzable tannin. We performed two similar experiments, one with large and one with small differences in tannic acid concentration. With small differences in tannic acid concentration, the ratio of the consumption per low- and high-tannin bowl was independent of frequency of occurrence, but with large differences in tannic acid concentration, we found frequency-dependent food choice. The deer ate proportionally less from high-tannin bowls if these occurred at low relative frequency. Variation between frequency treatments in the average order of encounter of bowl types might have produced this effect, because we found that the deer left a high-tannin bowl more quickly if they had switched to it from a low-tannin bowl. We argue that the perceived contrast between the tastes of different food types can play a role for food choice by mammalian herbivores.

Keyword
apostatic selection, contrast effect, Dama dama, fallow deer, frequency dependence, mammalian herbivory, plant secondary compounds, tannic acid, tannin
National Category
Behavioral Sciences Biology
Research subject
Ethology
Identifiers
urn:nbn:se:su:diva-24224 (URN)10.1890/04-0978 (DOI)
Available from: 2007-05-04 Created: 2007-04-20 Last updated: 2017-12-13Bibliographically approved
3. Associational effects of plant defences in relation to within- and between-patch food choice by a mammalian herbivore: neighbour contrast susceptibility and defence
Open this publication in new window or tab >>Associational effects of plant defences in relation to within- and between-patch food choice by a mammalian herbivore: neighbour contrast susceptibility and defence
Show others...
2006 In: Oecologia, ISSN 0029-8549, Vol. 147, no 2, 253-260 p.Article in journal (Refereed) Published
Identifiers
urn:nbn:se:su:diva-24225 (URN)
Note
Part of urn:nbn:se:su:diva-6789Available from: 2007-05-04 Created: 2007-04-20Bibliographically approved
4. A test of simultaneous and successive negative contrast in fallow deer foraging behaviour
Open this publication in new window or tab >>A test of simultaneous and successive negative contrast in fallow deer foraging behaviour
2007 (English)In: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 74, no 3, 395-402 p.Article in journal (Refereed) Published
Abstract [en]

The study of contrast investigates how rewards influence behaviour when animals are exposed to two or more levels of rewards compared to when they experience only a single level. The appearance of an exaggerated response to a shift in reward is referred to as a contrast effect and is an empirically well-established phenomenon. Although contrast effects could be important in foraging behaviour, no direct experimental tests of contrast effects in foraging by mammalian herbivores exist. During foraging, mammalian herbivores can encounter a range of plants that vary in the amount of nutrients and toxins. They may thus compare food items by taste, which in turn can give rise to contrast effects. In feeding experiments with fallow deer, Dama dama, we investigated the presence of simultaneous negative contrast. We found that the deer consumed less from a bowl of pellets containing 1% tannin when they shifted to it from a bowl with pellets containing only 0.25% tannin than when they shifted from another bowl with pellets containing 1% tannin. We estimated a fourfold difference between treatments in test food consumption at the highest levels of preloading, but none at the lowest levels. We found no support for successive negative contrast in experiments where the deer approached food in a runway, comparing a current reward with the memory of a previous reward. We suggest that simultaneous negative contrast can influence foraging decisions in mammalian herbivores.

Keyword
contrast effect, Dama dama, fallow deer, food choice, foraging, mammalian herbivore, tannin
National Category
Zoology
Identifiers
urn:nbn:se:su:diva-24226 (URN)10.1016/j.anbehav.2006.08.018 (DOI)
Available from: 2007-05-04 Created: 2007-04-20 Last updated: 2017-12-13
5. Behavioral syndromes and development of feeding selectivity in fallow deer
Open this publication in new window or tab >>Behavioral syndromes and development of feeding selectivity in fallow deer
Manuscript (Other academic)
Identifiers
urn:nbn:se:su:diva-24227 (URN)
Note
Part of urn:nbn:se:su:diva-6789Available from: 2007-05-04 Created: 2007-04-20 Last updated: 2010-01-13Bibliographically approved

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