Wild Carrion Crows Choose Walnuts Based on Visual and Weight Cues

Wild Carrion Crows Choose Walnuts Based on Visual and Weight Cues | 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 Search Search ADVANCED SEARCH SCROLL Ecology and Evolution This is a preprint and has not been peer reviewed.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 Wild Carrion Crows Choose Walnuts Based on Visual and Weight Cues Authors : Torito Hamano [email protected] , Yurika Mitsuhashi [email protected] , Noriko Kondo [email protected] , Masaki Shimada [email protected] , and Akitsugu Konno 0000-0003-2517-7761 [email protected] Authors Info & Affiliations https://doi.org/10.22541/authorea.15003054/v1 Under Review Ecology and Evolution Peer review timeline 21 views N/A downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract Assessment of the physical properties of concealed food items provides insight into the perceptual and cognitive mechanisms of animals. This study investigated the walnut selection behavior of wild carrion crows (Corvus corone) through two field experiments. In Experiment 1 (visual size preference), we presented walnuts with distinct visual sizes. Crows significantly preferred the larger walnut in both their first contact and final retrieval. In Experiment 2 (internal content preference), we presented walnuts of similar size but with different internal contents: filled or empty. While there was no preference for the first contact, crows significantly selected the filled walnut for final retrieval. The final selection was significantly influenced by the crows’ handling behavior. The occurrence of switching behavior (interacting with both walnuts) significantly increased the probability of selecting the higher-quality walnut in both experiments. In Experiment 2, the probability of switching was significantly higher when the first contact walnut was empty. Pre-retrieval lifting behavior also played a distinct role in each experiment. In Experiment 1, lifting either the larger or smaller walnut increased the probability of it being ultimately retrieved, regardless of its size. In contrast, in Experiment 2, the number of pre-retrieval lifts of the filled walnut significantly predicted its correct selection, whereas lifting the empty walnut had no such reinforcing effect on its retrieval. In both experiments, the probability of selecting the higher-quality option increased with the log-transformed weight ratio between the two walnuts, consistent with psychophysical principles of proportional weight discrimination. These findings demonstrate that wild crows flexibly integrate visual and weight information, utilizing active haptic sampling to compensate for unreliable visual cues and optimize foraging choices in a natural setting. Supplementary Material File (crownutselection_size.csv) crownutselection_size Download 21.62 KB File (crownutselection_content.csv) crownutselection_content Download 7.39 KB Information & Authors Information Version history V1 Version 1 12 May 2026 Peer review timeline Under Review Ecology and Evolution 15 May 2026 Under Review Collection Ecology and Evolution Authors Affiliations Torito Hamano [email protected] Teikyo University of Science - Uenohara Campus, Uenohara, Japan, 409-0193 View all articles by this author Yurika Mitsuhashi [email protected] Teikyo University of Science - Uenohara Campus, Uenohara, Japan, 409-0193 View all articles by this author Noriko Kondo [email protected] Teikyo University of Science - Uenohara Campus, Uenohara, Japan, 409-0193 View all articles by this author Masaki Shimada [email protected] Teikyo University of Science - Uenohara Campus, Uenohara, Japan, 409-0193 View all articles by this author Akitsugu Konno 0000-0003-2517-7761 [email protected] Teikyo University of Science - Uenohara Campus, Uenohara, Japan, 409-0193 View all articles by this author Metrics & Citations Metrics Article Usage 21 views N/A downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Torito Hamano, Yurika Mitsuhashi, Noriko Kondo, et al. Wild Carrion Crows Choose Walnuts Based on Visual and Weight Cues. Authorea . 12 May 2026. DOI: https://doi.org/10.22541/authorea.15003054/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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