Impacts of density and large mammals on space use by the pouched mouse (<i>Saccostomus mearnsi</i>) in central Kenya

Keesing, Felicia; Crawford, Tara Gancos

doi:10.1017/s0266467401001328

Cited by 14 publications

(16 citation statements)

References 21 publications

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“…Effects of grazing may depend also on the scale of sampling [67], with more rapid small mammal responses likely to be observed in small, fenced exclosures that keep out cattle and all other large mammals (e.g. Keesing and Crawford [68]) than in the very large scale cattle removal studied here.…”

Section: Discussionmentioning

confidence: 94%

Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

et al. 2013

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Arid grasslands are used worldwide for grazing by domestic livestock, generating debate about how this pastoral enterprise may influence native desert biota. One approach to resolving this question is to experimentally reduce livestock numbers and measure the effects. However, a key challenge in doing this is that historical grazing impacts are likely to be cumulative and may therefore confound comparisons of the short-term responses of desert biota to changes in stocking levels. Arid areas are also subject to infrequent flooding rainfalls that drive productivity and dramatically alter abundances of flora and fauna. We took advantage of an opportunity to study the recent effects of a property-scale cattle removal on two properties with similarly varied grazing histories in central Australia. Following the removal of cattle in 2006 and before and after a significant rainfall event at the beginning of 2007, we sampled vegetation and small vertebrates on eight occasions until October 2008. Our results revealed significant interactions of time of survey with both grazing history and grazing removal for vascular plants, small mammals and reptiles. The mammals exhibited a three-way interaction of time, grazing history and grazing removal, thus highlighting the importance of careful sampling designs and timing for future monitoring. The strongest response to the cessation of grazing after two years was depressed reproductive output of plants in areas where cattle continued to graze. Our results confirm that neither vegetation nor small vertebrates necessarily respond immediately to the removal of livestock, but that rainfall events and cumulative grazing history are key determinants of floral and faunal performance in grassland landscapes with low and variable rainfall. We suggest that improved assessments could be made of the health of arid grazing environments if long-term monitoring were implemented to track the complex interactions that influence how native biota respond to grazing.

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Section: Discussionmentioning

confidence: 94%

Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

et al. 2013

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“…Indeed, a generalist herbivore (the sheep) may be competitively superior to those with a narrower diet (e.g., Latham et al 1996;Johnson et al 2000;Hulbert and Andersen 2001) such as voles. Earlier studies on the relationship between small rodents and large ungulates simply compare grazed to ungrazed plots (Hanley and Page 1980;Hewson 1982;Putman et al 1989;Jones and Longland 1999;Keesing and Crawford 2001;Weickert et al 2001). However, from competition theory (Tokeshi 1999), it is clearly evident that the level of grazing will determine whether or not competition (or other interaction) occurs, not just whether or not another grazing species is present.…”

Section: Discussionmentioning

confidence: 99%

“…Scattered observational evidence in the literature from salt deserts to high arctic ecosystems report both increases (Jones and Longland 1999;Keesing and Crawford 2001) and decreases in the activity or abundance of rodents when subject to ungulate grazing (Jones and Longland 1999;Weickert et al 2001). In some instances, respective increases or decreases depended on the habitat type (Hanley and Page 1980;Hewson 1982) or rodent species involved (Hanley and Page 1980;Jones and Longland 1999).…”

Section: Introductionmentioning

confidence: 99%

Sheep grazing and rodent populations: evidence of negative interactions from a landscape scale experiment

2005

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Inter-specific competition, facilitation and predation influence herbivore assemblages, but no study has experimentally explored the interactions between large ungulates and small rodents. In a fully replicated, landscape scale experiment, we manipulated densities of domestic sheep in mountain pastures in Norway. We then determined population growth and densities of rodents by live trapping in each of the areas with different sheep densities. We found that the (summer) population growth rate and autumn density of the field vole (Microtus agrestis) was lower at high sheep density. This provides the first experimental evidence of negative interactions between an ungulate and small rodent species. There was no effect on the bank vole (Clethrionomys glareolus), whose diet differs from sheep. Sheep density, therefore, potentially alters the pattern of inter-specific population synchrony amongst voles. Our study shows that negative interactions between large ungulates and small rodents may be species-specific and negative population consequences for the rodent population appear above threshold ungulate densities.

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“…To begin to fill this gap, we examined the effect of large wildlife loss on immune function of wild rodents in a natural setting. Large mammals, both domestic and wild, can greatly impact the density and behaviour of rodents (Heske & Campbell ; Keesing and Crawford , Smit et al . ; Keesing & Young ).…”

Section: Introductionmentioning

confidence: 99%

Large wildlife removal drives immune defence increases in rodents

et al. 2015

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Summary 1.Anthropogenic disturbances involving land use change, climate disruption, pollution and invasive species have been shown to impact immune function of wild animals. These immune changes have direct impacts on the fitness of impacted animals and, also, potentially indirect effects on other species and on ecological processes, notably involving the spread of infectious disease. Here, we investigate whether the selective loss of large wildlife can also drive changes in immune function of other consumer species. 2. Using a long-standing large-scale exclosure experiment in East Africa, we investigated the effects of selective removal of large wildlife on multiple measures of immune function in the dominant small rodent in the system, the East African pouched mouse, Saccostomus mearnsi. 3. We find support for a general increase in immune function in landscapes where large wildlife has been removed, but with some variation across immune parameters. These changes may be mediated in part by increased pathogen pressure in plots where large wildlife has been removed due to major increases in rodent density in such plots, but other factors such as changes in food resources are also likely involved. 4. Overall, our research reveals that the elimination of large-bodied wildlife -now recognized as another major form of global anthropogenic change -may have cascading effects on immune health, with the potential for these effects to also impact disease dynamics in ecological communities.

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Impacts of density and large mammals on space use by the pouched mouse (Saccostomus mearnsi) in central Kenya

Cited by 14 publications

References 21 publications

Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

Interactions of Grazing History, Cattle Removal and Time since Rain Drive Divergent Short-Term Responses by Desert Biota

Sheep grazing and rodent populations: evidence of negative interactions from a landscape scale experiment

Large wildlife removal drives immune defence increases in rodents

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