Fleeing to unsafe refuges: effects of conspicuousness and refuge safety on the escape decisions of the lizard Psammodromus algirus

2000 ◽  
Vol 78 (2) ◽  
pp. 265-270 ◽  
Author(s):  
José Martín ◽  
Pilar López
Keyword(s):  
Escape Behavior ◽  
Theoretical Models ◽  
Flight Distance ◽  
Escape Performance ◽  
Lizard Species ◽  
Approach Distance ◽  
Optimal Distance ◽  
Psammodromus Algirus ◽  
Escape Decision ◽  
Escape Speed

Theoretical models of escape behavior suggest that the optimal distance at which an animal starts to flee (approach distance) increases with distance to the refuge. However, the extent of reliance on refuges may strongly affect this relationship. The lizard Psammodromus algirus escapes a predator by fleeing into leaf litter, which is very abundant but not a safe refuge because the predator could still locate and capture a concealed lizard. We test the hypothesis that escape decisions of this lizard species are based on the conspicuousness of individuals and the type of refuge used, rather than on the distance to cover per se. A field study showed that approach distance was not significantly correlated with distance to available refuges or distance actually fled. However, the type of microhabitat and the type of refuge used influenced the approach distance. Lizards started to flee earlier in microhabitats where they were presumably more visible to potential predators. Lizards ran to refuges that were similar in quality to, but farther from, the nearest available one. A longer flight may be needed to mislead the predator. However, because fleeing may be costly, the flight distance should be optimized. Thus, lizards ran farther and faster when they fled through unsafe microhabitats. Lizards with a low body temperature have lower escape performance and their approach distances should be greater. However, although air temperature affected escape speed, it was not significantly correlated with approach distance or flight distance. The relatively low reliance on refuges by P. algirus indicated that the expected relationship between escape decision and distance to the refuge did not exist. However, the results indicate that P. algirus optimizes its escape decisions according to the costs of fleeing and the costs of remaining.

Escape Behaviour of Juvenile Psammodromus Algirus Lizards: Constraint of or Compensation for Limitations in Body Size?

Behaviour ◽  
1995 ◽  
Vol 132 (3-4) ◽  
pp. 181-192 ◽  
Author(s):  
Pilar López ◽  
José Martín
Keyword(s):  
Body Size ◽  
Escape Response ◽  
Environmental Temperature ◽  
Escape Performance ◽  
Escape Behaviour ◽  
Approach Distance ◽  
Air Temperatures ◽  
Psammodromus Algirus ◽  
Using Data ◽  
Short Flight

AbstractWe compared the escape behaviour of juvenile and adult Psammodromus algirus lizards, by using data of escape performance in the laboratory and field observations of escape behaviour. We specifically examined whether a differential escape response is a constraint of body size, or whether juveniles behave differently in order to maximize their escape possibilities taking into account their size-related speed limitations. In the laboratory, juvenile lizards were slower than adult lizards, and escaped during less time and to shorter distances, even when removing the effect of body size. In the field, juveniles allowed closer approaches and after a short flight usually did not hide immediately, but did so after successive short runs if the attack persists. Approach distance of juveniles was not affected by habitat, but initial and total flight distances were shorter in covered microhabitats. There was no significant effect of environmental temperature on approach and initial flight distances of juveniles. However, the total flight distances were significantly correlated with air temperatures.

Factors affecting escape behavior of Iberian green frogs (Rana perezi)

2005 ◽  
Vol 83 (9) ◽  
pp. 1189-1194 ◽  
Author(s):  
José Martín ◽  
Juán José Luque-Larena ◽  
Pilar López
Keyword(s):  
Body Size ◽  
Predation Risk ◽  
Vegetation Cover ◽  
Escape Response ◽  
Water Surface ◽  
Escape Behavior ◽  
Theoretical Models ◽  
Factors Affecting ◽  
Approach Distance ◽  
Rana Perezi

