Holling meets habitat selection: functional response of large herbivores revisited

Table 3 Parameters estimated for Holling’s equations fitted to the functional response curves describing the use of the available habitat types by male roe deer in the Bavarian Forest National Park in summer (June) at different times of day (noon/midnight)

Habitat	Sex	Month	Hour	type	a	b	a/b	\(x^{*}\)
Old mixed	m	6	0	I	0.71			0
			12	I	0.94			0
Bark beetle area	m	6	0	I	0.40			0
			12	II	0.39	0.17	2.34	0.23
Unmanaged meadows	m	6	0	II	0.29	0.03	9.16	0.26
			12	II	0.39	0.17	2.31	0.22
Cultivated meadows	m	6	0	II	0.24	0.01	22.67	0.23
			12	III	0.02	0.04	0.40	0
Clearcuts	m	6	0	II	0.18	0.07	2.51	0.11
			12	II	0.20	0.09	2.35	0.12
Young stands	m	6	0	II	0.16	0.12	1.35	0.04
			12	II	0.20	0.06	3.52	0.15
Old deciduous	m	6	0	II	0.24	0.18	1.32	0.06
			12	II	0.30	0.21	1.45	0.09
Old coniferous	m	6	0	I	0.37			0
			12	I	0.46			0
Medium mixed	m	6	0	III	0.19	0.21	0.90	0
			12	II	0.82	0.72	1.14	0.10
Medium deciduous	m	6	0	II	0.13	1.00	0.13	0
			12	II	0.00	0.00	0.87	0
Anthropogenic	m	6	0	II	0.05	1.00	0.05	0
			12	II	0.00	1.00	0.00	0

Associated curves are shown in Fig. 2. Holling’s equations for type I \(h_I(x)=a x\), where x is the availability of a habitat; for type II: \(h_{II} (x)=\frac{ax}{b+x}\) and for type III: \(h_{III} (x)=\frac{ax^2}{b^2+x^2}\). The fraction \(\frac{a}{b}\) indicates the selection strength independent of availability of a habitat: the greater the value the greater the general use. The value \(x^* = a-b\) for Holling type II is the availability when use equals availability, hence the value of relative availability at which no selection occurs, which is the tipping point at which habitat selection switches to habitat avoidance (Fig. 1)

ISSN: 2051-3933