ABSTRACTSeasonal migrations are central ecological processes connecting populations, species and ... more ABSTRACTSeasonal migrations are central ecological processes connecting populations, species and ecosystems in time and space. Land migrations, such as those of ungulates, are particularly threatened by habitat transformations and fragmentation, climate change and other environmental changes caused by anthropogenic activities. Mountain ungulate migrations are neglected because they are relatively short, although traversing highly heterogeneous altitudinal gradients particularly exposed to anthropogenic threats. Detecting migration routes of these species and understanding their drivers is therefore of primary importance to predict connectivity and preserve ecosystem functions and services. The populations of Alpine ibexCapra ibex, an iconic species endemic to the Alps, have all been reintroduced from the last remnant source population. Because of their biology and conservation history, Alpine ibex populations are mostly disconnected. Hence, despite a general increase in abundance an...
This project is aimed at investigating trophic cascades originating from the successive exclusion... more This project is aimed at investigating trophic cascades originating from the successive exclusion of herbivores of various sizes from subalpine grasslands of the Swiss National Park (SNP). Historical grazing patterns in the SNP have developed two distinct vegetation types – heavily grazed short grass vegetation and lightly grazed tall grass vegetation – derived from former land use which differ in vegetation quality, community composition and usage by herbivores. This poster presents some of the methods we use to study how herbivore exclusion affects ecosystem properties and processes.
Protected areas provide unique opportunities to investigate species interactions under natural co... more Protected areas provide unique opportunities to investigate species interactions under natural conditions. In the absence of large predators, ungulates have reached relatively high densities in the Swiss National Park, and in some valleys, chamois, alpine ibex and red deer co-occur in close proximity. We explored the potential for resource competition between the three species by integrating information on local diet composition and finescale spatial distribution with respect to environmental parameters in the valley with the highest ungulate density in the Park. We then tested for correlations in a) their respective population sizes from census data collected over the last 21 years, and b) correlations between census sizes and body condition of chamois and ibex, measured as yearling horn growth. Based on a correspondence analysis, no difference was detected in diet composition between the three species during spring and summer. Chamois and ibex showed significantly different diets ...
Monitoring of visitor flow in recreational parks is important to various tasks of management, e.g... more Monitoring of visitor flow in recreational parks is important to various tasks of management, e.g. to assess the impact of visitors to the nature, to get information about the signification to the regional market or to estimate the demand trends for the future (Cessford & Muhar 2003). However, data acquisition is a very time-consuming and money-intensive assignment. There are three main categories of data collection methods: self-counting, directcounting and indirect counting (Hollenhorst et al. 1992). Depending on the goal of visitor monitoring, different data collection types are used. Self-counting methods are quite uncertain because their backflow is low. With direct-counting methods a lot of information, such as visitor characteristics, visitor behaviour and visitor numbers can be collected. The disadvantage of these methods is their big costs. A lot of human resources are needed to collect data. Indirect-counting systems generate simple estimations of recreational use, which a...
Die saisonalen Wanderungen der Rothirsche sind gut erforscht und haben sich in den letzten Jahren... more Die saisonalen Wanderungen der Rothirsche sind gut erforscht und haben sich in den letzten Jahren nicht grundsatzlich verandert (Seite 148). Doch nutzen die Hirsche uber zwei Jahrzehnte ein Gebiet immer gleich? Verandert sich der Tagesgang der Raumnutzung mit der Zeit? Aus der Val Foraz liegt ein Datensatz vor, der den Tagesgang des Raumverhaltens der Rothirsche langfristig dokumentiert. Die Herausforderung liegt oft nicht nur in der Erhebung, sondern auch in der Visualisierung und Auswertung der Daten. 2012 entstand eine komplexe Karte, welche die Veranderung der Raumnutzung uber die Zeit sichtbar machen soll.
