scholarly journals Shrub cover homogenizes small mammals’ activity and perceived predation risk

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Anne A. Loggins ◽  
Adrian M. Shrader ◽  
Ara Monadjem ◽  
Robert A. McCleery
Keyword(s):  
Predation Risk ◽  
Small Mammals ◽  
Vegetation Structure ◽  
Shrub Cover ◽  
African Savanna ◽  
Use Of Space ◽  
Disturbance Regimes ◽  
Woody Cover ◽  
Animal Communities ◽  
Perceived Predation Risk

AbstractAltered disturbance regimes, increasing atmospheric CO2, and other processes have increased woody cover and homogenized vegetation in savannas across the planet. African savannas with extensive versus minimal woody cover often have vastly different animal communities. However, we lack a clear mechanistic understanding of why animal communities are changing with vegetation structure. Our goal for this study was to understand how vegetation structure in an African savanna shaped the perceived predation risk of small mammals, hence affecting their activity. Using a reciprocal measure of standard giving-up-densities, amount of food eaten, we found sharp declines in rodents’ perceived predation risk and increased rodent activity underneath shrub cover. This response was consistent across species; however, species showed subtle differences in their responses to grassy vegetation. Our findings suggest that areas of minimal or extensive shrub cover (shrub encroachment) may be homogenizing rodents’ perceptions of predation risk and thus shaping their use of space.

Perceived predation risk, parasitism, and the foraging behavior of a freshwater snail (Potamopyrgus antipodarum)

1998 ◽  
Vol 76 (10) ◽  
pp. 1878-1884 ◽  
Author(s):  
Edward P Levri
Keyword(s):  
Predation Risk ◽  
Foraging Behavior ◽  
Freshwater Snail ◽  
Potamopyrgus Antipodarum ◽  
Plain Water ◽  
Fish Diet ◽  
Fish Predator ◽  
Size Dependent ◽  
Individual Size ◽  
Perceived Predation Risk

Foraging behavior can be influenced by such factors as predation risk, individual size, and parasite infection. Snails (Potamopyrgus antipodarum) placed in tanks with large rocks were exposed to four types of water: (1) water with crushed snails, (2) water from a tank in which fish (Gobiomorphus cotidianus) were fed only trout chow, (3) water from a tank where the fish were also fed snails, and (4) plain water. Snails could respond by moving to the top of rocks (where algal food was present) or to the bottom of rocks (where the predation risk was lower). The snails responded to fish chemicals by moving to the bottom of rocks. The response was dependent on snail size and fish diet. Smaller snails moved to the bottom of rocks more than larger snails did. Trematode-infected snails were found on top of the rocks more than other classes of snails, but infected snails still moved to the bottom of rocks in response to the fish predator. Snails eaten by fish in the field tend to be smaller than snails in the overall available population. Thus, snails that are more vulnerable to predation respond more intensely to the odor of fish by moving to the bottom of rocks. This size-dependent response to fish appears to be independent of the occurrence of trematode infection.

Functional Traits, Flocking Propensity, and Perceived Predation Risk in an Amazonian Understory Bird Community

2016 ◽  
Vol 187 (5) ◽  
pp. 607-619 ◽  
Author(s):  
Ari E. Martínez ◽  
Juan P. Gomez ◽  
José Miguel Ponciano ◽  
Scott K. Robinson
Keyword(s):  
Predation Risk ◽  
Functional Traits ◽  
Bird Community ◽  
Perceived Predation Risk

The short-term responses of small mammals to wildfire in semiarid mallee shrubland, Australia

2010 ◽  
Vol 37 (4) ◽  
pp. 293 ◽  
Author(s):  
Luke T. Kelly ◽  
Dale G. Nimmo ◽  
Lisa M. Spence-Bailey ◽  
Michael F. Clarke ◽  
Andrew F. Bennett
Keyword(s):  
Life History ◽  
Small Mammals ◽  
Small Mammal ◽  
Vegetation Structure ◽  
Large Scale ◽  
Response Patterns ◽  
Before And After ◽  
Resource Requirements ◽  
Small Mammal Community ◽  
And Function

Context. Wildfire is a major driver of the structure and function of mallee eucalypt- and spinifex-dominated landscapes. Understanding how fire influences the distribution of biota in these fire-prone environments is essential for effective ecological and conservation-based management. Aims. We aimed to (1) determine the effects of an extensive wildfire (118 000 ha) on a small mammal community in the mallee shrublands of semiarid Australia and (2) assess the hypothesis that the fire-response patterns of small mammals can be predicted by their life-history characteristics. Methods. Small-mammal surveys were undertaken concurrently at 26 sites: once before the fire and on four occasions following the fire (including 14 sites that remained unburnt). We documented changes in small-mammal occurrence before and after the fire, and compared burnt and unburnt sites. In addition, key components of vegetation structure were assessed at each site. Key results. Wildfire had a strong influence on vegetation structure and on the occurrence of small mammals. The mallee ningaui, Ningaui yvonneae, a dasyurid marsupial, showed a marked decline in the immediate post-fire environment, corresponding with a reduction in hummock-grass cover in recently burnt vegetation. Species richness of native small mammals was positively associated with unburnt vegetation, although some species showed no clear response to wildfire. Conclusions. Our results are consistent with the contention that mammal responses to fire are associated with their known life-history traits. The species most strongly affected by wildfire, N. yvonneae, has the most specific habitat requirements and restricted life history of the small mammals in the study area. The only species positively associated with recently burnt vegetation, the introduced house mouse, Mus domesticus, has a flexible life history and non-specialised resource requirements. Implications. Maintaining sources for recolonisation after large-scale wildfires will be vital to the conservation of native small mammals in mallee ecosystems.

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