Breeding short-tailed shearwaters buffer local environmental variability in south-eastern Australia by foraging in Antarctic waters

Table 2 Inter-annual comparison of mean (± SD) environmental parameters for the short-tailed shearwater chick-rearing period (January–April)

Local conditions		2012	2013	2014	F	df	P-value
Gabo Island	SST (°C)	19.7 ± 0.8^*	20.2 ± 0.9^*	21.2 ± 0.8^**	12.37	2, 44	<0.001
	Chl-a (mg.m⁻³)	0.5 ± 1.0	0.5 ± 0.6	1.1 ± 1.1	2.55	2, 44	0.09
	Wind speed (m.s⁻¹)	8.6 ± 2.2	8.4 ± 2.0	9.0 ± 2.4	1.01	2, 358	0.36
	Wind direction (°)	138.7 ± 47.9	138.9 ± 48.7	132.2 ± 55.9	0.86	2, 358	0.43
Griffith Island	SST (°C)	18.0 ± 0.6^*	18.7 ± 0.5^**	17.6 ± 0.5^*	10.45	2, 42	<0.001
	Chl-a (mg.m⁻³)	0.2 ± 0.2	0.2 ± 0.2	0.2 ± 1.1	1.58	2, 42	0.22
	Wind speed (m.s⁻¹)	7.8 ± 1.8	7.1 ± 1.7	7.8 ± 1.7	0.64	2, 358	0.53
	Wind direction (°)	156.5 ± 52.0	173.4 ± 58.6	179.1 ± 43.4	1.30	2, 358	0.27
Meso and large-scale processes
Bonney Upwelling SST (°C)		17.6 ± 0.7^*	18.8 ± 0.5^**	17.6 ± 0.6^*	13.31	2, 32	<0.001
SOI		−0.8 ± 5.7	4.0 ± 5.8	−2.1 ± 8.4	2.67	2, 31	0.09
Sea ice concentration (%)		57.2 ± 27.4^*	70.5 ± 26.5^**	59.6 ± 27.7^*	31.04	2, 47	<0.001

Local conditions included sea surface temperature (SST), sea surface chlorophyll-a concentration (Chl-a), wind speed and wind direction. Meso-scale process included Bonney Upwelling sea surface temperatures (SST) over the austral summer (January–March) and large-scale processes included the Southern Oscillation Index (SOI) over a yearly period and the sea ice concentration in the Antarctic region. Significant results are indicated in bold and homogenous subsets (P > 0.05) are indicated by asterisks