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This code was created to run a bioenergetics-based model of movement for Galapagos tortoises. It calculates energetic surplus or deficit at a daily time scale based on inputted temperature (6 times a day) and NDVI value (a single value per days), as well as the mass of an individual. It then uses dynamic programming to determine the optimal timing of movement between two foraging habitats, given time-series of NDVI in each habitat, and temperatures in both habitats and in a transition zone between habitats. The model relies on a variety of empirically derived relationships, including allometric relationships, derived for different groups of organisms (i.e., some relationships are based on analyses across multiples...
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Ambient-shade temperature was measured every 4 h with iButton thermochrons (Maxim Integrated Products, Inc., Sunnyville, CA, USA) placed at 1m above-ground level for a previous paper (Blake et al., 2012 – DOI 10.1111/1365-2656.12020). The Normalized Difference Vegetation Index (NDVI) of the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument (Huete et al. 2002 - http://dx.doi.org/10.1016/S0034-4257(02)00096-2) was used as an index of vegetation quantity. Monthly average NDVI values within the range of each tortoise population were derived based on grid sampling within the convex hull created by upland and lowland relocations of migratory individuals during their sedentary (non-migratory) phases of movement....


    map background search result map search result map Full annual cycle bioenergetics model of migration applied to Galapagos tortoises—Data Full annual cycle bioenergetics model of migration applied to Galapagos tortoises—Model Full annual cycle bioenergetics model of migration applied to Galapagos tortoises—Data Full annual cycle bioenergetics model of migration applied to Galapagos tortoises—Model