A mad tree is troubling a red fox

By Chetan Misher and Abi Tamim Vanak

Indian desert fox or also known as the white-footed fox is a sub-species of red fox found across arid plains and sand-dunes of western India. Although red foxes are among the well-studied carnivore across their distribution range there has been little information available on the ecology of this Indian sub-species Vulpes vulpes pusilla. As a frequently seen fox species in the sandy region of the Thar desert in Rajasthan, the sighting of Indian desert fox is surprisingly low in the Banni grassland of Kutch district of Gujarat state.

Banni, once considered among Asia’s finest tropical grasslands is a vast expansion of low laying saline area between salt plains of the Greater Rann of Kutch and the elevated rocky habitat of mainland Kutch. The area spanning over around 2500 square km was predominantly formed of the mosaic of saline grasslands and brushland of Suaeda nudiflora along with seasonal wetlands formed during monsoon. Rapid encroachment of a woody invasive Prosopis juliflora in the past few decades has altered large parts of this open landscape into dense woodland. Due to its fast growth and drought tolerant capacity, P. juliflora locally known as “Ganda Bawal” or “mad-tree” has not only affected the livestock-based livelihood of pastorals by reducing grazing areas but also have ecosystem-wide impacts. We assumed that the Indian desert fox, described as open habitat specialist will be adversely affected by such massive structural change in the landscape.

In our paper, we studied the influence of woody invasive induced habitat transformation on the area occupied by the Indian desert fox in the Banni landscape. We were interested in knowing, how the structural change in habitat due to invasive P. juliflora, drives habitat selection of Indian desert fox at the landscape and den-site level. We used a landcover land use map to extract data on vegetation cover at the landscape level and collected ground-based variables at multiple den-sites. We also determined its food habits through analyses of scat samples collected from the den.

We found that the expansion of woody invasive shrub has a negative influence on desert fox occupancy at the landscape level. Expanding woodland is shrinking the Suaeda brushland and saline plains, the habitat which Indian desert fox is more likely to occupy. Due to seasonal waterlogging and high salinity, these habitats have avoided colonization of woody invasive shrub and provide suitable open and visible grasslands to the Desert fox. Den making is crucial for the most desert-dwelling animal to avoid the extreme climatic variability in deserts. We found that Indian desert fox makes their den in proximity to seasonal wetlands under rich cover of native grasses and forbs. Dietary analyses reveal that the Indian desert fox is highly dependent on insect and plant-based diets. Its food habit is completely adapted to the desert climatic condition as insects and plants are rich sources of water and nutrient in resource-poor desert landscapes.

These preliminary results can have significant conservation implications in managing the threatened grasslands of India. Woody encroachment is a major driver of grassland degradation and can have cascading impacts by affecting species at different levels. Such woody encroachment in grasslands can favor some generalist species such as Jackal by providing additional cover while reducing the availability of suitable habitat for specialists such as Indian desert fox. These differential impacts of woody invasion can completely alter the structure of ecological communities in the landscape. It is important to understand these differential impacts of plant invasion of different trophic groups for better management of these landscapes.  

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