Mammal inventories serve many purposes: they can help evaluate human impact on mammal activities, show diversity in a survey area of interest, allow for comparisons among different areas, and help layout distribution maps for species as well as individuals. A thorough knowledge of the presence as well as distribution of animals in a given area is particularly important when considering conservation strategies for a region. Methods commonly used to detect mammals in a survey area consist of line transects, direct observations, camera traps, and trapping individuals. While these surveys are useful when identifying relatively abundant species they often fail to record rare, elusive, and cryptic species (Tobler et al. 2008).
Extracting and identifying DNA from the environment has recently proven to be noteworthy when monitoring rare, elusive, and endangered species. Information derived from environmental DNA (eDNA) gives insights to ecological and evolutionary processes. Using eDNA has improved the ability to explore eco-system level processes, quantitatively analyze species, community diversity, and dynamics. eDNA has provided unique opportunities through the use of time-serial samples and sensitivity for detecting rare or difficult to sample species. eDNA sampling methods have improved detection sensitivity and cost efficiency. The use of environmental DNA has great potential for the conservation of biodiversity (Bohmann et al. 2014).
Detection Methods and Results
The use of eDNA can be used to survey many different species using many different detection methods. Survey methods include, but are not limited to, owl pellet dissection, snow collection samples, water samples, scat samples and hair samples.
Pellets from owls are a well-suited, non-invasive, molecular investigation in a given environment. Pellets are formed from the bones, teeth, fur, and other non-digestible parts of prey consumed by owls. They are usually regurgitated multiple times per day, which makes them relatively abundant and often easy to come by. In addition, pellets often contain high amounts of DNA especially in generalist species such as the Tawny owl (Strix aluco). Buś et al. (2013) also noted that owls often use various hunting techniques, utilize different habitats and therefor kill a wide range of prey, resulting in high amounts of DNA content in their pellets (as cited in Mikkola, 1983). Buś et al. (2013) extracted DNA from the remains of the harvest mouse (Micromys mutus) found in owl pellets.
The general goals of this study were to test and select the most successful methodology for using owl pellets as a source of DNA for prey species; with the hopes that this non-invasive sampling technique can facilitate new data on the molecular characteristics of populations for many mammal species. Buś et al. (2013) found that the expected number of prey species per sampled individual was higher in comparison to standard live-trapping; therefore, they predict it is more-probable to detect rare species in pellets than they would during a live-trapping event.