The negative impact of anthropogenic disturbance and land-use changes on large mammals is general... more The negative impact of anthropogenic disturbance and land-use changes on large mammals is generally recognized within conservation biology. In southeastern Norway, both moose (Alces alces) and roe deer (Capreolus capreolus) occur throughout human-modified landscapes, facilitating an interesting comparative study of their habitat use. By using pellet group counts, we looked at the importance of forest structure, vegetation characteristics and human disturbance (e.g., distance to the nearest house, nearest paved road, and nearest edge between field and forest) in shaping the winter distribution of both species at multiple spatial scales, in non-agricultural habitats. Moose occurred more often in areas with higher densities of heather and Vaccinium sp. in the ground layer, and used areas with more open forest structure. The proportion of built-up areas, within a 1,000-m buffer, negatively influenced moose occurrence. Roe deer occurred more often in areas with deciduous trees and patches with juniper and Vaccinium sp. in the ground layer, used areas near roads less, but were significantly associated with areas near the field–forest ecotone. The proportion of built-up areas positively influenced roe deer distribution within a 2,500-m buffer. Roe deer seem to be able to persist in more human-dominated landscapes, possibly due to the availability of field–forest edges providing both high-quality fodder and cover in close proximity. Moose, on the contrary, did not show any preference for areas associated with human disturbance, and their distribution was only associated with patches providing food.
The choice of neonatal hiding place is critical for ungulates adopting hiding anti-predator strat... more The choice of neonatal hiding place is critical for ungulates adopting hiding anti-predator strategies, but the consequences of different decisions have rarely been evaluated with respect to offspring survival. First, we investigated how landscape-scale choices made by roe deer fawns and their mothers affected predation risk by red foxes in a forest–farmland mosaic in southeastern Norway. After, we examined the effect of site-specific characteristics and behaviour (i.e. visibility, mother–fawn distance and abundance of the predator’s main prey item—small rodents) on predation risk. The study of habitat use, selection and habitat-specific mortality revealed that roe deer utilised the landscape matrix in a functional way, with different habitats used for feeding, providing maternal care and as refugia from predation. Mothers faced a trade-off between foraging and offspring survival. At the landscape-scale decisions were primarily determined by maternal energetic constraints and only secondarily by risk avoidance. Indeed, forage-rich habitats were strongly selected notwithstanding the exceptionally high densities of rodents which increased fawn predation. At fine spatial scales, a high visibility of the mother was the major factor determining predation risk; however, mothers adjusted their behaviour to the level of risk at the bed site to minimise predation. Fawns selected both landscape-scale refugia and concealed bed sites, but failure to segregate from the main prey of red foxes led to higher predation. This study provides evidence for the occurrence of spatial heterogeneity in predation risk and shows that energetically stressed individuals can tackle the foraging-safety trade-off by adopting scale-dependent anti-predator responses.
1. Notwithstanding the growing amount of literature emphasizing the link between habitat, life-h... more 1. Notwithstanding the growing amount of literature emphasizing the link between habitat, life-history traits and behaviour, few empirical studies investigated the combined effect of these parameters on individual predation risk. We investigated direct and indirect consequences of habitat composition at multiple spatial scales on predation risk by red foxes on 151 radio-monitored roe deer fawns. We hypothesized that the higher resource availability in fragmented agricultural areas increased predation risk because of: (i) shorter prey movements, which may increase predictability; (ii) larger litter size and faster growth rates, which may increase detectability in species adopting a hiding neonatal anti-predator strategy. The sharing of risky habitat among littermates was expected to promote whole-litter losses as a result of predation.2. The landscape-scale availability of agricultural areas negatively affected pre-weaning movements, but did not influence growth rates or litter size. Predation risk was best described by the interplay between movements and fine-scale habitat fragmentation: a higher mobility increased the encounter rate and predation risk in highly fragmented home ranges, while it reduced predation risk in forest-dominated areas with clumped resources because of decreased predictability. This is one of the first demonstrations that movement patterns can be an efficient anti-predator strategy when adjusted to local conditions.3. In accordance with previous studies documenting the existence of family effects (i.e. non-independence among siblings) in survival, littermates survived or died together more often than expected by chance. In addition, our study specifically demonstrated the occurrence of behaviourally mediated family effects in predation risk: after a fox killed one fawn the probability of a sibling being killed within a few days rose from 20% to 47%, likely because of the win-stay strategy (i.e. return to a previously rewarding site) adopted by the predator. Hence, the predator’s hunting strategy has the potential to raise fawn mortality disproportionately to predator abundance.4. There is increasing evidence that fawns inhabiting highly productive predator-free habitats are granted lifetime fitness benefits; these potential advantages, however, can be cancelled out when predation risk increases in the very same high-productivity areas, which might thus turn into attractive sinks.
