FEAR and DREAD: starting distance, escape decisions and time hiding in refuge

Behaviour ◽  
2015 ◽  
Vol 152 (10) ◽  
pp. 1371-1389 ◽  
Author(s):  
William E. Cooper ◽  
Wade C. Sherbrooke
Keyword(s):  
Flight Initiation Distance ◽  
Predator Prey ◽  
Sceloporus Virgatus ◽  
Flight Initiation

Flight initiation distance (FID = predator–prey distance when escape begins) increases as starting distance (predator–prey distance when approach begins) increases. The flush early and avoid the rush (FEAR) hypothesis proposes that this relationship exists because monitoring an approach is costly. Hypothesized causes are increase in assessed risk and decrease in obtainable benefits while monitoring as starting distance increases. We propose the delay risking emergence and avoid dying (DREAD) hypothesis: hiding time in refuge increases as starting distance increases because prey use risk assessed during approach to estimate risk upon emerging. In the lizard Callisaurus draconoides, FID increased as standardized starting distance increased at faster approach speeds, supporting the FEAR hypothesis. In its first test, the DREAD hypothesis was supported: hiding time in the lizard Sceloporus virgatus increased as standardized starting distance increased. No large benefits were attainable, suggesting that dynamic increase in assessed risk accounts for these findings.

Compensatory changes in escape and refuge use following autotomy in the lizard Sceloporus virgatus

2007 ◽  
Vol 85 (1) ◽  
pp. 99-107 ◽  
Author(s):  
W.E. Cooper, Jr.
Keyword(s):  
Body Part ◽  
Control Group ◽  
Flight Initiation Distance ◽  
Refuge Use ◽  
Predator Prey ◽  
Escape Theory ◽  
Antipredatory Strategies ◽  
Sceloporus Virgatus ◽  
Flight Initiation ◽  
Predator Effects

Following autotomy of a body part to escape from a predator, prey may alter antipredatory strategies to compensate for the inability to use autotomy and impaired escape ability. Because prey that have been captured may increase their assessment of risk posed by a predator, effects of capture may have been attributed to autotomy. I conducted an experiment using three groups of striped plateau lizards ( Sceloporus virgatus Smith, 1938): control, captured, and autotomized. Captured and autotomized lizards were less active on the day after autotomy than controls. Flight initiation distance and distance fled were greater in both experimental groups than in the control group, but did not differ between experimental groups. Flight initiation distance was greater in autotomized than in captured lizards only in males. No sex difference occurred for distance fled. Autotomized lizards entered refuges more than other groups. Escape strategy changed after autotomy to increased reliance on refuge and, in males, to increased flight initiation distance; behaviours that are appropriate to compensate for impaired escape ability. Decreased activity and increased distance fled might erroneously have been considered effects of autotomy, had effects of capture not been assessed. Predictions of escape theory that flight initiation distance and distance fled increase with predation risk were supported.

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.

Stop-and-go approach by a predator: a novel predation risk factor for the phrynosomatid lizards Sceloporus virgatus and Callisaurus draconoides

2015 ◽  
Vol 36 (4) ◽  
pp. 401-409
Author(s):  
William E. Cooper ◽  
Wade C. Sherbrooke
Keyword(s):  
Field Experiments ◽  
Empirical Studies ◽  
Pause Duration ◽  
Predator Prey ◽  
Escape Theory ◽  
Stop And Go ◽  
Approach Speed ◽  
Sceloporus Virgatus ◽  
Escape Behaviors ◽  
Flight Initiation

As an immobile prey monitors an approaching predator, the predator may move at a constant speed directly toward the prey or on a path that bypasses the prey. These scenarios have been studied extensively. Economic escape theory successfully predicts flight initiation distance (FID = predator-prey distance when escape begins). However, predators often alter their speed and may exhibit stops and starts during approaches. Empirical studies have shown that prey rapidly adjust assessed risk to a predator’s changes in approach speed and direction, but effects of interrupted (stop-start) approach are unknown. Because a prey is likely to assess that a nearby predator that resumes approaching has detected it and is attacking, escape theory predicts that assessed risk is greater at a given predator-prey distance when approach resumes than is continuous. Therefore, we predicted that FID is longer when a predator approaches, stops nearby, and renews its approach than when it approaches continuously. Second, although assessed risk increases as duration of the predator’s stop nearby increases, as indicated by latency to flee, we predicted that pause duration does not affect FID because prey interpret resumed approach as attack. Field experiments with two lizards, Sceloporus virgatus and Callisaurus draconoides, verified the predictions: FID was longer for discontinuous than continuous approaches and pause duration did not affect FID. We also observed distance fled and probability of entering refuge, escape behaviors for which theory is undeveloped. Distance fled was unrelated to continuity of approach in both species, as was refuge entry in S. virgatus.

