Use of temperature telemetry to monitor ingestion by a harbour seal mother and her pup throughout la
April Hedd, Rosemary Gales, Deane Renouf
Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, NF, Canada, A1C 5S7
Polar Biology. 15: 155 - 160. 1994
Abstract: The applicability of using stomach temperature telemetry to detect and estimate milk intake throughout lactation was investigated in harbour seals
(Phoca vitulina). Observations of a mother-pup pair were conducted daily while stomach temperature was concurrently logged. Milk intake caused a decrease in the pup's stomach temperature. The duration of stomach temperature change was related to the length of the nursing bout (r2 = 0.82, P < 0.001). Laboratory stomach simulations suggested a strong relationship between milk volume and duration of temperature change (r2 = 0.98, P < 0.001). This relationship was used to estimate the volume of milk consumed by the pup. Suckling bout length and the estimated milk in-take per bout increased, as a weekly average, with pup age (one-way ANOVA, F3.67 = 11.66, P < 0.001) over the 5-week lactation period. A diel change in nursing time was noted, with a transition from largely nocturnal to daytime feedings. Although not visually confirmed, stomach temperature data collected from the mother provided evidence of seawater ingestion. Methods that could improve estimates of milk intake are discussed. Stomach temperature telemetry proved to be a useful technique for detecting ingestion events in harbour seals, and may provide a valuable tool for investigating lactation energetics and aspects of maternal investment in a variety of nursing species.