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This preprint experimentally elevated perceived nest predation risk before egg-laying in seven bird species, testing how plastic allocation shapes within-brood variation in egg and offspring size.",{"@graph":14,"@context":72},[15,34,55],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/template/","Template",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/template/paper-templates/","Paper Templates",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/template/elevated-nest-predation-risk-promotes-offspring-size-variation-in-birds-with-prolonged-parental-care/177605/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/elevated-nest-predation-risk-promotes-offspring-size-variation-in-birds-with-prolonged-parental-care/177605.png","ImageObject",442,249,{"name":42,"@type":43},"Ethan Miller","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/octet-stream","2026-10-16","2026-09-02",true,{"@type":52,"interactionType":53,"userInteractionCount":30},"InteractionCounter",{"@type":54},"ViewAction",{"@type":56,"mainEntity":57},"FAQPage",[58,64,68],{"name":59,"@type":60,"acceptedAnswer":61},"What question does the study address about nest predation risk?","Question",{"text":62,"@type":63},"How perceived nest predation risk early in the reproductive cycle influences reproductive strategies and subsequent offspring investment.","Answer",{"name":65,"@type":60,"acceptedAnswer":66},"How was the risk manipulated in the experiment?",{"text":67,"@type":63},"The study experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species.",{"name":69,"@type":60,"acceptedAnswer":70},"What was the main result regarding offspring size variation?",{"text":71,"@type":63},"Bird species with prolonged parent–offspring associations increased within-brood variation in egg size and, subsequently, offspring size under higher early predation risk.","https://schema.org",{"og:url":32,"og:type":74,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":76,"canonical":32},"index,follow",{"doc_id":78,"site_id":7},177605,1791576876,{"code":4,"msg":81,"data":82},"success",[83,88,93,98,103,108,113,118,122],{"id":84,"doc_module":22,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},11,"Presentations",90,"presentations",{"id":89,"doc_module":22,"doc_module_name":25,"category_name":90,"show_sort_weight":91,"slug":92},12,"Resumes",80,"resumes",{"id":94,"doc_module":22,"doc_module_name":25,"category_name":95,"show_sort_weight":96,"slug":97},14,"Invoices",70,"invoices",{"id":99,"doc_module":22,"doc_module_name":25,"category_name":100,"show_sort_weight":101,"slug":102},15,"Posters",60,"posters",{"id":104,"doc_module":22,"doc_module_name":25,"category_name":105,"show_sort_weight":106,"slug":107},16,"Social Media",50,"social-media",{"id":109,"doc_module":22,"doc_module_name":25,"category_name":110,"show_sort_weight":111,"slug":112},17,"Forms",40,"forms",{"id":114,"doc_module":22,"doc_module_name":25,"category_name":115,"show_sort_weight":116,"slug":117},18,"Letters",30,"letters",{"id":119,"doc_module":22,"doc_module_name":25,"category_name":29,"show_sort_weight":120,"slug":121},21,5,"papers-templates",{"id":123,"doc_module":22,"doc_module_name":25,"category_name":124,"show_sort_weight":4,"slug":125},158,"General","general-158",{"code":4,"msg":81,"data":127},{"doc_id":78,"user_id":128,"nickname":42,"user_avatar":129,"doc_module":22,"category_id":119,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":130,"file_id":131,"file_url":132,"file_type":133,"file_size":134,"view_count":30,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":114,"language":135,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":136,"faqs":137,"seo_title":138,"seo_description":12,"update_tm":139,"read_time":140},687207017582,"https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d","Title: Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.