scholarly journals Morph Composition Matters in the Gouldian Finch (Chloebia gouldiae): Involvement of Red-Headed Birds Increases Vigilance

Birds ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 404-414
Author(s):  
Claudia Mettke-Hofmann
Keyword(s):  
Predation Risk ◽  
Group Composition ◽  
Predation Pressure ◽  
Head Movements ◽  
Species Assemblages ◽  
Same Sex ◽  
Mixed Species ◽  
Polymorphic Species ◽  
Gouldian Finch ◽  
Tracking Strategy

Animals invest in costly vigilance to detect threats. Joining groups reduces these costs, which can be further reduced in mixed-species assemblages. In colour-polymorphic species, morphs often experience different predation pressure and vary in a variety of traits. However, little is known about differences in vigilance or how group composition affects vigilance. The aim was to investigate whether higher conspicuousness increased vigilance and whether vigilance was reduced in mixed-morph groups like in mixed-species assemblages. I tested vigilance in the colour-polymorphic Gouldian Finch (Chloebia gouldiae). Same sex pairs of different age and of either pure (red-red or black-black) or mixed head colour were exposed to three contexts (familiar, changed and novel environment) and head movements were recorded. All birds reduced the frequency of head movements with increasing novelty, indicating different vigilance strategies (switching from a searching to a tracking strategy) depending on the situation. While vigilance did not differ between morphs, morph composition mattered. Black-headed pairs made fewer head movements than mixed-head colour pairs. Results indicated that conspicuousness did not affect vigilance, possibly due to existing adaptations to reduce predation risk. However, whenever red-headed birds were involved, vigilance increased either because of higher group conspicuousness or prevalence of aggression.

scholarly journals Mixed-species herding levels the landscape of fear

2020 ◽  
Vol 287 (1922) ◽  
pp. 20192555 ◽  
Author(s):  
Keenan Stears ◽  
Melissa H. Schmitt ◽  
Christopher C. Wilmers ◽  
Adrian M. Shrader
Keyword(s):  
High Risk ◽  
Predation Risk ◽  
Social Information ◽  
Single Species ◽  
Herd Size ◽  
Low Risk ◽  
Mixed Species ◽  
Landscape Of Fear ◽  
Trade Off ◽  
Risk Areas

Prey anti-predator behaviours are influenced by perceived predation risk in a landscape and social information gleaned from herd mates regarding predation risk. It is well documented that high-quality social information about risk can come from heterospecific herd mates. Here, we integrate social information with the landscape of fear to quantify how these landscapes are modified by mixed-species herding. To do this, we investigated zebra vigilance in single- and mixed-species herds across different levels of predation risk (lion versus no lion), and assessed how they manage herd size and the competition–information trade-off associated with grouping behaviour. Overall, zebra performed higher vigilance in high-risk areas. However, mixed-species herding reduced vigilance levels. We estimate that zebra in single-species herds would have to feed for approximately 35 min more per day in low-risk areas and approximately 51 min more in high-risk areas to compensate for the cost of higher vigilance. Furthermore, zebra benefitted from the competition–information trade-off by increasing the number of heterospecifics while keeping the number of zebra in a herd constant. Ultimately, we show that mixed-species herding reduces the effects of predation risk, whereby zebra in mixed-species herds, under high predation risk, perform similar levels of vigilance compared with zebra in low-risk scenarios.

scholarly journals Behavioural differences and interactions between two sessile bivalves forming mixed-species assemblages

2021 ◽  
Vol 171 ◽  
pp. 13-28
Author(s):  
Łukasz Jermacz ◽  
Csilla Balogh ◽  
Jarosław Kobak
Keyword(s):  
Species Assemblages ◽  
Mixed Species

scholarly journals Zebra reduce predation risk in mixed-species herds by eavesdropping on cues from giraffe

2016 ◽  
Vol 27 (4) ◽  
pp. 1073-1077 ◽  
Author(s):  
Melissa H. Schmitt ◽  
Keenan Stears ◽  
Adrian M. Shrader
Keyword(s):  
Predation Risk ◽  
Mixed Species

Habitat as a source of intrapopulational variation of ornament size in Galápagos lava lizards (Microlophus albemarlensis complex)

