PRIMARY RESEARCH PAPER

Perceived predation risk decreases movement and increases
aggregation of Amazon milk frog (Anura, Hylidae) tadpoles
throughout ontogeny

Isabel Casillas-Barragán . Raul Costa-Pereira .

Paulo Enrique Cardoso Peixoto

Received: 23 March 2015 / Revised: 20 July 2015 /Accepted: 5 August 2015 / Published online: 15 August 2015

� Springer International Publishing Switzerland 2015

Abstract In order to maximize escaping success,

prey may change their predator avoidance behaviors

according to their susceptibility. Morphological devel-

opment during ontogeny may lead to different sus-

ceptibility to predators. Consequently, prey may

exhibit different predator avoidance strategies accord-

ing to the ontogenetic state. In this study, we used

tadpoles of the Amazon milk frog Trachycephalus

resinifictrix (Anura, Hylidae) to evaluate how varia-

tion in the ability to actively escape owed to the

mobility acquired through ontogeny affects the adop-

tion of predator avoidance strategies. We sampled

tadpoles (N = 384) in temporary ponds and divided

them in four consecutive developmental stages

according to body size and mobility capacity. Subse-

quently, we measured their movement and spatial

distribution when subjected to chemical cues of

predators or control solutions. We found that they

spent less time moving and increased spatial aggre-

gation after receiving solutions with predator cues,

independent of their developmental stage. These

results indicate that the variation in escape capacity

through larval ontogeny does not determine their

antipredator strategy. Since tadpoles of T. resinifictrix

typically grow in environments with reduced space for

active escaping, such as tree holes and bromeliads, it

may be that the ability to flee from predators is absent,

even when this behavior increases the survival

chances.

Keywords Antipredator strategies � Amazon milk

frog � Ontogenetic stages � Distribution � Chemical

cues � Dilution effect

Introduction

Predation risk is an important selective force shaping

the evolution of many different animal life-history

traits (Lima & Dill, 1990; Sih, 1992; Langerhans,

2007; De Block et al., 2008). Characteristics that

reduce predation risk may be favored because they

reduce the encounter rate with predators (Sih, 1992;

Handling editor: Lee B. Kats

Electronic supplementary material The online version of
this article (doi:10.1007/s10750-015-2433-8) contains supple-
mentary material, which is available to authorized users.

I. Casillas-Barragán (&)

Department of Physiology, São Paulo University,

São Paulo, Brazil

e-mail: isabelcasillasbarragan@gmail.com

R. Costa-Pereira

Programa de Pós Graduação em Ecologia &

Biodiversidade, Universidade Estadual Paulista ‘Julio de

Mesquita Filho’, Rio Claro, SP, Brazil

P. E. C. Peixoto

Programa de Pós-graduação em Zoologia, Universidade

Estadual de Feira de Santana, Feira De Santana, BA,

Brazil

123

Hydrobiologia (2016) 765:379–386

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Sansom et al., 2009) or because they increase the

chances of escaping after being detected (Langerhans,

2007). For example, camouflage seems to have

evolved in multiple prey species as a strategy to

reduce detectability (Thery & Casas, 2002). In the

same way, a reduction in foraging activity when

predators are nearby may decrease the chances of

detection (Sih et al., 2004). On the other hand, prey

may increase apparent size (Peckarsky, 1980; Wil-

liams et al., 2000; Toledo et al., 2011), or rely on fast-

moving abilities to escape from predators after being

detected (Bauwens & Thoen, 1981; Irschick & Losos,

1998).

Among species that live in groups, spatial aggre-

gation of individuals may also work as an antipredator

strategy (Watt et al., 1997; Spieler & Linsenmair,

1999; Gallie et al., 2001; Spieler, 2003). Aggregations

(situation in which individuals remain in close prox-

imity) may decrease predation risk by intimidating

predators through coordinated movements, increasing

the vigilance efficiency, or reducing the probability of

individual detection due to the dilution effect (Davies

et al., 2012). The dilution effect is particularly

intriguing because this strategy is evolutionary stable

only if the increased detection risk of groups of prey is

offset by the reduced individual risk of predation

(Wrona & Dixon, 1991).

