Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI/Dissertation Abstracts International.

A knowledge representation system is presented for studying hummingbird behaviour in a laboratory environment. It is shown that a set of procedural rules can be developed, based on numerical, symbolic and heuristic techniques to aid in discovering how a hummingbird learns a simple spatial grid pattern of food sources. The use of different types of tree-like data structures facilitates a systematic representation of the knowledge fragments and allows a thorough cross-examination of both the experimental designs and the hypotheses. The problem of analyzing a non-uniformly sampled time series of behaviour observations is discussed and a solution proposed that uses a mathematical matching algorithm called warping. A trajectory of individual feeder visitations is generated by a bird behaviour model. The technique of warping is used to test if this trajectory can be mapped to another generated by a bird foraging. The two-dimensional analogue of the warping technique is applied to the spatial grid in order to evaluate the degree of spatial specialization in the bird's foraging behaviour. A correlation measure is applied to groups of pairs of rule combinations to ascertain which of these account for most of the observed behaviour. It is shown that by using a collection of different types of similarity measures a procedural approach can be formulated to aid in the representation of the knowledge accumulated by a hummingbird during the course of a spatially distributed foraging experiment. These procedures are arranged in a hierarchy of choices and implemented in an interpreter which formed the basis for an expert system in hummingbird spatial foraging. Experimental applications of these numerical algorithms and data structures are presented. The system was then tested on a complete series of behaviours by testing five different individuals on the same design. The procedural algorithms were calibrated on the first individual and then applied to subsequent individuals to test the knowledge representation derived from the first case. The results from this experiment suggest that a knowledge representation system composed from these rule fragments can be developed into a grammar that would standardize the testing of all spatial foraging experiments. In addition it is indicated that representing knowledge as a hierarchy of procedural options is of use in testing the way in which experimental knowledge is gathered. The implications of this knowledge of spatial foraging can be tested interactively as an experiment progresses. / Graduate and Postdoctoral Studies / Graduate

Previous authors have concluded that hummingbird territorial boundaries would restrict pollen flow. I questioned the validity of this on the time scale of a blooming season for a system in which individual plants remained in flower while the territories surrounding them often changed in size and shape. To determine the effects of hummingbird foraging behavior on pollen flow, I studied six components of a hummingbird-plant pollination system: hummingbird territorial behavior, plant blooming time, foraging flight distances, pollen carry over, other pollinators, and plant breeding systems. Using this information I found I could depict pollen flow between two plants as a function of: 1) The flowering times of the plants. 2) The distance between the plants. 3) The amount of time these plants are surrounded by the same territorial boundaries. 4) The number of plants (or flowers) the bird visits before visiting the second plant. I found that the influence of territorial boundaries on pollen flow is determined not by the boundary of a single territory, but by the influence of all the territorial boundaries surrounding a plant while it is in bloom. Within these boundaries, the probability of pollen being transfered between two plants is a function of the amount of time they are within the same boundary. The length of hummingbird foraging flights is also a major determinant of pollen flow and the predominance of short flights between plants may restrict pollen flow probabilities. The restriction imposed by these short flights may be reduced by 1) long pollen carry over distances and 2) the longer flight distances between a perch and a plant. / Science, Faculty of / Zoology, Department of / Graduate

I consider two types of foraging situations. In the first type, the forager knows the location and quality of no more than one food item or habitat at a time. I call this myopic foraging. In the second situation, the forager may know the location and quality of more than one food item or habitat at a time. I call this periscopic foraging. I develop theoretically both models and the predictions generated by each. Myopic models predict that foragers should have a so-called "bang-bang" control with respect to the choice of food types. Periscopic models predict that foragers will have a continuous control with respect to the choice of food types. I experimentally tested for the presence of each type of control in a field study that employed hummingbirds feeding on artificial resources. As predicted by the theory, the transition of behavior from picky to opportunistic was significantly sharper for the myopic than for the periscopic foragers. Furthermore, theory predicts that there should be some range of relative values of the rich and poor food types over which the myopic foragers are opportunistic, while the periscopic foragers exhibit a partial preference. This prediction was supported by the data. I predicted that the partial preferences of periscopic foragers would result from the hummingbirds exploiting those poor quality feeders which were located nearest to the best foraging path among rich feeders. The data supported this prediction. Periscopic foragers also performed as predicted by becoming more selective on rich feeders as the densities of both rich and poor feeders increased. I developed a model of optimal sampling behavior that hypothesized birds have evolved in an environment of exploitative competition. The model predicted a rule of departure from a resource patch that depended on the presence or absence of nectar in a sampled as well as the expected quality of the nectar. Hummingbirds performed according to the model's predictions.

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Note: / During 14 months at San BIas, Nayarit, Mexico, 1 studied the energy èconomlcs of foraging hummingbirds. Amazilia rutila and Cynanthus latirostris were always the commonest species present and l documented their responses to food and competitors as resources changed between habitats and seasons. / Durant 14 mois j'ai 4tudié les aspects énergétiques économiques de la recherche de la nourriture chez les colibris, a San Blas, Nayurit en Mexique. Amazilia rutila et Cynanthus latirosis étaient les espèces les plus communes tout au long de l'année et j'ai étudié leur réponses aux compétiteurs intra- et inter spécifiques à mesure que leur ressources changeaient entre les habitats et au cours des saisons.

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