Summing the strokes: energy economy in northern elephant seals during large-scale foraging migrations

Table 2 Comparison of different metrics for estimating at-sea FMRs of northern elephant seals

Migration	Seal	FMR (“True”) kJ kg⁻¹ d⁻¹	FMR (Alternate) kJ kg⁻¹ d⁻¹	FMR Error: (Alternate - “True“)
ST: Short trip	U954	90.7	93.6	3.03
	U605	91.1	91.2	0.14
	U627	97.4	99.8	2.42
	T911	85.8	91.2	5.90
	1015	92.9	91.4	−1.62
	X851	94.6	88.9	−6.48
	T35	96.6	90.8	−6.35
	N796A	92.7	87.2	−6.35
	R541	97.5	91.6	−6.42
	1733	83.2	91.2	8.78
	N796B	92.4	83.6	−10.52
	W1095	91.8	79.6	−15.34
	R382	76.1	83.5	8.79
LT: Long trip (pregnancy)	U458	72.9	76.3	4.42
	T730	75.0	76.0	1.28
	X106	70.5	70.5	−0.08
	U754	77.1	68.4	−12.71
	2036	62.9	62.6	−0.59
	U203	57.9	62.1	6.80
DG: Short trip (added drag)	1234	104.5	104.7	0.22
	M780	103.2	92.5	−11.52
	2370	105.1	83.3	−26.23
Mean ST		91.0	89.5	6.3
(S.E.)				(2.1)
Mean LT		69.4	69.3	4.3
(S.E.)				(2.8)
Mean DG		104.2	93.5	12.7
(S.E.)				(7.7)

FMR (“True”) is the field metabolic rate based on total number of measured flipper strokes and individual stroke costs, and FMR (Alternate) is based on the alternate metric with the strongest predictive relationship: mass and days at sea for ST and DG seals (eq. [2] in text), and mass for LT seals (eq. [4] in text). Error column represents percent difference in FMRs estimated using the different approaches, with mean (± SE) absolute error indicated

ISSN: 2051-3933