scholarly journals Host alarm calls attract the unwanted attention of the brood parasitic common cuckoo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Attila Marton ◽  
Attila Fülöp ◽  
Katalin Ozogány ◽  
Csaba Moskát ◽  
Miklós Bán

AbstractIt is well known that avian brood parasites lay their eggs in the nests of other bird species, called hosts. It remains less clear, however, just how parasites are able to recognize their hosts and identify the exact location of the appropriate nests to lay their eggs in. While previous studies attributed high importance to visual signals in finding the hosts’ nests (e.g. nest building activity or the distance and direct sight of the nest from vantage points used by the brood parasites), the role of host acoustic signals during the nest searching stage has been largely neglected. We present experimental evidence that both female and male common cuckoos Cuculus canorus pay attention to their host’s, the great reed warbler’s Acrocephalus arundinaceus alarm calls, relative to the calls of an unparasitized species used as controls. Parallel to this, we found no difference between the visibility of parasitized and unparasitized nests during drone flights, but great reed warblers that alarmed more frequently experienced higher rates of parasitism. We conclude that alarm calls might be advantageous for the hosts when used against enemies or for alerting conspecifics, but can act in a detrimental manner by providing important nest location cues for eavesdropping brood parasites. Our results suggest that host alarm calls may constitute a suitable trait on which cuckoo nestlings can imprint on to recognize their primary host species later in life. Our study contributes to the growing body of knowledge regarding the context-dependency of animal signals, by providing a novel example of a beneficial acoustic trait intercepted by a heterospecific and used against the emitter.

2012 ◽  
Vol 279 (1742) ◽  
pp. 3401-3408 ◽  
Author(s):  
María C. De Mársico ◽  
Mariela G. Gantchoff ◽  
Juan C. Reboreda

Egg mimicry by obligate avian brood parasites and host rejection of non-mimetic eggs are well-known textbook examples of host–parasite coevolution. By contrast, reciprocal adaptations and counteradaptations beyond the egg stage in brood parasites and their hosts have received less attention. The screaming cowbird ( Molothrus rufoaxillaris ) is a specialist obligate brood parasite whose fledglings look identical to those of its primary host, the baywing ( Agelaioides badius ). Such a resemblance has been proposed as an adaptation in response to host discrimination against odd-looking young, but evidence supporting this idea is scarce. Here, we examined this hypothesis by comparing the survival rates of young screaming cowbirds and non-mimetic shiny cowbirds ( Molothrus bonariensis ) cross-fostered to baywing nests and quantifying the similarity in plumage colour and begging calls between host and cowbird fledglings. Shiny cowbirds suffered higher post-fledging mortality rates (83%) than screaming cowbirds (0%) owing to host rejection. Visual modelling revealed that screaming cowbirds, but not shiny cowbirds, were indistinguishable from host young in plumage colour. Similarly, screaming cowbirds matched baywings' begging calls more closely than shiny cowbirds. Our results strongly support the occurrence of host fledgling mimicry in screaming cowbirds and suggest a role of visual and vocal cues in fledgling discrimination by baywings.


2020 ◽  
Author(s):  
Shelby L. Lawson ◽  
Nora Leuschner ◽  
Brian J. Gill ◽  
Janice K. Enos ◽  
Mark E. Hauber

ABSTRACTMany avian hosts of brood parasitic birds discriminate between different types of threats and may respond with categorically different, specifically anti-predatory or anti-parasitic behaviors. Alternatively, hosts may adjust their responses to threat level in a graded manner, responding more aggressively to brood parasites during the laying and incubation stages of nesting, when nests are most susceptible to parasitism, and more aggressively to nest predators during the nestling and fledgling stages when predation would be more costly than parasitism. In New Zealand, endemic host Whiteheads act inconspicuously around their nests in the presence of sympatric Long-tailed Cuckoos, their obligate brood parasite, perhaps to avoid disclosing nest location. We tested behavioral responses of a Whitehead population on Tiritiri Matangi Island that has been breeding allopatrically from cuckoos for 17 years. We presented models of the allopatric parasite, a sympatric predator (Morepork Owl), and a sympatric non-threatening heterospecific (Song Thrush) during the egg and chick stages, and to groups of cooperatively breeding Whiteheads. We compared responses across nest stage and stimulus type. We found that, unlike sympatric Whiteheads elsewhere in New Zealand, Whiteheads on Tiritiri Matangi produced alarm calls in response to the cuckoo model. Furthermore, the rate of alarm calling was similar towards the cuckoo and the owl and across egg and chick stage and higher than to the control stimulus. These results are consistent with allopatric Whiteheads having lost their specific anti-parasitic defense tactics in response to brood parasitic cuckoos.