\nGretchen F. Wagner1,2*, Emeline Mourocq1, Michael Griesser1,3\n1 Department of Anthropology, University of Zürich, Zürich, Switzerland\n2 Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands\n3 Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland\n*corresponding author \u0013 HYPERLINK \"mailto:gretchen.wagner@uzh.ch\" \u0014g.wagner@nioo.knaw.nl\u0015\nKey-words: egg size variation, nest predation, reproductive allocation, reproductive flexibility, reproductive success\nAcknowledgements: We thank Carlota Gutiérrez Arce, Javier Cotín Martínez, Juan Diego Ibáñez-Álamo, Francisco Espinosa Alemany, Álvaro de las Heras Pardo, Marta Peris Cabré, Sharon Schillewaert, Patrick Kelly, Margherita Bandini, John Kronenberger, Tania Bobbo, Victor Jiménez García, Matteo Belpinati, Juan Naredo Turrado, Daniel Colette and Hailey Scofield for assistance in the field; Manuel Soler and Alberto Redondo for support at the study sites; Szymon Drobniak, Juan Diego Ibáñez-Álamo, Andrew Russell, Liana Zanette and Carel Van Schaik for helpful discussions and/or comments on the manuscript. This study was supported by the Swiss National Science Foundation (PPOOP3_123520, PP00P3_150752). Permits for field work in Spain were provided by the Junta de Andalucía and the Bird Migration Center (CMA) of the Spanish Ornithological Society (SEO). \u000f\nAbstract\nPredation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging. \u000f\nPredation of eggs and dependent young is a major cause of reproductive failure in many systems, affecting the evolution of reproductive allocation strategies\u0013 ADDIN EN.CITE \u0013 ADDIN EN.CITE.DATA \u0015\u00141-3\u0015. Effects of fear of predation can even surpass the lethal effects of direct predation\u0013 ADDIN EN.CITE \u0013 ADDIN EN.CITE.DATA \u0015\u00144-6\u0015. Therefore, fear of offspring predation likely shapes reproductive decisions to increase the probability of successful reproduction\u0013 ADDIN EN.CITE \u0013 ADDIN EN.CITE.DATA \u0015\u00142,7,8\u0015. However, benefits derived from fear can be offset by costs, such as reduced reproductive success, even in the absence of direct predation\u0013 ADDIN EN.CITE \u0013 ADDIN EN.CITE.DATA \u0015\u00145,9,10\u0015.\nPredation risk is ubiquitously variable and can change rapidly in time and space. Accordingly, field studies have investigated changes in parental decisions over natural risk gradients\u0013 ADDIN EN.CITE \u0013 ADDIN EN.CITE.DATA \u0015\u001410,11\u0015 and in response to experimental modifications of perceived risk\u0013 ADDIN EN.CITE \u003CEndNote>\u003CCite>\u003CAuthor>Fuller\u003C/Author>\u003CYear>1996\u003C/Year>\u003CRecNum>237\u003C/RecNum>\u003CDisplayText>\u003Cstyle face=\"superscript\">12,13\u003C/style>\u003C/DisplayText>\u003Crecord>\u003Crec-number>237\u003C/rec-number>\u003Cforeign-keys>\u003Ckey app=\"EN\" db-id=\"2tv5depfs0rvvxepvt5psdwyftserzrz5art\" timestamp=\"1461593238\">237\u003C/key>\u003C/foreign-keys>\u003Cref-type name=\"Journal Article\">17\u003C/ref-type>\u003Ccontributors>\u003Cauthors>\u003Cauthor>Fuller, Rebecca\u003C/author>\u003Cauthor>Berglund, Anders\u003C/author>\u003C/autho","cbCaijvhQkJYUEMv","https://ap.wps.com/l/cbCaijvhQkJYUEMv","doc",321673,"English","# Abstract\n## Predation risk variability and reproductive strategy\n## Experimental design and species coverage\n## Key findings on egg and offspring size variation","[{\"question\":\"What question does the study address about nest predation risk?\",\"answer\":\"How perceived nest predation risk early in the reproductive cycle influences reproductive strategies and subsequent offspring investment.\"},{\"question\":\"How was the risk manipulated in the experiment?\",\"answer\":\"The study experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species.\"},{\"question\":\"What was the main result regarding offspring size variation?\",\"answer\":\"Bird species with prolonged parent–offspring associations increased within-brood variation in egg size and, subsequently, offspring size under higher early predation risk.\"}]","Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care | DOC",1788328514,6]