Non-territorial nesting in a Central California breeding population of Wilson's Warblers

Non-territorial nesting in a Central California breeding population of Wilson's Warblers | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL Ecology and Evolution This is a preprint and has not been peer reviewed. Data may be preliminary. 12 May 2026 V1 Latest version Share on Non-territorial nesting in a Central California breeding population of Wilson's Warblers Author : William M. Gilbert 0000-0001-7758-4305 [email protected] Authors Info & Affiliations https://doi.org/10.22541/authorea.15003128/v1 11 views 4 downloads Contents Abstract Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract ABSTRACT A previous study established that Wilson’s Warblers, at a study site in central inner-coastal California, U.S.A., returned to breeding grounds in two migratory waves, and that birds in the first wave formed Type A breeding territories, while birds in the second wave, returning about four weeks later, never formed Type A breeding territories, even when suitable habitat appeared to be available. The two migratory return groups thus were early-returning “territorials,” and later-returning “non-territorials.” Since territoriality in territorial passerines previously has been considered to be essential for substantial reproductive success, it was speculated that non-territorial Wilson’s Warblers in second return groups might have behavioral mechanisms compensating for loss of reproductive ability because of no territoriality. Indeed, this study shows that birds in second return groups have behaviors distinctly different from birds in first return groups, and those different behaviors appear to compensate, at least in part, for reproduction lost because of no territoriality. Most importantly, this study documents non-territorial nesting by later-returning Wilson’s Warbler females, with guarding of nest-building and/or brood-care assistance often provided by “attaching” non-territorial males. Excluding cases of independent female nesting inside male territories, possibly assignable to polygyny, non-territorial nesting always occurred outside of, or peripheral to, Type A breeding territories. Evidence for the adaptive value of non-territorial nesting is seen in similar fledging rates from intact territorial and non-territorial nests. Also, failures in non-territorial nest-building attempts, compared with essentially none in territorial nest building, suggests possible adaptive value in non-territorial females gaining nest-building experience. It currently is not known if males that attach to non-territorial nesting females share gene types with progeny of the females they assist. Information & Authors Information Version history V1 Version 1 12 May 2026 Collection Ecology and Evolution Authors Affiliations William M. Gilbert 0000-0001-7758-4305 [email protected] View all articles by this author Metrics & Citations Metrics Article Usage 11 views 4 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation William M. Gilbert. Non-territorial nesting in a Central California breeding population of Wilson's Warblers. Authorea . 12 May 2026. DOI: https://doi.org/10.22541/authorea.15003128/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . 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