Averted predator gaze reduces latency to flee by zebra-tailed lizards (Callisaurus draconoides)

2015 ◽  
Vol 65 (3-4) ◽  
pp. 299-310
Author(s):  
William E. Cooper ◽  
Wade C. Sherbrooke
Keyword(s):  
Short Interval ◽  
Fixed Interval ◽  
Short Latency ◽  
Flight Initiation Distance ◽  
Predator Prey ◽  
Direct Gaze ◽  
The Cost ◽  
Averted Gaze ◽  
Over Time ◽  
Flight Initiation

Directness of a predator’s gaze affects several aspects of antipredatory behavior, including flight initiation distance (FID = predator-prey distance when fleeing begins), which is longer under direct than averted gaze. However, the effect of gaze directness on probability of fleeing or latency to flee (LF) in a short interval when a prey is immobile near an immobile predator is unknown. We predicted that probability of fleeing is greater and LF is shorter if the predator’s gaze is averted than direct. If the predator has not detected the prey, it will detect it immediately and attack when the prey moves while under direct gaze. Therefore, the prey is less likely to flee than if the predator is looking elsewhere. Under direct gaze the cost of fleeing decreases over time because the predator is increasingly likely to detect the prey. Under averted gaze, risk of being detected is constant for immobile prey and increases if the prey flees. Cost of fleeing under averted gaze is therefore constant and lower if the prey flees than under direct gaze at short latency, predicting shorter LF and greater likelihood of fleeing within a short fixed interval. We test this novel prediction of a model of the effect of gaze directness using the zebra-tailed lizard, Callisaurus draconoides. The proportion of lizards that fled was three times greater for averted than direct gaze, suggesting that prey under scrutiny reduce movement to avoid being detected. We discuss effects of gaze on FID, LF and probability of fleeing.

Beyond optimal escape theory: microhabitats as well as predation risk affect escape and refuge use by the phrynosomatid lizard Sceloporus virgatus

Behaviour ◽  
2007 ◽  
Vol 144 (10) ◽  
pp. 1235-1254 ◽  
Author(s):  
Dawn Wilson ◽  
William Cooper
Keyword(s):  
Risk Factors ◽  
Individual Differences ◽  
Predation Risk ◽  
Flight Initiation Distance ◽  
Refuge Use ◽  
Escape Theory ◽  
Sceloporus Virgatus ◽  
Flight Initiation

AbstractEscape studies often focus on one variable, but tactics and refuge use vary with microhabitats, exposure, distance to refuge, and temperature. We studied these effects and effects of microhabitats and risk factors (distance from refuge, temperature) on flight initiation distance (FID, distance between predator and prey when escape begins) and distance fled (DF) in the lizard Sceloporus virgatus. FID increased as distance to refuge increased and temperature decreased. DF increased as FID increased, supporting the hypothesis that individual differences in boldness are consistent among encounter phases. Refuges were rock crevices, trees, logs, and grass clumps. Interhabitat differences in FID and DF matched those in distance to refuge. FID was longer for lizards on rocks and ground than trees due to proximity to and use of refuge. Lizards on trees rarely changed microhabitats, moving to the far side and unpredictably up or down. Lizards on slopes fled long distances up slopes. Most lizards on rocks entered crevices or switched microhabitats. Lizards on ground usually changed microhabitats. Optimal escape theory accurately predicted effects of risk on FID, but initial microhabitats and final microhabitats and refuges affected tactics, FID and DF. DF was affected by risk, being longer when lizards remained visible.

When and how do predator starting distances affect flight initiation distances?

