Experimental assessment of the effects of substrate choice on the duration of chemical signals in fecal scent-marks of free-ranging Iberian wolves

Chemical communication, typically based on feces, urine and glandular secretions, plays a key role in social organization and communication among many mammals, especially carnivores. Scent marking is crucial for diverse functions. This study assesses experimentally whether the type of substrate chosen for fecal deposition and the temperature reached by these substrates influence the persistence of volatile compounds in feces of the Iberian wolf (<i>Canis lupus signatus</i>), considering their role in chemical communication. Fresh fecal scats collected in the wild were divided into equal fragments and positioned in an experimental setup on four different types of substrates exposed to the natural environment. Thereafter, small fecal samples from each fragment were collected at seven different time intervals for chemical analysis using gas chromatography-mass spectrometry (GC-MS). The variations in temperature of each substrate were also monitored. The number of compounds in feces decreased with time since deposition. Also, differences in the total number of compounds were found across time and different types of substrates. Substrate temperature only influenced the persistence of some chemical compounds, though lower temperatures may slightly prolong scent mark duration. These results suggest that, when wolves select a substrate to deposit the feces, enhancing visual cues (for example, different conspicuity of the feces in different substrates) may play a more important role in fecal marking than trying to increase the persistence of the olfactory signal. Overall, our study may help to enhance the understanding of fecal marking behavior in the Iberian wolf, especially regarding the interplay between visual and chemical signaling.