scholarly journals Separating spatial search and efficiency rates as components of predation risk

2012 ◽  
Vol 279 (1747) ◽  
pp. 4626-4633 ◽  
Author(s):  
Nicholas J. DeCesare
Keyword(s):  
Predation Risk ◽  
Resource Selection ◽  
Population Level ◽  
Search Rate ◽  
Proportional Hazard ◽  
Predator Prey ◽  
Multiple Components ◽  
Predation Efficiency ◽  
Aggregative Response ◽  
Spatial Hazard

Predation risk is an important driver of ecosystems, and local spatial variation in risk can have population-level consequences by affecting multiple components of the predation process. I use resource selection and proportional hazard time-to-event modelling to assess the spatial drivers of two key components of risk—the search rate (i.e. aggregative response) and predation efficiency rate (i.e. functional response)—imposed by wolves ( Canis lupus ) in a multi-prey system. In my study area, both components of risk increased according to topographic variation, but anthropogenic features affected only the search rate. Predicted models of the cumulative hazard, or risk of a kill, underlying wolf search paths validated well with broad-scale variation in kill rates, suggesting that spatial hazard models provide a means of scaling up from local heterogeneity in predation risk to population-level dynamics in predator–prey systems. Additionally, I estimated an integrated model of relative spatial predation risk as the product of the search and efficiency rates, combining the distinct contributions of spatial heterogeneity to each component of risk.

scholarly journals Global analysis of a predator–prey model with variable predator search rate

2020 ◽  
Vol 81 (1) ◽  
pp. 159-183 ◽  
Author(s):  
Benjamin D. Dalziel ◽  
Enrique Thomann ◽  
Jan Medlock ◽  
Patrick De Leenheer
Keyword(s):  
Global Analysis ◽  
Search Rate ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey Model

scholarly journals Temperature alters the physiological response of spiny lobsters under predation risk

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Felipe A Briceño ◽  
Quinn P Fitzgibbon ◽  
Elias T Polymeropoulos ◽  
Iván A Hinojosa ◽  
Gretta T Pecl
Keyword(s):  
Climate Change ◽  
Predation Risk ◽  
Environmental Changes ◽  
Environmental Drivers ◽  
Climate Change Scenarios ◽  
Metabolic Rates ◽  
Energetic Costs ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Spiny Lobsters

Abstract Predation risk can strongly shape prey ecological traits, with specific anti-predator responses displayed to reduce encounters with predators. Key environmental drivers, such as temperature, can profoundly modulate prey energetic costs in ectotherms, although we currently lack knowledge of how both temperature and predation risk can challenge prey physiology and ecology. Such uncertainties in predator–prey interactions are particularly relevant for marine regions experiencing rapid environmental changes due to climate change. Using the octopus (Octopus maorum)–spiny lobster (Jasus edwardsii) interaction as a predator–prey model, we examined different metabolic traits of sub adult spiny lobsters under predation risk in combination with two thermal scenarios: ‘current’ (20°C) and ‘warming’ (23°C), based on projections of sea-surface temperature under climate change. We examined lobster standard metabolic rates to define the energetic requirements at specific temperatures. Routine metabolic rates (RMRs) within a respirometer were used as a proxy of lobster activity during night and day time, and active metabolic rates, aerobic scope and excess post-exercise oxygen consumption were used to assess the energetic costs associated with escape responses (i.e. tail-flipping) in both thermal scenarios. Lobster standard metabolic rate increased at 23°C, suggesting an elevated energetic requirement (39%) compared to 20°C. Unthreatened lobsters displayed a strong circadian pattern in RMR with higher rates during the night compared with the day, which were strongly magnified at 23°C. Once exposed to predation risk, lobsters at 20°C quickly reduced their RMR by ~29%, suggesting an immobility or ‘freezing’ response to avoid predators. Conversely, lobsters acclimated to 23°C did not display such an anti-predator response. These findings suggest that warmer temperatures may induce a change to the typical immobility predation risk response of lobsters. It is hypothesized that heightened energetic maintenance requirements at higher temperatures may act to override the normal predator-risk responses under climate-change scenarios.