Although aggregation reduces the individual

chances of predation, its relative benefits may be

surpassed by alternative escaping behaviors. For

example, for species with fast-moving abilities,

active escape from predators might be more effec-

tive to avoid predation than remaining in groups

(Lima & Dill, 1990). Besides varying among

species, escape behaviors may also vary throughout

ontogeny, especially in organisms that experience

extreme morphological and physiological transfor-

mations (Johnson & Sih, 2007; Langerhans, 2007;

Hossie & Murray, 2012). During relatively slow-

moving developmental stages, strategies related to

low detectability may be used, such as remaining

static. However, with the development of morpho-

logical and physiological traits associated with an

increase in movement capacity, active escape

behaviors after detection of predators should be

favored (Martı́n & López, 2003).

Anurans experience dramatic changes during

ontogeny (Fabrezi et al., 2014). Furthermore, the

kinematics of swimming tadpoles is closely paired to

their size and shape (Liu et al., 1997). On the initial

stages, tadpoles usually have incipient swimming

capacity and they often live in groups (McDiarmid &

Altig, 1999). As their ontogenetic stage advances, the

swimming and breathing structures develop, increas-

ing their mobility, swimming speed, and maneuver-

ability (Wassersug & Sperry, 1977; Huey, 1980).

Thus, the morphological variation through ontoge-

netic stages on tadpoles may lead to different suscep-

tibility to predators (Azevedo-Ramos & Magnusson,

1999) and to the adoption of different predator

avoidance strategies (Crump, 1984; Dayton et al.,

2005; Jara & Perotti, 2009).

In this study, we used tadpoles of Amazon milk

frog Trachycephalus resinifictrix (Goeldi, 1907) to

evaluate how variation in mobility capacity through

ontogeny affects the adoption of different predator

avoidance strategies. This species has been previ-

ously reported to occur in phytotelmata, such as

ground bromeliads (Hero, 1990) and tree holes

(Schiesari et al., 2003). Tree holes, in particular,

have been identified as calling, breeding, and devel-

opmental sites for this frog. In this habitat, they

apparently face a low predation pressure and, prob-

ably due to the low nutrient availability, tadpoles

usually feed on eggs from subsequent clutches

(Schiesari et al., 2003). However, different from these

descriptions, we recently found populations of this

species occurring in temporary ponds in Central

Amazon Forest. Such places often present greater

area and higher predation pressure than the previously

reported habitats for this species. Because predators in

temporary ponds are often sit-and-wait invertebrates,

tadpoles with better mobility capacity located in these

areas should be likely to show active responses to

predatory attempts (Wellborn et al., 1996).

Because the swimming ability of tadpoles increases

during their development (Landberg & Azizi, 2010)

and because tadpoles present in temporary ponds may

face greater predation pressure than in tree holes, we

hypothesized that individuals in early developmental

stages preferentially aggregate under predation risk,

but change to active escape in the latter stages of

development. If this hypothesis is true, we expect that

recently hatched tadpoles will reduce their distance to

conspecifics and their movement after receiving cues

of predator presence, while individuals near the adult

stage will increase their distance to conspecifics and

their movement after perceiving predation risk.

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Materials and methods

Study area

We carried out the experiment in November 2014, in

Reserva 1501 (Km 41) (02�240S; 59�430W), ARIE-

PDBFF (Biological Dynamics of Forest Fragments

Project), in the Central Amazon Forest, approximately

80 km north from Manaus, Amazonas, Brazil. It is a

primary tropical rainforest characterized by annual

average temperatures of 27�C and annual average

precipitation of 1900–2500 mm (Bierregaard Jr. et al.,

1992).

We collected tadpoles of the Amazon milk frog T.

resinifictrix from temporary ponds located at a sandy

road that gives access to the reserve (pond́s size ranged

from 1 9 0.3 to 7 9 3 m). Each pond contained a

high density group of tadpoles organized in polarized

schools in similar developmental stage, suggesting

that they may belong to a single clutch. Species

confirmation was performed by (1) examination of

specific larval traits such as the larval tooth formula;

and (2) morphological observation of nearly meta-

morphosed individuals (Gosner stage 44; Gosner,

1960). All traits were compared with the known

tadpoles from amazon region (see Hero, 1990).