Theoretical models and empirical evidence suggest that prey should not flee immediately upon detecting an approaching predator, but instead should adjust their escape response to minimize the costs of flight. Similarly, after deciding to escape, animals should tend to adjust the magnitude and characteristics of their escape response according to the perceived level of predation risk. Although these hypotheses have been tested in some prey types, it remains for their applicability to a wider range of taxa to be ascertained and for a larger variety of microhabitat and environmental conditions to be considered. We simulated predator approaches to Iberian green frogs (Rana perezi Seoane, 1885) in the field. Frogs were approached while they were foraging alone at the edge of water, and they escaped by jumping into the water. Results showed that escape decisions of frogs are influenced by microhabitat variables and body size. Both the approach distance allowed to the predator and the distance jumped by the frogs in response to the approach were positively correlated with the initial distance of the frog from the water's edge; they were also dependent on vegetation cover at the edge of and in the water. Small frogs appeared to rely on crypsis more than large frogs and allowed shorter predator approach distances. They also remained still on the water surface after jumping more often than large frogs. We conclude that such flexibility in the escape response may allow frogs to reduce predation risk without incurring excessive costs.

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.

scholarly journals Does ecophysiology mediate reptile responses to fire regimes? Evidence from Iberian lizards

2016 ◽  
Author(s):  
Catarina C Ferreira ◽  
Xavier Santos ◽  
Miguel A. Carretero
Keyword(s):  
Repeated Measures ◽  
Fire History ◽  
Fire Regimes ◽  
Biological Traits ◽  
Adult Males ◽  
Lizard Species ◽  
Water Losses ◽  
Evaporative Water ◽  
Interspecific Differences ◽  
Psammodromus Algirus

Background. Reptiles are sensitive to habitat disturbance induced by wildfires but species frequently show opposing responses. Functional causes of such variability have been scarcely explored. In the northernmost limit of the Mediterranean bioregion, lizard species of Mediterranean affinity (Psammodromus algirus and Podarcis guadarramae) increase in abundance in burnt areas whereas Atlantic species (Lacerta schreiberi and Podarcis bocagei) decrease. Timon lepidus, the largest Mediterranean lizard in the region, show mixed responses depending on the locality and fire history. We tested if such interspecific differences are of functional nature, namely, if lizard ecophysiological traits may determine their response to fire. Based on the variation in habitat structure between burnt and unburnt sites, we hypothesise that Mediterranean species increasing density in open habitats promoted by frequent fire regimes should be more thermophile and suffer lower water losses than Atlantic species. Methods. We submitted 6-10 adult males of the five species to standard experiments for assessing preferred body temperatures (Tp) and evaporative water loss rates (EWL), and examined the variation among species and along time by means of repeated-measures AN(C)OVAs. Results. Results only partially supported our initial expectations, since the medium-sized P. algirus clearly attained higher Tp and lower EWL. The two small wall lizards (P. bocagei and P. guadarramae) displayed low Tp and high EWL while the two large green lizards (T. lepidus and L. schreiberi) displayed intermediate values for both parameters. Discussion. The predicted differences according to the biogeographic affinities within each pair were not fully confirmed. We conclude that ecophysiology may help to understand functional reptile responses to fire but other biological traits are also to be considered.

scholarly journals Does ecophysiology mediate reptile responses to fire regimes? Evidence from Iberian lizards

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2107 ◽  
Author(s):  
Catarina C. Ferreira ◽  
Xavier Santos ◽  
Miguel A. Carretero
Keyword(s):  
Repeated Measures ◽  
Fire History ◽  
Fire Regimes ◽  
Biological Traits ◽  
Adult Males ◽  
Lizard Species ◽  
Water Losses ◽  
Interspecific Differences ◽  
Psammodromus Algirus ◽  
The Mediterranean

Background.Reptiles are sensitive to habitat disturbance induced by wildfires, but some species frequently show opposing responses. The functional causes of such variability have been scarcely explored. In the northernmost limit of the Mediterranean bioregion, a lizard species of Mediterranean affinity (Psammodromus algirusandPodarcis guadarramae) increase in abundance in burnt areas whereas Atlantic species (Lacerta schreiberiandPodarcis bocagei) decrease.Timon lepidus, the largest Mediterranean lizard in the region, shows mixed responses depending on the locality and fire history. We tested whether such interspecific differences are of a functional nature; namely, if ecophysiological traits may determine lizard response to fire. Based on the variation in habitat structure between burnt and unburnt sites, we hypothesise that the Mediterranean species, which increase density in open habitats promoted by frequent fire regimes, should be more thermophile and suffer lower water losses than Atlantic species.Methods.We submitted 6–10 adult males of the five species to standard experiments for assessing preferred body temperatures (Tp) and evaporativewater loss rates (EWL), and examined the variation among species and along time by means of repeated-measures AN(C)OVAs.Results.Results only partially supported our initial expectations, since the medium-sizedP. algirusclearly attained higherTpand lower EWL. The two small wall lizards (P. bocageiandP. guadarramae) displayed lowTpand high EWL while the two large green lizards (T. lepidusandL. schreiberi) displayed intermediate values for both parameters.Discussion.The predicted differences according to the biogeographic affinities within each pair were not fully confirmed. We conclude that ecophysiology may help to understand functional reptile responses to fire but other biological traits are also to be considered.

