Influence of nest burrow microclimate on chick growth in a colonial High-Arctic seabird, the little auk

Figures & data

Figure 1. Nest temperatures (mean ± SE) in phase 1 (20 July–2 August) and phase 2 (5–8 August) of the chick-rearing period, and during the post-breeding period (25–27 August). All inter-nest differences are significant (random effects ANOVA, p > 0.05, N = 1296 temperature records for each nest; separate analyses for particular phases), except for those shown by horizontal lines.

Figure 2. Mean ± SD nest temperatures in the 24 hr cycle (mean value from three loggers for a three-day period) in three nests (different altitude) in (a) phase 1 (20 July–2 August), (b) phase 2 (5–8 August) of chick rearing and (c) during the post-breeding period (25–27 August). The thermoneutral zone of little auks (4.5°C; Gabrielsen et al. 1991) is shown by the horizontal black line. The “day” and “night” hours are shown at the bottom of the graph by the horizontal light and dark grey bars, respectively.

Figure 3. Relationship between nest temperature (mean ± SD, mean daily temperatures calculated from the three locations in a burrow during consecutive three days) and altitude in nests during two chick-rearing phases and the post-breeding period. Regression lines are shown for significant relationships.

Table 1. Nest and ambient temperatures (mean ± SE) during the post-breeding period (25–27 August), results of paired sample t-tests for each nest with its altitude, and the difference between ambient and nest temperatures. Significant differences (p < 0.05) are shown in boldface.

					Paired samples t-tests
	Altitude	Nest	Ambient	Temperature	Nest vs Ambient
Nest ID	(m a.s.l.)	temperature (°C)	temperature (°C)	difference (°C)	df	t	p
N1	52	4.48 ± 0.043	3.92 ± 0.073	−0.56	431	−6.15	<0.001
N2	61	4.82 ± 0.028	4.19 ± 0.084	−0.63	431	−10.08	<0.001
N3	42	3.71 ± 0.042	3.55 ± 0.061	−0.16	431	3.33	0.11
N4	46	3.96 ± 0.032	3.90 ± 0.054	−0.06	431	1.98	0.09
N5	59	4.41 ± 0.008	4.14 ± 0.092	−0.27	431	1.15	0.004
N6	62	5.01 ± 0.077	4.68 ± 0.068	−0.33	431	−12.87	0.011
N7	54	5.42 ± 0.040	4.86 ± 0.048	−0.56	431	−17.43	<0.001
N8	74	6.27 ± 0.085	5.77 ± 0.063	−0.50	431	−12.33	<0.001
N9	64	4.88 ± 0.026	4.28 ± 0.073	−0.60	431	−15.94	<0.001
N10	67	5.88 ± 0.052	5.30 ± 0.077	−0.58	431	−15.33	<0.001
All nests combined		4.84 ± 0.092	4.02 ± 0.094	−0.43 ± 0.08	4319	−27.32	<0.001

Table 2. Comparisons of 24 hr distributions of nest and ambient temperatures. Student t-tests comparing the difference between “night” and “day” ambient and nest temperatures during the post-breeding period (24 hr cycle, 25–27 August). Significant differences (p < 0.05) are in boldface.

					Comparison of “day” vs “night” temperatures (Student t-tests)
	Altitude 24 h distribution of nest vs ambient temperatures (K-S test^a)				Ambient temperatures			Nest temperatures
Nest ID	(m a.s.l.)	df	D	p	df	t	p	df	t	p
N1	52	431	0.198	0.211	431	34.54	0.032	1295	8.72	0.091
N2	61	431	0.598	0.034	431	54.32	0.021	1295	9.14	0.166
N3	42	431	0.134	0.245	431	44.16	0.027	1295	11.21	0.089
N4	46	431	0.242	0.152	431	27.67	0.045	1295	7.76	0.176
N5	59	431	0.692	0.038	431	65.44	0.011	1295	14.45	0.056
N6	62	431	0.789	0.001	431	58.65	0.019	1295	15.64	0.059
N7	54	431	0.287	0.167	431	55.11	0.022	1295	11.26	0.092
N8	74	431	0.754	0.011	431	67.12	0.015	1295	19.78	0.047
N9	64	431	0.684	0.034	431	39.15	0.016	1295	12.98	0.083
N10	67	431	0.722	0.022	431	48.76	0.025	1295	17.16	0.044
All nest combined		4309	0.432	0.047	4309	32.18	<0.001	12 959	12.56	0.105

^aKolmogorov-Smirnov test comparing distributions of mean hour nest and ambient temperatures.

Figure 4. Temperature inside nests and ambient (outside) temperature (mean ± SE) during the post-breeding period (25–27 August). The arrows indicate significant differences between nests and ambient temperatures for particular burrows (paired samples t-tests, p < 0.05, N = 432).

Figure 5. The mean ± SD nest and ambient temperatures in the 24 hr cycle in three nests (different altitude) during the post-breeding period (25–27 August). The thermoneutral zone of little auks (4.5°C; Gabrielsen et al. 1991) is shown by a horizontal black line. The “day” and “night” hours are shown at the bottom of the graph by the horizontal light and dark grey bars, respectively.

Figure 6. Relationship between mean nest temperatures in phase 1 (30 July–2 August) and phase 2 (5–8 August) of the chick-rearing period and the AGR of little auk chicks (AGR1 and AGR2) based on (a, c) HBL and (b, d) body mass. Regression lines are shown for significant relationships.

Gabrielsen G.W., Taylor J.R., Konarzewski M. & Mehlum F. 1991. Field and laboratory metabolism and thermoregulation in dovekies (Alle alle). The Auk 108, 71–78.

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