Rodent-avoidance, topography and forest structure shape territory selection of a forest bird

Pasinelli, Gilberto; Grendelmeier, Alex; Gerber, Michael; Arlettaz, Raphaël

doi:10.1186/s12898-016-0078-8

BMC Ecology

Table 4 Model selection results of the analysis of breeding territories (n = 56) vs. abandoned territories (n = 20)

From: Rodent-avoidance, topography and forest structure shape territory selection of a forest bird

Hypothesis	Variables in model	LL	K	AICc	ΔAICc	Weight
Forest structure
(a) Ground variables	Number of tussocks, year, number of tussocks x year	−22.315	7	60.277	0	0.202
	Number of tussocks, number of bushes²	−22.774	7	61.194	0.917	0.128
	Number of tussocks, number of bushes², cover of herb layer	−21.562	8	61.273	0.996	0.123
	Number of tussocks, year, number of tussocks x year, number of bushes	−21.798	8	61.745	1.468	0.097
	Number of tussocks, year, number of tussocks x year, cover of herb layer	−21.986	8	62.122	1.845	0.080
	…
	Null	−31.868	4	72.299	12.022	0.000
(b) Tree variables	Number of trees², tree dbh², tree species diversity²	−17.092	10	57.569	0	0.091
	Number of trees, tree species diversity²	−21.187	7	58.020	0.452	0.072
	Number of trees, tree dbh², tree species diversity²	−18.652	9	58.031	0.462	0.072
	Number of trees²	−22.514	6	58.246	0.677	0.065
	Number of trees, tree species diversity², tree dbh	−20.060	8	58.269	0.701	0.064
	Number of trees, tree dbh², tree species diversity², sky visibility	−17.695	10	58.776	1.207	0.050
	Number of trees², tree dbh², tree species diversity², sky visibility	−16.336	11	58.797	1.229	0.049
	Number of trees², tree species diversity²	−20.364	8	58.877	1.308	0.047
	Number of trees², tree dbh², tree species diversity², sky visibility²	−15.234	12	59.420	1.852	0.036
	…
	Null	−31.868	4	72.299	14.730	0.000
(c) Tree species composition	Proportion conifers	−29.723	5	70.303	0	0.265
	Proportion conifers, proportion beech	−29.533	6	72.283	1.981	0.098
	Proportion conifers, proportion other deciduous trees	−29.539	6	72.295	1.992	0.098
	…
	Null	−31.868	4	72.299	1.996	0.098
Rodent-avoidance	Null	−31.868	4	72.299	0	0.575
	Rodent numbers	−31.023	5	72.903	0.605	0.425
Disturbance	Distance to forest edge, distance to path²	−20.719	7	57.084	0	0.694
	Distance to forest edge², distance to path²	−20.453	8	59.055	1.97	0.259
	…
	Null	−31.868	4	72.299	15.214	0.000
Topography	Slope steepness², elevation², southness, eastness	−13.541	10	50.467	0	0.692
	…
	Null	−31.868	4	72.299	21.832	0.000
Across hypotheses^a	Slope steepness, distance to forest edge, number of trees	−14.985	7	45.457	0	0.734
	…
	Null	−31.868	4	72.299	26.842	0.000

For each hypothesis, the top-ranked model (ΔAICc = 0), the models with ΔAICc < 2 to the top-ranked model and the null model (referred to as “null”) are shown. “…” refers to additional models examined, but not listed in detail to avoid overlong table
LL log-likelihood; K number of parameters in the model (including intercept), weight Akaike weight (chance of the model to be the best one, given the candidate models)
The quadratic effect of a variable x, composed of a linear and a quadratic component (x ± x²), is denoted as x²
Each model included x- and y-coordinates (and their interaction) of territories to account for spatial autocorrelation
^a Only linear terms of variables from best models per hypothesis and at most three habitat variables jointly used due to convergence problems with quadratic terms and more than three habitat variable per model

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ISSN: 1472-6785

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