Understanding components of interspecific competition has long been a major goal in ecological st... more Understanding components of interspecific competition has long been a major goal in ecological studies. Classical models of competition typically consider equal responses of all individuals to the density of competitors, however responses may differ both among individuals from the same population, and between populations. Based on individual long-term monitoring of two chamois populations in sympatry with red deer, we built a multi-event capture-recapture model to assess how vital rates of the smaller chamois are affected by competition from the larger red deer. In both populations, mortality and breeding probabilities of female chamois depend on age and in most cases, of breeding status the preceding year. Successful breeders always performed better the next year, indicating that some females are of high quality. In one population where there was high spatial overlap between the two species, the survival of old female chamois that were successful breeders the preceding year (high-quality) was negatively related to an index of red deer population size suggesting that they tend to skip reproduction instead of jeopardizing their own survival when the number of competitors increases. The breeding probability of young breeders (ages 2 and 3) was similarly affected by red deer population size. In contrast, in the second site with low spatial overlap between the two species, the vital rates of female chamois were not related to red deer population size. We provide evidence for population-specific responses to interspecific competition and more generally, for context-, age- and state-dependent effects of interspecific competition. Our results also suggest that the classical assumption of equal responses of all individuals to interspecific competition should be relaxed, and emphasize the need to move towards more mechanistic approaches to better understand how natural populations respond to changes in their environment.
Weaponry in ungulates may be costly to grow and maintain, and different selective pressures in ma... more Weaponry in ungulates may be costly to grow and maintain, and different selective pressures in males and females may lead to sex‐biased natural survival. Sexual differences in the relationship between weapon growth and survival may increase under anthropogenic selection through culling, for example because of trophy hunting. Selection on weaponry growth under different scenarios has been largely investigated in males of highly dimorphic ungulates, for which survival costs (either natural or hunting related) are thought to be greatest. Little is known, however, about the survival costs of weaponry in males and females of weakly dimorphic species. We collected information on horn length and age at death/shooting of 407 chamois Rupicapra rupicapra in a protected population and in two hunted populations with different hunting regimes, to explore sexual differences in the selection on early horn growth under contrasting selective pressures. We also investigated the variation of horn grow...
ABSTRACTSeasonal migrations are central ecological processes connecting populations, species and ... more ABSTRACTSeasonal migrations are central ecological processes connecting populations, species and ecosystems in time and space. Land migrations, such as those of ungulates, are particularly threatened by habitat transformations and fragmentation, climate change and other environmental changes caused by anthropogenic activities. Mountain ungulate migrations are neglected because they are relatively short, although traversing highly heterogeneous altitudinal gradients particularly exposed to anthropogenic threats. Detecting migration routes of these species and understanding their drivers is therefore of primary importance to predict connectivity and preserve ecosystem functions and services. The populations of Alpine ibexCapra ibex, an iconic species endemic to the Alps, have all been reintroduced from the last remnant source population. Because of their biology and conservation history, Alpine ibex populations are mostly disconnected. Hence, despite a general increase in abundance an...
This project is aimed at investigating trophic cascades originating from the successive exclusion... more This project is aimed at investigating trophic cascades originating from the successive exclusion of herbivores of various sizes from subalpine grasslands of the Swiss National Park (SNP). Historical grazing patterns in the SNP have developed two distinct vegetation types – heavily grazed short grass vegetation and lightly grazed tall grass vegetation – derived from former land use which differ in vegetation quality, community composition and usage by herbivores. This poster presents some of the methods we use to study how herbivore exclusion affects ecosystem properties and processes.
Protected areas provide unique opportunities to investigate species interactions under natural co... more Protected areas provide unique opportunities to investigate species interactions under natural conditions. In the absence of large predators, ungulates have reached relatively high densities in the Swiss National Park, and in some valleys, chamois, alpine ibex and red deer co-occur in close proximity. We explored the potential for resource competition between the three species by integrating information on local diet composition and finescale spatial distribution with respect to environmental parameters in the valley with the highest ungulate density in the Park. We then tested for correlations in a) their respective population sizes from census data collected over the last 21 years, and b) correlations between census sizes and body condition of chamois and ibex, measured as yearling horn growth. Based on a correspondence analysis, no difference was detected in diet composition between the three species during spring and summer. Chamois and ibex showed significantly different diets ...
