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Probability Learning in Prey Selection with a Great Horned Owl and a Red-Tailed Hawk

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Probability Learning in Prey Selection with a Great Horned Owl and a Red-Tailed Hawk Utah State University DigitalCommons@USU All Graduate Theses and Dissertations Graduate Studies 5-1976 Probability Learning in Prey Selection with a Great Horned Owl and a Red-tailed Hawk Deborah L. Mueller Utah State University Follow this and additional works at: https://digitalcommons.usu.edu/etd Part of the Psychology Commons Recommended Citation Mueller, Deborah L., "Probability Learning in Prey Selection with a Great Horned Owl and a Red-tailed Hawk" (1976). All Graduate Theses and Dissertations. 5796. https://digitalcommons.usu.edu/etd/5796 This Thesis is brought to you for free and open access by the Graduate Studies at DigitalCommons@USU. It has been accepted for inclusion in All Graduate Theses and Dissertations by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. ii ACKNOWLEDGEMENTS I wish to express my thanks to Dr. E. K. Crossman and Dr. Len Ruggiero for serving as committee members for my thesis. I also wish to express my thanks to Dr. David Balph who so graciously agreed to substitute for Len at my defense. To Dr. Carl D. Cheney, my chairman, I wish to express a special thanks for his support. Without his enthusiasm for com­ parative research, this study would not have been possible. I would also like to thank Newton and Bones, my subjects, whose cooperation made it all possible. Deborah L. Mueller iii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ii LIST OF TABLES V LIST OF FIGURES vi ABSTRACT vii INTRODUCTION 1 SURVEY OF RELEVANT RESEARCH 2 Ecological Approach 2 Hunting Strategy 5 Psychological Research 7 METHODS AND RESULTS • . • • . • • . • • • . • . • • . • • . 14 Experiment I 14 Subjects •• 14 Apparatus 14 Procedure 17 Results 18 Experiment II . 21 Subjects ••. 22 Apparatus . ... 22 Procedure .. 22 Results ... 22 Experiment III . 23 Subjects •••. 23 Apparatus 23 Procedure 23 Results 24 iv TABLE OF CONTENTS (Continued) Page DISCUSSION . 28 REFERENCES . 34 APPENDIX' . • . 37 VITA . 42 V LIST OF TABLES Table Page 1. Results from Visual and Spatial Discrete Trial Probability Problems with Pigeons . • • . • • . • . • • . • 10 2. Data from all Three Experiments for the Hawk and Owl 25 3. A Summary of Number of Correct First Responses and Reward Following Data from all Three Experiments for the Hawk and Owl . • . • . • . • . • • • . • . • • . • 26 4. Raw Data for Owl for Experiments I, IT, and III 38 5. Raw Data for Hawk for Experiments I, IT, and III 40 vi LIST OF FIGURES Figure Page 1. Response limits necessary to meet criteria for matching, maximizing, or randomizing .....•.....••. 13 2. Apparatus as positioned when testing the hawk. Boxes and perches were turned and appropriately placed for testing the owl . 15 3. Apparatus used in all three experiments . • . • . • . • • • . 16 4. Owl data from Experiments I, II, and III . • . • . • . 19 5. Hawk data from Experiments I, II, and III . • . 20 vii ABSTRACT Probability Learning in Prey Selection with a Great Horned Owl and a Red-tailed Hawk by Deborah L. Mueller, Master of Science Utah State University, 1976 Major Professor: Dr. Carl D. Cheney Department: Psychology The purpose of this study was to examine the hunting strategies of birds of prey in a probability learning situation. One great horned owl and one red-tailed hawk served as subjects. Three boxes and associated perches, each representing different potential prey areas, were placed in a room adjacent to the birds' regular housing and served as test apparatus. One box was loaded with an available prey item (mouse) on each trial and the birds were required to land on a perch in order to gain access to the associated box and to the potential prey. A discrete-trial, self-eorrection procedure was used. In Experiment I, Box 1 was loaded with a live laboratory mouse on 60% of the trials, Box 2 on 30% of the trials, and Box 3 on the remaining 10%. A response r equirement of sitting on the perch 5 seconds was programmed. In Experiment II, the probability of reinforcement was reversed for the 10 and 60% boxes and the response requirement was increased from 5 to 20 seconds. Experiment III returned the probability of reinforcement for each box to the viii values used in Experiment I. In Experiment III the mice were euthanized prior to each trial. The owl matched responses to probability of reinforcement in all three experiments while the hawk matched in Experiment II and showed matching toward two of the three boxes in Experiment III. In Experiment I the hawk had a Box 2 preference. This research extends the generality of the matching concept and suggests that predatory birds do not randomly hunt or hunt in only one location, but rather tend to search according to the probability of reinforcement for that location. (50 pages) INTRODUCTION The study of predator-prey relationships has warranted much con­ cern in recent years and led to extensive research. The interest ranges from concern