Impact of agrarian land use and land cover practices on survival and conservation of nilgai antelope (Boselaphus tragocamelus) in and around the Abohar wildlife sanctuary, northwestern India

Demographic effects of road mortality on mammalian populations: a systematic review

In light of rapidly expanding road networks worldwide, there is increasing global awareness of the growing amount of mammalian roadkill. However, the ways in which road mortality affects the population dynamics of different species remains largely unclear. We aimed to categorise the demographic parameters in mammalian populations around the world that are directly or indirectly affected by road mortality, as well as identify the most effective study designs for quantifying population-level consequences of road mortality. We conducted a comprehensive systematic review to synthesise literature published between 2000 and 2021 and out of 11,238 unique studies returned, 83 studies were retained comprising 69 mammalian species and 150 populations. A bias towards research-intensive countries and larger mammals was apparent. Although searches were conducted in five languages, all studies meeting the inclusion criteria were in English. Relatively few studies (13.3%) provided relevant demographic context to roadkill figures, hampering understanding of the impacts on population persistence. We categorised five direct demographic parameters affected by road mortality: sex- and age-biased mortality, the percentage of a population killed on roads per year (values up to 50% were reported), the contribution of roadkill to total mortality rates (up to 80%), and roadkill during inter-patch or long-distance movements. Female-biased mortality may be more prevalent than previously recognised and is likely to be critical to population dynamics. Roadkill was the greatest source of mortality for 28% of studied populations and both additive and compensatory mechanisms to roadkill were found to occur, bringing varied challenges to conservation around roads. In addition, intra-specific population differences in demographic effects of road mortality were common. This highlights that the relative importance of road mortality is likely to be context specific as the road configuration and habitat quality surrounding a population can vary. Road ecology studies that collect data on key life parameters, such as age/stage/sex-specific survival and dispersal success, and that use a combination of methods are critical in understanding long-term impacts. Quantifying the demographic impacts of road mortality is an important yet complex consideration for proactive road management.

Effectiveness of different management strategies against Nilgai population (Boselaphus tragocamelus) in Punjab Province of India

Crop raiding has been reported in many parts of Punjab as a result of an overabundance of nilgai antelopes (Boselaphus tragocamelus) and farmers are constantly battling to save their crops. In the present study, various management strategies such as physical deterrents (nylon rope, nylon net and garden net), visual repellents (scarecrow and reflective ribbon), chemical repellents (different concentrations of Neelbo and Ecodon (based on ricinoleic acid) applied by spraying, soaking jute rope, soaked in wood shavings packed in plastic bags and paper cups) and biological deterrents (bioacoustic device and different concentrations of faecal solution of horse, tiger and Himalayan black bear) were evaluated to minimize the damage caused by nilgai. Nylon net was the most promising method, providing complete protection against nilgai, which can be used for protecting crops at vulnerable stages with a one-time cost. The nylon rope and garden net provided partial protection from nilgai damage. The bioacoustic device and reflective ribbon were also effective for a short period of time. Neelbo was found more effective as chemical repellent against nilgai. The faecal solution of horse and Himalayan black bear remained effective as repellent for 10 days. It is thus concluded that while comprehensive damage prevention may be difficult, animal management devices can help reduce nilgai damage at vulnerable stages of the crop. The employment of a range of management devices at the proper time can be part of a cost-effective system to keep nilgai damage at acceptable levels.