Johansson, O., Alexander, J. S., Lkhagvajav, P., Mishra, C., Samelius, G. (2024). Natal dispersal and exploratory forays through atypical habitat in the mountain-bound snow leopard. Ecology, 2024(e4264), 1–4.
Abstract: Understanding how landscapes affect animal movements is key to effective conservation and management (Rudnick et al., 2012; Zeller et al., 2012). Movement defines animal home ranges, where animals generally access resources such as food and mates, and also their dispersal and exploratory forays. These movements are important for individual survival and fitness through genetic exchange within and between populations and for colonization of unoccupied habitats (Baguette et al., 2013; MacArthur & Wilson, 1967). Dispersal and exploratory movements typically occur when young animals leave their natal range and establish more permanent home ranges (Greenwood, 1980; Howard, 1960). In mammals, natal dispersal of males is usually more frequent and happens over greater distances compared with that of females (Clobert et al., 2001; Greenwood, 1980).
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Sharma, M., Khanyari, M., Khara, A., Bijoor, A., Mishra, C., Suryawanshi, K. R. (2024). Can livestock grazing dampen density-dependent fluctuations in wild herbivore populations? Journal of Applied Ecology, , 1–12.
Abstract: 1. Conservation policy for the high mountains of Asia increasingly recognises the need to encompass large multi-use landscapes beyond the protected area network. Due to limited long-term research in this region, our understanding of even fundamental processes, such as factors regulating large mammal populations is poor.
2. Understanding the factors that regulate animal populations, especially those generating cyclicity, is a long-standing problem in ecology. Long-term research across multiple taxa (mainly from Europe and North America) has focussed on the relative roles of food and predation in generating cyclicity in population dynamics. It remains unclear how trophic interactions that are influenced by anthropogenic stressors can affect population dynamics in human-modified landscapes.
3. We present a 10-year study to compare the effects of livestock grazing on density-dependent dynamics in two populations of bharal, Pseudois nayaur, in the Himalayas. We combine this with a mechanistic understanding of whether density dependence in these two sites acts predominantly by affecting adult survival or recruitment. We compared and quantified density dependence in the bharal population by fitting Bayesian Gompertz state-space models.
4. We found evidence for negative density dependence which indicates possible cyclic dynamics in the bharal population of the site (Tabo) with low livestock density. The population dynamics of this site were driven by recruited offspring—with a 2-year density-dependent lag effect—rather than adult survival. In the site with high livestock density (Kibber), this density dependence was not detected. We postulate the potential role of excessive grazing by livestock in affecting offspring recruitment, thereby affecting the bharal population in Kibber.
5. Synthesis and applications: Our results suggest that conservation action to facilitate wild herbivore population recovery, such as the development of protected areas and village reserves, needs to account for density-dependent regulation. Sites with trophy hunting require continuous monitoring to understand the effects of density dependence so that appropriate hunting quotas can be formulated.
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