Poaching activities, particularly of the rhinoceroses for its horn, has been a major concern for the authorities. Between 1980 and 2005, 567 rhinoceroses were hunted by poachers. Following a decreasing trend for the past few years, 18 one-horned rhinoceroses were killed by poachers in 2007. Reports have suggested that there are links between these poaching activities and funding of terrorist organizations. But these could not be substantiated in later years. Preventive measures such as construction of anti-poaching camps and maintenance of existing ones, patrolling, intelligence gathering, and control over the use of firearms around the park have reduced the number of casualties. Since 2013, the park used cameras on drones which are monitored by security guards to protect the rhino from armed poachers. Perennial flooding and heavy rains have resulted in death of wild animals and damage to the conservation infrastructures. To escape the water-logged areas, many animals migrate to elevated regions outside the park boundaries where they are susceptible to hunting, hit by speeding vehicles, or subject to reprisals by villagers for damaging their crops. To mitigate the losses, the authorities have increased patrols, purchased additional speedboats for patrol, and created artificial highlands for shelter. Several corridors have been set up for the safe passage of animals across National Highway–37 which skirts around the southern boundary of the park. To prevent the spread of diseases and to maintain the genetic distinctness of the wild species, systematic steps such as immunization of livestock in surrounding villages and fencing of sensitive areas of the park, which are susceptible to encroachment by local cattle, are undertaken periodically. Water pollution due to run-off from pesticides from tea gardens, and run-off from a petroleum refinery at Numaligarh, pose a hazard to the ecology of the region. Invasive species such as Mimosa and wild rose have posed a threat to the native plants in the region. To control the growth and irradiation of invasive species, research on biological methods for controlling weeds, manual uprooting and weeding before seed settling are carried out at regular intervals. Grassland management techniques, such as controlled burning, are effected annually to avoid forest fires. Observing the wildlife, including birding, is the main visitor activity in and around the park. Guided tours by elephant or Jeep are available. Hiking is prohibited in the park to avoid potential human-animal conflicts. Observation towers are situated at Sohola, Mihimukh, Kathpara, Foliamari, and Harmoti for wildlife viewing.