3.1 Literature review
We reviewed 162 peer-reviewed research studies that used either radio transmitters or GPS tags to record the locations and movements of frugivorous animals. Of these 162 studies, 148 tracked frugivorous animals and 14 tracked seeds or fruits directly. Most of these studies focused on animal ecology and behaviour, and included themes such ascompetition, behaviour, foraging ecology, habitat use, landscape connectivity, migration, movement ecology and/ or resource selection , whereas 40 studies focused primarily on plant ecology , including seed dispersal and plant recruitment . The 162 articles identified in our search were published in 70 different journals covering different scientific themes, but principallyanimal ecology, conservation biology and tropical ecology . The most common journal was Biotropica, which published 11% of the studies reviewed here (see Supplementary Material 3).
The number of studies tracking frugivores increased from the first studies in the late 1970s to a peak of 13 per year in 2016 and 2018 (Fig 1). The earliest studies to use remote tracking techniques for monitoring frugivores were conducted in 1978 (see Heithaus & Fleming, 1978; Morrison, 1978a; Morrison, 1978b), but it was not until 2005 that more than three studies were published per year (Fig 1). Before 2005, a total of 33 studies were published (in 26 years from 1978 to 2004) and since 2005, 129 studies have been published (in 17 years from 2005 to 2022). The first studies to track frugivores using GPS tags were undertaken in 2008, and both focused on elephants (see Blake et al. 2008; Campos-Arceiz et al. 2008; Fig 1). Since then, the use of GPS tags in frugivore monitoring studies has increased, and from 2017, GPS tracking tags became more commonly used than radio transmitters (Fig 1).