scholarly journals Predation risks of signalling and searching: bats prefer moving katydids

2020 ◽  
Vol 16 (4) ◽  
pp. 20190837 ◽  
Author(s):  
Inga Geipel ◽  
Ciara E. Kernan ◽  
Amber S. Litterer ◽  
Gerald G. Carter ◽  
Rachel A. Page ◽  
...  
Keyword(s):  
At Risk ◽  
Predation Risk ◽  
Mate Searching ◽  
Mating Signals ◽  
Vibrational Signals ◽  
Choice Tests ◽  
Male Signals

Males signalling their attractiveness to females are at risk from predators that exploit mating signals to detect and locate prey. Signalling, however, is not the only risky activity in sexual interactions: mate searching can incur risk as well. Male Neotropical pseudophylline katydids produce both acoustic and vibrational signals (tremulations). Females reply to male signals with tremulations of their own, and both sexes walk to find one another. We asked if movement increases predation risk, and whether tremulation or walking was more attractive to predators. We offered the Neotropical gleaning bat Micronycteris microtis a series of two-choice tests, presenting the bats with katydid models that were motionless or moved in a way to mimic either tremulating or walking. We found that prey movements do put prey at risk. Although M. microtis can detect motionless prey on leaves, they preferred moving prey. Our study shows that movement can put searching or signalling prey in danger, potentially explaining why silent female katydids are frequently consumed by gleaning bats.

Reproductive strategy of the Nearctic leafhopper Scaphoideus titanus Ball (Hemiptera: Cicadellidae)

2008 ◽  
Vol 99 (4) ◽  
pp. 401-413 ◽  
Author(s):  
Valerio Mazzoni ◽  
Janez Prešern ◽  
Andrea Lucchi ◽  
Meta Virant-Doberlet
Keyword(s):  
Mating Behaviour ◽  
Single Pulse ◽  
Dominant Frequency ◽  
Pair Formation ◽  
Laser Vibrometer ◽  
Alternative Tactics ◽  
Flavescence Dorée ◽  
Scaphoideus Titanus ◽  
Vibrational Signals ◽  
Male Signals

AbstractMating behaviour of Scaphoideus titanus Ball, the vector of the grapevine disease Flavescence dorée, was investigated in order to determine the role of substrate-borne vibrational signals in intra-specific communication and pair formation. Vibrational signals were recorded from grapevine leaves with a laser vibrometer. Signalling activity of single males changed throughout the day and the peak in activity was associated with twilight and early night when ‘call and fly’ behaviour was observed. Pair formation began with the spontaneous emission of male signals. The male calling signal consisted of a single series of pulses, partially accompanied with a ‘rumble’. The male courtship phrase consisted of four consecutive sections characterized by two sound elements, pulse and ‘buzz’. Female vibrational signals were emitted only in response to male signals. The female response was a single pulse that closely resembled male pulses and was inserted between pulses within the male signals. All recorded vibrational signals of S. titanus have a dominant frequency below 900 Hz. A unique feature of vibrational communication in S. titanus is well-developed intrasexual competition; males may use alternative tactics, in the form of disturbance signals, or silently approach duetting females (satellite behaviour). While the male-female duet appears to be essential for successful localization of females and copulation, it is also vulnerable to, and easily disrupted by, alternative tactics like masking.

Bumblebees avoid flowers containing evidence of past predation events

2006 ◽  
Vol 84 (9) ◽  
pp. 1240-1247 ◽  
Author(s):  
K.R. Abbott
Keyword(s):  
At Risk ◽  
Predation Risk ◽  
Field Experiments ◽  
The Other ◽  
Risk Of Predation ◽  
Series Of Experiments ◽  
Indirect Cues ◽  
Artificial Flowers ◽  
Ambush Predators

Bees are at risk of predation from flower-dwelling ambush predators. Since these predators tend to be cryptic, bees trying to mitigate predation risk may need to make use of indirect cues of the predator’s presence. For example, they may use cues of past predation events as indirect cues of current predation risk. I conducted a series of experiments that examined how bumblebees (genus Bombus Latreille, 1802) respond to cues of past predation events. In two field experiments, I found that wild rose (genus Rosa L.) flowers containing a freshly killed bumblebee, or the scent of a freshly killed bumblebee, received fewer bumblebee visits than control flowers. To test the possibility that bumblebees in the first two experiments were avoiding cues of competition risk rather than cues of predation risk, captive-reared bumblebees were given a choice between two artificial flowers — one containing a freeze-killed bumblebee (relatively more similar to a live foraging bee) and the other containing a crush-killed bumblebee (relatively more similar to a bee killed by a predator). Most bumblebees chose the flower containing the freeze-killed bee, supporting the hypothesis that the bumblebees in the first two experiments were attempting to avoid predation.

scholarly journals Odour cues influence predation risk at artificial bat roosts in urban bushland

