Across the world, vertebrates cause considerable annual damage to agriculture, property, human health and safety, and natural resources referred as human-wildlife conflict (HWC). Among all vertebrate groups the species most often involved in serious damage are birds and mammals. Agro-ecosystems have provided many new opportunities for vertebrates to exploit, resulting in their becoming serious " pests & quot;.
This conflict has intensified as the human population has increased, efforts to get more production out of traditional croplands have intensified, and marginal lands have been placed into crop production. Additionally with the increasing demand of food due to increasing population, increased urbanization etc the wild life are facing habitat loss problem resulting in more human-wildlife conflicts. India is the home to many wild animals.
The Wild life Protection Act of India has further helped increase in the population of several herbivorous wild life which are very frequently migrating to crop fields causing immense damage to standing crops. Incidence of crop raiding by mammals like Hanuman langur (Presbytis entellus), Elephant (Elephas maximus), Blue bull (Boselaphustragocamelus), Sambar deer (Cervus unicolor), Black buck (Antilope cervicapra), Chinkara (Gazella gazellabennetti), Wild boar (Sus scrofa) etc has been widely reported from all over the country.
Nilgai or blue bull is one species which has been a matter of serious concern for farmers, scientists and policy makers alike, as it inflict serious damage to almost all the crops. Due to prolonged breeding activity and lack of potential predators, population of nilgai have increased considerably and become locally overabundant in the states of Gujarat, Uttar Pradesh, Haryana, Punjab, Rajasthan, Madhya Pradesh and Delhi. The extent of human-nilgai conflict varied from place to place within these states. Nilgai are reported to be capable of causing extensive damage to most agricultural crops. In low density areas, losses to wheat, gram, moong, guar and cotton crops are to the extent of 20-30%, 40-55%, 40- 45%, 20-35% and 25-40%, respectively. Whereas in high-density areas, the damage to these crops are as high as 60%. During our surveys, we have recorded 20% damage in mustard at flowering stage and 17% damage in mature castor besides trampling of crops like methi, mustard, wheat, guar etc.
In recent years incidences of road mishaps (7-12 cases/state/year) due to vehicular collisions have also increased. In Gujarat, they are colonised in all districts and their locally overabundant population is thriving well in crop fields. Since these animals are protected under Wildlife Protection Act (1972), their management through non-lethal approach is the pre requisite to minimize the crop losses as well as man- animal conflict.
Nilgai, B. tragocamelus is endemic to the Peninsular Indian and Indus divisions of the Indian Sub-region in the Asian Indo-Malayan Region (Corbet and Hill 1992). Crop-raiding by locally overabundant populations of nilgai has been widely reported in many parts of the country (Chauhan, 2011). The animal is strictly herbivore and crepuscular in habit, found inhabiting mainly the grasslands and woodlands. It avoids dense forest and has preference for plains and low hills with shrubs. In deserts earlier their activities were limited but with the extension in agriculture due to proliferation of irrigation system like canals and tube-wells, their problem in agriculture has increased manifold. It is found to damage most agricultural crops to a considerable extent (Chauhan and Singh, 1990; Chauhan, 2011).
Breeding occurs throughout the year in India, but the peak of mating is December-March, with the resulting calves born in September and October (Sankar et al, 2004). Nilgai are partially social in their habits (Roberts 1977), the heard size ranging from 2-7 in Western Rajasthan (Personal Observation), 2-43 individuals, with a mean group size of 4.0 in Sariska (Sankar 1994), mean group size of 2.2 in Gir, (Khan et al. 1995). In agricultural areas, nilgai will feed throughout the night in open fields
And retreat to the cover of forests during the day (Bohra et al. 1992; Mathai 1999; Prajapati and Singh 1994; Sharma 1981; Shukla and Khare 1998) and causes extensive damage to most agricultural crops. The signs of hoof marks, broken plants, uprooted plants, damaged crop and feeding marks give the indirect evidence of presence of nilgai in crop field from dusk to dawn (Goyal and Rajpurohit, 2000). In low density nilgai areas, losses to wheat, gram and moong crops were 20-30%, 40-55% and 40-45%, respectively. Damage to guar and cotton was 20-35% and 25-40%, respectively. Whereas in high density nilgai areas, damage to wheat, gram and moong was 35-60%, 50-70% and 45-60%, respectively (Chauhan, 2011).
The farmers reduced the area of cultivation for pulses (green gram & black gram), groundnut and cluster bean and shifted to sorghum and cotton in kharif and similarly area under gram has been reduced and farmers switched to taramira cultivation during rabi (Meena et al., 2014). Farmers across the nation are suffering badly due to their menace. Since these animals are protected under Wildlife Protection Act (1972), their management through non-lethal approach is the pre requisite to minimize the crop losses as well as man animal conflict (Tripathi and Rao, 2016).
The populations of nilgai occurring in U.S.A., Mexico and South Africa is introduced from Bangladesh (Lever 1985). It prefers open grassland and savannas and locally it is a significant problem species in agriculture (Leslie Jr., 2008). In southern Texas Captive female B. tragocamelus can breed at just over 2 years of age (Acharjyo and Misra 1971, 1973), and births in captivity occur in any month of the year when males and females are housed together (Acharjyo and Misra 1972). Nilgai exhibited sexual segregation, except during the breeding season (December to March) in USA, when groups were formed with a male, and one or more females and their calves (Sheffield et al. 1983). Maximum life span of Nilgai is 12–13 years in the wild (Berwick 1974; Mungall 2000; Mungall and Sheffield 1994) and 20–21 years in captivity (Grzimek 1990, Jones 1982 and Weigl 2005).
In southern Texas where confinement to large tracts of fenced land does not limit habitat availability, B. tragocamelus avoids dense woodlands and frequents improved pasture, sparse forests of live oak (Quercus virginiana) and scrub, and coastal prairies (Ables and Ramsey 1972; Schmidly 1994; Sheffield et al. 1971, 1983). Home ranges of B. tragocamelus in a 5,680-ha fenced area in southern Texas averaged 4.3 km 2 (0.6–8.1 km 2 ); males were transient, often traversing their entire home range daily, and were not completely impeded by fences (Sheffield et al. 1983).
Evaluation of various Management Strategies
The popular management strategies detailed will be evaluated to find out the best management
practice.
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Spraying of male excreta around the crop bunds
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Spraying of repellents
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Dusting of tobacco dust on top of crop early in the morning
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Barrier crop
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Bioacoustics
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Use of Fear provoking stimuli
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Traditional fencing and pulsating power fencing
REFERENCES
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Acharjyo, L. N., and Misra, R. 1973. A note on age of sexual maturity of two species of antelopes in captivity. Journal of the Bombay Natural History Society 70:378.
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Author Details
Dr. Jyoti. G. Dulera
Assistant Professor
AINPVPM; Agril. Ornitholgy
Anand Agriculture University
Anand-388110
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