Table 4.

Summary of results from tracked northern gannets between 2017 and 2018. Individuals were tracked using a combination of accelerometry, time depth recorders and GPS. Energy expenditure is calculated from the approach outlined in figure 2 and chick demands are accounted for by the amount of energy required by a four-week-old chick. Modelled average kJ per successful dive includes results from a Bayesian mixed model from isotope analysis and is produced as a figure for each sex per year. The kJ value of a successful dive, the number of dives undertaken and the overall energetic demands are then used to consider how many dives must be successful for a northern gannet to survive and raise a chick.

bird ID	sex	year of study	tracking duration (days)	number of dives	dives per day	total energy expenditure during tracking (kJ)	total energy expenditure during tracking plus chick demands (kJ)	energy expenditure per day with chick demands (kJ)	modelled average kJ per successful dive	number of successful dives to meet energy demands	per cent of recorded dives needed to be successful
D01	male	2017	4.9	113	23.06	17 024	19 763	4033	1005.04	19.66	17.4
D02	male	2017	2.86	36	12.56	8940	10 538	3684	1005.04	10.48	29.13
D03	unknown	2017	5.08	189	37.15	15 840	NA	NA	NA	NA	NA
D04	female	2017	0.97	65	66.89	3341	4154	4282	1005.96	4.13	6.35
D05	female	2017	1.83	39	21.31	6109	7643	4176	1005.96	7.6	19.48
D12	female	2017	4.68	90	19.19	16 147	20 070	4288	1005.96	19.95	22.17
D13	male	2017	4.72	87	18.44	14 761	17 399	3686	1005.04	17.31	19.9
D16	male	2017	1.99	18	9.06	6063	7175	3605	1005.04	7.14	39.66
D25	female	2018	3.04	37	12.17	10 436	12 984	4271	1563.34	8.31	22.45
D26	male	2018	2.92	36	12.31	11 096	12 728	4359	1552.61	8.2	22.77
D28	male	2018	4.61	230	49.84	14 155	16 731	3629	1552.61	10.78	4.68
D41	male	2018	4.83	39	8.07	15 351	18 051	3737	1552.61	11.63	29.81
D52	female	2018	4.32	42	9.72	13 786	17 408	4029	1563.34	11.14	26.51
D53	male	2018	5.05	25	4.95	16 375	19 198	3801	1552.61	12.37	49.46