The number of species varies greatly among taxa. In birds, for example, the parvorder Passerida contains 3556 species while the Odontophorida (New World Quails) contains only six species. This uneven distribution of species among avian taxa is not random and therefore warrants an explanation. The behavioral drive hypothesis stipulates that the capacity for innovation, coupled with the rapid transmission of the behavioral novelty to conspecifics, may expose individuals to new selective pressures and help fix mutations that would otherwise not be expressed. This should lead to accelerated rates of evolution. I test this hypothesis by examining the link between behavioral flexibility and the number of species per taxon. I adopt a comparative approach and seek a general explanation of richness, thereby removing the traditional focus placed on the success of the songbirds and on their complex singing apparatus. I use two measures of flexibility, feeding innovation rate and relative brain size. (Abstract shortened by UMI.)

A model is presented which predicts the simultaneous searching strategy (walking speed) and diet choice of a terrestrial predator, assuming the behaviour is selected to maximize the net rate of energy gain The model predicts an inverse relationship between predator velocity and prey availability, independent of prey type, and that predators should stop foraging below a critical prey availability. It is predicted that diet choice should become more restricted with increases in the availability of highly profitable prey (ie net energy return per second spent handling) but broader with increases in the relative density of low profitability prey. Parameters of the model, prey availability, energy content and handling time were measured for the common prey of two estuarine wading birds - the Redshank (Tringa totanus L.) and the Oystercatcher (Heamatopus ostralegus L ) on the mid—estuarine Firth of Forth, Scotland. Predator energy expenditures whilst handling and searching for prey were estimated using radiotelemetry of the heart rate from six unrestrained Redshank in an outdoor aviary. At the lower critical temperature (16°C), the handling costs averaged l.9xBMR (Aschoff and Pohl 1971) and 2.OxBMR for pecking and probing respectively, whilst searching cost l.7xBMR (walking at 30cm.s-1). Observed walking speeds in both species were well matched with the model's predictions at medium and high encounter rates, but at low encounter rates (2 items m walked-1) were lower than predicted The critical low availability at which it is profitable to stop foraging did not occur in the field during the study period (February 1981-May 1982). In Redshank the observed diet was not consistent with the net energy maximization model in Autumn or Early and Late winter and instead fitted better a model of gross protein maximization. In spring the observed diet was best described by the maximization of net energy gain. Including costs had a significant effect on the diet predictions in the Redshank. Differences between predicted and observed diet choice in the Oystercatcher were a result of the underselection of very large, high profitability items and partial selection of low ranking prey. Including costs had no effect on the model's predictions for the Oystercatcher. Differences between model predictions and the observed behaviour are discussed In the 'prizing' Oystercatcher differences appeared to be a result of inaccuracy in collection of one of the model parameters (unsuccessful manipulation rates) and invalid assumptions concerning the discriminant abilities of the predator. Whilst conflicting selective pressures - protein requirements and the avoidance of bill damage, probably explain the deviations in Redshank and 'hammering' Oystercatchers respectively.

I studied foraging ecology of black oystercatchers (Haematopus bachmani) in the rocky intertidal. The aims of this study were: 1) to analyze prey choice and patch choice by adult black oystercatchers and evaluate how well their foraging performance was predicted by foraging theory; 2) to study development of foraging in young oystercatchers; 3) to indirectly examine the relationship between parental foraging performance and fitness by measuring chick growth and chick production. The following conclusions were reached: 1) Prey selection by oystercatchers was generally as predicted by theory, but birds showed partial preferences for prey. Patch choice followed general theoretical predictions, but profitabilities achieved within particular patch types were highly variable. Reasons for this are discussed. 2) Growth and physical maturation are important components in development of foraging. During the period of this study, chicks were heavily dependent on parental feeding, and the ability of chicks to forage independently developed after chicks left their natal area at about 50 days of age. 3) Chick growth varied between one-chick and two-chick broods, and this may be related to parental foraging performance. However, during this study chick production was constrained by weather and predation, and no relationship between parental foraging performance and fitness could be defined. / Science, Faculty of / Zoology, Department of / Graduate

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published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

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This research seeks to pinpoint the telencephalic structures most closely correlated with feeding flexibility, which is operationalised as feeding innovation rate per taxon. By calculating a weighted average per taxon of 1030 feeding innovations collated from five zones of the world (western Europe, North America, Australia, New Zealand and India), the study shows that relative size of the hyperstriatum ventrale and, to a lesser extent, the neostriatum , best predicts weighted innovation rate; these two structures are thought to be functionally equivalent to the mammalian neocortex. The worst telencephalic predictors of innovation rate are two structures respectively thought to be involved in primary visual projection and the control of stereotyped, species-specific behaviour, the wulst area and the paleostriatum. / A second presumed correlate of behavioural flexibility, taxonomic variation in the use of urbanised and other anthropogenically-modified habitats, shows a consistent pattern in four geographical zones (Great Britain, North America, Australia and New Guinea), as well as a qualitative association with the relative size of the forebrain. There is no linear correlation, however, between urbanisation rate per taxon and either forebrain size or innovation rate, suggesting that other variables like diet, tameness and neophilia may have to be quantified at finer taxonomic levels in future studies of opportunism in habitat use.