Avian Nest Defence: Theoretical Models and Evidence

During nest defence, yellow warblers (Dendroica petechia) give "seet" and "chip" calls. Seet calls are given preferentially toward brood parasitic brown-headed cowbirds (Molothrus ater) during the yellow warblers' egg-laying period, whereas chip calls are given toward mammalian and avian nest predators throughout the nesting period. In this study, we investigated two possible functions of seet and chip calls during nest defence by playing alarm calls to nesting yellow warblers. We tested whether nest owners give seet and chip calls during defence to alert their offspring and their mates about nest threats and, in the latter case, whether the alarm calls differ in function depending on nesting stage. In response to playbacks, nestlings remained inactive for a significantly longer period when chip calls were played than when seet calls were played. Female yellow warblers returned to their nesting areas more quickly when seet calls were played than when chip calls were played, but pairs were equally likely to return to the nesting area in response to both call types. These findings suggests that both seet and chip calls alert mates but that only chip calls function to alert nestlings of potential danger.

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Evolutionary significance of antiparasite, antipredator and learning phenotypes of avian nest defence

Scientific Reports ◽

10.1038/s41598-018-28275-3 ◽

2018 ◽

Vol 8 (1) ◽

Cited By ~ 8

Author(s):

Daniela Campobello ◽

Spencer G. Sealy

Keyword(s):

Nest Defence ◽

Evolutionary Significance ◽

Avian Nest

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Nest Defence By Yellow Warblers: Recognition of a Brood Parasite and an Avian Nest Predator

Behaviour ◽

10.1163/156853996x00143 ◽

1996 ◽

Vol 133 (3-4) ◽

pp. 263-282 ◽

Cited By ~ 56

Author(s):

Sharon A. Gill ◽

Spencer G. Sealy

Keyword(s):

Brood Parasitism ◽

Nest Defence ◽

Brood Parasite ◽

Yellow Warbler ◽

Nest Protection ◽

Yellow Warblers ◽

Avian Nest ◽

Defensive Behaviours ◽

And Control ◽

Nest Predator

AbstractYellow warblers (Dendroica petechia) were exposed to taxidermic mounts of a brood parasite (brown-headed cowbird, Molothrus ater), avian nest predator (common grackle, Quiscalus quiscula) and control (fox sparrow, Passerella iliaca) during their laying and nestling stages to determine whether nest owners distinguish between the threats of brood parasitism and predation. Yellow warblers responded more intensely to the cowbird at the laying stage, performing two unique behaviours (seet calling and nest-protection behaviour) in response to this threat. By contrast, yellow warbler responses to the grackle were greater at the nestling stage, consisting largely of alarm calls (chip, metallic chip and warble calls). The sparrow model infrequently elicited aggressive behaviour from nest owners at either stage. These responses support the hypothesis that yellow warblers discriminate between threats of brood parasitism and nest predation. Yellow warblers may perform specific behaviours to cowbirds because defensive behaviours used against predators may be incompatible with cowbird deterrence. Female nest owners responded more frequently than males at the laying stage, and more intensely than males at both nesting stages. The distance that females and males approached the models and several aggressive behaviours were positively correlated. The greater responsiveness of females may be because they dominate their mates and because females are more experienced with intruders near the nest.

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Does the intrusion of an avian nest predator elicit a change in the behaviour of a canopy-nesting passerine?

Behaviour ◽

10.1163/1568539x-bja10078 ◽

2021 ◽

pp. 1-26

Author(s):

Alexander R. Sharp ◽

Kamal Islam

Keyword(s):

