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Showing posts from July, 2017

Animal Migration: Tactical Freedom During Strategic Constraint

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Recent research on animal migration continue to challenge the paradigm of assuming relatively straight-line routes between start locations and respective targets, as shown in a study on blackpoll warblers Setophaga striata (Brown and Taylor 2017). The warblers had a surprisingly high degree of back-and-forth displacements during migration; apparently more than can be explained by adjusting steps to local habitat attributes along the path.

Migration regards an endpoint on the scale continuum from short term movement bouts to long-distance seasonal displacements. Thus, one of the core challenges for more realistic models in wildlife ecology regards how to conceptualize and then formulate (in short: understand from simulations and from testing model predictions) the multi-scaled cognitive processing of environmental information and displacement decisions in animals. This insight should account for all time resolutions up to the migration scale.

From Insecta to Aves and Mammalia, indi…

Fowler’s Toads: the MRW Model Gains Additional Support

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Over the years our Multi-scaled Random Walk (MRW) model has been empirically supported by various anecdotal observations and pilot tests, but also more extensive results, in particular our multi-faceted statistical analysis of a large database of red deer Cervus elaphus movement (Gautestad et al. 2013). The MRW model has now also been scrutinized by a team working on data from a non-mammalian species, Fowler’s toads Anaxyrus fowleri (Marchand et al. 2017).

In its generic form, the MRW represents a very basic statistical-mechanical description of animal space use, implementing complex space use from spatial and temporal memory utilization. It illustrates a statistically scale-free distribution of displacements (you may call it Lévy-like) in combination with a given frequency of return events to previously visited locations. By changing the values of a small set of parameters the model can be put into the context of specific biological-ecological settings. Conversely, by fitting the mo…