Usually, tadpoles of this species develop until meta-

morphosis in tree holes and bromeliad water (Hero,

1990), making this the first report of clutching of this

species on temporary ponds. Our initial observations

on natural ponds indicated that individuals in the first

developmental stages remained aggregated and

motionless. After any disturbance, they scattered,

aggregated back, and remained motionless again.

Nevertheless, individuals in later stages remained

scattered and active, increasing the movement imme-

diately after any disturbance. There were abundant

predators in these ponds, such as giant water bugs,

odonata larvae, and water spiders.

Data collection

We sampled tadpoles of T. resinifictrix (N = 384) in

four consecutive ontogenetic stages indicated by

increasing body size (stage 1: 0.27 ± 0.05 cm, stage

2: 0.73 ± 0.07 cm, stage 3: 0.92 ± 0.15, and stage 4:

2.03 ± 0.39 cm; average ± SD length) with a sieve

of 2 mm net in four temporary ponds. Despite using

arbitrary classifications for ontogenetic stages, the

differences in body size were clearly related to

different developmental stages in regards to morpho-

logical structures and swimming behavior. After the

experiments, we returned the tadpoles to the sampling

ponds.

To evaluate if predation risk affects the movement

and aggregation behaviors of tadpoles at different

ontogenetic stages, we established experimental are-

nas in the field near the ponds for each stage. Each

arena consisted of 16 plastic plates of 20 cm diameter

and 2 cm deep with approximately 100 ml of pond

water. Before placing the tadpoles in the plastic plates,

we mixed the clutches to remove parental effects on

tadpole behavior. Afterwards, we simultaneously

placed six larvae of similar sizes and same develop-

mental stage (according to our classification) in the

same plate and allowed them to acclimate for 30 min.

After acclimation, we recorded the tadpoles’ behavior

using a camera Fujifilm Finepix S2800 for 30 s. At the

end of the recording, we took a snapshot of the

tadpoles’ positions in each plastic plate. Although the

natural aggregations in ponds contained many more

individuals than in our experimental setup, we noted

that when using groups of six individuals in the plates,

the tadpoles exhibited very similar behaviors to the

ones observed in the ponds.

After the initial record and snapshot, we alternated

the inoculation of different treatments simulating the

presence of a predator or a control stimulus (just one

treatment per plate). To simulate the presence of a

predator, we produced a solution with chemical cues

of giant water bugs (Belostomatidae), that is one of the

most voracious predators of tadpoles in ponds

(Toledo, 2005) and frequently found in the study area.

To obtain this solution, we maintained ten giant water

bugs in 250 ml of water for 24 h before the experi-

ment. We considered treatment as the careful inocu-

lation of 2.0 ml of predator solution on eight plates of

each ontogenetic stage, and control as the inoculation

of 2.0 ml of filtered water on the other eight plates of

each stage. To avoid disturbance effects, we always

inoculated the predator or control solutions in the

corner of the plates and as far as possible from any

tadpole. Immediately after each inoculation, we

repeated the video recording and snapshot procedures.

We considered each plate of six larvae as a single

replicate (totaling eight replicates per treatment). We

conducted all experiments in the afternoon (3 pm) on

two consecutive days that had similar climatic

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conditions, avoiding possible alterations in tadpoles

activity associated with variations in temperature and

circadian rhythms between samples. In addition, we

never used individuals in more than one test.

Movement data

To quantify changes in movement of the tadpoles

under predation risk, we measured the time spent in

movement by at least one individual using the

recordings taken before and after the inoculation of

the solution (treatment or control). Then, we calcu-

lated the difference between the time spent in move-

ment before and after the solution inoculation. In this

way, positive values for the difference of the time

spent in movement before and after treatment indicate

that the larvae increased the movement after the

inoculation.

Given that the tadpoles acquire higher mobility

capacity along their development (Wassersug &

Sperry, 1977; Huey, 1980) and that they are able to

recognize predator chemical cues (Kiesecker et al.,

1996), our expectation was that tadpoles in later

developmental stages would mainly rely on active

escape. Consequently, we expected that larvae in the

initial developmental stages would show negative

values for time spent in movement after the inocula-

tion of the solution containing predator cues and no

difference when the inoculation contained only water.

