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Enhancing Animal Movement Analyses: Spatiotemporal Matching of Animal Positions with Remotely Sensed Data Using Google Earth Engine and R

1
Conservation Ecology Center, Smithsonian National Zoo and Conservation Biology Institute, 1500 Remount Rd, Front Royal, VA 22630, USA
2
Working Land and Seascapes, Conservation Commons, Smithsonian Institution, Washington, DC 20013, USA
3
Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health & Comparative Medicine (IBAHCM), University of Glasgow, Glasgow G12 8QQ, UK
*
Author to whom correspondence should be addressed.
Academic Editor: Qiusheng Wu
Remote Sens. 2021, 13(20), 4154; https://doi.org/10.3390/rs13204154
Received: 20 September 2021 / Revised: 11 October 2021 / Accepted: 14 October 2021 / Published: 16 October 2021
Movement ecologists have witnessed a rapid increase in the amount of animal position data collected over the past few decades, as well as a concomitant increase in the availability of ecologically relevant remotely sensed data. Many researchers, however, lack the computing resources necessary to incorporate the vast spatiotemporal aspects of datasets available, especially in countries with less economic resources, limiting the scope of ecological inquiry. We developed an R coding workflow that bridges the gap between R and the multi-petabyte catalogue of remotely sensed data available in Google Earth Engine (GEE) to efficiently extract raster pixel values that best match the spatiotemporal aspects (i.e., spatial location and time) of each animal’s GPS position. We tested our approach using movement data freely available on Movebank (movebank.org). In a first case study, we extracted Normalized Difference Vegetation Index information from the MOD13Q1 data product for 12,344 GPS animal locations by matching the closest MODIS image in the time series to each GPS fix. Data extractions were completed in approximately 3 min. In a second case study, we extracted hourly air temperature from the ERA5-Land dataset for 33,074 GPS fixes from 12 different wildebeest (Connochaetes taurinus) in approximately 34 min. We then investigated the relationship between step length (i.e., the net distance between sequential GPS locations) and temperature and found that animals move less as temperature increases. These case studies illustrate the potential to explore novel questions in animal movement research using high-temporal-resolution, remotely sensed data products. The workflow we present is efficient and customizable, with data extractions occurring over relatively short time periods. While computing times to extract remotely sensed data from GEE will vary depending on internet speed, the approach described has the potential to facilitate access to computationally demanding processes for a greater variety of researchers and may lead to increased use of remotely sensed data in the field of movement ecology. We present a step-by-step tutorial on how to use the code and adapt it to other data products that are available in GEE. View Full-Text
Keywords: movement ecology; MODIS; NDVI; remote sensing; telemetry; tracking devices movement ecology; MODIS; NDVI; remote sensing; telemetry; tracking devices
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MDPI and ACS Style

Crego, R.D.; Masolele, M.M.; Connette, G.; Stabach, J.A. Enhancing Animal Movement Analyses: Spatiotemporal Matching of Animal Positions with Remotely Sensed Data Using Google Earth Engine and R. Remote Sens. 2021, 13, 4154. https://doi.org/10.3390/rs13204154

AMA Style

Crego RD, Masolele MM, Connette G, Stabach JA. Enhancing Animal Movement Analyses: Spatiotemporal Matching of Animal Positions with Remotely Sensed Data Using Google Earth Engine and R. Remote Sensing. 2021; 13(20):4154. https://doi.org/10.3390/rs13204154

Chicago/Turabian Style

Crego, Ramiro D., Majaliwa M. Masolele, Grant Connette, and Jared A. Stabach. 2021. "Enhancing Animal Movement Analyses: Spatiotemporal Matching of Animal Positions with Remotely Sensed Data Using Google Earth Engine and R" Remote Sensing 13, no. 20: 4154. https://doi.org/10.3390/rs13204154

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