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Intensity of space use reveals conditional sex-specific effects of prey and conspecific density on home range size.

Aronsson M, Low M, López-Bao JV, Persson J, Odden J, Linnell JD, Andrén H - Ecol Evol (2016)

Bottom Line: However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important.Males reduced their HR size during the mating season, likely to remain close to individual females in estrous.Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology Swedish University of Agricultural Sciences Grimsö Wildlife Research Station SE-73091 Riddarhyttan Sweden.

ABSTRACT
Home range (HR) size variation is often linked to resource abundance, with sex differences expected to relate to sex-specific fitness consequences. However, studies generally fail to disentangle the effects of the two main drivers of HR size variation, food and conspecific density, and rarely consider how their relative influence change over spatiotemporal scales. We used location data from 77 Eurasian lynx (Lynx lynx) from a 16-year Scandinavian study to examine HR sizes variation relative to prey and conspecific density at different spatiotemporal scales. By varying the isopleth parameter (intensity of use) defining the HR, we show that sex-specific effects were conditional on the spatial scale considered. Males had larger HRs than females in all seasons. Females' total HR size declined as prey and conspecific density increased, whereas males' total HR was only affected by conspecific density. However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important. Thus, prey influenced the size of key regions within male HRs, despite total HR size being independent of prey density. Males reduced their HR size during the mating season, likely to remain close to individual females in estrous. Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young. Our findings highlight the importance of simultaneously considering resources and intraspecific interactions as HR size determinants. We show that sex-specific demands influence the importance of prey and conspecific density on space use at different spatiotemporal scales. Thus, unless a gradient of space use intensity is examined, factors not related to total HR size might be disregarded despite their importance in determining size of key regions within the HR.

No MeSH data available.


Home range (HR) estimation obtained as a probability density function of intensity of area use (A). We estimated lynx HR size at 5 use intensities represented by the 90% (total HR), 80%, 70%, 60%, and 50% isopleths where intensity of use increases with decreasing isopleth level (i.e., darker areas = higher use). We predict that range size determinants will vary within an animal's HR relative to the intensity of use (B). Female HRs should be just large enough to contain sufficient food resources to survive and nourish offspring, and hence, the negative effect of prey density on range size should be strongest on the total HR size (90% isopleth, light grey) and become less important with decreasing isopleth level. We predict the opposite pattern for males as total HR size is set to maximizing mating opportunities whereas basal energy needs should affect space use at a lower isopleth levels (darker grey). For females, we expect conspecific density to show its greatest effect on total HR size due to territorial behavior. For males, however, conspecific density represent both resources (females) and competitors (males), and thus, we expect the effect of conspecific density on male spacing behavior to vary with conspecific density per se.
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ece32032-fig-0001: Home range (HR) estimation obtained as a probability density function of intensity of area use (A). We estimated lynx HR size at 5 use intensities represented by the 90% (total HR), 80%, 70%, 60%, and 50% isopleths where intensity of use increases with decreasing isopleth level (i.e., darker areas = higher use). We predict that range size determinants will vary within an animal's HR relative to the intensity of use (B). Female HRs should be just large enough to contain sufficient food resources to survive and nourish offspring, and hence, the negative effect of prey density on range size should be strongest on the total HR size (90% isopleth, light grey) and become less important with decreasing isopleth level. We predict the opposite pattern for males as total HR size is set to maximizing mating opportunities whereas basal energy needs should affect space use at a lower isopleth levels (darker grey). For females, we expect conspecific density to show its greatest effect on total HR size due to territorial behavior. For males, however, conspecific density represent both resources (females) and competitors (males), and thus, we expect the effect of conspecific density on male spacing behavior to vary with conspecific density per se.

Mentions: Because resource distribution and conspecific interactions are not uniform, the relative importance of resources and conspecifics in relation to HR variation should change both in space and time (Börger et al. 2006a; van Beest et al. 2011; Campos et al. 2014). As HRs are often defined in terms of some minimum intensity of space use by the focal animal (Kie et al. 2010), critical insights can be gained by examining how the effect of range size determinants changes as intensity of space use changes within the HR (Fig. 1). For example, factors that are important for determining total HR may become less important in determining the size of more intensively used areas within the HR and vice versa (i.e., compared to the second‐ and third‐order habitat selection; Johnson 1980). Similarly, relationships between conspecifics, resources, and HR use should show temporal variation associated with seasonal breeding (Gittleman and Thompson 1988).


Intensity of space use reveals conditional sex-specific effects of prey and conspecific density on home range size.

