Risk factors affecting escape behaviour by Puerto Rican Anolis lizards

2006 ◽  
Vol 84 (4) ◽  
pp. 495-504 ◽  
Author(s):  
W.E. Cooper
Keyword(s):  
Risk Factors ◽  
Puerto Rican ◽  
Ground Level ◽  
Flight Initiation Distance ◽  
Running Speed ◽  
Escape Behaviour ◽  
Factors Affecting ◽  
Narrow Temperature Range ◽  
Approach Distance ◽  
Flight Initiation

Approach distance (flight initiation distance) and escape methods depend on predation risk. I studied escape methods and effects of risk factors (temperature, perch height and orientation, conspicuousness) on approach distance in seven Puerto Rican anoles. Approach distance increased as temperature decreased in Anolis gundlachi Peters, 1876, presumably because of decreasing running speed, but not in other species (probably because of narrow temperature range). Perch height and approach distance varied inversely in four arboreal species that escape upward, positively in two grass–bush species that are more conspicuous when higher and flee downward, and were unrelated in cryptic Anolis stratulus Cope, 1861. Approach distance was shortest in cryptic A. stratulus and shorter intraspecifically in three species for partially concealed lizards and at sites providing more cover in two species. Approach distance was shorter for A. gundlachi on vertical than nonvertical perches, suggesting that ease of escape upward affects assessed risk. Escape behaviours have been proposed to vary among anole ecomorphs. Grass–bush species fled downward as proposed, or horizontally near ground level. Contrary to predictions of escape downward by trunk–ground and upward by trunk–crown anoles, all arboreal species escaped upward. Only trunk anoles were proposed to use squirreling, but species from four ecomorphs did as well.

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.

Ecological factors affecting flight initiation distance in Daurian ground squirrels ( Spermophilus dauricus )

Ethology ◽  
2019 ◽  
Vol 125 (7) ◽  
pp. 415-420
Author(s):  
Ling‐Ying Shuai ◽  
Yang Zhou ◽  
Yu‐Xia Yang ◽  
Qi‐Qian Xue ◽  
Zi‐Yang Xie ◽  
...  
Keyword(s):  
Ecological Factors ◽  
Ground Squirrels ◽  
Flight Initiation Distance ◽  
Factors Affecting ◽  
Flight Initiation

Risk factors affecting escape behavior by the desert iguana, Dipsosaurus dorsalis: speed and directness of predator approach, degree of cover, direction of turning by a predator, and temperature

2003 ◽  
Vol 81 (6) ◽  
pp. 979-984 ◽  
Author(s):  
W E Cooper Jr.
Keyword(s):  
Risk Factors ◽  
Body Temperature ◽  
Escape Behavior ◽  
Primary Response ◽  
Single Individual ◽  
Factors Affecting ◽  
Escape Theory ◽  
Approach Distance ◽  
Dipsosaurus Dorsalis ◽  
Air Temperatures

Escape from predators by desert iguanas (Dipsosaurus dorsalis) conforms to predictions of optimal escape theory based on risk. I simulated an approaching predator to study risk factors. The primary response variable was approach distance (= flight-initiation distance), i.e., the distance between predator and prey when the prey initiates escape. In additional studies, I recorded whether lizards permitted me to approach close enough to noose them (an indicator of wariness) and the method of escape. Approach distance was greater when the predator approached rapidly than slowly and directly than indirectly, and when the predator turned toward the lizard rather than away. It was greater in open than in more densely covered habitats, which may reflect greater risk due to conspicuousness and (or) a greater distance to refuge. Early in the day at lower air temperatures, desert iguanas permitted a closer approach before initiating escape. While basking after emergence from burrows, lizards escaped into burrows; later in the day they fled. Lizards that fled had high body temperatures; a single individual captured immediately after entering a burrow had a lower body temperature. Lizards presumably enter burrows when low body temperature limits the running speed, but burrow use is costly because attainment of the activity temperature is delayed because of time elapsed and the temperature decrease in burrows.

Escape behavior by prey blocked from entering the nearest refuge

1999 ◽  
Vol 77 (4) ◽  
pp. 671-674 ◽  
Author(s):  
William E Cooper, Jr.
Keyword(s):  
Escape Behavior ◽  
Free Access ◽  
Flight Initiation Distance ◽  
Approach Distance ◽  
Increase Risk ◽  
Time Required ◽  
Optimal Approach ◽  
Flight Initiation

Current models of optimal antipredation behavior do not apply to prey blocked by a predator from access to the primary refuge because the predator is closer than the optimal approach distance and flight toward the refuge would increase risk. If other alternative refuges are available, the prey should flee toward the best alternative one. I studied the effect of an approaching human simulated predator interposed between prey and refuge on the use of alternative refuges and on flight-initiation distance in the keeled earless lizard, Holbrookia propinqua. When the predator approached on a line between a lizard and its closest refuge, the lizard invariably fled to or toward an alternative refuge. Lizards were significantly more likely to use alternative refuges than lizards approached on a line connecting the closest refuge, prey, and predator, but with the lizard between the predator and the refuge. Flight-initiation distance was significantly greater for lizards having free access to the closest refuge than for those blocked from it, perhaps because of the time required to assess the new risk posed by blockage of the closest refuge, to select the best alternative refuge, or to wait for the predator to commit to a closing pattern before choosing the best flight option.

