Human activities increase vigilance, movement and home range size of the endangered mountain nyala (Tragelaphus buxtoni) at the cost of foraging and resting

Ejigu Alemayehu Worku,Paul Evangelista,Anagaw Atickem,Nils Chr Stenseth,Afework Bekele,Jakob Bro-Jørgensen

doi:10.1016/j.gecco.2021.e01900

Abstract

Behavioral responses in wildlife due to human activities may often go unnoticed but have significant effects on population viability. This is a particular concern with endangered species characterized by small population sizes. From June 2016 to May 2017, we measured the effects of human activities on daily the activity budget and home range size of mountain nyala ( Tragelaphus buxtoni ), an endemic antelope of the Ethiopian highlands. We tracked two groups of mountain nyala from two study sites that differ in the level of human activities; Adaba-Dodola Community Conservation Area (Adaba-Dodola CCA) and Arsi Mountains National Park (Arsi Mountains NP). Our results showed that the time spent on vigilance and movement was dramatically higher in Adaba-Dodola Community CCA, where human presence is significant, than in Arsi Mountains NP, whereas the opposite was true for time spent foraging and resting. In addition, mean home range size (95% KDE) was significantly larger for the Adaba-Dodola CCA group (13 ± 7.4 km 2 ) than for the Arsi Mountains NP group (6.3 ± 2.7 km 2 ) covering larger areas during the dry season (18.7 ± 6.9 km 2 ) than the wet season (4.9 ± 1.0 km 2 ). The finding that increased investment in vigilance and movement trade-off against the restorative behaviors of foraging and resting in human-disturbed areas have implications for conservation managements; specifically, it underscores the need to (i) establish the fitness consequences of behavioral changes, and (ii) monitoring behavioral change in the disturbed population with the aim of bringing it closer to the undisturbed baseline. The study highlights the importance of protected areas, limiting human activities and monitoring the behavioral change of endangered species in human-disturbed areas. • Mountain nyala spent more time on vigilance and movement at the cost of restorative behaviors in high human impact areas. • High human activities lead to significantly larger home range size of mountain nyala. • The study highlights the importance of limiting human activities and monitoring behavioral changes in endangered species.

Highlights

Human activities can severely threaten the well-being of wildlife, by causing habitat loss and direct mortality, and by altering the wildlife’s behavior (Wilson et al, 2020)
We aimed to investigate the effect of human activities on the activity budgets and home range size of an endangered species, the mountain nyala, and its possible variations over seasons
We found a significant difference in 95% Kernel Density Estimations (KDEs) and 50% kernel isopleths to depict core areas (50% KDE) (Wilcoxon test, W = 112.5, p < 0.021) between the study groups, with greater home range size observed at the Adaba-Dodola CCA relative to the Arsi Mountains NP

Summary

Introduction

Human activities can severely threaten the well-being of wildlife, by causing habitat loss and direct mortality, and by altering the wildlife’s behavior (Wilson et al, 2020). Previous studies on ungulates have documented human activities affecting escape responses (Stankowich, 2008), activity budgets (e.g. impala Aepyceros melampus; Wronski et al, 2015), habitat use (e.g. mountain gazelles Gazella gazelle; Manor and Saltz, 2003, 2005), and home range size (e.g. giraffes Giraffa camelopardalis; Knüsel et al, 2019). These changes in behavioral responses can have severe consequences. This may be explained by a trade-off between the time and energy spent being alert and the time spent for foraging (Wang et al, 2011)

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