Amplified predation after fire suppresses rodent populations in Australia’s tropical savannas

2015 ◽  
Vol 42 (8) ◽  
pp. 705 ◽  
Author(s):  
Lily Leahy ◽  
Sarah M. Legge ◽  
Katherine Tuft ◽  
Hugh W. McGregor ◽  
Leon A. Barmuta ◽  
...  
Keyword(s):  
Small Mammals ◽  
High Intensity ◽  
Direct Evidence ◽  
Population Decline ◽  
Ground Cover ◽  
Ground Vegetation ◽  
Northern Australia ◽  
Feral Cats ◽  
Live Trapping ◽  
Rodent Populations

Context Changes in abundance following fire are commonly reported for vertebrate species, but the mechanisms causing these changes are rarely tested. Currently, many species of small mammals are declining in the savannas of northern Australia. These declines have been linked to intense and frequent fires in the late dry season; however, why such fires cause declines of small mammals is unknown. Aims We aimed to discover the mechanisms causing decline in abundance of two species of small mammals, the pale field rat, Rattus tunneyi, and the western chestnut mouse, Pseudomys nanus, in response to fire. Candidate mechanisms were (1) direct mortality because of fire itself, (2) mortality after fire because of removal of food by fire, (3) reduced reproductive success, (4) emigration, and (5) increased mortality because of predation following fire. Methods We used live trapping to monitor populations of these two species under the following three experimental fire treatments: high-intensity fire that removed all ground vegetation, low-intensity fire that produced a patchy burn, and an unburnt control. We also radio-tracked 38 R. tunneyi individuals to discover the fates of individual animals. Key results Abundance of both species declined after fire, and especially following the high-intensity burn. There was no support for any of the first four mechanisms of population decline, but mortality owing to predation increased after fire. This was related to loss of ground cover (which was greater in the high-intensity fire treatment), which evidently left animals exposed to predators. Also, local activity of two predators, feral cats and dingoes, increased after the burns, and we found direct evidence of predation by feral cats and snakes. Conclusions Fire in the northern savannas has little direct effect on populations of these small mammals, but it causes declines by amplifying the impacts of predators. These effects are most severe for high-intensity burns that remove a high proportion of vegetation cover. Implications To prevent further declines in northern Australia, fire should be managed in ways that limit the effects of increased predation. This could be achieved by setting cool fires that produce patchy burns, avoiding hot fires, and minimising the total area burnt.

Density and home range of feral cats in north-western Australia

2015 ◽  
Vol 42 (3) ◽  
pp. 223 ◽  
Author(s):  
Hugh W. McGregor ◽  
Sarah Legge ◽  
Joanne Potts ◽  
Menna E. Jones ◽  
Christopher N. Johnson
Keyword(s):  
Population Density ◽  
Home Range ◽  
Small Mammals ◽  
Small Mammal ◽  
Livestock Grazing ◽  
Home Ranges ◽  
Low Density ◽  
Northern Australia ◽  
Feral Cats ◽  
North Western

Context Feral cats (Felis catus) pose a significant threat to biodiversity in Australia, and are implicated in current declines of small mammals in the savannas of northern Australia. Basic information on population density and ranging behaviour is essential to understand and manage threats from feral cats. Aims In this study, we provide robust estimates of density and home range of feral cats in the central Kimberley region of north-western Australia, and we test whether population density is affected by livestock grazing, small mammal abundance and other environmental factors. Methods Densities were measured at six transects sampled between 2011 and 2013 using arrays of infrared cameras. Cats were individually identified, and densities estimated using spatially explicit capture–recapture analysis. Home range was measured from GPS tracking of 32 cats. Key results Densities were similar across all transects and deployments, with a mean of 0.18 cats km–2 (range = 0.09–0.34 km–2). We found no evidence that population density was related to livestock grazing or abundance of small mammals. Home ranges of males were, on average, 855 ha (±156 ha (95% CI), n = 25), and those of females were half the size at 397 ha (±275 ha (95% CI), n = 7). There was little overlap in ranges of cats of the same sex. Conclusions Compared with elsewhere in Australia outside of semiarid regions, feral cats occur at low density and have large home ranges in the central Kimberley. However, other evidence shows that despite this low density, cats are contributing to declines of small mammal populations across northern Australia. Implications It will be very difficult to reduce these already-sparse populations by direct control. Instead, land-management practices that reduce the impacts of cats on prey should be investigated.

