The grey wolf (Canis lupus) was extirpated from the Central System (Iberian Peninsula) in 1976, but the species recolonized the area by 2006. We monitored this new population from 2010 to 2018 using non-invasive sampling techniques; we determined its biological parameters and we described the necessary field work to obtain the required information for evidence-based decision- making regarding the management of wolf populations. Data collection was primarily based on the detection of wolf marking signs along sampling routes (e.g. dirt roads, trails, paths) and the scats, in particular, were used to delineate pack territories. Camera trapping was generally used to confirm pack size and reproduction. We detected a maximum of 13 wolf packs distributed in the study area during the eight years of monitoring; the mean pack size was 3.5 wolves. Reproduction always occurred when the mean pack size was at least 4 individuals by the end of winter (52.7%). We also determined that the scat-marked territory of breeding packs (i.e., those with >4 individuals) was >60 km² during the reproductive period. Overall, our results suggest that the low-cost monitoring methods commonly used to assess the status of wolf populations in Spain tend to overestimate both population size and reproductive success, suggesting the need for alternative methods.