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UBC Theses and Dissertations

A knowledge representation system for hummingbird foraging behaviour in a laboratory environment Cahoon, Peter G.


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.

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