Nest Defence ◽

Cyanocitta Cristata ◽

Potential Predator ◽

Reduce Activity ◽

Provisioning Rate ◽

Avian Nest ◽

Cerulean Warblers ◽

Stage 1 ◽

Nest Predator ◽

Nest Predators

Abstract Many studies have shown that nest predators affect their prey indirectly by inducing changes in the behaviour of the prey. Studies suggest that the type and degree of nest defence strategies depends heavily on species, along with nest type and location. One such strategy, nest vigilance, allows individuals to collect information and make informed decisions based on their surroundings. In this study, we simulated the intrusion of a common avian nest predator (blue jay, Cyanocitta cristata) into the territory of nesting cerulean warblers (Setophaga cerulea) and evaluated eight different behavioural variables to determine their response to the nest predator. Female cerulean warblers were more vigilant on their nest when exposed to a potential predator compared to a nest with lower threat of predation. Females exposed to a nest predator increased incubation bout by 109% and brooding bout by 60%. Our data also suggest that male cerulean warblers reduce their provisioning rate during the early nestling stage (−1 feeding/hour) and late nestling stage (−3 feedings/hour), although more data are needed. Modification of incubation bout length and nestling provisioning rate are common strategies employed by songbirds to reduce activity around the nest, by decreasing detection opportunities of visually-oriented nest predators. Currently, the only understanding we have on how cerulean warblers respond to a nest predator is based on observational data. The results of this study provide the first evidence that cerulean warblers are able to identify species that pose a threat to the safety of their nest, and that they modify their behaviour to reduce nest detection by predators. The results of this study provide a better understanding of a relatively unknown aspect of the breeding behaviour of this species. This study is also first to describe how an open-cup, canopy-nesting species responds to an increase in nest predation threat.

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Why Does Intensity of Avian Nest Defense Increase During the Nesting Cycle?

The Auk ◽

10.1093/auk/103.2.318 ◽

1986 ◽

Vol 103 (2) ◽

pp. 318-327 ◽

Cited By ~ 126

Author(s):

Richard L. Knight ◽

Stanley A. Temple

Keyword(s):

Positive Reinforcement ◽

Theoretical Models ◽

Nest Defense ◽

Agelaius Phoeniceus ◽

Turdus Migratorius ◽

Defense Behavior ◽

Multiple Visit ◽

American Robins ◽

Avian Nest ◽

Nest Predator

Abstract Theoretical models predict that intensity of avian nest defense should increase with age of the offspring. Empirical observations conforming with this prediction have been taken as support for these models. We here present a new explanation for the observed correlations between offspring age and level of nest defense. We propose that increased intensity of nest-defense behavior is largely a result of the methods used by the researchers who made the observations. We suggest that when an observer repeatedly visits or brings a potential nest predator to a nest, nest-defense behavior of parents is modified by positive reinforcement and loss of fear. We tested this hypothesis by measuring nest-defense behavior of female American Robins (Turdus migratorius) and male and female Red-winged Blackbirds (Agelaius phoeniceus). The tests were performed at nests visited only once during different stages of the nesting cycle and at a group of nests visited repeatedly from initiation of incubation to fledging. Nest-defense intensity (as measured by call rates, closest approach to the predator, and numbers of dives and strikes) of robins and blackbirds at nests visited once, in most cases, did not increase through the nesting cycle. At nests visited repeatedly through the nesting cycle, intensity of nest defense by both robins and blackbirds, in many cases, increased significantly. In addition to intensity of nest defense increasing at multiple-visit nests, we observed higher proportions of birds at these nests performing nest-defense behaviors than at single-visit nests.

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Analytical Electron Microscopy of Surface-Modified Ceramics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118291 ◽

1985 ◽

Vol 43 ◽

pp. 276-279

Author(s):

P. S. Sklad

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Theoretical Models ◽

Ceramic Materials ◽

Solute Concentration ◽

Second Phase ◽

Analytical Electron ◽

Implantation Techniques ◽

Lattice Damage ◽

Surface Modified

Over the past several years, it has become increasingly evident that materials for proposed advanced energy systems will be required to operate at high temperatures and in aggressive environments. These constraints make structural ceramics attractive materials for these systems. However it is well known that the condition of the specimen surface of ceramic materials is often critical in controlling properties such as fracture toughness, oxidation resistance, and wear resistance. Ion implantation techniques offer the potential of overcoming some of the surface related limitations.While the effects of implantation on surface sensitive properties may be measured indpendently, it is important to understand the microstructural evolution leading to these changes. Analytical electron microscopy provides a useful tool for characterizing the microstructures produced in terms of solute concentration profiles, second phase formation, lattice damage, crystallinity of the implanted layer, and annealing behavior. Such analyses allow correlations to be made with theoretical models, property measurements, and results of complimentary techniques.