2013 ◽  
Vol 9 (3) ◽  
pp. 20121144 ◽  
Author(s):  
Caragh Threlfall ◽  
Bradley Law ◽  
Peter B. Banks
Keyword(s):  
At Risk ◽  
Predation Risk ◽  
Untreated Control ◽  
Olfactory Cues ◽  
Refresh Rate ◽  
Insectivorous Bats ◽  
Tree Hollows ◽  
Risk Of Predation ◽  
Sydney Australia

Odours that accumulate from roosting can attract predators and increase predation risk. Consequently, selection should favour strategies that allow prey to evade detection by predators, including changing roosts. Insectivorous bats that roost in tree hollows regularly switch roosts and roost in different sized groups, strategies that would alter the accumulation of roost odours and are hypothesized to reduce predation risk. We experimentally manipulated the amount and refresh rate of roosting odour cues at 90 artificial bat roosts in Sydney, Australia, to test the hypothesis that odours increase predator visitation. Predators visited roosts with bat faeces significantly more often than untreated control roosts. Roosts with small amounts of faeces mimicking sites used by solitary bats had the greatest rate of visitation. This suggests that bats roosting alone, rather than in groups, have a greater likelihood of disturbance or predation. Roost switching probably decreases the predictability of finding occupied roosts; however, we show that all roosts (those currently or recently occupied) were visited by predators, suggesting generalist urban predators readily investigate potential roosts. This is the first demonstration that bat odours are attractive to predators that use olfactory cues, showing that bats are at risk of predation in visually cryptic roosts.

Competitive masking of vibrational signals during mate searching in a treehopper

2012 ◽  
Vol 83 (2) ◽  
pp. 361-368 ◽  
Author(s):  
Frédéric Legendre ◽  
Peter R. Marting ◽  
Reginald B. Cocroft
Keyword(s):  
Mate Searching ◽  
Vibrational Signals

scholarly journals Sex differences in alternative reproductive tactics in response to predation risk in tree crickets

2019 ◽  
Author(s):  
Viraj R. Torsekar ◽  
Rohini Balakrishnan
Keyword(s):  
Predation Risk ◽  
Mating Success ◽  
Empirical Studies ◽  
Search Strategies ◽  
Negative Effects ◽  
Reproductive Tactics ◽  
Mate Searching ◽  
Searching Behaviour ◽  
Mate Search

AbstractPredation risk has been hypothesised to drive the evolution of alternative mate-search strategies, but few empirical studies have examined this. In crickets, mate-search involves acoustic signalling by males and acoustic-mediated movement by females. It is unclear whether predators affect fitness of both sexes directly, by reducing survival, or indirectly, by affecting mate-searching. We empirically examined effects of increased predation risk on mate-searching behaviour and survival of male and female tree crickets, and their effects on mating success, using field-enclosure experiments with tree crickets Oecanthus henryi and their primary predator, green lynx spiders, Peucetia viridans. Crickets were allocated into three treatments with differential levels of predation risk. Increased predation risk strongly reduced survival, and thereby mating success, for both sexes. With increasing predation risk, males reduced calling and increased movement towards neighbouring callers, which had negative effects on mating success. Using simulations, we found male movement was significantly directed towards other calling males implying a switch to satellite strategies. Female movement behaviour, however, remained unaltered. Males and females thus differed in their response to comparable levels of predation risk, showing that the role of predation as a driver of alternative mate search strategies is sex and strategy-specific.

scholarly journals Is the predation risk of mate-searching different between the sexes?

2018 ◽  
Author(s):  
Viraj R. Torsekar ◽  
Kavita Isvaran ◽  
Rohini Balakrishnan
Keyword(s):  
Predation Risk ◽  
Natural Populations ◽  
Pair Formation ◽  
Mate Searching ◽  
Direct Benefits ◽  
Extensive Field ◽  
Tree Cricket ◽  
Manipulative Experiments ◽  
Sexual Selection Theory ◽  
Behavioural Strategies

AbstractIn animals that communicate for pair formation, generally one sex invests more effort in mate searching. Differential predation risk of mate searching between the sexes is hypothesised to determine which sex invests more effort in mate searching. Although searching by males is prevalent in most animals, in orthopteran insects and some other taxa females physically move to localise signalling males who are predominantly sedentary. Although the two sexes thus share mate searching effort in orthopterans, their behavioural strategies are different and sexual selection theory predicts that signalling males may be following the riskier strategy and incurring higher costs. However, relative levels of risk posed by the two mate searching strategies remain largely unexplored. Hence, we estimated the relative predation risk experienced in natural populations by signalling males and responding females. We did this by quantifying predation risk as a probability of mortality in the context of acoustic communication in a tree cricket, Oecanthus henryi from its ecologically relevant predator, a lynx spider, Peucetia viridans. Spiders may perceive calling in males and movement in females by their ability to detect both airborne acoustic cues and substrate-borne vibratory cues. Probability of mortality was quantified by partitioning it into three spatial components at which crickets and spiders interact, using a combination of extensive field observations and manipulative experiments in a semi-natural setup. We found no differences in predation risk faced by calling males and responding females, supporting the prediction that similar sex-specific costs can explain shared mate searching responsibilities. Our findings therefore suggest that direct benefits offered by males to females upon pair formation may better explain shared mate searching effort between the sexes in orthopterans.

scholarly journals Is the predation risk of mate-searching different between the sexes?