2008 ◽  
Vol 29 (2) ◽  
pp. 278-283 ◽  
Author(s):  
Mark Jordan ◽  
Howard Snell ◽  
Jennifer Hollis ◽  
Paul Stone
Keyword(s):  
Predation Risk ◽  
Body Mass ◽  
Predator Avoidance ◽  
Habitat Structure ◽  
Predation Pressure ◽  
Residual Body ◽  
Galápagos Islands ◽  
Vegetative Cover ◽  
High Predation ◽  
Intrapopulational Variation

Abstract Gradients in habitat structure are expected to influence the outcome of selection on traits that contribute to communicative display. Galápagos lava lizards (Microlophus albemarlensis complex) on Isla Plaza Sur in the Galápagos Islands occur across a gradient of vegetative cover. Previous work in this population has shown that traits associated with predator avoidance are magnified in habitats with low vegetative cover. This pattern suggests that predation pressure differs by habitat and thus, may act to select against the elaboration of ornamentation. We measured the size of the chin patch, an ornament known to be used in intraspecific signaling, to test this hypothesis. The area of the chin patch was dependent on both snout-vent length and residual body mass. In contrast to expectation, males had larger chin patches in the sparsely vegetated habitat suggested to have high predation risk. This result raises questions about the presumed survival cost of ornament elaboration.

scholarly journals Trophic shift and the origin of birds

2020 ◽  
Author(s):  
Yonghua Wu
Keyword(s):  
Predation Risk ◽  
Digestive System ◽  
Predation Pressure ◽  
Flapping Flight ◽  
Foraging Efficiency ◽  
Fat Digestion ◽  
Trophic Shift ◽  
High Predation ◽  
High Predation Pressure ◽  
Selection Of

AbstractBirds are characterized by evolutionary specializations of both locomotion (e.g., flapping flight) and digestive system (toothless, crop, and gizzard), while the potential selection pressures responsible for these evolutionary specializations remain unclear. Here we used a recently developed molecular phyloecological method to reconstruct the diets of the ancestral archosaur and of the common ancestor of living birds (CALB). Our results showed that the ancestral archosaur exhibited a predominant Darwinian selection of protein and fat digestion and absorption, whereas the CALB showed a marked enhanced selection of carbohydrate and fat digestion and absorption, suggesting a trophic shift from carnivory to herbivory (fruit, seed, and/or nut-eater) at the archosaur-to-bird transition. The evolutionary shift of the CALB to herbivory may have essentially made them become a low-level consumer and, consequently, subject to relatively high predation risk from potential predators such as gliding maniraptorans, from which birds descended. Under the relatively high predation pressure, ancestral birds with gliding capability may have then evolved not only flapping flight as a possible anti-predator strategy against gliding predatory maniraptorans but also the specialized digestive system as an evolutionary tradeoff of maximizing foraging efficiency and minimizing predation risk. Our results suggest that the powered flight and specialized digestive system of birds may have evolved as a result of their tropic shift-associated predation pressure.

scholarly journals Relaxed risk of predation drives parallel evolution of stickleback behaviour

2022 ◽  
Author(s):  
Antoine Fraimout ◽  
Elisa Päiviö ◽  
Juha Merilä
Keyword(s):  
Phenotypic Plasticity ◽  
Predation Risk ◽  
Parallel Evolution ◽  
Predation Pressure ◽  
Evolutionary Divergence ◽  
Pungitius Pungitius ◽  
Risk Of Predation ◽  
Selective Agents ◽  
Habitat Similarity ◽  
Evolution By Natural Selection

The occurrence of similar phenotypes in multiple independent populations (viz. parallel evolution) is a testimony of evolution by natural selection. Parallel evolution implies that populations share a common phenotypic response to a common selection pressure associated with habitat similarity. Examples of parallel evolution at the genetic and phenotypic levels are fairly common, but the driving selective agents often remain elusive. Similarly, the role of phenotypic plasticity in facilitating early stages of parallel evolution is unclear. We investigated whether the relaxation of predation pressure associated with the colonization of freshwater ponds by nine-spined sticklebacks (Pungitius pungitius) likely explains the divergence in complex behaviours between marine and pond populations, and whether this divergence is parallel. Using laboratory-raised individuals exposed to different levels of perceived predation risk, we calculated vectors of phenotypic divergence for four behavioural traits between habitats and predation risk treatments. We found a significant correlation between the directions of evolutionary divergence and phenotypic plasticity, suggesting that habitat divergence in behaviour is aligned with the response to relaxation of predation pressure. Finally, we show that this alignment is found across multiple pairs of populations, and that the relaxation of predation pressure has likely driven parallel evolution of behaviour in this species.