Crypsis influences escape decisions in the Round-tailed Horned Lizard (Phrynosoma modestum)

2010 ◽  
Vol 88 (10) ◽  
pp. 1003-1010 ◽  
Author(s):  
William E. Cooper, ◽  
Wade C. Sherbrooke
Keyword(s):  
Body Temperature ◽  
Predation Risk ◽  
Upright Posture ◽  
Flight Initiation Distance ◽  
Lower Body ◽  
Running Speed ◽  
Predator Prey ◽  
Sandy Area ◽  
Lower Body Temperature ◽  
Flight Initiation

Flight initiation distance (predator–prey distance when escape begins) increases as predation risk increases. Prey should have longer flight initiation distance when their background, movement, or current posture reduces crypsis. Flight initiation distance of ectotherms may increase at lower body temperature to compensate for slower running speed. However, for cryptic prey, fleeing might increase the probability of being detected. The Round-tailed Horned Lizard ( Phrynosoma modestum Girard, 1852) is eucryptic and resembles small stones. We predicted that flight initiation distance by P. modestum is shorter among stones than on uniform sand. Because movement and upright posture disrupt crypsis, we predicted that flight initiation distance is greater after movement and when standing than when still and lying on the ground. As predicted, flight initiation distances were shorter on a rocky than sandy area, when lying flat than standing, and while immobile than after moving. We measured running speed and flight initiation distance to determine relationships among body temperature, speed, and escape decisions. Running speed and flight initiation distance were reduced at lower body temperature, suggesting that crypsis reinforced by immobility is more advantageous than longer flight initiation distance for cool, slow lizards. The lizards adjusted escape decisions to current effectiveness of crypsis and escape ability.

Population-level resource selection by sympatric brown and American black bears in Alaska

Polar Biology ◽  
2009 ◽  
Vol 33 (1) ◽  
pp. 31-40 ◽  
Author(s):  
Jerrold L. Belant ◽  
Brad Griffith ◽  
Yingte Zhang ◽  
Erich H. Follmann ◽  
Layne G. Adams
Keyword(s):  
Resource Selection ◽  
Population Level ◽  
Black Bears ◽  
American Black ◽  
American Black Bears

scholarly journals Predator-prey instability: individual-level mechanisms for population-level results

1997 ◽  
Vol 11 (1) ◽  
pp. 112-120 ◽  
Author(s):  
B. E. BEISNER ◽  
E. MCCAULEY ◽  
F. J. WRONA
Keyword(s):  
Population Level ◽  
Predator Prey ◽  
Individual Level

Black bear (Ursus americanus) functional resource selection relative to intraspecific competition and human risk

2017 ◽  
Vol 95 (3) ◽  
pp. 203-212 ◽  
Author(s):  
Jared F. Duquette ◽  
Jerrold L. Belant ◽  
Clay M. Wilton ◽  
Nicholas Fowler ◽  
Brittany W. Waller ◽  
...  
Keyword(s):  
Intraspecific Competition ◽  
Resource Selection ◽  
Ursus Americanus ◽  
Spatial Scales ◽  
Population Level ◽  
Reproductive Age ◽  
Functional Responses ◽  
Vegetation Productivity ◽  
Riparian Corridors ◽  
Trade Offs

The spatial scales at which animals make behavioral trade-offs is assumed to relate to the scales at which factors most limiting resources and increasing mortality risk occur. We used global positioning system collar locations of 29 reproductive-age female black bears (Ursus americanus Pallas, 1780) in three states to assess resource selection relative to bear population-specific density, an index of vegetation productivity, riparian corridors, or two road classes of and within home ranges during spring–summer of 2009–2013. Female resource selection was best explained by functional responses to vegetation productivity across nearly all populations and spatial scales, which appeared to be influenced by variation in bear density (i.e., intraspecific competition). Behavioral trade-offs were greatest at the landscape scale, but except for vegetation productivity, were consistent for populations across spatial scales. Females across populations selected locations nearer to tertiary roads, but females in Michigan and Mississippi selected main roads and avoided riparian corridors, whereas females in Missouri did the opposite, suggesting population-level trade-offs between resource (e.g., food) acquisition and mortality risks (e.g., vehicle collisions). Our study emphasizes that female bear population-level resource selection can be influenced by multiple spatially dependent factors, and that scale-dependent functional behavior should be identified for management of bears across their range.

scholarly journals Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys

2009 ◽  
Vol 6 (1) ◽  
pp. 48-50 ◽  
Author(s):  
Alta De Vos ◽  
M. Justin O'Riain
Keyword(s):  
Experimental Evidence ◽  
Predation Risk ◽  
Prey Species ◽  
Group Formation ◽  
Predator Prey ◽  
Selfish Herd ◽  
Fur Seal ◽  
Cape Fur Seal ◽  
Shark Attacks ◽  
Proportional Reduction

Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator–prey systems. To solve this, we manipulated the domains of danger of Cape fur seal ( Arctocephalus pusillus pusillus ) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a ‘theoretical curiosity’.

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