1.2. Drivers of Demand
1.3. Drivers of Supply
2. Requirement of Poaching Detection Systems
- Energy Efficiency: Many locations in wildlife areas are very remote and do not have available infrastructure such as road, power lines, and network. Therefore, an APS can be isolated from power lines and rely solely on battery power and energy harvesting technologies. Any solution that is deployed in areas without infrastructure should be to operate for long periods of time to minimize costs and effort. The goal of an APS could be to have devices placed on animals or in the field, unattended, for months or years to come. Each device should be able to efficiently manage its local power supply in order to maximize the total system life-time in the long run, by deploying it on the field with a solar panel or energy harvesting mechanism to increase the energy efficiency by considering a hardware solution.
- Deployment issues: Game park managers are often uncomfortable with obtrusive technologies such as sensor poles or solar panels. These type of technologies are perceived to be unnatural. An APS usually covers a large area in which environmental factors such as weather conditions and wildlife interaction will eventually disable components of the APS. Hence, an APS should be easily maintainable so that a continuous protection of wildlife can be guaranteed. In addition, deployment of an APS should be camouflaged from poachers. Otherwise poachers might damage components and attempt to disable the APS. The system should avoid attracting visual attention, for instance, blinking LEDs, colorful mounting devices and other obviously visible pillars.
- Robustness: An APS should endure various technical and environmental deployment factors. Problems in a detection system can occur at any point between the poaching event, detection and surveillance process. For instance, the destruction of individual components should not lead to a complete failure of the overall system. Key challenges in wildlife parks include, but are not limited to, severe tropical storms, lightning strikes, flooding (near rivers) and field fires. Wildlife in parks can dig holes in the ground and play with any infrastructure that is placed in the park. Elephants and baboons, for example, can be very destructive. Hence, an APS should be robust to at least common technical faults among the distributed system components, and demonstrate strong resilience so that information remain uncorrupted.
- Scalability: The areas that are vulnerable to poaching activities are often very large. The APS should therefore be scalable. Technologically, the APS should be able to accommodate a growing number of additional devices joining the system. Scalability can be achieved by means of hardware and software techniques. When the APS is scaled up by introducing new hardware components, the system should seamlessly accept new components with no or little manual modification. Scalability also means the possibility of extending an APS in order to cover large areas, whilst staying within the bounds of other requirements denoted in this section.
- Coverage: Providing full coverage of the protected field is a very important aspect for a successful surveillance technique. In order to reduce coverage overlap, optimization methods should be used to select the best placement of the system devices. The system deployment should be positioned efficiently within a specified region to cover security blind spots and prevent intruders from exploiting these spots.
- Ethical and Legal Issues: When designing an APS that utilizes sensors located on or near animals, ethical and legal implications should be considered. When for example wildlife is collared, a general rule of thumb for the weight of an animal collar is usually 5% of their body weight . Brooks et al.  found a significant effect of collar weight and its fit on the travel rate of zebra females. The authors compared two types of Global Positioning System (GPS) collars. Although types of GPS collars were well within accepted norms of collar weight, the slightly heavier collars (0.6% of the total body mass) reduced the rate of travel by more than 5% when foraging compared with the collar that was 0.4% of total body mass. When utilizing animals for an APS or related research, all aspects of animal handling and research should comply with methods such as those proposed by the American Society of Mammalogists for research on wild mammals .
3. Existing Poaching Detection Technologies
3.1. Types of Sensor Technologies
3.1.6. Infrared and Thermal
3.1.7. Radio Frequency
3.1.11. Animal Sentinels
3.2. Perimeter Based Technologies
3.3. Ground Based Technologies
3.4. Aerial Based Technologies
3.5. Animal Tagging Technologies
3.6. Research Challenges and Future Directions
3.6.1. Sensitivity and Reliability
3.6.2. Sensor Development
3.6.4. Legal and Politics
4. Prevention of Poaching
4.2. Law Enforcement
4.3. Negative Reinforcement
4.5. Demand Reduction
Conflicts of Interest
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|Energy Efficiency||Energy saving capability of an anti-poaching technology is still an open issue|
|Deployment issues||Running power consumption, stealthiness to the environment, maintainability and its easy of deployment are categorized into deployment issues|
|Robustness||An Anti-Poaching System (APS) should be robust to at least common technical faults|
|Scalability||The capability of an APS to seamless integrate additional number of devices with the system|
|Coverage||The ability of an APS to provide full surveillance coverage of a certain protective region|
|Ethical and legal||The ability of an APS to deal with moral principles and to be abide by the regulations and laws, especially wildlife conservation laws|