Comparing the non-lethal and lethal effects of predation risk ‬on goldfish anti-predatory behavior

2016 ◽  
Vol 62 (3-4) ◽  
pp. 121-127 ◽  
Author(s):  
Merav Wacht Katz ◽  
Zvika Abramsky ◽  
Burt P. Kotler ◽  
Michael L Rosenzweig ◽  
Ofir Altstein ◽  
...  
Keyword(s):  
Predation Risk ◽  
Predatory Behavior ◽  
Predation Pressure ◽  
Activity Level ◽  
Experimental Theater ◽  
Lethal Effects ◽  
Predator Prey ◽  
Behavioral Game ◽  
Player Game

Little egrets (Egretta garzetta) and common goldfish (Carassius auratus) interacted in experimental theaters that challenge them with a behavioral game. We studied the behavioral tactics of both players. The experimental theaters consist of three equally spaced pools, each with a shelter in its center. The fish can take shelter in a safe but foodless habitat, or swim exposed in the open that contains food. The egrets can move among the pools to catch the exposed fish. We investigated the importance of non-lethal effects versus lethal effects on predator–prey interactions. We created a variance in predation pressure by keeping the number of egrets fixed but varying the number of pools of the experimental theater between 1 and 3 pools. In all treatments, even when the egret was present, individual goldfish emerged from protected cover occasionally, exposing at least their heads and sometimes their entire bodies in apparent disregard for the possibly lethal consequences. We assumed that this behavior stems from the fish's constant need to collect information about its surroundings. The fish responded appropriately to the variations in predation pressure by changing their activity level outside the cover, i.e., the fish drastically and significantly reduced their exposure outside the cover, as well as the rate of peeping, as predation pressure increased. The results demonstrate the importance role of non-lethal effects, and how they drive the behavior of prey in response to predation risk, which in turn, drives the action of the predator in an asymmetric two-player game of stealth and fear.

scholarly journals Unequivocal Differences in Predation Pressure on Large Carabid Beetles between Forestry Treatments

Diversity ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 484
Author(s):  
Jana Růžičková ◽  
Zoltán Elek
Keyword(s):  
Predation Risk ◽  
Predation Pressure ◽  
Ecological Trap ◽  
Carabid Beetles ◽  
Ecological Interactions ◽  
Ecological Network ◽  
Forest Environment ◽  
Forestry Practices ◽  
3D Printed ◽  
And Control

Carabid beetles (Coleoptera: Carabidae) are considered as one of the most cardinal invertebrate predatory groups in many ecosystems, including forests. Previous studies revealed that the predation pressure provided by carabids significantly regulates the ecological network of invertebrates. Nevertheless, there is no direct estimation of the predation risk on carabids, which can be an important proxy for the phenomenon called ecological trap. In our study, we aimed to explore the predation pressure on carabids using 3D-printed decoys installed in two types of forestry treatments, preparation cuts and clear cuts, and control plots in a Hungarian oak–hornbeam forest. We estimated the seasonal, diurnal and treatment-specific aspects of the predation pressure on carabids. Our results reveal a significantly higher predation risk on carabids in both forestry treatments than in the control. Moreover, it was also higher in the nighttime than daytime. Contrarily, no effects of season and microhabitat features were found. Based on these clues we assume that habitats modified by forestry practices may act as an ecological trap for carabids. Our findings contribute to a better understanding of how ecological interactions between species may change in a modified forest environment.

An Exploratory Analysis of Effect of Sex on Shift in Choices

1980 ◽  
Vol 46 (2) ◽  
pp. 499-504 ◽  
Author(s):  
Irmtraud Seeborg ◽  
William Lafollette ◽  
James Belohlav
Keyword(s):  
Decision Making ◽  
Undergraduate Students ◽  
Group Decision Making ◽  
Group Composition ◽  
Group Decision ◽  
Exploratory Analysis ◽  
Group Decisions ◽  
Same Sex ◽  
Sex Composition

This study investigated the effect of group composition by sex on choice shifts in group decision-making. The Choice Dilemmas Questionnaire was administered to 93 undergraduate students divided into same-sex or mixed-sex groups. The results suggest that groups' sex composition can affect group decisions. All-male groups tended to make slightly risky group decisions while all-female groups tended to be slightly cautious in their group decisions. However, a counterbalancing appears to occur in mixed-sex groups where no significant choice shifts appear in either direction.

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