Local versus landscape-scale determinants of nest-site selection in the Barbary Partridge Alectoris barbara

Figures & data

Figure 1. Map showing the location of the study area and positions of grid cells sampled in 2016 (black squares) and 2017 (white squares).

Table 1. Description of habitat variables measured around survey points (nest-site and random points) within two spatial levels (local- and landscape scales) and used in the analyses of Barbary Partridge nest habitat selection model.

Abbreviations	Descriptions
Nest-site variables
NT	Number of tree within 5 m plot
DT	Distance from nest to the nearest tree (m)
RSH	Number of shrub species within 5 m plot
HSH	Maximum height of shrub cover (m)
SCV	Percentage cover of shrub (estimated by the same investigator)
Landscape cover/topographic variables
ELEVM	Mean (4 points) elevation (m) in 50 m radius plot
FCV	% Forest vegetation (shrub and trees)
WCV	% Waterbody vegetation
CCV	% Cereal fields (durum wheat, bread wheat and barley)
PCCV	% Permanent crops
BCV	% Bare ground
DC	Distance from nest to the nearest cereal field (m)
DE	Distance from nest to the closest water point (natural or managed) (m)
DFE	Distance from nest to the closest forest edge (m)
DTR	Distance from nest to the closest track (m)
DH	Distance from nest to the closest human habitation (m)

Table 2. Descriptive statistics for variables (mean ± se) measured at Barbary Partridge nests and random points using t tests. Wilks lambda = 0.580; F = 4.759; P < 0.001 (Multivariate analysis of variance).

	Nests	Random points	t value	P
Nest-site variables
NT	1.17 ± 0.15	0.71 ± 0.09	−2.613	0.010
DT	9.98 ± 1.59	29.25 ± 7.32	2.573	0.012
RSH	1.59 ± 0.10	1.19 ± 0.11	−2.794	0.006
HSH	1.52 ± 0.12	1.16 ± 0.10	−2.321	0.022
SCV	66.68 ± 2.71	45.42 ± 4.13	−4.306	<0.003*
Landscape cover/topographic variables
ELEVM	449.05 ± 9.47	462.02 ± 8.98	0.989	0.325
FCV	26.05 ± 4.02	9.69 ± 2.51	−3.450	0.001*
WCV	5.77 ± 1.98	7.33 ± 2.73	0.467	0.641
CCV	41.37 ± 5.06	55.20 ± 5.64	1.830	0.070
PCCV	14.18 ± 3.31	10.17 ± 3.28	−0.859	0.392
BCV	12.68 ± 3.12	7.39 ± 2.19	−1.389	0.168
DC	120.50 ± 29.66	75.94 ± 28.07	−1.086	0.280
DE	337.78 ± 44.38	324.24 ± 48.69	−0.206	0.837
DFE	384.23 ± 221.49	230.17 ± 37.09	−0.654	0.514
DTR	260.34 ± 33.26	143.28 ± 19.80	−3.024	0.002*
DH	297.86 ± 25.21	358.80 ± 44.42	1.222	0.224

Note: The 0.05 alpha level is adjusted to 0.003 using a Bonferroni correction.

Figure 2. Probability of presence of Barbary Partridge nests according to: (a) forest cover, (b) shrub cover, (c) distance to the nearest track and (d) to nearest tree, in an agroforestry system of Central Morocco. The shaded grey areas are the lower and upper 95% confidence limits.

Table 3. Summary of the GLMs describing Barbary Partridge nest habitat selection at local- and landscape scales. Variable abbreviations are explained in Table 1.

Scale	Models^a	k^b	logLik	AICc	ΔAICc	wi^c
Local scale
	Log (DT) + SCV + (SCV)^2	4	−58.43	125.20	0.00	0.80
	Log (DT) + SCV	3	−60.95	128.10	2.91	0.19
	Null model	1	−84.42	170.87	39.19	0.00
Landscape scale
	DH + DTR + FCV + (FCV)^2	5	−72.57	155.65	0.00	0.46
	CCV + DH + DTR	4	−74.35	157.05	1.39	0.23
	Null model	1	−84.42	170.87	15.21	0.00
Local- and landscape scales
	Log (DT) + DTR + FCV + (FCV)^2 + SCV + (SCV)^2	8	−49.50	113.99	0.00	0.65
	Log (DT) + DTR + FCV + (FCV)^2 + SCV	7	−52.40	117.53	3.55	0.11
	Null model	1	−84.42	170.87	52.04	0.00

Table 4. Estimates of the best models fitted for Barbary Partridge nest habitat selection at local- and landscape scales using binomial error and logistic link function. RVI = Relative Variable Importance. Variable abbreviations are explained in Table 1.

Scale	Variable	β-coefficient	se	Z-value	P	RVI
Local-scale model
	Intercept	−2.514	0.991	−2.537	0.0112	—
	Log (DT)	−0.751	0.183	−4.113	<0.0001	—
	SCV	0.121	0.039	3.103	0.0019	—
	SCV^2	−0.0007	0.0003	−2.134	0.0328	—
Landscape-scale model
	Intercept	0.148	0.595	0.247	0.8048	—
	DH	−0.003	0.001	2.128	0.0334	1.00
	DTR	0.004	0.001	3.355	0.0008	1.00
	FCV	0.063	0.027	2.334	0.0196	0.67
	FCV^2	−0.0007	0.0003	2.099	0.0358	0.67
	CCV	−0.008	0.005	1.658	0.0973	0.33
Local and landscape models
	Intercept	−5.494	1.748	−3.143	0.0017	—
	Log (DT)	−0.656	0.202	−3.243	0.0012	—
	DTR	0.005	0.002	2.818	0.0048	—
	SCV	0.164	0.055	2.968	0.0029	—
	SCV^2	−0.0009	0.0004	−2.161	0.0307	—
	FCV	0.099	0.039	2.540	0.0111	—
	FCV^2	0.056	0.019	−2.307	0.0210	—