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On the Relationship Between General Auditory Sensitivity and Speech Perception: An Examination of Pitch and Lexical Tone Perception in 4- to 6-Year-Old Children

Journal of Speech Language and Hearing Research ◽

10.1044/2019_jslhr-19-00104 ◽

2020 ◽

Vol 63 (2) ◽

pp. 487-498

Author(s):

Puisan Wong ◽

Man Wai Cheng

Keyword(s):

Speech Perception ◽

Theoretical Models ◽

Developmental Trajectory ◽

Auditory Sensitivity ◽

Pitch Discrimination ◽

Lexical Tone ◽

Perceptual Training ◽

Lexical Tones ◽

Tone Perception ◽

Tone Discrimination

Purpose Theoretical models and substantial research have proposed that general auditory sensitivity is a developmental foundation for speech perception and language acquisition. Nonetheless, controversies exist about the effectiveness of general auditory training in improving speech and language skills. This research investigated the relationships among general auditory sensitivity, phonemic speech perception, and word-level speech perception via the examination of pitch and lexical tone perception in children. Method Forty-eight typically developing 4- to 6-year-old Cantonese-speaking children were tested on the discrimination of the pitch patterns of lexical tones in synthetic stimuli, discrimination of naturally produced lexical tones, and identification of lexical tone in familiar words. Results The findings revealed that accurate lexical tone discrimination and identification did not necessarily entail the accurate discrimination of nonlinguistic stimuli that followed the pitch levels and pitch shapes of lexical tones. Although pitch discrimination and tone discrimination abilities were strongly correlated, accuracy in pitch discrimination was lower than that in tone discrimination, and nonspeech pitch discrimination ability did not precede linguistic tone discrimination in the developmental trajectory. Conclusions Contradicting the theoretical models, the findings of this study suggest that general auditory sensitivity and speech perception may not be causally or hierarchically related. The finding that accuracy in pitch discrimination is lower than that in tone discrimination suggests that comparable nonlinguistic auditory perceptual ability may not be necessary for accurate speech perception and language learning. The results cast doubt on the use of nonlinguistic auditory perceptual training to improve children's speech, language, and literacy abilities.

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Positive Arousal Enhances the Consolidation of Item Memory

Swiss Journal of Psychology ◽

10.1024/1421-0185/a000151 ◽

2015 ◽

Vol 74 (2) ◽

pp. 91-104 ◽

Cited By ~ 1

Author(s):

Bo Wang

Keyword(s):

Episodic Memory ◽

Memory Consolidation ◽

Source Memory ◽

Emotional Arousal ◽

Theoretical Models ◽

Memory Test ◽

Learning Phase ◽

Item Memory ◽

Memory Tests ◽

Immediate Memory

Emotional arousal induced after learning has been shown to modulate memory consolidation. However, it is unclear whether the effect of postlearning arousal can extend to different aspects of memory. This study examined the effect of postlearning positive arousal on both item memory and source memory. Participants learned a list of neutral words and took an immediate memory test. Then they watched a positive or a neutral videoclip and took delayed memory tests after either 25 minutes or 1 week had elapsed after the learning phase. In both delay conditions, positive arousal enhanced consolidation of item memory as measured by overall recognition. Furthermore, positive arousal enhanced consolidation of familiarity but not recollection. However, positive arousal appeared to have no effect on consolidation of source memory. These findings have implications for building theoretical models of the effect of emotional arousal on consolidation of episodic memory and for applying postlearning emotional arousal as a technique of memory intervention.

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