Spatial positioning of individuals in a group of feral horses: a case study using drone technology
Spatial positioning of individuals in animal groups has been studied from numerous perspectives. However, although many studies have focused on spatial position in flocks of birds and schools of fish, relatively few studies have been conducted in mammals with high accuracy. Because some mammal species form societies, we wondered how social relationships among mammals within a group influence each individual’s spatial position. To address this issue, we used drones to obtain accurate positioning of individuals in a feral horse group on the Serra D’ Arga mountain in Portugal. The results of our study revealed the following characteristics: (1) the male in between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology. The harem group was located in the periphery; (2) as in other species, individuals had areas of repulsion and attraction, and (3) nearest neighbors were located more toward the sides than to the back or front. We also measured the social relationships between individuals in terms of grooming frequency. Social network analyses of the correlation between social and spatial relationships indicated that they are independent from each other. The present study is the first to reveal the characteristics of spatial positioning in a mammalian group using drone technology.
KeywordsDrone Horse Nearest neighbor Repulsion and attraction Spatial position Social relationship
Special thanks are due to Viana do Castelo city for supporting our project. We are also grateful to Agostinho Costinha, the director of Descubra Minho, Lourenço Almada of Associação O Caminho do Garrano. We also thank the villagers in Montaria for their support during our stay, Tetsuro Matsuzawa for the generous guidance throughout the study, and Dora Biro and Valéria Romano for helpful comments on an earlier version of our manuscript.
The study was financially supported by grants from the Japan Society for the Promotion of Science (JSPS core-to-core CCSN and JSPS-LGP-U04 to Tetsuro Matsuzawa, KAKENHI Nos. 15H01619 and 15H05309 to Shinya Yamamoto) and the Ministry of Education, Culture, Sports, Science, and Technology in Japan (MEXT No.16H06283 to Tetsuro Matsuzawa). We thank Lilly Gray and Adam Phillips, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.
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