Identifying the time scale of synchronous movement: a study on tropical snakes

Movement Ecology

Richard Shine²  Gregory P Brown²  Benjamin L Phillips³  Tom Lindström¹ 

[1] Department of Physics, Biology and Chemistry, Linköping University, Linköping, 58183, Sweden;School of Biological Sciences, University of Sydney, Sydney 2006, NSW, Australia;School of Biosciences, University of Melbourne, Melbourne 3010, VIC, Australia

关键词: Ectotherms;    Elapidae;    Relocation data;    Hierarchical Bayes;    Periodogram;   

Others  :  1182904
DOI  :  10.1186/s40462-015-0038-5

 received in 2015-02-02, accepted in 2015-03-09,  发布年份 2015

【 摘 要 】

Background

Individual movement is critical to organismal fitness and also influences broader population processes such as demographic stochasticity and gene flow. Climatic change and habitat fragmentation render the drivers of individual movement especially critical to understand. Rates of movement of free-ranging animals through the landscape are influenced both by intrinsic attributes of an organism (e.g., size, body condition, age), and by external forces (e.g., weather, predation risk). Statistical modelling can clarify the relative importance of those processes, because externally-imposed pressures should generate synchronous displacements among individuals within a population, whereas intrinsic factors should generate consistency through time within each individual. External and intrinsic factors may vary in importance at different time scales.

Results

In this study we focused on daily displacement of an ambush-foraging snake from tropical Australia (the Northern Death Adder Acanthophis praelongus), based on a radiotelemetric study. We used a mixture of spectral representation and Bayesian inference to study synchrony in snake displacement by phase shift analysis. We further studied autocorrelation in fluctuations of displacement distances as “one over f noise”. Displacement distances were positively autocorrelated with all considered noise colour parameters estimated as >0. We show how the methodology can reveal time scales of particular interest for synchrony and found that for the analysed data, synchrony was only present at time scales above approximately three weeks.

Conclusion

We conclude that the spectral representation combined with Bayesian inference is a promising approach for analysis of movement data. Applying the framework to telemetry data of A. praelongus, we were able to identify a cut-off time scale above which we found support for synchrony, thus revealing a time scale where global external drivers have a larger impact on the movement behaviour. Our results suggest that for the considered study period, movement at shorter time scales was primarily driven by factors at the individual level; daily fluctuations in weather conditions had little effect on snake movement.

【 授权许可】

   
2015 Lindström et al.; licensee BioMed Central.

【 图 表 】

Figure 1.

Figure 2.

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