A spring cold snap is followed by an extreme reproductive failure event in a mountain population of Pied Flycatchers Ficedula hypoleuca

Figures & data

Figure 1. Minimum temperatures near the study area for the period 20 April to 10 May for 2010 (open dots) and for 1991–2014 excluding 2010 (means as filled symbols ± 95% confidence intervals).

Table 1. Comparisons between experimental treatments in mortality and reproductive success variables (median and quartiles or mean ± se) with non-parametric (Kruskal Wallis, H) or parametric tests (anova, F).

	Reduced (n = 21)	Control (n = 30)	Enlarged (n = 21)	Test
Brood size after manipulation	3 (3–4)	5 (4–6)	7 (7–8)	H = 52.9, P < 0.001
Nestling mortality1–3 days	0 (0–0)	0 (0–0)	0 (0–0)	H = 1.91, P = 0.38
Nestling mortality 3–7 days	0 (0–0)	0 (0–1)	0 (0–1)	H = 4.44, P = 0.11
Nestling mortality 7–9 days	0 (0–0)	0 (0–0)	0 (0–1)	H = 5.04, P = 0.08
Nestling mortality 9–11 days	0 (0–0)	0 (0–1)	0 (0–1)	H = 4.47, P = 0.11
Nestling mortality 11–13 days	0 (0–0)	0 (0–0)	0 (0–0)	H = 2.11, P = 0.35
% Nestling mortality 1–7 days	0 (0–0)	0 (0–20)	0 (0–20)	H = 1.69, P = 0.43
% Nestling mortality 7–13 days	0 (0–0)	8.3 (0–40)	28.6 (0–100)	H = 7.72, P = 0.021
% Total nestling mortality	0 (0–33)	29.2 (0–100)	100 (28.6–100)	H = 20, P < 0.001
Fledged young	3 (2–3)	3.5 (0–5)	0 (0–5)	H = 1.68, P = 0.43
Fledgling tarsus length (mm)	17.01 ± 0.14	16.78 ± 0.13	16.56 ± 0.18	F = 2.06, P = 0.14
Fledgling mass (g)	13.77 ± 0.28	12.60 ± 0.27	12.22 ± 0.37	F = 6.93, P = 0.002
Fledgling wing length (mm)	42.5 ± 0.8	41.4 ± 0.8	38.4 ± 1.1	F = 4.61, P = 0.015

Figure 2. Correlations between hatching date (1 April = 1) and (a) number of fledglings (Kendall τ₇₁= 0.17, P < 0.05) and (b) nestling mortality in the second week of life (Kendall τ₇₁= −0.30, P < 0.05).