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.

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.

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.

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.

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.

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.

Flight initiation distance is differentially sensitive to the costs of staying and leaving food patches in a small-mammal prey

2009 ◽  
Vol 87 (11) ◽  
pp. 1016-1023 ◽  
Author(s):  
Patricio A. Lagos ◽  
Andrea Meier ◽  
Liliana Ortiz Tolhuysen ◽  
Rodrigo A. Castro ◽  
Francisco Bozinovic ◽  
...  
Keyword(s):  
Small Mammal ◽  
Antipredator Behavior ◽  
Interactive Effect ◽  
Flight Initiation Distance ◽  
Food Patch ◽  
Supplementary Food ◽  
Escape Theory ◽  
Risk Of Predation ◽  
The Cost ◽  
Flight Initiation

Escape theory predicts that a prey should flee from an approaching predator at a point in which the cost of staying equals the cost of escape. We manipulated the cost of fleeing upon approaching human predators by providing the small mammal Octodon degus (Molina, 1782) with varying amounts of supplementary food likely to disappear while the animals are not in the food patch (e.g., hidden in their burrows). Simultaneously, we manipulated the risk of remaining in the patch by providing supplementary food at varying distances from the nearest burrow. Degus fled at a shorter distance to approaching predators when foraging in patches closer to the nearest burrow and supplied with relatively high abundance of food, but only when these rodents were foraging socially. Also, degus fled at a greater distance to approaching predators when foraging in patches far from the nearest burrow. Thus, functions linked to the loss of feeding opportunities and the risk of predation interact to influence flight initiation distance after a simulated attack. This study represented one of the few demonstrations of an interactive effect between cost and risks on antipredator behavior in a small, social prey mammal.

Opposite companion effect on flight initiation distance in sympatric species: plateau pika (Ochotona curzoniae) and White-rumped Snowfinch (Onychostruthus taczanowskii)

2016 ◽  
Vol 94 (2) ◽  
pp. 109-114 ◽  
Author(s):  
He Zhang ◽  
Wenjing Li ◽  
Yanping Hu ◽  
Yanming Zhang
Keyword(s):  
Linear Models ◽  
Antipredator Behavior ◽  
Sympatric Species ◽  
Flight Initiation Distance ◽  
Plateau Pika ◽  
Escape Theory ◽  
Ochotona Curzoniae ◽  
Positive Correlations ◽  
Escape Decision ◽  
Flight Initiation

There are many factors influencing prey’s risk perception and escape decision during predator–prey encounters. The distance at which animals move away from perceived danger (often quantified as flight initiation distance or FID) has been used by behavioral ecologists to understand the economics of antipredator behavior. Using general linear models, we investigated escape decision-making processes in plateau pika (Ochotona curzoniae (Hodgson, 1858)) and White-rumped Snowfinch (Onychostruthus taczanowskii (Prjevalsky, 1876), formerly known as Montifringilla taczanowskii Przewalski, 1876) together and we found that (i) there are significant positive correlations between starting distance and FID in both species; (ii) pika escapes at a longer distance from an approaching intruder when it is far from its burrow; (iii) foraging animals tolerate closer distances than watching ones, both in pikas and in Snowfinches; (iv) conspecifics seem to have no effect on pikas’ escaping behavior, while the appearance of Snowfinches dramatically decreases the FID of pikas. On the contrary, conspecifics significantly decrease the FID of Snowfinches, while the presence of pikas has no effects. These findings provide new evidence, which are consistent with optimal escape theory. These novel results in multispecies interactions prompt us to pay attention to the potential relationship between pikas and Snowfinches, as well as the “bird–pika in one hole” phenomenon.

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.

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