2005 ◽  
Vol 83 (8) ◽  
pp. 1045-1050 ◽  
Author(s):  
W E Cooper, Jr.
Keyword(s):  
Bird Species ◽  
Ecological Factors ◽  
Flight Initiation Distance ◽  
Lizard Species ◽  
Urosaurus Ornatus ◽  
Approach Speed ◽  
Monitoring Costs ◽  
Sceloporus Virgatus ◽  
The Relationship ◽  
Flight Initiation

The distance separating predator and prey when the predator begins to approach, starting distance, was recently shown to affect flight initiation distance in many bird species, raising questions about the effect's generality, variation with ecological factors, and economic basis. I studied the effect in two lizard species that forage by ambush and escape into nearby refuges. Monitoring costs during approach are absent because ambushers remain immobile while scanning for prey and predators. Risks are minimized because of the proximity to refuge. Flight initiation distance increased weakly with starting distance in Sceloporus virgatus Smith, 1938 significantly only at rapid approach speed. It was not significant in Urosaurus ornatus (Baird and Girard, 1852) at slow approach speed. Flight initiation distance is predicted to increase with starting distance, owing to monitoring costs and assessment by prey of greater risk during prolonged approaches. The significant effect in S. virgatus, which lacks monitoring costs, is the first indication that risk affects the relationship between starting distance and flight initiation distance. Conditions in which starting distance is important and its possible effects in earlier studies are discussed, as well as standardizing approaches and possible artifactual effects of starting distance.

scholarly journals Optimal escape theory predicts escape behaviors beyond flight initiation distance: risk assessment and escape by striped plateau lizards Sceloporus virgatus

2009 ◽  
Vol 55 (2) ◽  
pp. 123-131 ◽  
Author(s):  
William E. Cooper
Keyword(s):  
Risk Factors ◽  
Risk Assessment ◽  
Predation Risk ◽  
Flight Initiation Distance ◽  
Risk Levels ◽  
Escape Theory ◽  
Growing Body ◽  
Sceloporus Virgatus ◽  
Escape Behaviors ◽  
Flight Initiation

Abstract Escape theory predicts that flight initiation distance (FID = distance between predator and prey when escape begins) is longer when risk is greater and shorter when escape is more costly. A few tests suggest that escape theory applies to distance fled. Escape models have not addressed stochastic variables, such as probability of fleeing and of entering refuge, but their economic logic might be applicable. Experiments on several risk factors in the lizard Sceloporus virgatus confirmed all predictions for the above escape variables. FID was greater when approach was faster and more direct, for lizards on ground than on trees, for lizards rarely exposed to humans, for the second of two approaches, and when the predator turned toward lizards rather than away. Lizards fled further during rapid and second consecutive approaches. They were more likely to flee when approached directly, when a predator turned toward them, and during second approaches. They were more likely to enter refuge when approached rapidly. A novel finding is that perch height in trees was unrelated to FID because lizards escaped by moving out of sight, then moving up or down unpredictably. These findings add to a growing body of evidence supporting predictions of escape theory for FID and distance fled. They show that two probabilistic aspects of escape are predictable based on relative predation risk levels. Because individuals differ in boldness, the assessed optimal FID and threshold risks for fleeing and entering refuge are exceeded for an increasing proportion of individuals as risk increases.

Conspicuousness and vestigial escape behaviour by two dendrobatid frogs, Dendrobates auratus and Oophaga pumilio

Behaviour ◽  
2009 ◽  
Vol 146 (3) ◽  
pp. 325-349 ◽  
Author(s):  
Janalee Caldwell ◽  
Laurie Vitt ◽  
William Cooper
Keyword(s):  
Defensive Behavior ◽  
Close Approach ◽  
Flight Initiation Distance ◽  
Escape Behaviour ◽  
Predator Prey ◽  
Poison Frogs ◽  
Oophaga Pumilio ◽  
Approach Speed ◽  
Dendrobates Auratus ◽  
Flight Initiation

AbstractAposematic prey are thought to move slowly and openly near predators, but exhibit reduced escape behaviour. We studied conspicuousness and escape by aposematic poison frogs (Dendrobates auratus and Oophaga pumilio). In circles of leaf litter, observers detected poison frogs quickly. Flight initiation distance (FID, predator-prey distance when escape begins) increases with approach speed in non-cryptic palatable prey, but not for frogs in clearings, which permitted close approach. On trails frogs moved slowly into forest and FID in D. auratus increased with approach speed. Distance from cover and handling exposing predators to distastefulness may account for greater reliance on aposematism in clearings. We observed responses to a simulated predator (stick with painted face) in three conditions: not approached, approached, and touched. Latency to hop and time to exit circles decreased and exit from circles was directed further away from the approach path in the order not approached, approached, touched. Oophaga pumilio changed directions less when approached than not; many exhibited no escape behaviour. Aposematic dendrobatids move slowly near predators, but retain risk-assessment mechanisms due to occasional predation. Differences in escape between dendrobatids and palatable Craugastor frogs suggest that dendrobatid defensive behavior may have been molded to maximize the effectiveness of aposematism.

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