This difference would turn to positive values for

tadpoles in the latter developmental stages.

Distribution data

To assess changes in aggregation of the tadpoles under

predation risk, we measured the area occupied by each

tadpoles’ group using the snapshots taken before and

after inoculation of the treatment or control solutions.

For each snapshot, we marked the position of each

individual tadpole and then calculated the area of the

minimum polygon formed by the six tadpoles in each

plate using the Image J software (version 1.48v;

Schneider et al., 2012). Then, we calculated the

difference between the area of the polygons con-

formed by the position of the individuals before and

after the inoculation of treatment or control solutions.

Negative values for the difference between the areas of

the polygons before and after treatment would indicate

that the larvae decreased aggregation after solution

inoculation, while positive values would indicate that

they increased aggregation.

Given that tadpoles acquire higher movement

abilities throughout their development, our expecta-

tion was that tadpoles in the final developmental states

would show decreased aggregation under predation

risk. Consequently, we expected that the difference in

polygons areas before and after the inoculation of the

predation solution to be positive when compared to the

control for tadpoles in the initial developmental

stages. This difference should turn to negative for

tadpoles at the final developmental stages (Fig. 1).

Statistical analysis

We investigated changes on movement and aggrega-

tion of the tadpoles in response to the risk of predation

using factorial ANOVA. We considered the ontoge-

netic stage (3 levels), treatment (2 levels) and their

interaction as the explanatory variables and time spent

moving as the response variables. We did not include

the first stage in the movement time analyses because

at this stage the movement time was always 0. In order

to discern the differences between stages that moved,

we removed this stage for the statistical analysis to

avoid significant results derived only to the effect of

the first stage. For the second analysis, we considered

the ontogenetic stage (4 levels), treatment (2 levels)

and their interaction as the explanatory variables and

the polygon area formed by tadpoles as the response

variable. We considered the level of significance

a B 0.05, and performed all statistics analyses using

R. According to the visual inspection of residuals, the

data followed all test assumptions (Quinn & Keough,

2002).

Results

In the experimental arenas, tadpoles behaved in a

similar way that we observed in natural ponds. After

acclimation, tadpoles became motionless in the bot-

tom of the plates. In this position, they sometimes

moved the end of their tails, but without any evident

displacement. No individual showed any signs of

injury or oxygen depletion like putting their mouths

outside the water. After the inoculation of predator

solution, the time spent moving by tadpoles was

reduced independently of their developmental stage

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(Table 1). Pooling all stages together, individuals

spent 6.73 ± 6.46 s (mean ± SE) less time moving

after receiving a solution with predator cue, while they

spent 0.29 ± 9.74 s more after receiving the control

treatment. In the same way, independent of their

developmental stage, the reduction in the area of

the positional polygon formed by tadpoles groups

was greater after receiving a predator cue

(12.4 ± 27.5 cm2), in comparison to the area reduc-

tion observed after receiving the control solution

(0.52 ± 23.2 cm2) (Table 1).

Discussion

We found that tadpoles of T. resinifictrix spent less

time moving and reduced the distance among indi-

viduals after receiving a solution containing predator

cues. These results indicate that tadpoles of Amazon

milk frog are, in fact, able to detect chemical cues of

predators in the water and choose to aggregate and

remain motionless. This pattern occurred even among

individuals in advanced developmental stages that

presented higher swimming capacity. Consequently,

the improvement in alternative predator escaping

behaviors was insufficient to trigger changes in the

antipredator strategy.

