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Insights into short and long-term crop-foraging strategies in a chacma baboon (Papio ursinus) from GPS and accelerometer data

Citation

Walton, Ben; Findlay, Leah; Hill, Russell (2021), Insights into short and long-term crop-foraging strategies in a chacma baboon (Papio ursinus) from GPS and accelerometer data, Dryad, Dataset, https://doi.org/10.5061/dryad.zw3r22870

Abstract

Crop-foraging by animals is a leading cause of human-wildlife ‘conflict’ globally, affecting farmers and resulting in the death of many animals in retaliation, including primates. Despite significant research into crop-foraging by primates, relatively little is understood about the behaviour and movements of primates in and around crop fields, largely due to the limitations of traditional observational methods. Crop-foraging by primates in large scale agriculture has also received little attention. We used GPS and accelerometer bio-loggers, along with environmental data, to gain an understanding of the spatial and temporal patterns of activity for a female in a crop-foraging baboon group in and around commercial farms in South Africa over one year. Crop fields were avoided for most of the year, suggesting that fields are perceived as a high-risk habitat. When field visits did occur, this was generally when plant primary productivity was low, suggesting that crops were a ‘fallback food’. All recorded field visits were at or before 15:00. Activity was significantly higher in crop fields than in the landscape in general, evidence that crop-foraging is an energetically costly strategy and that fields are perceived as a risky habitat. In contrast, activity was significantly lower within 100m of the field edge than in the rest of the landscape, suggesting that baboons wait near the field edge to assess risks before crop-foraging. Together this understanding of the spatiotemporal dynamics of crop-foraging can help to inform crop protection strategies and reduce conflict between humans and baboons in South Africa.

Methods

NDVI data:

Data from the Moderate Resolution Imaging Spectrometer (MODIS) on board of NASA's TERRA satellite were retrieved using the Google Earth Engine website (https://earthengine.google.com, Gorelick et al., 2017) and monthly NDVI values were downloaded from the MOD13Q1 data set (250m spatial resolution) over the home range of the study group (based on a minimum convex polygon of 62.7km2). Pixels were discarded based on associated quality assessment data sets, where only pixels with associated quality values of 0 (good) were retained. Average NDVI values were then taken from the remaining pixels for each month.

GPS and accelerometer data:

One adult female chacma baboon was fitted with a GPS and accelerometer collar with an automatic timer activated drop-off (Vectronic GPS‐PLUS collars 18; VECTRONIC Aerospace, Berlin, Germany). The collar recorded data for full days between 26/10/2013 and 18/10/2014. The collar took hourly GPS fixes from 05:00 to 19:00 South African Standard Time, with a further nocturnal fix at 24:00 to identify sleeping sites (N = 5728 fixes).  The collar also contained a bi-axial accelerometer, positioned at the back of the baboon’s neck, which recorded acceleration in the x-axis and y-axis at 4 Hz. The collar averaged acceleration in the two axes over 120s for storage.

Funding

NERC, Award: NE/S007431/1

NERC, Award: NE/J500215/1

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Durham University

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