Monitoring of visitor flow in recreational parks is important to various tasks of management, e.g... more Monitoring of visitor flow in recreational parks is important to various tasks of management, e.g. to assess the impact of visitors to the nature, to get information about the signification to the regional market or to estimate the demand trends for the future (Cessford & Muhar 2003). However, data acquisition is a very time-consuming and money-intensive assignment. There are three main categories of data collection methods: self-counting, directcounting and indirect counting (Hollenhorst et al. 1992). Depending on the goal of visitor monitoring, different data collection types are used. Self-counting methods are quite uncertain because their backflow is low. With direct-counting methods a lot of information, such as visitor characteristics, visitor behaviour and visitor numbers can be collected. The disadvantage of these methods is their big costs. A lot of human resources are needed to collect data. Indirect-counting systems generate simple estimations of recreational use, which a...
Die saisonalen Wanderungen der Rothirsche sind gut erforscht und haben sich in den letzten Jahren... more Die saisonalen Wanderungen der Rothirsche sind gut erforscht und haben sich in den letzten Jahren nicht grundsatzlich verandert (Seite 148). Doch nutzen die Hirsche uber zwei Jahrzehnte ein Gebiet immer gleich? Verandert sich der Tagesgang der Raumnutzung mit der Zeit? Aus der Val Foraz liegt ein Datensatz vor, der den Tagesgang des Raumverhaltens der Rothirsche langfristig dokumentiert. Die Herausforderung liegt oft nicht nur in der Erhebung, sondern auch in der Visualisierung und Auswertung der Daten. 2012 entstand eine komplexe Karte, welche die Veranderung der Raumnutzung uber die Zeit sichtbar machen soll.
Understanding components of interspecific competition has long been a major goal in ecological st... more Understanding components of interspecific competition has long been a major goal in ecological studies. Classical models of competition typically consider equal responses of all individuals to the density of competitors, however responses may differ both among individuals from the same population, and between populations. Based on individual long-term monitoring of two chamois populations in sympatry with red deer, we built a multi-event capture-recapture model to assess how vital rates of the smaller chamois are affected by competition from the larger red deer. In both populations, mortality and breeding probabilities of female chamois depend on age and in most cases, of breeding status the preceding year. Successful breeders always performed better the next year, indicating that some females are of high quality. In one population where there was high spatial overlap between the two species, the survival of old female chamois that were successful breeders the preceding year (high-quality) was negatively related to an index of red deer population size suggesting that they tend to skip reproduction instead of jeopardizing their own survival when the number of competitors increases. The breeding probability of young breeders (ages 2 and 3) was similarly affected by red deer population size. In contrast, in the second site with low spatial overlap between the two species, the vital rates of female chamois were not related to red deer population size. We provide evidence for population-specific responses to interspecific competition and more generally, for context-, age- and state-dependent effects of interspecific competition. Our results also suggest that the classical assumption of equal responses of all individuals to interspecific competition should be relaxed, and emphasize the need to move towards more mechanistic approaches to better understand how natural populations respond to changes in their environment.
Weaponry in ungulates may be costly to grow and maintain, and different selective pressures in ma... more Weaponry in ungulates may be costly to grow and maintain, and different selective pressures in males and females may lead to sex‐biased natural survival. Sexual differences in the relationship between weapon growth and survival may increase under anthropogenic selection through culling, for example because of trophy hunting. Selection on weaponry growth under different scenarios has been largely investigated in males of highly dimorphic ungulates, for which survival costs (either natural or hunting related) are thought to be greatest. Little is known, however, about the survival costs of weaponry in males and females of weakly dimorphic species. We collected information on horn length and age at death/shooting of 407 chamois Rupicapra rupicapra in a protected population and in two hunted populations with different hunting regimes, to explore sexual differences in the selection on early horn growth under contrasting selective pressures. We also investigated the variation of horn grow...
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