Using Canines to Detect Carrion in Support of the American Burying Beetle
Current methodologies for surveying the endangered American Burying Beetle’s (Nicrophorus americanus) (ABB) habitat require the use of pitfall traps. These pitfall traps are baited with carrion (dead and decaying flesh of an animal), which ABB utilize as a food source, and is an elemental component of the ABB reproductive cycle. If an ABB is found within the trap then the location is deemed to be an ABB positive area. If this area is being surveyed as a development project area, the developer is recommended to follow a set of guidelines approved by the U.S. Fish and Wildlife Service (The Service) before any development can take place. The options for developers are very limited and some of the examples include, but are not limited to, purchasing credits from a mitigation bank or removal of carrion from the project area. Removal of carrion is done by having people walk the project area for several days prior to disturbance. This method is much more cost efficient compared to purchasing credits, however, has limitations due to the human error factor. The use of detection canines has been demonstrated as a practical and more effective method for finding carrion, as the carrion detection activities do not pose a threat to the ABB directly, and because it uses scent based cues rather than simple visual cues in locating target specimens. These scents are carried primarily though bulk movement of vapor molecules through air. It is this ability to search for target odor that makes canines ideal for rapid target recognition in the field. Through a controlled training program, the canines were subjected to the vapor from the carrion with live specimens employed as controls to establish the efficacy of the carrion detection abilities of the canines.
During this study canines were initially introduced to varying types of carrion at gradually decreasing post mortem age. Decreasing the stages of decomposition allows for the canines to be able to recognize lower levels of the scent. Once the canines were able to routinely detect the source of the scent, the carrion was then buried at gradually increasing depths to limit the amount of scent being carried by the atmosphere. Lastly, the canines were exposed to the ABB natural habitat in a surveying pattern designed relative to specific environmental factors. This pattern is designed to help determine the range for which the specific scent being trained may first be detected (effective range).
Based on the findings of this trial, the data concludes that canines are able to find and respond to carrion in an ABB occupied habitat. This technique allows the use of detection canines to identify carrion within a project area. For this reason, canines can be used safely, efficiently, and cost effectively as a tool for detecting the presence of ABB resources on lands considered for development.
Introduction
The ABB was federally listed as an endangered species in July 1989. Current methods for identifying an ABB occupied area are through the deployment of pitfall traps baited with carrion, which the beetles require for food and reproduction. By using these pitfall traps, surveyors can determine if a specific area is occupied by the ABB. Once an area has been deemed to be a positive ABB 追蹤定位 area, developers are required to take additional steps to protect any unnecessary take of the ABB. There are limited options available to these industries to continue their development. One of the options that have been utilized is carrion removal. However, standards for carrion removal utilized people to walk the project area for up to two weeks prior to any ground disturbance. This potentially poses great risk to the ABB, as the human abilities to find carrion in, often times, thick vegetation can be quite limited. In addition, relying on humans to find and remove carrion can only be done on a surface level, leaving the buried ABB vulnerable to injury or death. An alternative method of using canines to find carrion within the project area would prevent the ABB from being attracted to the project area, thus limiting the risk to the species.
Canines have been successfully utilized for many years, most predominantly to aid in the detection of illegal contraband and explosive materials by the military, law enforcement, and the private sector. Canines were also studied during the 1970’s for the purpose of searching for human remains, additionally, canines have been used in the conservation arena where they have been deployed successfully in locating endangered species across the world. For instance, in 2008, detection canines were used to detect Mojave Desert tortoises (Gopherus agassizii), with a 96% success rate. Canines have been used for a number of other wildlife and biological detection purposes as well including locating bat carcasses under wind generators, seeking household mold, pests or diseases on agricultural products, invasive plants, and even offflavor catfish. There have been a series of studies conducted under behavior laboratory conditions to determine canine sensitivity to various substances. Research has shown that trained detection dogs and electronic devices can detect minute quantities of odorants. Through those studies, and additional ongoing studies by the Penn Vet Working Dog Center, the canine’s olfactory limitations has been determined to be from 1-2 parts per trillion.
Based on these studies there is reason to believe these thresholds are representative of thresholds for the scent proposed in this study. The ability to search for specific target odor(s) makes canines ideal for rapid target recognition in the field. Canines were initially introduced to varying types of carrion at gradually decreasing stages of decomposition. Once the canines were able to routinely recognize the scent, the carrion was then buried at gradually increasing depths to limit the amount of scent being carried by the atmosphere. Lastly, the canines were exposed to the ABB natural habitat in a surveying pattern specially designed relative to wind speed and direction, temperature, humidity. This design helps to determine the range for which this specific scent may be detected (effective range). This technique allows the use of detection canines to identify carrion within a project area. Canines can be used as a tool for detecting the presence of ABB on lands considered for development. The content of this paper will illustrate the ability of canines to detect the presence of carrion (on the surface or buried beneath the soil) in ABB inhabited areas using scent based techniques.