Escape behaviour in the leopard lizard (Gambelia wislizenii): effects of starting distance and sex

2016 ◽  
Vol 37 (3) ◽  
pp. 320-324 ◽  
Author(s):  
Faelan Jacobson ◽  
Grace Garrison ◽  
Jacob Penner ◽  
João Zecchini Gebin ◽  
Maria Eifler ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Decision Making ◽  
Resource Use ◽  
Environmental Variables ◽  
Flight Distance ◽  
Flight Initiation Distance ◽  
Ecological Role ◽  
Escape Behaviour ◽  
Behavioural Responses ◽  
Flight Initiation

Predation risk influences decision making, escape behaviour, and resource use. Risk assessment and behavioural responses to predation can depend on demographic and environmental factors. We studied the escape behaviour of the long-nosed leopard lizard (Gambelia wislizenii) when approached by a human predator (= “simulated predator”), analysing flight initiation distance (FID) and flight distance (FD) relative to demographic and environmental variables. Starting distance (SD) of the simulated predator and orientation of prey lizards relative to the simulated predator influenced FID, but body size of the prey lizard did not. Sex interacted with SD to affect FID. Females lengthened their FIDs as SD increased, while male FID was unrelated to SD. Flight distance increased with increasing SD. Gambelia wislizenii’s ecological role as an ambush predator may explain their escape behaviour; reproductive status potentially affected the interaction between sex and SD.

Factors Affecting Flight Initiation Distance in American Robins

2006 ◽  
Vol 70 (6) ◽  
pp. 1796-1800 ◽  
Author(s):  
PERRI K. EASON ◽  
PETER T. SHERMAN ◽  
OTWELL RANKIN ◽  
BRIAN COLEMAN
Keyword(s):  
Flight Initiation Distance ◽  
Factors Affecting ◽  
American Robins ◽  
Flight Initiation

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.

Risk factors and escape strategy in the grasshopper Dissosteira carolina

Behaviour ◽  
2006 ◽  
Vol 143 (10) ◽  
pp. 1201-1218 ◽  
Author(s):  
William E. Cooper
Keyword(s):  
Risk Factors ◽  
Field Experiments ◽  
Escape Behavior ◽  
Sudden Change ◽  
Flight Initiation Distance ◽  
Initial Direction ◽  
Escape Strategy ◽  
Approach Speed ◽  
Lateral Escape ◽  
Flight Initiation

AbstractTo determine aspects of escape strategy by the Carolina grasshopper, Dissosteira carolina, and applicability of models of escape behavior applied primarily to vertebrates, I conducted three field experiments by simulating an approaching predator. Escape theory predicts that flight initiation distance (distance from predator when escape begins) and distance fled increase as predation risk increases. Some aspects of escape are not predicted, and theory does not identify escape strategies including several components. I examined effects of risk factors (predator approach speed, directness of approach, and repeated approach) on flight initiation distance, distance fled, and the initial direction of escape. Flight initiation distance and distance fled were predicted to increase with approach speed. Because predators approaching directly may bypass prey without detecting it, probability of fleeing and flight initiation distance were predicted to increase with directness of approach. Because a persistent predator poses greater threat, flight initiation distance and distance fled were predicted to be greater for the second of two successive approaches. All findings were consistent with predictions of the Ydenberg & Dill (1986) model, suggesting that risk assessment and escape decisions by visually oriented insects may be similar to those of vertebrates. Although escape directly away from the predator might be expected to minimize risk, most grasshoppers escaped by flying at nearly right angles to the approach path. Lateral escape may be part of an escape strategy in which dark wing colour during flight rapidly disappears upon landing. With sudden change in colour and movement, the grasshopper becomes cryptic and difficult to relocate. Lateral escape may increase difficulty of maintaining visual contact with the grasshopper until it lands. It also avoids need for further escape from a predator that continues in its initial direction.

Predation risk, escape and refuge use by mountain spiny lizards (Sceloporus jarrovii)

2010 ◽  
Vol 31 (3) ◽  
pp. 363-373 ◽  
Author(s):  
Arián Avalos ◽  
William Cooper, Jr.
Keyword(s):  
Risk Factors ◽  
Predation Risk ◽  
Additive Effects ◽  
Flight Initiation Distance ◽  
Refuge Use ◽  
Economic Theories ◽  
Approach Speed ◽  
Theoretical Predictions ◽  
Expected Fitness ◽  
Flight Initiation

AbstractEconomic theories of antipredatory behavior take into account expected fitness losses and gains to predict escape decisions. Prey at greater risk are predicted to have longer flight initiation distance (= distance from predator when escape begins), flee farther, be more likely to enter refuge, and have longer hiding time (= time between entering and exiting refuge). We simulated predators to study effects of risk factors in the lizard Sceloporus jarrovii. Flight initiation distance, distance fled and probability of entering refuge increased with approach speed. Flight initiation distance increased additively with increases in speed and directness of approach. Lizards habituated to human presence had shorter flight initiation distances than unhabituated lizards. As predicted from greater threat posed by a persistent predator, flight initiation distance and hiding time were longer after the second of two approaches. Fleeing was more likely when an investigator stood nearby and turned toward them than when farther way or turned away. These findings verify theoretical predictions of escape and refuge use for several risk factors and most are consistent with those for other lizards. However, speed and directness of approach had additive effects in S. jarrovii, but interacted in other species. Another novel finding was a small interaction between individual investigator and directness of approach. Although outcomes of tests of escape and refuge use theories consistently confirm qualitative predictions, quantitative comparisons between studies by different investigators may have limited value unless information is available about relative responses by prey to each investigator.

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.

Sign in / Sign up

Export Citation Format

Share Document