The ‘mad babul’ spreads its roots, dominating Indian desert fox habitat

Gujarat’s Banni grasslands are home to 40 species of grasses – from a rare grass that has no local name to one that almost only grows inside well-walls. The grasses, in turn, support a variety of wildlife, from the endemic spiny-tailed lizard to migratory birds that make their way here after the monsoon transforms dry tracts into lush wetlands. But a woody invasive plant, Prosopis juliflora, is encroaching much of the grassland. This in turn is resulting in the loss of habitat and resources for the Indian desert fox, an open habitat species. This could potentially impact the conservation status of this already range-restricted species in India.

Banni, once one of Asia’s largest tropical grasslands, is situated at the northern border of Kutch district in Gujarat. It falls within the hot semi-arid region of India, with around 300 mm average annual rainfall. The vegetation here is typically grass-dominated along with halophilic vegetation in high saline areas.

In the 1950s, the damming of rivers that drained into Banni caused a sudden spurt in salinity incursion. Local authorities identified it as a cause for concern. To arrest it, the state government began to introduce a tree from South America, known as Prosopis juliflora, to the area in the 1960s. “The salt-tolerant and fruit-bearing tree has flourished in the region ever since. We call it gando baval or ‘mad babul’ now, since it now grows everywhere,” says Madhav, a local resident who has been working with researchers in the area to document the spread of the particular species.

Ecologically, Prosopis juliflora is a resilient species and can withstand extremely harsh weather and soil conditions. Its extensive root system enables it to tap groundwater easily, so it remains green even in peak summer. “It is exactly the reason why the species was systematically planted across different dry landscapes of India – to ‘green-ify’ deserts, and provide livelihood and fuelwood to locals in these areas,” says Chetan Misher, a researcher at the Ashoka Trust for Research in Ecology and the Environment, who co-published a paper in 2021 on the occupancy and diet of the Indian desert fox in a Prosopis juliflora-invaded, semi-arid grassland.

Naturally dry landscapes also present less complex vegetation communities, therefore posing less resistance to any newly introduced species. Thus, the Prosopis juliflora has spread rapidly in the region. In fact, since the introduction of the invasive species in the 1960s, more than 50% of the Banni grasslands have been transformed into stable woody vegetation-dominated landscape. 

Reducing habitat

The rapid expansion of the woody species is, however, shrinking the suitable habitat for the desert fox, affecting its population negatively. “The desert fox (which is a specialist in open dry grasslands and deserts) avoids the habitat encroached by Prosopis and uses native saline brushlands more often,” says Misher.

The Indian desert fox (Vulpes vulpes pusilla) is one among three subspecies of red fox found in India. The other two subspecies are the Kashmir fox and the Tibetan red fox. Not much is published about the Indian desert fox, but what is known by those studying it is that its habitat includes dunes, saline scrub grasslands and semi-arid scrub savannah. It shelters in burrows dug in the ground near the vegetation cover of reeds and bushes. Gerbils, other rodents and spiny-tailed lizards are its main prey.

This sub-species has been given the highest legal protection in India (Schedule I) under the Indian Wildlife (Protection) Act, 1972. But despite its legal status, it is poached for its fur and meat. Rapid urbanisation, industrialisation and the introduction of invasive plant species, like the Prosopis juliflora in their habitats have also had an impact on the desert fox numbers. “Like any other species in the desert landscape, the Indian desert fox is also found commonly in human-dominated areas and there is no particular conservation plan for the species in place currently. But Prosopis encroachment tends to provide a favourable habitat to some generalist species such as the jackal, and that in turn increases the risk of intra-guild competition and predation for the desert fox, further affecting its population and distribution,” says Misher.

Way ahead 

While the local people and government agencies are aware of the impact of invasive species such as Prosopis juliflora, the problem lies in the lack of an inclusive plan, and involvement of locals and other stakeholders in decision-making when it comes to dealing with invasive species.

“Complete removal of Prosopis followed by regular removal of new seedlings for a few years is the more efficient way to restore native habitats who have been impacted by the Prosopis invasion. But restoration is multi-disciplinary and other aspects of Prosopis need to be looked upon before any steps are taken, such as livelihood dependency of locals on the Prosopis,” says Misher. Their recent study also showed that mechanical removal of the Prosopis leads to three-time higher species richness and six-time higher vegetation cover of herbaceous plants.

Also, this isn’t just about the desert fox. Most desert species are ignored, note the researchers. Little is known about them or the impact invasive species have on them. “Our study found that the native habitats of the Banni landscape support the unique dryland adapted species such as pigmy gerbils and desert gerbils, and these species were totally absent from any Prosopis encroached habitat showing their sensitivity towards bush encroachment. So yes, long-term ecological monitoring is required for both invasive species and wildlife population management,” says Misher.

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Banner image: Desert fox pups at a den. Photo by Sumeet Moghe/Wikimedia Commons.