Red fox Vulpes vulpes predation on roe deer Capreolus capreolus fawns has the potential to strong... more Red fox Vulpes vulpes predation on roe deer Capreolus capreolus fawns has the potential to strongly affect prey population dynamics, but it is unclear whether this relationship is symmetrical or not. We analysed the spring–summer diet of adult foxes and of their cubs in a fragmented agricultural area of southeastern Norway, where a parallel study showed that the predator kills annually 25% of the radio-monitored roe deer fawns. The overall diet was highly varied and was dominated by small mammals (33% volume), especially Microtus agrestis, and medium-large mammals (25%), largely represented by fawns. The frequency of occurrence (FO) of fawns in the diet of adult foxes was highest in early spring, thus, supporting previous studies showing that the predator started actively hunting for fawns from the very beginning of the birth season. During the summer, the FO of both fawns and small mammals markedly declined, while that of berries and invertebrates increased. As expected for central-place foragers, cubs consumed a higher proportion of large prey items compared to adults. In particular, 25% of scats from cubs—versus 9% from adults—contained roe deer remains, suggesting a high profitability of fawns for vixens raising offspring. However, considering the wide food spectrum and the availability of several large prey items in our study area, it seems unlikely that the importance of fawns to the diet and population dynamics of red foxes could be as great as the impact of the predator on roe deer populations. This asymmetrical relationship implies that there are unlikely to be any stabilising feedback mechanisms in the predator–prey relationship.
The negative impact of anthropogenic disturbance and land-use changes on large mammals is general... more The negative impact of anthropogenic disturbance and land-use changes on large mammals is generally recognized within conservation biology. In southeastern Norway, both moose (Alces alces) and roe deer (Capreolus capreolus) occur throughout human-modified landscapes, facilitating an interesting comparative study of their habitat use. By using pellet group counts, we looked at the importance of forest structure, vegetation characteristics and human disturbance (e.g., distance to the nearest house, nearest paved road, and nearest edge between field and forest) in shaping the winter distribution of both species at multiple spatial scales, in non-agricultural habitats. Moose occurred more often in areas with higher densities of heather and Vaccinium sp. in the ground layer, and used areas with more open forest structure. The proportion of built-up areas, within a 1,000-m buffer, negatively influenced moose occurrence. Roe deer occurred more often in areas with deciduous trees and patches with juniper and Vaccinium sp. in the ground layer, used areas near roads less, but were significantly associated with areas near the field–forest ecotone. The proportion of built-up areas positively influenced roe deer distribution within a 2,500-m buffer. Roe deer seem to be able to persist in more human-dominated landscapes, possibly due to the availability of field–forest edges providing both high-quality fodder and cover in close proximity. Moose, on the contrary, did not show any preference for areas associated with human disturbance, and their distribution was only associated with patches providing food.
