Nesting habitat and nest features of Water Rails Rallus aquaticus and Little Crakes Zapornia parva on large wetlands

Figures & data

Figure 1. Study area location, wetlands, and distribution of breeding populations of Water Rails and Little Crakes in the Fizeş Basin, Romania.

Figure 2. Comparison of nest site characteristics of Water Rails (1) and Little Crakes (0) (Boxplots: horizontal bar = median, whiskers = last observation within 1.5 times the interquartile range). Features are: water depth (Wdepth, cm), vegetation density (VegD, stems/m²), cattail percentage cover (Typha, %), reed percentage cover (Phr, %), distance to open water (DistOpW, m), distance to the shore (Shore, m), nest diameter (Ndiam, cm), distance from the water surface to the centre of the nest cup bottom (Wndist, cm) and distance from inside the nest cup to the nearest upright vegetation (NvegDis, cm).

Table 1. Summary of nesting site characteristics and nest habitat features of Water Rails and Little Crakes. Parametric (ANOVA; F statistic) and nonparametric (Kruskal–Wallis; H statistic) one-way models compare differences between the two species. Features are: water depth (Wdepth, cm), vegetation density (VegD, stems/m²), cattail percentage cover (Typha, %), reed percentage cover (Phr, %), distance to open water (DistOpW, m), distance to the shore (Shore, m), nest diameter (Ndiam, cm), distance from the water surface to the centre of the nest cup bottom (Wndist, cm) and distance from inside the nest cup to the nearest upright vegetation (NvegDis, cm).

	Water Rail					Little Crake					H/F	P
	n	min.	max.	mean	sd	n	min.	max.	mean	sd
Wdepth	76	2.00	45.00	9.84	6.13	43	9.00	91.00	58.27	17.43	408.77	<0.001
Wndist	76	0.00	40.00	5.52	6.62	43	0.00	70.00	23.90	16.70	72.36	<0.001
NvegDis	74	5.00	60.00	26.24	11.52	42	3.00	31.00	14.47	6.50	37.02	<0.001
Ndiam	71	13.00	30.00	19.94	3.09	36	6.00	17.00	12.36	2.07	37.02	<0.001
DistOpW	80	5.00	350.16	151.81	70.63	40	0.250	3.00	0.98	0.59	1096.99	<0.001
VegD	76	160.00	944.00	411.92	119.19	45	96.00	480.00	315.46	70.35	21.44	<0.001
Typha	79	0.00	100.00	40.18	27.48	46	60.00	100.00	98.91	6.04	83.10	<0.001
Phr	79	0.00	100.00	59.81	27.48	46	0.00	40.00	1.08	6.04	84.10	<0.001
Shore	79	11.50	236.31	139.84	58.89	46	9.48	96.88	57.41	26.17	80.62	<0.001

Figure 3. Two-dimensional ordination of nest site habitat characteristics of Water Rails (Rallus) and Little Crakes (Zapornia).

Figure 4. Two-dimensional ordination of nest features of Water Rails (Rallus) and Little Crakes (Zapornia).

Table 2. Summary statistics for the discriminant function analysis: correlations between original variables and discriminant function, and discriminant scores for each group (Eigenvalue = 2.284; Group centroids for Water Rail – 0.438; and Little Crake 0.780). Features are: water depth (Wdepth, cm), vegetation density (VegD, stems/m²), cattail percentage cover (Typha, %), reed percentage cover (Phr, %), distance to open water (DistOpW, m), distance to the shore (Shore, m), nest diameter (Ndiam, cm), distance from the water surface to the centre of the nest cup bottom (Wndist, cm) and distance from inside the nest cup to the nearest upright vegetation (NvegDis, cm).

	Wndist	Wdepth	VegD	Typha	Phr	DistOpW	Shore	NVegDis
R	1	0.588	0.034	0.01	−0.01	−0.187	−0.237	−0.259