The reduced movement after perceiving higher

predation risk is widespread among anurans (Skelly,

1994; Nicieza, 1999; Laurila, 2000; Gallie et al., 2001;

Bridges, 2002; Mathis et al., 2003). This behavioral

strategy may decrease the detection rates because the

tadpoles’ predators are usually visually oriented (e.g.,

odonata larvae) or use water vibrations to perceive

Fig. 1 Schematic

representation of the

methods used to

experimentally measure the

variation in the movement

(using footage) and

aggregation (using

photographs) of

Trachycephalus resinifictrix

tadpoles in the presence or

absence of predation risk

Table 1 ANOVA models showing the effects of ontogenetic

stage (four ontogenetic classes) and treatment (control, pre-

dation risk) on aggregation and movement time of tadpoles of

Trachycephalus resinifictrix

Effect d.f. F P

D aggregation area

Ontogenetic stage (O) 3 0.471 0.703

Treatment (Tr) 1 3.843 0.054

Interaction (Tr 9 O) 3 0.377 0.769

Residual 66

D movement time

Ontogenetic stage (O) 2 2.525 0.093

Treatment (Tr) 1 9.407 0.004

Interaction (Tr 9 O) 2 0.259 0.773

Residual 40

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prey, particularly for individuals that occur in tempo-

rary ponds (Persons, 1999). In fact, we observed many

predator species that rely on visual (i.e., odonata

larvae) or vibrational (i.e., aquatic spiders) cues to

forage. In such environments, active escape from one

predator may propagate water vibrations or increase

the chance of visual detection by additional predators

(Bleckmann & Lotz, 1987). Furthermore, temporary

ponds are also more prone to desiccation, which

shrinks water volume and limits the space available for

escaping (Skelly, 1996; De Block et al., 2008).

The tendency to aggregate may explain why

individuals reduced movement and indicated that

individuals of T. resinifictrix may also benefit from

the dilution effect. Aggregations may incur additional

benefits such as increased vigilance or group defense

(Davies et al., 2012). However, none of the other

possible advantages of aggregation to avoid predation

seem to explain aggregation of tadpoles in our studied

system. Given that the water in ponds is highly turbid,

the increased vigilance and the coordinated group

movements may not decrease the predation risk to

tadpoles (McDiarmid & Altig, 1999). Such prey

strategies are effective when predators are able to

see many preys together (Pritchard, 1965). Neverthe-

less, even the dragonfly larvae must be near tadpoles to

detect them visually. Consequently, it is probable that

the main advantage in the aggregation occurs because

predators may attack any individual in the group.

Consequently, the greater the group, the lower the

probability of individual predation (Wrona & Dixon,

1991). If escape strategies that rely on rapid movement

are less efficient due to low space available and the

presence of different predator species with distinct

hunting strategies (e.g., Relyea, 2001), aggregations

may be the most profitable predator avoidance strategy

throughout all ontogenetic development.

Because the efficiency of the dilution effect

depends on the number of individuals that form the

group, it may be less efficient for tadpoles in latter

developmental stages. Probably, the aggregations of

tadpoles in later stages of development are smaller in

number in comparison to other ontogenetic stages due

to a natural cumulative effect of mortality with

increasing age (Kirkwood & Holliday, 1979). Fur-

thermore, older tadpoles have a higher probability of

detection due to their greater size. Consequently,

unless greater size reduces the number of potential

predators (Tejedo, 1993), older tadpoles may face

higher predation pressure than younger and smaller

ones. Therefore, it seems intriguing that they exhibited

the same predator avoidance strategies observed in

individuals in early developmental stages. It is possi-

ble that their predator avoidance strategies are not

flexible (Sih et al., 2004). If this is the case, the anti-

predatory behaviors observed may be a unique strat-

egy that has different efficiencies under distinct

ontogenetic stages. Perhaps, it represents the option

that maximizes survivorship at the end of the whole

development, even if it is not the most profitable one

for specific stages. Alternatively, it is important to note

that T. resinifictrix tadpoles typically occur in tree

holes (Hero, 1990), which represent areas with

restricted space for active escaping and probably low

predation pressure. In fact, tree holes seem to be the

main reproductive site for this species and territorial

adult males are often found defending these areas

(Schiesari et al., 2003). Since males defend territories

associated with tree holes, it is possible that tadpoles

found in ponds were laid by females that mated with

males that adopted an alternative mate-locating tactic.

On the other hand, hylids females could also show

plasticity in oviposition (Touchon & Warkentin,

2008), and temporary pounds could be the opportunity

to nest in an alternative place when the preferred

clutching site is limited. If one or both situations are

true, tadpoles in ponds may lack the ability to change

the behavior according to their swimming capacity

because they are an example of a population that

evolved in a habitat with low predation pressure.

