Air temperature and humidity effects on the performance of conservation detection dogs

Air temperature and relative humidity affect both the emanation of the biogenic volatile organic compounds characterizing the scent of target species on which conservation detection dogs (CDDs) are trained on, as well as their physiological state and may thus affect their ability to reliably detect these target scents. While field studies increasingly monitor and account for environmental conditions, a systematic assessment of how air temperature and relative humidity affect the performance of CDDs under controlled conditions is missing. To overcome this limitation, seven CDDs were exposed to a wide range of simulated air temperature and relative humidity combinations in a controlled climate chamber setting and their ability to detect four target scents was quantified in a standardized fashion. Limited by replication, we found only weak statistical evidence for temperature and relative humidity to affect the performance of CDDs. Diagnostic sensitivity tended to decrease at lower temperatures, while diagnostic specificity decreased at higher temperatures, which we hypothesize to reflect reduced scent production at lower and increasing physiological stress at higher temperatures, respectively. Statistical evidence for effects on relative humidity were weaker and less consistent compared to temperature. Generally, significant differences were observed between individual CDDs and target scents and interactions between these, which may have contributed to the observed limited statistical evidence and calls for better replication in future research. We conclude that air temperature and relative humidity affect CDD performance in complex ways and should thus be monitored and, to the degree that this is feasible, controlled for during field surveys.