The choice of neonatal hiding place is critical for ungulates adopting hiding anti-predator strat... more The choice of neonatal hiding place is critical for ungulates adopting hiding anti-predator strategies, but the consequences of different decisions have rarely been evaluated with respect to offspring survival. First, we investigated how landscape-scale choices made by roe deer fawns and their mothers affected predation risk by red foxes in a forest–farmland mosaic in southeastern Norway. After, we examined the effect of site-specific characteristics and behaviour (i.e. visibility, mother–fawn distance and abundance of the predator’s main prey item—small rodents) on predation risk. The study of habitat use, selection and habitat-specific mortality revealed that roe deer utilised the landscape matrix in a functional way, with different habitats used for feeding, providing maternal care and as refugia from predation. Mothers faced a trade-off between foraging and offspring survival. At the landscape-scale decisions were primarily determined by maternal energetic constraints and only secondarily by risk avoidance. Indeed, forage-rich habitats were strongly selected notwithstanding the exceptionally high densities of rodents which increased fawn predation. At fine spatial scales, a high visibility of the mother was the major factor determining predation risk; however, mothers adjusted their behaviour to the level of risk at the bed site to minimise predation. Fawns selected both landscape-scale refugia and concealed bed sites, but failure to segregate from the main prey of red foxes led to higher predation. This study provides evidence for the occurrence of spatial heterogeneity in predation risk and shows that energetically stressed individuals can tackle the foraging-safety trade-off by adopting scale-dependent anti-predator responses.
1. Notwithstanding the growing amount of literature emphasizing the link between habitat, life-h... more 1. Notwithstanding the growing amount of literature emphasizing the link between habitat, life-history traits and behaviour, few empirical studies investigated the combined effect of these parameters on individual predation risk. We investigated direct and indirect consequences of habitat composition at multiple spatial scales on predation risk by red foxes on 151 radio-monitored roe deer fawns. We hypothesized that the higher resource availability in fragmented agricultural areas increased predation risk because of: (i) shorter prey movements, which may increase predictability; (ii) larger litter size and faster growth rates, which may increase detectability in species adopting a hiding neonatal anti-predator strategy. The sharing of risky habitat among littermates was expected to promote whole-litter losses as a result of predation.2. The landscape-scale availability of agricultural areas negatively affected pre-weaning movements, but did not influence growth rates or litter size. Predation risk was best described by the interplay between movements and fine-scale habitat fragmentation: a higher mobility increased the encounter rate and predation risk in highly fragmented home ranges, while it reduced predation risk in forest-dominated areas with clumped resources because of decreased predictability. This is one of the first demonstrations that movement patterns can be an efficient anti-predator strategy when adjusted to local conditions.3. In accordance with previous studies documenting the existence of family effects (i.e. non-independence among siblings) in survival, littermates survived or died together more often than expected by chance. In addition, our study specifically demonstrated the occurrence of behaviourally mediated family effects in predation risk: after a fox killed one fawn the probability of a sibling being killed within a few days rose from 20% to 47%, likely because of the win-stay strategy (i.e. return to a previously rewarding site) adopted by the predator. Hence, the predator’s hunting strategy has the potential to raise fawn mortality disproportionately to predator abundance.4. There is increasing evidence that fawns inhabiting highly productive predator-free habitats are granted lifetime fitness benefits; these potential advantages, however, can be cancelled out when predation risk increases in the very same high-productivity areas, which might thus turn into attractive sinks.
Red fox Vulpes vulpes predation on roe deer Capreolus capreolus fawns has the potential to strong... more Red fox Vulpes vulpes predation on roe deer Capreolus capreolus fawns has the potential to strongly affect prey population dynamics, but it is unclear whether this relationship is symmetrical or not. We analysed the spring–summer diet of adult foxes and of their cubs in a fragmented agricultural area of southeastern Norway, where a parallel study showed that the predator kills annually 25% of the radio-monitored roe deer fawns. The overall diet was highly varied and was dominated by small mammals (33% volume), especially Microtus agrestis, and medium-large mammals (25%), largely represented by fawns. The frequency of occurrence (FO) of fawns in the diet of adult foxes was highest in early spring, thus, supporting previous studies showing that the predator started actively hunting for fawns from the very beginning of the birth season. During the summer, the FO of both fawns and small mammals markedly declined, while that of berries and invertebrates increased. As expected for central-place foragers, cubs consumed a higher proportion of large prey items compared to adults. In particular, 25% of scats from cubs—versus 9% from adults—contained roe deer remains, suggesting a high profitability of fawns for vixens raising offspring. However, considering the wide food spectrum and the availability of several large prey items in our study area, it seems unlikely that the importance of fawns to the diet and population dynamics of red foxes could be as great as the impact of the predator on roe deer populations. This asymmetrical relationship implies that there are unlikely to be any stabilising feedback mechanisms in the predator–prey relationship.
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