One of the immediate consequences for individuals

that reduce activity when predators are nearby is the

concomitant reduction in foraging activity (Verdolin,

2006). Our results indicated that this might occur in T.

resinifictrix. Consequently, individuals of this species

may face a trade-off between foraging needs and

predator avoidance. Such demand may be particularly

important for individuals that occur in temporary

ponds, since in this habitat they may suffer a higher

rate of predation.

Conclusion

Tadpoles of the Amazonmilk frog choose to aggregate

and remain motionless under predation risk indepen-

dent of their developmental stage. The improvement

in swimming performance does not trigger any

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alternative escaping behavior and the tendency of

tadpoles to show a greater spatial aggregation after

perceiving predator cues indicates that individuals of

T. resinifictrix may benefit from the dilution effect.

Perhaps, the adoption of active escaping increases the

chances of detection by non-visual predators. Alter-

natively, it may be that tadpoles of this species lack the

ability to change their behavior according to their

developmental stages because they originally evolved

in restricted habitats with low predation pressure.

Acknowledgments We would like to thank the anonymous

reviewers for their valuable comments and their contribution to

the discussion and further improvement of this manuscript. We

would like to thank Pedro Henrique do Santos Dias for the

species identification and his valuable comments about the

natural history of tree frogs. IC is grateful to the EFACommittee

to give me the opportunity to carry out my research in the

Reserva ARIE-PDBFF (Biological Dynamics of Forest

Fragments Project), in the Central Amazon Forest. This is the

study No. 677 of the PDBFF - INPA/STRI. I would like to thank

all my colleagues and teachers for their priceless contribution

from the idea conception until the fieldwork and further

discussion of the ideas. I am also grateful to the CNPq

(Conselho Nacional de Pesquisa) for grant #2449505

721687633. RC is grateful to Fundação de Amparo à Pesquisa

do Estado de São Paulo for grant #2014/20924-5.

References

Azevedo-Ramos, C. & W. E. Magnusson, 1999. Tropical tad-

pole vulnerability to predation: association between labo-

ratory results and prey distribution in an Amazonian

savanna. Copeia 1999: 58–67.

Bauwens, D. & C. Thoen, 1981. Escape tactics and vulnerability

to predation associated with reproduction in the lizard

Lacerta vivipara. Journal of Animal Ecology 50: 733–743.

Bierregaard Jr., R. O., T. E. Lovejoy, V. Kapos, A. A. dos Santos

& R. W. Hutchings, 1992. The biological dynamics of

tropical rainforest fragments. BioScience 42: 859–866.

Bleckmann, H. & T. Lotz, 1987. The vertebrate-catching

behaviour of the fishing spider Dolomedes triton (Araneae,

Pisauridae). Animal Behaviour 35: 641–651.

Bridges, C. M., 2002. Tadpoles balance foraging and predator

avoidance: effects of predation, pond drying, and hunger.

Journal of Herpetology 36: 434–627.

Crump, M. L., 1984. Ontogenetic changes in vulnerability to

predation in tadpoles of Hyla pseudopuma. Herpetologica

40: 265–271.

Davies, N. B., J. R. Krebs & S. A. West, 2012. An Introduction

to Behavioural Ecology. Wiley, Hoboken, NJ.

Dayton, G. H., D. Saenz, K. A. Baum, R. B. Langerhans & T.

J. DeWitt, 2005. Body shape, burst speed and escape

behavior of larval anurans. Oikos 111: 582–591.

De Block, M., M. A. McPeek & R. Stoks, 2008. Life-history

evolution when Lestes damselflies invaded vernal ponds.

Evolution 62: 485–493.

Fabrezi, M., A. Manzano, V. Abdala & F. Lobo, 2014. Anuran

locomotion: ontogeny and morphological variation of a

distinctive set of muscles. Evolutionary Biology 41:

308–326.

Gallie, J. A., R. L.Mumme& S. A.Wissinger, 2001. Experience

has no effect on the development of chemosensory recog-

nition of predators by tadpoles of the American toad, Bufo

americanus. Herpetologica 57: 376–383.