2013 ◽  
Vol 1 (1) ◽  
pp. 125-142 ◽  
Author(s):  
Susanne Durst ◽  
Ingi Runar Edvardsson ◽  
Guido Bruns

Studies on knowledge creation are limited in general, and there is a particular shortage of research on the topic in small and medium-sized enterprises (SMEs). Given the importance of SMEs for the economy and the vital role of knowledge creation in innovation, this situation is unsatisfactory. Accordingly, the purpose of our study is to increase our understanding of how SMEs create new knowledge. Data are obtained through semi-structured interviews with ten managing directors of German SMEs operating in the building and construction industry. The findings demonstrate the influence of external knowledge sources on knowledge creation activities. Even though the managing directors take advantage of different external knowledge sources, they seem to put an emphasis on informed knowledge sources. The study´s findings advance the limited body of knowledge regarding knowledge creation in SMEs.


2021 ◽  
pp. 002188632110330
Author(s):  
Teresa Beste

This paper investigates the role of microlearning on cost-efficiency on knowledge transfer in a project-based organization. As part of an action research study in a Norwegian public sector organization working with construction projects, a microlearning series was initiated to increase knowledge transfer on cost-efficiency. Seven microlearning lessons were distributed to 334 employees, including short questionnaires after the first and last lesson. The study reflects on the design process of the lessons, on the participation rate, and on how it contributes to an increase of knowledge. Microlearning was perceived as relevant by the participants. It makes knowledge transfer less arbitrary by providing a common body of knowledge to all project teams. For the organizational practice, this implies that microlearning also has potential for knowledge sharing on other topics in the project-based organization. Updating the microlearning series with further examples and new lessons is expected to contribute to continuous learning on cost-efficiency.


2020 ◽  
Vol 13 (1) ◽  
pp. 96
Author(s):  
Carmen Bălan

The academic literature on consumer engagement and sustainable consumption has developed gradually over the last two decades. The body of knowledge related to the role of food and non-food retailers in this context, however, is only beginning to develop. The purpose of this systematic review is to analyse the existing literature on how retailers fulfil their role in engaging consumers in sustainable consumption. The need for a study with this purpose is proven by the fact that academic literature lacks a systematic review on this topic, despite the ascending trend in the number of published articles in the field. This systematic review is based on a five-step process to ensure quality, replicability, transparency, and reliable conclusions. The reviewed articles were published relatively recently in academic journals from different domains. This review identified seven distinct types of retail marketing interventions (involvement of retailers in marketing actions with the aim to engage consumers in sustainable consumption), 30 types of retail marketing mechanisms (consisting in marketing strategies, techniques, tools, and channels used by retailers), and 14 distinct types of consumer engagement in sustainable consumption patterns. The review suggests an agenda for further research and identifies practical implications for retail management.


2010 ◽  
Vol 22 (5) ◽  
pp. 888-902 ◽  
Author(s):  
Marco Tamietto ◽  
Franco Cauda ◽  
Luca Latini Corazzini ◽  
Silvia Savazzi ◽  
Carlo A. Marzi ◽  
...  

Following destruction or deafferentation of primary visual cortex (area V1, striate cortex), clinical blindness ensues, but residual visual functions may, nevertheless, persist without perceptual consciousness (a condition termed blindsight). The study of patients with such lesions thus offers a unique opportunity to investigate what visual capacities are mediated by the extrastriate pathways that bypass V1. Here we provide evidence for a crucial role of the collicular–extrastriate pathway in nonconscious visuomotor integration by showing that, in the absence of V1, the superior colliculus (SC) is essential to translate visual signals that cannot be consciously perceived into motor outputs. We found that a gray stimulus presented in the blind field of a patient with unilateral V1 loss, although not consciously seen, can influence his behavioral and pupillary responses to consciously perceived stimuli in the intact field (implicit bilateral summation). Notably, this effect was accompanied by selective activations in the SC and in occipito-temporal extrastriate areas. However, when instead of gray stimuli we presented purple stimuli, which predominantly draw on S-cones and are thus invisible to the SC, any evidence of implicit visuomotor integration disappeared and activations in the SC dropped significantly. The present findings show that the SC acts as an interface between sensory and motor processing in the human brain, thereby providing a contribution to visually guided behavior that may remain functionally and anatomically segregated from the geniculo-striate pathway and entirely outside conscious visual experience.


2012 ◽  
Vol 279 (1742) ◽  
pp. 3520-3526 ◽  
Author(s):  
Brian Tilston Smith ◽  
Amei Amei ◽  
John Klicka

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropics there has been few comparative studies, particularly, those that include non-rainforest taxa. We used bird species that inhabit humid or dry habitats that dispersed across the Panamanian Isthmus to characterize temporal and spatial patterns of speciation across this barrier. Here, we show that these two assemblages of birds exhibit temporally different speciation time patterns that supports multiple cycles of speciation. Evidence for these cycles is further corroborated by the finding that both assemblages consist of ‘young’ and ‘old’ species, despite dry habitat species pairs being geographically more distant than pairs of humid habitat species. The matrix of humid and dry habitats in the tropics not only allows for the maintenance of high species richness, but additionally this study suggests that these environments may have promoted speciation. We conclude that differentially expanding and contracting distributions of dry and humid habitats was probably an important contributor to speciation in the tropics.