Aronsson M, Low M, López-Bao JV, Persson J, Odden J, Linnell JD, Andrén H - Ecol Evol (2016)

Home range (HR) estimation obtained as a probability density function of intensity of area use (A). We estimated lynx HR size at 5 use intensities represented by the 90% (total HR), 80%, 70%, 60%, and 50% isopleths where intensity of use increases with decreasing isopleth level (i.e., darker areas = higher use). We predict that range size determinants will vary within an animal's HR relative to the intensity of use (B). Female HRs should be just large enough to contain sufficient food resources to survive and nourish offspring, and hence, the negative effect of prey density on range size should be strongest on the total HR size (90% isopleth, light grey) and become less important with decreasing isopleth level. We predict the opposite pattern for males as total HR size is set to maximizing mating opportunities whereas basal energy needs should affect space use at a lower isopleth levels (darker grey). For females, we expect conspecific density to show its greatest effect on total HR size due to territorial behavior. For males, however, conspecific density represent both resources (females) and competitors (males), and thus, we expect the effect of conspecific density on male spacing behavior to vary with conspecific density per se.
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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ece32032-fig-0001: Home range (HR) estimation obtained as a probability density function of intensity of area use (A). We estimated lynx HR size at 5 use intensities represented by the 90% (total HR), 80%, 70%, 60%, and 50% isopleths where intensity of use increases with decreasing isopleth level (i.e., darker areas = higher use). We predict that range size determinants will vary within an animal's HR relative to the intensity of use (B). Female HRs should be just large enough to contain sufficient food resources to survive and nourish offspring, and hence, the negative effect of prey density on range size should be strongest on the total HR size (90% isopleth, light grey) and become less important with decreasing isopleth level. We predict the opposite pattern for males as total HR size is set to maximizing mating opportunities whereas basal energy needs should affect space use at a lower isopleth levels (darker grey). For females, we expect conspecific density to show its greatest effect on total HR size due to territorial behavior. For males, however, conspecific density represent both resources (females) and competitors (males), and thus, we expect the effect of conspecific density on male spacing behavior to vary with conspecific density per se.
Mentions: Because resource distribution and conspecific interactions are not uniform, the relative importance of resources and conspecifics in relation to HR variation should change both in space and time (Börger et al. 2006a; van Beest et al. 2011; Campos et al. 2014). As HRs are often defined in terms of some minimum intensity of space use by the focal animal (Kie et al. 2010), critical insights can be gained by examining how the effect of range size determinants changes as intensity of space use changes within the HR (Fig. 1). For example, factors that are important for determining total HR may become less important in determining the size of more intensively used areas within the HR and vice versa (i.e., compared to the second‐ and third‐order habitat selection; Johnson 1980). Similarly, relationships between conspecifics, resources, and HR use should show temporal variation associated with seasonal breeding (Gittleman and Thompson 1988).

Bottom Line: However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important.Males reduced their HR size during the mating season, likely to remain close to individual females in estrous.Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology Swedish University of Agricultural Sciences Grimsö Wildlife Research Station SE-73091 Riddarhyttan Sweden.

ABSTRACT
Home range (HR) size variation is often linked to resource abundance, with sex differences expected to relate to sex-specific fitness consequences. However, studies generally fail to disentangle the effects of the two main drivers of HR size variation, food and conspecific density, and rarely consider how their relative influence change over spatiotemporal scales. We used location data from 77 Eurasian lynx (Lynx lynx) from a 16-year Scandinavian study to examine HR sizes variation relative to prey and conspecific density at different spatiotemporal scales. By varying the isopleth parameter (intensity of use) defining the HR, we show that sex-specific effects were conditional on the spatial scale considered. Males had larger HRs than females in all seasons. Females' total HR size declined as prey and conspecific density increased, whereas males' total HR was only affected by conspecific density. However, as the intensity of use within the HR increased (from 90% to 50% isopleth), the relationship between prey density and area showed opposing patterns for females and males; for females, the prey density effect was reduced, while for males, prey became increasingly important. Thus, prey influenced the size of key regions within male HRs, despite total HR size being independent of prey density. Males reduced their HR size during the mating season, likely to remain close to individual females in estrous. Females reduced their HR size postreproduction probably because of movement constrains imposed by dependent young. Our findings highlight the importance of simultaneously considering resources and intraspecific interactions as HR size determinants. We show that sex-specific demands influence the importance of prey and conspecific density on space use at different spatiotemporal scales. Thus, unless a gradient of space use intensity is examined, factors not related to total HR size might be disregarded despite their importance in determining size of key regions within the HR.

No MeSH data available.