Making a killing: photographic evidence of predation of a Tasmanian pademelon (Thylogale billardierii) by a feral cat (Felis catus)

2015 ◽  
Vol 37 (1) ◽  
pp. 120 ◽  
Author(s):  
Bronwyn A. Fancourt
Keyword(s):  
Predation Risk ◽  
Adult Female ◽  
Small Mammals ◽  
Direct Evidence ◽  
Felis Catus ◽  
Compelling Evidence ◽  
Feral Cat ◽  
Feral Cats ◽  
Major Threat ◽  
Photographic Evidence

Feral cats (Felis catus) have contributed to the extinction of numerous Australian mammals and are a major threat to many species of conservation significance. Small mammals are considered to be those at greatest risk of cat predation, with risk typically inferred from dietary studies. However, dietary studies may provide only weak inference as to the risk of cat predation for some species. The most compelling evidence of predation risk comes from direct observation of killing events; however, such observations are rare and photographic evidence is even rarer. I present photographic evidence of a feral cat killing and consuming an adult female Tasmanian pademelon (Thylogale billardierii). This observation provides direct evidence that feral cats can kill prey up to 4 kg in body mass, with potential implications for the conservation of medium-sized mammals.

Reproduction and demography of the northern quoll, Dasyurus hallucatus, in the lowland savanna of northern Australia

2000 ◽  
Vol 48 (5) ◽  
pp. 519 ◽  
Author(s):  
Meri Oakwood
Keyword(s):  
National Park ◽  
Ground Cover ◽  
Adult Mortality ◽  
Breeding Cycle ◽  
First Year ◽  
Northern Australia ◽  
Proximate Cause ◽  
Live Trapping ◽  
The Mean ◽  
Second Year

Reproduction and demography of the northern quoll, Dasyurus hallucatus, was assessed using live-trapping and radio-tracking at a lowland savanna site in Kakadu National Park between 1992 and 1995. Northern quolls were found to exhibit a highly synchronous breeding cycle with mating occurring late May/early June. The greatest peak in apparent male abundance was during the mating season, but this was probably due to their increased mobility at this time. Males demonstrated complete post-mating mortality, with most males dying within two weeks of mating. Young were born in mid to late June with the mean initial litter size for 8-teated females being 7.3. First-year mothers were more likely to have predominantly male litters, whereas second-year mothers had more females. The survival rate of pouch young was high but, once young were left in the den, survival was poor. Peaks in abundance for both sexes occurred when the juveniles first entered the trappable population in November each year. Mortality of females was high, with only 27% of females surviving to wean a second litter, and none bore a third. The most common proximate cause of adult mortality was predation. Increased predation pressure on adults, in particular due to a reduction in shelter and ground cover from too-frequent fire may make northern quolls vulnerable to local extinction in lowland savanna.

Feral cats are more abundant under severe disturbance regimes in an Australian tropical savanna

2020 ◽  
Vol 47 (8) ◽  
pp. 624 ◽  
Author(s):  
Hugh F. Davies ◽  
Stefan W. Maier ◽  
Brett P. Murphy
Keyword(s):  
Small Mammals ◽  
Ground Layer ◽  
Northern Australia ◽  
Remotely Sensed Data ◽  
Feral Cat ◽  
Feral Cats ◽  
Environmental Correlates ◽  
Disturbance Regimes ◽  
High Severity ◽  
Severe Disturbance

Abstract ContextThere is an increasing awareness that feral cats play a key role in driving the ongoing decline of small mammals across northern Australia; yet, the factors that control the distribution, abundance and behaviour of feral cats are poorly understood. These key knowledge gaps make it near-impossible for managers to mitigate the impacts of cats on small mammals. AimsWe investigated the environmental correlates of feral cat activity and abundance across the savanna woodlands of Melville Island, the larger of the two main Tiwi Islands, northern Australia. MethodsWe conducted camera-trap surveys at 88 sites, and related cat activity and abundance to a range of biophysical variables, either measured in the field or derived from remotely sensed data. Key resultsWe found that feral cat activity and abundance tended to be highest in areas characterised by severe disturbance regimes, namely high frequencies of severe fires and high feral herbivore activity. ConclusionsOur results have contributed to the growing body of research demonstrating that in northern Australian savanna landscapes, disturbance regimes characterised by frequent high-severity fires and grazing by feral herbivores may benefit feral cats. This is most likely to be a result of high-severity fire and grazing removing understorey biomass, which increases the time that the habitat remains in an open state in which cats can hunt more efficiently. This is due to both the frequent and extensive removal, and longer-term thinning of ground layer vegetation by severe fires, as well as the suppressed post-fire recovery of ground layer vegetation due to grazing by feral herbivores. ImplicationsManagement that reduces the frequency of severe fires and the density of feral herbivores could disadvantage feral cat populations on Melville Island. A firm understanding of how threatening processes interact, and how they vary across landscapes with different environmental conditions, is critical for ensuring management success.