2021 ◽  
Vol 177 ◽  
pp. 241-251
Author(s):  
Louis Bliard ◽  
Anna Qvarnström ◽  
David Wheatcroft

1992 ◽  
Vol 16 (4) ◽  
pp. 415-428 ◽  
Author(s):  
Cynthia L. Miller ◽  
A. Gaye Cummins

Historically, theoretical and popular conceptions about power have not included or addressed women's experiences. This study adds to the growing body of knowledge about women by examining women's perceptions of and relationship to power. One hundred twenty-five women, ranging in age from 21 to 63, were asked to define and explore power through a variety of structured and open-ended questions. The results showed that women's definition of power differed significantly from their perception of society's definition of power, as well as from the way power has traditionally been conceptualized. More theoretical and empirical attention should be given to understanding the role of personal authority in both women's and men's experience of power.


2021 ◽  
Vol 15 (1) ◽  
pp. 121-150
Author(s):  
Rocco Bellanova ◽  
Kristina Irion ◽  
Katja Lindskov Jacobsen ◽  
Francesco Ragazzi ◽  
Rune Saugmann ◽  
...  

Abstract Questions about how algorithms contribute to (in)security are under discussion across international political sociology. Building upon and adding to these debates, our collective discussion foregrounds questions about algorithmic violence. We argue that it is important to examine how algorithmic systems feed (into) specific forms of violence, and how they justify violent actions or redefine what forms of violence are deemed legitimate. Bringing together different disciplinary and conceptual vantage points, this collective discussion opens a conversation about algorithmic violence focusing both on its specific instances and on the challenges that arise in conceptualizing and studying it. Overall, the discussion converges on three areas of concern—the violence undergirding the creation and feeding of data infrastructures; the translation processes at play in the use of computer/machine vision across diverse security practices; and the institutional governing of algorithmic violence, especially its organization, limitation, and legitimation. Our two-fold aim is to show the potential of a cross-disciplinary conversation and to move toward an interactional research agenda. While our approaches diverge, they also enrich each other. Ultimately, we highlight the critical purchase of studying the role of algorithmic violence in the fabric of the international through a situated analysis of algorithmic systems as part of complex, and often messy, practices. Les questions concernant la manière dont les algorithmes affectent l’(in)sécurité deviennent de plus en plus courantes en sociologie politique internationale. Notre discussion collective s'appuie sur ces débats et les enrichit en abordant les questions portant sur la violence algorithmique. Nous soutenons qu'il est important d'analyser et de discuter de la manière dont les systèmes algorithmiques alimentent (et entretiennent) des formes spécifiques de violence, ainsi que de la façon dont ils justifient des actes violents ou redéfinissent les formes de violence jugées légitimes. Cette discussion collective réunit différents points de vue disciplinaires et conceptuels pour ouvrir un débat sur la violence algorithmique en se concentrant à la fois sur des exemples spécifiques et sur les défis à relever pour la conceptualiser et l’étudier. Cette discussion se concentre sur trois sujets de préoccupation : la violence qui sous-tend la création et l'alimentation des infrastructures de données, les processus de conversion en jeu dans l'utilisation de la vision informatique/machine à travers diverses pratiques de sécurité, et la gouvernance institutionnelle de la violence algorithmique, en particulier son organisation, sa limitation et sa légitimation. Notre double objectif est de montrer le potentiel d'une discussion interdisciplinaire et d'avancer vers un programme de recherche interactionnel. Bien que nos approches divergent, elles s'enrichissent mutuellement. Notre but est de mettre en évidence les possibilités analytiques ouvertes par l'étude de la violence algorithmique et de son role dans la fabrique des relations internationales, par le biais d'une étude des systèmes algorithmiques dans le cadre de pratiques complexes et désordonnées. Las preguntas acerca de cómo afectan los algoritmos a la (in)seguridad son cada vez más comunes en la Sociología Política Internacional. A fin de construir y sumar a estos debates, nuestro Debate Colectivo pone en primer plano las preguntas sobre la violencia algorítmica. Sostenemos que es importante abrir el debate acerca de cómo los sistemas algorítmicos alimentan (en) formas específicas de violencia, cómo justifican las acciones violentas o redefinen qué formas de violencia se consideran legítimas. A partir de la reunión de diferentes puntos de vista disciplinarios y conceptuales, este Debate Colectivo abre una conversación sobre la violencia algorítmica centrándose tanto en sus instancias específicas como en los desafíos de su conceptualización y estudio. En general, el debate converge en tres áreas de interés: la violencia que sustenta la creación y alimentación de las infraestructuras de datos, los procesos de traducción en juego en la utilización de la visión de la computadora/máquina a través de diversas prácticas de seguridad y el gobierno institucional de la violencia algorítmica, especialmente su organización, limitación y legitimación. Nuestro doble objetivo es mostrar el potencial de una conversación interdisciplinaria y avanzar hacia una agenda de investigación interactiva. Si bien nuestros abordajes divergen, se enriquecen mutuamente. Finalmente, destacamos la adquisición fundamental del estudio de las funciones de la violencia algorítmica en el tejido de lo internacional a través de un análisis situado de los sistemas algorítmicos como parte de prácticas complejas y, a menudo, desordenadas.


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