over the indiscriminant shooting of eagles, to the coyote­ sheep predation controversy. The initial focus on predator-prey relations sprang from observational studies of the predator in his natural habitat. Ethologists, but primarily ecologists, would observe and record information on a particular species in a pre-determined study area. Such was the case in Craighead and Craighead's (1956) work in Michigan and Wyoming. Out of this study, valuable information was gathered concerning the number of nesting pairs of raptors in the study area, their clutch size and number, whether they returned year after year to the same nesting spot, and their prey selection habHs. Data collected in the wild on prey selection habits from the Craighead and Craighead study and others like it have generated interest in predators from an experimental viewpoint. Today, the approach to predator-prey study is both ecological and psychological in nature. 2 SURVEY OF RELEVANT RESEARCH Ecological Approach As noted, much of the early work done in the predator-prey area was observational in nature. Out of such work, Leopold (1933) proposed the existence of four components to the predator-prey interaction: 1. Prey density, 2. Predatory density, 3. Behavior of prey, 4. Behavior of predator. These four components were thus considered to govern predator density, prey density, and prey selection. Taking a somewhat different approach, but keep­ ing these four components in mind, Solomon (1949) chose to focus on responses. He proposed that a predator's response was either numerical or functional. A numerical response was simply a change in predator density while a functional response was a change in the number of prey of a population consumed by individual predators. Today, much of the ecological research is based on either Leopold's or Solomon's proposed components of predator-prey relation­ ship. In a classic study, Holling (1959) looked at small mammal predation on the European pine sawfly. He concluded that prey density was regulated by the predators and that only the first two of Leopold's four components were 3 important in predation. Holling emphasized, however, that such components as prey characteristics, density and quality of alternate foods, and the characteristics of the predator were important, although secondary to func­ tional and numerical responses. Holling (1966) expanded on the predator­ prey relationship by concluding that even though prey density determined predation, predator deprivation and proximity of prey were also important factors. Interest in raptors generated a great amount of observational research within an ecological/ethological framework. Fitch, Swenson, and Tillotson (1946) observed that red-tailed hawks on their study area in California preferred ground squirrels to other prey. This preference was attributed to a high density of ground squirrels since they were recently emerging from hibernation. Mclnvaille and Keith (1974) also reported a close correspondence between prey preference and prey density. When the snow­ shoe hare population in Alberta increased during 1970-71, great horned owls and red-tailed hawks responded by making the hare their preferred prey item. Each of the above studies contributed strong support to the first two of Leopold's components and to Solomon's functional and numerical responses in explaining prey preferences. But recently the last two of Leopold's components, the behavior of the predator and prey, have begun to receive extensive investigation. Much of this research orients about Tinbergen's (1960) "specific searching image," or SSI theory, which suggests that 4 each time a predator hunts, it tends to seek out the same prey species it encountered last. Tinbergen thus places prey selection ''within" the organism by attributing to the predator some mental image of the sought after prey. The importance of this hypothesis however, is that it emphasized the preda­ tor's behavior and the characteristics of the prey as instrumental in prey selection. Royama (1970) has criticized the SSI theory on the basis that Tinbergen's observations "cannot be explained by assuming the existence of search images in the predator's mind, nor can one prove the existence of search images" (p. 656), The outcome of the SSI controversy has been a shift to a more quantitative approach, with the emphasis on characteristics and behavior of both the predator and prey species. From a study with great tits, Royama (1970) suggested that predators may select larger and also more available prey items. Snyder (1975) studied both prey size and prey activity and found a clear interaction. Neither size nor activity alone, however, determined prey preference. Kaufman (1974b) presented _a live and a dead mouse simultaneously to owls and found a preference for live (active) mice. Mueller (1974, 1975) has suggested that kestrels may select "odd" prey, that is ones that differ in some manner from their conspecifics. "An odd animal in an aggregation might catch and hold the predator's attention more readily than the common animal" (Mueller, 1975, p.
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