Autecological Observations of Acanthodactylus erythrurus (Sauria: Lacertidae) in Southern Spain

1982 ◽  
Vol 3 (2) ◽  
pp. 237-255 ◽  
Author(s):  
Stephen D. Busack ◽  
Fabian M. Jaksic
Keyword(s):  
Plant Material ◽  
Sexual Maturity ◽  
Activity Period ◽  
Adult Size ◽  
Adult Males ◽  
Lizard Species ◽  
Male Population ◽  
Adult Females ◽  
Psammodromus Algirus ◽  
Human Predation

AbstractAutecological aspects of Acanthodactylus erythrurus were examined at La Algaida, Cádiz Province, Spain. The male population is composed of 60 % adult and 40 % subadult individuals; male hatchlings increase in size at a rate of 0.06 mm/day from hatching ( 31 mm snout-vent length) to sexual maturity (∼61 mm); 50 % do not survive beyond 1.5 years, but those which reach adult size may live 1.9 years. Females grow from hatching (∼ 28 mm) to sexual maturity( 57 mm) at a rate of 0.05 mm/day; less than half survive 1.4 years and the life span of some individuals is 2.1 years. Adult males outnumber adult females 1.4:1, but subadult ratios are 1:1. Adults and subadults associate with different plant species during their activity period, but each age class tends to avoid open sand patches. These 8.4-13 g lizards feed on a wide variety of insects and appreciable quantities of plant material. 49% ofall males and 82% ofall females actively consume Halimium halimifolium. We suspect this lizard species is wide ranging and non-territorial ; only one agonistic encounter was recorded and it was interspecific (with Psammodromus algirus). The frequency of escape from predation is estimated at 26.8 %, based on tail-loss figures, and the incidence of cestode parasitism (Oochoristica cf. tuberculata) is 2.1 %. The population studied was highly resilient to 16 months of intense human predation.

scholarly journals Escape behavior in gravid and non-gravid females of Gonatodes albogularis (Squamata: Sphaerodactylidae)

2018 ◽  
Vol 17 (1) ◽  
pp. 73 ◽  
Author(s):  
Moisés E. Domínguez-López ◽  
Federico Pablo Kacoliris ◽  
María Verónica Simoy
Keyword(s):  
Predation Risk ◽  
Escape Behavior ◽  
Function Analysis ◽  
Theoretical Models ◽  
Reproductive Status ◽  
Risk Of Predation ◽  
Behavioral Compensation ◽  
Adaptive Processes ◽  
Free Search ◽  
Gravid Females

Escape behavior in gravid and non-gravid females of Gonatodes albogularis (Squamata: Sphaerodactylidae). Theoretical models of predator-prey relationships describe tradeoffs between energetic and other costs of escape, effectiveness of escape behavior, and predation risk. These models predict that an animal will fee when the expected ftness cost due to risk of predation becomes equal to the the cost of the escape or post-encounter ftness is maximized, depending on the model. In this framework, several individual and ecological variables have been shown to affect escape patterns, but the effect of reproductive status has been studied in few species. We assess differences in escape behavior between gravid and non-gravid females of Gonatodes albogularis. Lizards were surveyed by applying a free search method along independent transects. For each lizard, we determined reproductive status as gravid or non-gravid and recorded several variables related to escape behavior. We made a discriminant function analysis to see whether the state of individuals affect escape behavior. Our results show that the escape variables distance fed, the fnal distance and the distance to refuge differ between gravid and non-gravid females. These fndings support predictions based on risk and cost, but do not support models of fight initiation distance. Such differences could be related to a physiological process known as behavioral compensation, through which some individuals (gravid females in our case) modify their behavior to offset predation risk. Further studies are needed to see if behavioral compensation can be explained in terms of adaptive processes in G. albogularis.

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