Table 3. Description of the samples used to estimate the responses of skylarks to rapeseed and maize crop areas.

	Factor	Rapeseed area (ha)				Maize area (ha)
	Group	Openfield east	Openfield west	Grassland east	Grassland west	Openfield east	Openfield west	Grassland east	Grassland west
Sample	Number of squares	107	134	70	80	91	139	120	98
	Variation of the factor	<1–103.7	<1–82	<1–67	<1–45	<1–315	<1–173	<1–118	1–112
	Factor/annual crop area: maximum (%)	39	33	34	26	84	71	100	85
	Variation of annual crop area (ha)	119–368	76–387	10–225	9–240	119–356	76–387	<1–225	6–240
	Skylark abundance (median–maximum)	16–53	11–37	6–43	3–32	14–53	11–62	3–43	3–41
Correlation	Annual crop area	0.33	0.41	0.67	0.50	0.14	−0.18	0.61	0.45
	Grass area	−0.18	−0.42	−0.52	−0.42	−0.21	0.35	−0.45	−0.30
	Rapeseed area	/	/	/	/	−0.63	−0.35	0.09	−0.26
	Maize area	−0.62	−0.37	−0.03	−0.31	/	/	/	/
	Cereal area	0.67	0.41	0.71	0.58	−0.68	−0.46	0.32	−0.02