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Full annual cycle bioenergetics model of migration applied to Galapagos tortoises—Model

Model for journal manuscript: Benefits of the destinations, not costs of the journeys, shape partial migration patterns


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Yackulic, C.B., 2017, Full Annual Cycle Bioenergetics model of migration applied to Galapagos tortoises—Model: U.S. Geological Survey software release,


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 species of poikilotherms, [...]


Point of Contact :
Charles Yackulic
Originator :
Charles B. Yackulic
Metadata Contact :
Terence Arundel
Publisher :
U.S. Geological Survey
Distributor :
U.S. Geological Survey - ScienceBase

Attached Files

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USGS_2017_CYackulic_Bioenergetics_Model_Software_Metadata.txt 5.04 KB
USGS_2017_CYackulic_Bioenergetics_Model_Software.txt 5.02 KB


The purpose of this code is run bioenergetics analyses based on inputted temperature, NDVI, and tortoise mass, calculate daily energetic surplus/deficits, determine whether migration is a better strategy than a sedentary strategy, and if migration is optimal determine the optimal timing of migration. The code relies on a number of empirically derived relationships and the model was parameterized for Galapagos tortoises on Santa Cruz Island. The code was also developed to determine the relative effects of tortoise mass on different aspects of the bioenergetics and movement portions of the model.


The author of this software code require that software code users contact them regarding intended use and to assist with understanding limitations and interpretation. This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from its authorized or unauthorized use.

Additional Information


Type Scheme Key
DOI doi:10.5066/F78K777N

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