We used GPS location **data** to detect active den sites. Putative active dens were first identified by examinations of collared wolf locations that were geographically focused in a restricted area during the period of time previously identified as the parturition period (between the last week of April and the second week of May; Person and Russell 2009). We also visited den sites 3-6 weeks after suspected parturition to verify pup production by visual observation. We approached sites on foot in groups of 1-3 people and recorded observations of wolves when they were seen or heard. We searched the area around the den entrances for signs of fresh wolf scat, hair, scrapings or other sign. We observed the den for wolf pups but limited our time in the area to < 1 h to avoid excessive disturbance of breeding wolves. Despite these efforts, 3 wolf packs relocated their pups to a nearby den (<0.5 km) during the study period. In 2 of these cases, additional visits were made by agency employees to the den after our field visits to observe pups, and in one case low-level helicopter flights for logging activities began immediately before the relocation event (Roffler et al. unpubl.). Person and Russell (2009) also reported a low number of relocations in response to human visits to den sites. In addition, we annually visited 26 dens previously recorded by Person and Russell (2009) during 1995 the same timing and techniques to make observations of wolves at historic dens.