Wednesday, August 6, 2008: 1:30 PM
103 C, Midwest Airlines Center
Background/Question/Methods
What do the following have in common: Peruvian and North Sea fishermen, grey seals, microzooplankton, wandering albatrosses, bumblebees, deer, reindeer, jackals and human hunter gatherers? Through a series of papers it has been claimed that they all exhibit similar movement patterns, known as Lévy flights (which are random walks whose step lengths come from probability distributions with heavy power-law tails). For fishing boats, it has been proposed that, using a Lévy flight analysis, the GPS movement data of the boats can be used to provide a real-time ecosystem indicator. However, the pioneering results concerning Lévy flights by albatrosses, bumblebees and deer, have recently been overturned (Edwards et al., Nature, 449:1044-1048, 2007).
Results/Conclusions
Here we clearly demonstrate, using Monte Carlo simulations, that the methods previously used to infer Lévy flights are inaccurate (Edwards, J. Anim. Ecology, submitted). Using likelihood methods and Akaike weights, re-analysis of some of the aforementioned data sets finds that the data are not described by a Lévy flight. Examination of the grey seal data, for example, suggest that no simple probability distribution will describe the data, and that a more detailed biological model would be required.
What do the following have in common: Peruvian and North Sea fishermen, grey seals, microzooplankton, wandering albatrosses, bumblebees, deer, reindeer, jackals and human hunter gatherers? Through a series of papers it has been claimed that they all exhibit similar movement patterns, known as Lévy flights (which are random walks whose step lengths come from probability distributions with heavy power-law tails). For fishing boats, it has been proposed that, using a Lévy flight analysis, the GPS movement data of the boats can be used to provide a real-time ecosystem indicator. However, the pioneering results concerning Lévy flights by albatrosses, bumblebees and deer, have recently been overturned (Edwards et al., Nature, 449:1044-1048, 2007).
Results/Conclusions
Here we clearly demonstrate, using Monte Carlo simulations, that the methods previously used to infer Lévy flights are inaccurate (Edwards, J. Anim. Ecology, submitted). Using likelihood methods and Akaike weights, re-analysis of some of the aforementioned data sets finds that the data are not described by a Lévy flight. Examination of the grey seal data, for example, suggest that no simple probability distribution will describe the data, and that a more detailed biological model would be required.
