4.1 Has there been a shift in the number of frugivorous tracking studies?
Seed dispersal and movement ecology are increasingly integrated, and the use of tracking technology to study frugivorous species has significantly increased in the past 17 years, from 33 studies between 1978 - 2004 to 129 studies from 2005 – present. The number of studies calculating seed dispersal distances from frugivore movement increased from 8 studies in 1988 – 2006 to 59 studies from 2007 - present (Fig 1).
Radio tracking was the most commonly used tracking method for frugivores up until 2017, but since then, GPS tags have become the most used method. These increases are likely associated with the advancement in tracking technology and specifically, the reduced costs and increased availability of tags (Kays et al, 2015; Pimm et al, 2015). The smallest commercially available GPS tag in 2006 was 9.5g (Microwave Telemetry Inc, 2021) whereas now tags weighing < 3g are commercially available from numerous companies (e-obs GmbH, 2021; TechnoSmart, 2021). In addition, an increasing number of interdisciplinary teams are constructing GPS tags using commercially available components (Allan et al, 2013; Fischer et al, 2018; Paden & Andrews, 2020). These tags tend to be cheaper than traditional tracking devices, potentially increasing the number of research studies that have access to tracking technology. The potential for remote data download, ongoing battery miniaturisation and implementing solar-powered recharge capabilities have enhanced our ability to monitor species across greater distances, in remote locations, and across diverse landscapes, where previous attempts failed (Bouten et al, 2013; Hart et al, 2020; Shimada et al, 2020).