Effects of logging and fire on small mammals in Mumbulla State Forest, near Bega, New South Wales

1987 ◽  
Vol 14 (2) ◽  
pp. 163 ◽  
Author(s):  
D. Lunney ◽  
B. Cullis ◽  
P. Eby
Keyword(s):  
Small Mammals ◽  
New South ◽  
New South Wales ◽  
Canopy Cover ◽  
Ground Cover ◽  
First Year ◽  
Severe Effect ◽  
South Wales ◽  
Antechinus Stuartii ◽  
Rattus Fuscipes

This study of the effects of logging on small mammals in Mumbulla State Forest on the south coast of New South Wales included the effects of a fire in November 1980 and a drought throughout the study period from June 1980 to June 1983. Rattus fuscipes was sensitive to change: logging had a significant impact on its numbers, response to ground cover, and recapture rate; fire had a more severe effect, and drought retarded the post-fire recovery of the population. The three species of dasyurid marsupials differed markedly in their response to ground cover, canopy cover, logging and fire. Antechinus stuartii was distributed evenly through all habitats and was not affected by logging, but fire had an immediate and adverse effect which was sustained by the intense drought. A. swainsonii markedly preferred the regenerating forest, and was not seen again after the fire, the failure of the population being attributed to its dependence on dense ground cover. Sminthopsis leucopus was found in low numbers, appeared to prefer forest with sparse ground cover, and showed no immediate response to logging or fire; its disappearance by the third year post-fire suggests that regenerating forest is inimical to the survival of this species. Mus musculus showed no response to logging. In the first year following the fire its numbers were still very low, but in the next year there was a short-lived plague which coincided with the only respite in the 3-year drought and, importantly, occurred in the intensely burnt parts of the forest. The options for managing this forest for the conservation of small mammals include minimising fire, retaining unlogged forest, extending the time over which alternate coupes are logged and minimising disturbance from heavy machinery.

Survey and control of small mammal populations on two hardwood plantations in southern Ontario

1974 ◽  
Vol 50 (5) ◽  
pp. 181-185 ◽  
Author(s):  
Andrew Radvanyi
Keyword(s):  
Small Mammal ◽  
Late Summer ◽  
Control Measures ◽  
Effective Control ◽  
Southern Ontario ◽  
Live Trapping ◽  
Surrounding Areas ◽  
And Control ◽  
Rodent Populations ◽  
Ingredient Cost

Live trapping and tagging methods were employed to assess small mammal populations within two hardwood plantations in southern Ontario. Excessive girdling damage in past years to young planted trees necessitated an evaluation of rodent populations and development of effective control measures. The application of an anticoagulant rodenticide to oat groats bait broadcast over the study area at an ingredient cost of approximately three dollars per acre virtually wiped out the small mammals. Reinvasion from surrounding areas was, however, fairly rapid, particularly during late summer. Further research on longer term control measures using poisoned bait feeder stations is recommended.

A population study of small rodents in a dry sub-humid grassland in Kenya

1985 ◽  
Vol 1 (3) ◽  
pp. 217-224 ◽  
Author(s):  
G. H. G. Martin
Keyword(s):  
Population Study ◽  
Annual Production ◽  
Small Rodents ◽  
Numerous Species ◽  
Tropical Grassland ◽  
Live Trapping ◽  
Mus Minutoides ◽  
Turn Over ◽  
Rodent Populations ◽  
Trapping Grid

ABSTRACTEstimates were made of rodent longevity, population biomass and production in a dry sub-humid grassland area in Kenya, The results were based on a live-trapping study made over a 27-month period. During this time fourteen species of rodents and four species of insectivores were recorded from the area of the trapping grid. The most numerous species were Praomys natalensis, Mus triton, Mus minutoides and Lemniscomys striatus.Breeding took place in both wet seasons, coinciding with peaks in rodent populations. Densities ranged from 6.6 ha-1 to 52.4 ha-1, and estimates of net annual production varied from 5485 g ha-1 year-1 to 7221 g ha-1 year-1. Rodent populations appear to turn over every six to nine months.The results are discussed in relation to studies in other tropical grassland areas of Africa.

scholarly journals Long-Term Trends in Small Mammals on a Right-of-Way in Pennsylvania, U.S.

