Collection of culpeo scats
This study is based on analysing scat contents to determine the culpeo’s diet. It is a non-invasive method that shows what the species real consumes (Putman, 1984; Corbett, 1989) and is widely used for studying the feeding habits of carnivores (e.g. Halter, 1967; Reynolds and Aebischer, 1991; Juarez and Marinho-Filho, 2002; Malo et al., 2004). In Particular, this method has already been used to study the culpeo’s diet (e.g. Iriarte et al., 1989; Ebensperger et al., 1991). All accessible areas of paramo in the PNP were sampled for culpeo scat collection. These areas were concentrated in three zones of the PNP known locally as Cajanuma, El Tiro and Cerro Toledo. A different number of fixed 1-km transects (16 in total) were established in each area on existing paths (see Fig. 1). During 2009 each 1-km transect was sampled in search of fresh scats once a month (thus resulting in a total of 192 km of overall sampling effort), at 30 day intervals and starting in the middle of each month (so that any scat found was assigned to the corresponding sampled month). Previously, a survey to remove old scats was undertaken in all transects. Samplings were always conducted by the same observers, who were well trained prior to starting the fieldwork (Lozano et al., 2013).
Collected scats were stored at -80 °C when clearly identified as belonging to Andean foxes. Scats were first identified based on a set of context-based diagnostic characteristics (Romo, 1995; Cornejo and Jiménez, 2001; Achilles, 2007; Palacios et al., 2012; Pia, 2013), which included location (scats directly on the path or close by), general morphology (canid-like scats, different from those of cats, bears, etc), and diameter (2-3 cm). In addition, genetic analyses were performed in the lab to confirm scat identification. 89 scats were randomly selected from the total sample, and DNA was extracted by applying the QIAGEN QIAamp DNA Stool Mini Kit (QIAGEN, CA.USA). The protocol described by De Barba et al., (2014) was used for mitochondrial DNA amplification. Amplification was successful for 81.2% of the total sample (i.e. 70 scats), the genetic material being positively identified as belonging to culpeo in all cases. Therefore, observers in the field had a 100% success rate in the identification of these 70 scats, demonstrating that with good previous training correct identification of culpeo scats based on external features is possible in the area (see Lozano et al., 2013). Hence, no relevant confusion with the scats of other animals inhabiting the same environment, such as pumas (Puma concolor), Andean bears (Tremarctos ornatus) or domestic dogs (Canis familiaris), was assumed.