Huckstadt LA, RR Holser, MS Tift and DP Costa. 2018. The extra burden of motherhood: reduced dive duration associated with pregnancy status in a deep-diving mammal, the northern elephant seal. Biology Letters 14: 20170722.
The cost of pregnancy is hard to study in marine mammals, particularly
in species that undergo pregnancy while diving continuously at sea such as elephant
seals (genus Mirounga).We analysed the diving behaviour of confirmed
pregnant and non-pregnant northern elephant seals (M. angustirostris, n = 172)
and showed that after an initial continuous increase in dive duration, dives of
pregnant females become shorter after week 17. The reasons for this reduction
in dive duration remain unknown, but we hypothesize that increased fetal
demand for oxygen could be the cause. Our findings reveal an opportunity
to explore the use of biologging data to investigate pregnancy status of
free-ranging marine mammals and factors that could affect pregnancy success.