Abstract: Research on a captive harbor seal (Phoca vitulina) mother-pup pair showed that ingestion of milk caused a decrease in stomach temperature (Hedd et al., 1995). Herein the feasibility of stomach temperature telemetry for measuring nursing behavior was tested in wild harbor seal pups from the St. Lawrence River Estuary. Fifteen pups were outfitted with time-depth recorders, stomach temperature transmitters (STT), and stomach temperature recorders in 2002 and 2003. Twelve pups were recaptured, and seven yielded usable stomach temperature data. Excluding a mortality that lost its transmitter the day of release, transmitter retention time ranged from at least 7 to 22 d (12.5 ± 1.45 d) based on a STT signal at recapture. Pups that gained more weight had a higher frequency of decreases in stomach temperature (DST) (R2 = 0.954, p < 0.001). Depth and external temperature data showed that most DST occurred while pups were "in the water" (57%) followed by "just before or after hauling out" (19%), "just before or after entering the water" (15%), and "hauled out" (9%) (χ2 = 56.376, p < 0.001). The frequency DST did not change with age, and there was no diel pattern of DST, which also did not change with age. These findings indicate that transmitter retention times are sufficient to monitor most of the nursing period for harbor seals, that stomach temperature can be used to quantify nursing characteristics in the field, and that a telemetric technique is needed for harbor seals as most nursing events occur in the water.
Key Words: telemetry, stomach temperature, harbor seal, Phoca vitulina, nursing, pups
Document Type: Research article
Page Numbers: 270-277