Perspectives on the Use of Unmanned Aerial Systems (UAS) to Monitor Cattle Outlook on Agriculture XX(X):1–9 c The Author(s) 2018 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/ToBeAssigned www.sagepub.com/ SAGE Jayme Garcia Arnal Barbedo 1 and Luciano Vieira Koenigkan 1 Abstract The use of unmanned aerial systems (UAS) in agriculture has been growing steadily in the last decade, but their use to monitor and count cattle has been very limited. This paper analyses the reasons for this apparent lack of progress, considering both the technical challenges and the difficulties in defining target users that would benefit from a UAS- based system for monitoring cattle. Such an analysis is combined with the findings reported in several investigations dedicated to counting and monitoring wildlife to draw a comprehensive picture on the current situation, to suggest possible solutions to technical issues, and to delineate applications that could be useful to both cattle farmers and governments. The text concludes by showing that there are unexplored viable uses for UAS in livestock monitoring, especially in countries like Brazil, where extensive stockbreeding prevails. Keywords Livestock, image processing, drones, UAS, UAV, counting Introduction Monitoring livestock population is an essential part of the farm management. However, this may not be a trivial task, especially in very large properties adopting extensive stockbreeding, which is very common in countries like Brazil. In this context, aerial surveys arise as a potential solution. Satellite images are not well suited for this task because most sensors do not have enough spatial resolution to resolve individual animals – sensors like GeoEye 1 and WorldView could theoretically deliver enough resolution (Xue et al. 2017), but even in this case cattle would be represented by only a few pixels, and the cost of the images is still very high. Furthermore, cloud contamination can obscure features of interest (Anderson and Gaston 2013). Using manned aircraft for surveying cattle farms, although technically feasible, has a number of drawbacks associated: operation costs are high, elevated noise levels associated to most aircraft can disturb animals (Chr´ etien et al. 2015; Christie et al. 2016), accidents can cause loss of human life (Chabot and Bird 2015; Chr´ etien et al. 2015), and aircraft are not always suited for the installation of image sensors. Given the limitations associated to satellites and manned aircraft, the use of UAS appears as a more viable option to tackle the cattle monitoring issue (Zhang and Kovacs 2012). Most UAS are lightweight, low-cost aircraft platforms consisting of an aircraft component (Unmanned Aerial Vehicle UAV, also known as drone), sensor payloads, and a ground control station (Anderson and Gaston 2013; Watts et al. 2012). Basically, there are two types of drones that can be used in agricultural applications: rotary, which are very portable but have limited sensor payload capabilities; and fixed-wing platforms, which tend to be faster and have better payload capabilities, but are usually less portable and more expensive to acquire and operate. One of the main advantages of UAS is that they come in such a wide variety of configurations and capabilities (Hogan et al. 2017) that technical requirements attached to any given application are likely to be met by some available system. Although extrinsic factors such as costs involved and government regulations may discourage UAS use (Watts et al., 2012), prices continue to fall and many regulatory barriers are being removed, so adoption levels are expected to increase in the near future (Hogan et al. 2017). UAS have been used in agricultural applications for some time, especially in the context of precision agricul- ture (Zhang and Kovacs 2012; Hunt Jr. et al. 2014; Beloev 2016). Currently, the only country to adopt them in large scale is Japan. This is facilitated by the small average farm size, in which case small electric rotary wing systems are more cost effective (Freeman and Freeland 2015). However, in the last few years there has been a steep growth in coun- tries like the U.S., where agricultural applications already respond for 19% of the whole UAS market (Hogan et al. 2017). The use of UAS for monitoring livestock, and cattle in particular, has been limited. A few academic investigations on this subject have been dedicated to animal detection and counting (Chamoso et al. 2014; Longmore et al. 2017), cattle roundup (Jung and Ariyur 2017), feeding behaviour (Nyamuryekunge et al. 2016) and health monitoring (Webb et al. 2017). There have been also some patents deposited (Horton and Vorpahl 2017b,a; Trumbull and Myrtle 2017). The reasons for this apparent lack of 1 Embrapa Agricultural Informatics, Brazil Corresponding author: Jayme Garcia Arnal Barbedo, Embrapa Agricultural Informatics, Campinas, SP, Brazil. Email: jayme.barbedo@embrapa.br Draft version. Published version address: https://doi.org/10.1177/0030727018781876