|Radar||Longer range; does not require direct line of sight; estimate velocity of target; tracking of target||No stealth due to active nature; sensitive to interference, such as precipitation and foliage; intruders can reduce radar signature; expensive||[16,17,18,19,20,21,22,23,24,25]|
|Magnetic||Detection of metal objects such as cars or weapons||Very short range||[21,26,27,28]|
|Acoustic||Long range; economical||Different acoustic characteristics found in different environments; large vocal repertoire||[26,29,30,31]|
|Ultrasonic||Long range; economical||Ultrasonic sound is easily absorbed by clothing and foliage|||
|Optical||Long range; identification of targets||Require line of sight; expensive||[26,33,34,35,36,37,38,39]|
|Infrared and Thermal||Possibility to detect target at night||Difficult to detect target in hot environments||[36,37,40,41]|
|Radio Frequency||Does not require line of sight; high level of stealth||Require (buried) cables along perimeter; limited volumetric range||[20,42,43,44,45,46]|
|Motion||Possibility to classify intrusion type on fences or structures; economical||Range limited to physical structure that sensors are attached to||[41,47,48,49,50,51,52,53]|
|Seismic||High level of stealth||Range and quality of seismic measurements is different for each environment (soil type)||[25,26,39]|
|Chemical||Can be used to mark targets for identification; tracking of poached items||Does not prevent animals from being killed; can be obtrusive to animals||[7,32,54,55,56,57]|
|Animal Sentinels||In theory very large volumetric range; high sensitivity||Many sensors needed; deployment difficulties such as power usage and collaring||[32,58,59,60]|
|Perimeter Based Technologies||Fences are often already in place (sometimes electrified) and can be fortified with the surveyed approaches; some of the surveyed approaches are commercially available||Detect intrusion only along the perimeter of an area, not inside the area itself (linear detection zone). Poachers can enter through the main gate, e.g., disguised as tourist operators.|
|Lasers combined with movement detection PIR sensors||Lasers can cover larger distances||No classification; triggered by plants and animals; large False Alarm Rate (FAR)|||
|Sensor nodes with accelerometers attached to a fence||Classification of intrusion event, thus lower FAR||Many sensors needed; low stealth||[47,48]|
|Microphonic cables attached to fence||Classification and localization of intrusion||200 m segments; a lot of infrastructure needed; low stealth||[49,50,51,52,53]|
|Optical fiber attached to fence||Classification and localization of intrusion; segments up to 1000 m; no power needed along segments; insensitive to electromagnetic inference; very sensitive; reliable||Expensive; low stealth.|||
|Buried optical fiber to detect footsteps||High stealth; harder to destroy; segment ranges up to 10 km||Difficult to bury cables in wildlife areas; soil types vary; expensive||[62,63]|
|Networked sensors of various types (infrared, magnetic, camera) on and around a fence||Higher resilience; some works include distributed algorithms that aim to decrease FAR||Many sensors needed; large overhead||[26,27,28,33,39,40,64,65]|
|Ground Based Technologies||Can detect intruders on larger area; not limited to linear zone.||Any infrastructure placed inside a wildlife area is prone to be damaged by wildlife.|
|Buried coaxial cable||High stealth. Field is wider than optical fiber approach. Commercially available.||Difficult to bury cables in wildlife areas; soil types vary; expensive; volumetric range is not very high.||[20,42,43,44,45]|
|Fixed sensor node placement with various sensors (RADAR, microphone, light intensity, magnetometers)||Improved animal tracking||Many sensors needed; deployment difficulties such as power usage and destruction of nodes||[21,23,35,66]|
|Recording animal sounds||Some animals can be heard 4 km away; thus larger range||More challenging approach because: necessary to understand animal sounds; different acoustic characteristics are found in different environments; difference in the vocal repertoire between different species|||
|Gunshot detection||Gunshots can be heard from far away; thus larger range||High chance of animal being killed before poacher detection|||
|Ultra Wide Band (UWB) WSN||Classification of intrusion event; thus lower FAR; higher stealth. Improved detection in forested areas.||Limited range; many sensors needed; deployment difficulties such as power usage and destruction of nodes||[67,68]|
|Aerial Based Technologies||Very agile and can cover large areas||Aerial based techniques are obtrusive to habitants and tourists; crashing drones can be a hazard to people and wildlife; can be vulnerable to shooting|
|Drones with heat sensing and camera equipment||Works up to 180 m height, thus large range||Unable to detect people under foliage; high running costs||[36,37,69]|
|Using predictive analytics for automated air surveillance||Improved surveillance accuracy; less sensors needed||Unable to detect people under foliage; high running costs||[70,71]|
|Animal Tagging Technologies||Can potentially cover very large areas with high sensitivity||Many sensors needed; deployment difficulties such as power usage and collaring|
|Attach various sensors (cameras, motion, GPS) to animals and classify anomalous behavior||Timely notification of anomalies||Difficult to classify anomalies||[58,59,60]|
|Monitor physiological status of rhino and implement camera + GPS in rhino horn||Timely notification of animal distress or death; possibility to identify poachers through photos taken from the horn||Still high chance of animal being killed; location data of rhinos is very valuable and can motivate corruption||[34,72]|
|Detect horn separation from body through RFID||Helps to notify rangers as soon as animal is poached and increases possibility of the poacher’s capture||Rhino will be killed; the RFID chips will grow out of the horn|||
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