Gosner, K. L., 1960. A simplified table for staging anuran

embryos and larvae with notes on identification. Herpeto-

logica 16: 183–190.

Hero, J. M., 1990. An illustrated key to tadpoles occurring in the

central amazon rain-forest, Manaus, Amazonas, Brasil.

Amazoniana 11: 201–262.

Hossie, T. J. & D. L. Murray, 2012. Assessing behavioural and

morphological responses of frog tadpoles to temporal

variability in predation risk. Journal of Zoology 288:

275–282.

Huey, R. B., 1980. Sprint velocity of tadpoles (Bufo boreas)

through metamorphosis. Copeia 3: 537–540.

Irschick, D. J. & J. B. Losos, 1998. A comparative analysis of

the ecological significance of maximal locomotor perfor-

mance in caribbean Anolis lizards. Evolution 52: 219–226.

Jara, F. G. & M. G. Perotti, 2009. Toad tadpole responses to

predator risk: ontogenetic change between constitutive and

inducible defenses. Journal of Herpetology 43: 82–88.

Johnson, J. C. & A. Sih, 2007. Fear, food, sex and parental care:

a syndrome of boldness in the fishing spider, Dolomedes

triton. Animal Behaviour 74: 1131–1138.

Kiesecker, J. M., D. P. Chivers & A. R. Blaustein, 1996. The use

of chemical cues in predator recognition by western toad

tadpoles. Animal Behaviour 52: 1237–1245.

Kirkwood, T. B. L. & R. Holliday, 1979. The evolution of

ageing and longevity. Proceedings of the Royal Society of

London B: Biological Sciences 205: 531–546.

Landberg, T. & E. Azizi, 2010. Ontogeny of escape swimming

performance in the spotted salamander. Functional Ecol-

ogy 24: 576–587.

Langerhans, R., 2007. Evolutionary consequences of predation:

avoidance, escape, reproduction, and diversification. In

Elewa, A. (ed.), Predation in Organisms: A Distinct Phe-

nomenon. Springer-Verlag, Heidelberg: 117–220.

Laurila, A., 2000. Behavioural responses to predator chemical

cues and local variation in antipredator performance in

Rana temporaria tadpoles. Oikos 88: 159–168.

Lima, S. L. & L. M. Dill, 1990. Behavioral decisions made

under the risk of predation: a review and prospectus.

Canadian Journal of Zoology 68: 619–640.

Liu, H., R. Wassersug & K. Kawachi, 1997. The three-dimen-

sional hydrodynamics of tadpole locomotion. The Journal

of Experimental Biology 200: 2807–2819.

Martı́n, J. & P. López, 2003. Ontogenetic variation in

antipredator behavior of Iberian rock lizards (Lacerta

monticola): effects of body-size-dependent thermal-ex-

change rates and costs of refuge use. Canadian Journal of

Zoology 81: 1131–1137.

Mathis, A., K. L.Murray&C. R. Hickman, 2003. Do experience

and body size play a role in responses of larval ringed

salamanders, Ambystoma annulatum, to predator kair-

omones? Laboratory and field assays. Ethology 109:

159–170.

Hydrobiologia (2016) 765:379–386 385

123



McDiarmid, R. W. & R. Altig, 1999. Tadpoles: the biology of

anuran larvae. In McDiarmid, R.W. &R. Altig (eds), Body

Plan: Development and Morphology. University of Chi-

cago Press, Chicago: 8–24.

Nicieza, A. G., 1999. Context-dependent aggregation in com-

mon frog Rana temporaria tadpoles: influence of devel-

opmental stage, predation risk and social environment.

Functional Ecology 13: 852–858.

Peckarsky, B. L., 1980. Predator-prey interactions between

stoneflies and mayflies: behavioral observations. Ecology

61: 932–943.

Persons, M. H., 1999. Hunger effects on foraging responses to

perceptual cues in immature and adult wolf spiders (Ly-

cosidae). Animal Behaviour 57: 81–88.

Pritchard, G., 1965. Prey capture by dragonfly larvae (Odo-

nata:Anisoptera). Canadian Journal of Zoology 43:

271–289.