2007 ◽  
Vol 33 (2) ◽  
pp. 147-152
Author(s):  
Richard Yahner ◽  
Richard Yahner ◽  
Russell Hutnik
Keyword(s):  
Small Mammals ◽  
Forest Cover ◽  
Common Species ◽  
The State ◽  
Mammal Species ◽  
Right Of Way ◽  
Live Trapping ◽  
Long Term Trends

The State Game Lands 33 Research and Demonstration Area, Centre County, Pennsylvania, U.S., has been studied since 1953 with the objective of comparing the effectiveness of commonly used mechanical and herbicidal maintenance treatments on vegetation and wildlife on a right-of-way (ROW). Small mammals are important wildlife species on a ROW by consuming tree seeds, thereby reducing invasion of undesirable tree species, and these mammals are important components of a healthy ecosystem. As a follow up to a 2-year study of small mammals conducted 15 years earlier (1989 to 1990) on the State Game Lands 33 ROW, we initiated a 2-year live-trapping study in 2004 on small mammal populations on this ROW. The objectives of our study were to determine relative abundance and species richness (number of species) in six major cover types and in the adjacent forest. One hundred twenty-one individuals of eight species were observed in 2004 and 2005 combined; the most common species was the white-footed mouse (Peromyscus leucopus). One of the most important cover types to small mammals on the ROW was forb-grass, whereas the forest cover type tended to be less diverse in terms of number of mammal species than in cover types on the ROW.

scholarly journals RELATION OF SOILS AND GROUND COVER VEGETATION IN EVEN-AGED PINE STANDS OF CENTRAL ALBERTA

1963 ◽  
Vol 39 (3) ◽  
pp. 273-278 ◽  
Author(s):  
P. K. Heringa ◽  
R. G. H. Cormack
Keyword(s):  
Ground Cover ◽  
Soil Conditions ◽  
Ground Vegetation ◽  
West Central ◽  
Pine Stands ◽  
Ground Cover Vegetation

The present paper describes the ground vegetation of even-aged pine stands in West Central Alberta on six different sites and attempts to relate the ground vegetation to soil conditions.

scholarly journals We need to worry about Bella and Charlie: the impacts of pet cats on Australian wildlife

2020 ◽  
Vol 47 (8) ◽  
pp. 523 ◽  
Author(s):  
Sarah Legge ◽  
John C. Z. Woinarski ◽  
Chris R. Dickman ◽  
Brett P. Murphy ◽  
Leigh-Ann Woolley ◽  
...  
Keyword(s):  
Introduced Species ◽  
Urban Areas ◽  
Native Species ◽  
Population Decline ◽  
Domestic Cat ◽  
Natural Environments ◽  
Residential Areas ◽  
Management Options ◽  
Feral Cats ◽  
Predation Rates

Research and management attention on the impacts of the introduced domestic cat (Felis catus) on Australian fauna have focussed mainly on the feral population. Here, we summarise the evidence for impacts of predation by pet cats on Australian wildlife. We collate examples of local wildlife population decline and extirpation as a result, at least in part, of predation by pet cats. We assemble information across 66 studies of predation by pet cats worldwide (including 24 Australian studies) to estimate the predation toll of pet cats in Australia, plus the predation pressure per unit area in residential areas. We compared these estimates to those published for feral cats in Australia. The per capita kill rate of pet cats is 25% that of feral cats. However, pet cats live at much higher densities, so the predation rate of pets per square kilometre in residential areas is 28–52 times larger than predation rates by feral cats in natural environments, and 1.3–2.3 times greater than predation rates per km2 by feral cats living in urban areas. Pet cats kill introduced species more often than do feral cats living in natural environments, but, nonetheless, the toll of native animals killed per square kilometre by pet cats in residential areas is still much higher than the toll per square kilometre by feral cats. There is no evidence that pet cats exert significant control of introduced species. The high predation toll of pet cats in residential areas, the documented examples of declines and extirpations in populations of native species caused by pet cats, and potential pathways for other, indirect effects (e.g. from disease, landscapes of fear, ecological footprints), and the context of extraordinary impacts from feral cats on Australian fauna, together support a default position that pet cat impacts are serious and should be reduced. From a technical perspective, the pet cat impacts can be reduced more effectively and humanely than those of feral cats, while also enhancing pet cat welfare. We review the management options for reducing predation by pet cats, and discuss the opportunities and challenges for improved pet cat management and welfare.

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