Biological response to Przewalski’s horse reintroduction in native desert grasslands: a case study on the spatial analysis of ticks

TL;DR

Reintroducing Przewalski's horses in a desert grassland affects tick distribution, highlighting ecological interactions that need consideration in conservation efforts.

Contribution

This study demonstrates a novel spatial analysis of tick distribution linked to Przewalski's horse reintroduction in desert grasslands.

Findings

Hyalomma asiaticum ticks are most prevalent near donkey trails and water sources with fresh horse feces.

Tick risk areas strongly overlap with the distribution of Przewalski's horses, especially in high-risk zones.

Generalized Linear Models confirm a positive correlation between H. asiaticum and horse feces presence.

Abstract

Reintroduction represents an effective strategy for the conservation of endangered wildlife, yet it might inadvertently impact the native ecosystems. This investigation assesses the impact of reintroducing endangered Przewalski's horses into the desert grassland ecosystem of the Kalamaili Nature Reserve (KNR), particularly its effect on the spatial distribution of ticks. In a 25 km2 core area of Przewalski's horse distribution, we set up 441 tick sampling sites across diverse habitats, including water sources, donkey trails, and grasslands, recording horse feces and characteristics to analyze the occurrence rate of ticks. Additionally, we gathered the data of 669 fresh feces of horses. To evaluate the spatial dynamics between these feces and ticks, we used methods such as Fixed Kernel Estimation (FKE), Moran’s I spatial autocorrelation index, and Generalized Linear Models (GLM).

The dominant species of ticks collected in the core area were adult Hyalomma asiaticum (91.36%). Their occurrence rate was higher near donkey trails (65.99%) and water sources (55.81%), particularly in areas with the fresh feces of Przewalski's horses. The ticks’ three risk areas, as defined by FKE, showed significant overlap and positive correlation with the distribution of Przewalski's horses, with respective overlap rates being 90.25% in high risk, 33.79% in medium risk, and 23.09% in low risk areas. Moran's I analysis revealed a clustering trend of the fresh feces of Przewalski's horses in these areas. The GLM confirmed a positive correlation between the distribution of H. asiaticum and the presence of horse fresh feces, alongside a negative correlation with the proximity to water sources and donkey trails.

This study reveals the strong spatial correlation between Przewalski's horses and H. asiaticum in desert grasslands, underlining the need to consider interspecific interactions in wildlife reintroductions. The findings are crucial for shaping effective strategies of wildlife conservation and maintaining ecological balance.

The online version contains supplementary material available at 10.1186/s12862-024-02252-z.

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