Quinn, G. P. & M. J. Keough, 2002. Experimental design and

data analysis for biologists. Cambridge University Press,

Cambridge.

Relyea, R. A., 2001. Morphological and behavioral plasticity of

larval anurans in response to different predators. Ecology

82: 523–540.

Sansom, A., J. Lind & W. Cresswell, 2009. Individual behavior

and survival: the roles of predator avoidance, foraging

success, and vigilance. Behavioral Ecology 20:

1168–1174.

Schiesari, L., M. Gordo & W. Hödl, 2003. Treeholes as calling,

breeding, and developmental sites for the Amazonian

canopy frog, Phrynohyas resinifictrix (Hylidae). Copeia

2003: 263–272.

Schneider, C. A., W. S. Rasband & K. W. Eliceiri, 2012. NIH

Image to ImageJ: 25 years of image analysis. Nat Meth 9:

671–675.

Sih, A., 1992. Prey uncertainty and the balancing of antipredator

and feeding needs. The American Naturalist 139:

1052–1069.

Sih, A., A. Bell & J. C. Johnson, 2004. Behavioral syndromes:

an ecological and evolutionary overview. Trends in Ecol-

ogy & Evolution 19: 372–378.

Skelly, D. K., 1994. Activity level and the susceptibility of

anuran larvae to predation. Animal Behavior 47: 465–468.

Skelly, D. K., 1996. Pond drying, predators, and the distribution

of Pseudacris tadpoles. Copeia 3: 599–605.

Spieler, M., 2003. Risk of predation affects aggregation size: a

study with tadpoles of Phrynomantis microps (Anura:

Microhylidae). Animal Behaviour 65: 179–184.

Spieler, M. &K. E. Linsenmair, 1999. Aggregation behaviour of

Bufo maculatus tadpoles as an antipredator mechanism.

Ethology 105: 665–686.

Verdolin, J. L., 2006. Meta-analysis of foraging and predation

risk trade-offs in terrestrial systems. Behavioral Ecology

and Sociobiology 60: 457–464.

Tejedo, M., 1993. Size-dependent vulnerability and behavioral

responses of tadpoles of two anuran species to beetle larvae

predators. Herpetologica 49: 287–294.

Thery, M. & J. Casas, 2002. Visual systems: predator and prey

views of spider camouflage. Nature 415: 133.

Toledo, L. F., 2005. Predation of juvenile and adult anurans by

invertebrates: current knowledge and perspectives. Her-

petological Review 36: 395–399.

Toledo, L. F., I. Sazima & C. F. B. Haddad, 2011. Behavioural

defences of anurans: an overview. Ethology Ecology &

Evolution 23: 1–25.

Touchon, J. C. & K. M. Warkentin, 2008. Reproductive mode

plasticity: aquatic and terrestrial oviposition in a treefrog.

Proceedings of the National Academy of Sciences of the

United States of America 105: 7495–7499.

Wassersug, R. J. & D. G. Sperry, 1977. The relationships of

locomotion to differential predation on Pseudacris trise-

riata (Anura: Hylidae). Ecology 58: 830–839.

Watt, P. J., S. F. Nottingham & S. Young, 1997. Toad tadpole

aggregation behaviour: evidence for a predator avoidance

function. Animal Behaviour 54: 865–872.

Wellborn, G. A., D. K. Skelly & E. E. Werner, 1996. Mecha-

nisms creating community structure across a freshwater

habitat gradient. Annual Review of Ecology and System-

atics 27: 337–363.

Williams, C. R., E. D. Brodie Jr, M. J. Tyler & S. J. Walker,

2000. Antipredator mechanisms of Australian frogs. Jour-

nal of Herpetology 3: 431–443.

Wrona, F. J. & R. W. J. Dixon, 1991. Group size and predation

risk: a field analysis of encounter and dilution effects. The

American Naturalist 137: 186–201.

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	Perceived predation risk decreases movement and increases aggregation of Amazon milk frog (Anura, Hylidae) tadpoles throughout ontogeny
	Abstract
	Introduction
	Materials and methods
	Study area
	Data collection
	Movement data
	Distribution data
	Statistical analysis

	Results
	Discussion
	Conclusion
	Acknowledgments
	References