2019 ◽  
Vol 33 (3) ◽  
pp. 329-343 ◽  
Author(s):  
Viraj R. Torsekar ◽  
Kavita Isvaran ◽  
Rohini Balakrishnan
Keyword(s):  
Predation Risk ◽  
Mate Searching

Vigilance in human groups: a test of alternative hypotheses

Behaviour ◽  
2002 ◽  
Vol 139 (5) ◽  
pp. 695-711 ◽  
Author(s):  
◽  
◽  
◽  
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Inverse Relationship ◽  
Mate Guarding ◽  
Mate Searching ◽  
Clear Cut ◽  
Vigilance Behaviour ◽  
Alternative Hypotheses

AbstractHumans exhibit the same inverse relationship between group size and vigilance rates that has been classically described in animals. We collected data on natural human vigilance behaviour in two different contemporary environments (a large refectory-style cafeteria and open parks) to test between four alternative hypotheses for this relationship: predation risk, searching for friends, mate searching and mate guarding. The results demonstrate that, at least in contemporary city environments, humans monitor their surroundings largely for reasons motivated by mate searching. Data on whom subjects look at in a busy environment indicate that males are significantly more likely to attend differentially to female passers-by, but that females show a less clear-cut discrimination. We conclude that vigilance patterns are determined by locally salient functions.

Phonological Awareness Screening to Identify At-Risk Readers

1998 ◽  
Vol 29 (2) ◽  
pp. 109-116 ◽  
Author(s):  
Margie Gilbertson ◽  
Ronald K. Bramlett
Keyword(s):  
At Risk ◽  
Phonological Awareness ◽  
Reading Ability ◽  
At Risk Students ◽  
First Grade ◽  
Receptive Vocabulary ◽  
Standardized Assessments ◽  
Cutoff Score ◽  
Invented Spelling ◽  
Reading Measures

The purpose of this study was to investigate informal phonological awareness measures as predictors of first-grade broad reading ability. Subjects were 91 former Head Start students who were administered standardized assessments of cognitive ability and receptive vocabulary, and informal phonological awareness measures during kindergarten and early first grade. Regression analyses indicated that three phonological awareness tasks, Invented Spelling, Categorization, and Blending, were the most predictive of standardized reading measures obtained at the end of first grade. Discriminant analyses indicated that these three phonological awareness tasks correctly identified at-risk students with 92% accuracy. Clinical use of a cutoff score for these measures is suggested, along with general intervention guidelines for practicing clinicians.

Effects of a Supplemental Spanish Phonological Awareness Intervention on Latinx Preschoolers' Dual Language Emergent Literacy Skills

2020 ◽  
Vol 29 (3) ◽  
pp. 1283-1300
Author(s):  
Xigrid T. Soto ◽  
Andres Crucet-Choi ◽  
Howard Goldstein
Keyword(s):  
At Risk ◽  
Phonological Awareness ◽  
Emergent Literacy ◽  
Language Learners ◽  
Literacy Instruction ◽  
Dual Language ◽  
Literacy Skills ◽  
Dual Language Learners ◽  
Probe Design ◽  
Emergent Literacy Skills

Purpose Preschoolers' phonological awareness (PA) and alphabet knowledge (AK) skills are two of the strongest predictors of future reading. Despite evidence that providing at-risk preschoolers with timely emergent literacy interventions can prevent academic difficulties, there is a scarcity of research focusing on Latinx preschoolers who are dual language learners. Despite evidence of benefits of providing Latinxs with Spanish emergent literacy instruction, few studies include preschoolers. This study examined the effects of a supplemental Spanish PA and AK intervention on the dual emergent literacy skills of at-risk Latinx preschoolers. Method A multiple probe design across four units of instruction evaluated the effects of a Spanish supplemental emergent literacy intervention that explicitly facilitated generalizations to English. Four Latinx preschoolers with limited emergent literacy skills in Spanish and English participated in this study. Bilingual researchers delivered scripted lessons targeting PA and AK skills in individual or small groups for 12–17 weeks. Results Children made large gains as each PA skill was introduced into intervention and generalized the PA skills they learned from Spanish to English. They also improved their English initial sound identification skills, a phonemic awareness task, when instruction was delivered in Spanish but with English words. Children made small to moderate gains in their Spanish letter naming and letter–sound correspondence skills and in generalizing this knowledge to English. Conclusion These findings provide preliminary evidence Latinx preschoolers who are dual language learners benefit from emergent literacy instruction that promotes their bilingual and biliterate development.

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