Strong between-site variation in New Caledonian crows’ use of hook-tool-making materials

Clair, James J. H. St; Klump, Barbara Christina; Wal, Jessica E. M. van der; Sugasawa, Shoko; Rutz, Christian

doi:10.1111/bij.12757

Cited by 20 publications

(26 citation statements)

References 30 publications

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“…2a -Researcher-made 'matched' hooked stick tools: A choice was offered of three researcher-made hooked stick tools prepared from stems of D. virgatus. These tools were intended to be exemplary, made from the same materials and incorporating the same three features (crafted hook; stripped bark; terminal curvature) characteristic of tools recovered from wild birds at the study site 5,6,8,9 . Tools were set out on the toolpresentation log in random order.…”

Section: A -Crow-made Hooked Stick Toolsmentioning

confidence: 99%

“…A simple baited extraction task was maintained in each subject's housing aviary, together with a selection of the locally-preferred raw material for hooked stick tool manufacture, forked stems of the shrub D. virgatus 8 , and assorted non-hooked twigs and leaf petioles. Of the 34 crows pre-tested: three were released before we finalised the experimental protocol; nine could not be confirmed to manufacture hooked tools during the pre-testing period (mean ± SD, 9.33 ± 4.61 days); and five were reluctant to engage with the apparatus during their first experimental trial, and were therefore released.…”

Section: Pre-testing Proceduresmentioning

confidence: 99%

“…Stems were wedged into small holes in the tool-presentation log as though growing, allowing crows to harvest material and manufacture tools as they would in the wild 6,8 . 1b -Crow-sourced non-hooked stick tools: A choice was offered of 100 sticks and leaf petioles of various lengths and diameters (within the range of sizes which crows are known to select for use in the wild 27 ), sourced from the leaf litter of local dryforest habitat, and scattered, thoroughly mixed, on the tool-presentation log.…”

Section: A -Crow-made Hooked Stick Toolsmentioning

confidence: 99%

“…1a, bottom), and 'hooked stick tools', which are crafted from freshly-harvested branching twigs, often incorporating a range of distinct design features 1,[4][5][6][7][8][9] ( Fig. 1a, top; Supplementary Video 1).…”

mentioning

confidence: 99%

“…We compared time-toextraction data in a survival-analysis framework, with poor 'survival' of prey indicating a superior tool design. Crows manufactured their own hooked stick tools from fresh stems of the locally-preferred raw material, the perennial shrub Desmanthus virgatus 8 , and in a separate treatment, chose non-hooked stick tools from 100 assorted (non-forked) twigs and leaf petioles that had been collected from forest leaf litter. In each 90-minute trial, subjects were given wooden logs containing 18 extraction tasks, in which one of two prey types was hidden in one of two hole sizes (vermiform prey in narrow holes, vermiform prey in wide holes, and spiders in wide holes).…”

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Hook innovation boosts foraging efficiency in tool-using crows

et al. 2018

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The New Caledonian crow is the only non-human animal known to craft hooked tools in the wild, but the ecological benefit of these relatively complex tools remains unknown. Here we show that crows acquire food several times faster when using hooked rather than non-hooked tools, regardless of tool material, prey type and extraction context. This implies that small changes to tool shape can strongly affect energy-intake rates, highlighting a powerful driver for technological advancement.New Caledonian (NC) crows Corvus moneduloides use a remarkable diversity of tool types for extractive foraging 1,2 , including 'non-hooked stick tools', which are simple unmodified twigs or leaf petioles 3 (Fig. 1a, bottom), and 'hooked stick tools', which are crafted from freshly-harvested branching twigs, often incorporating a range of distinct design features 1,[4][5][6][7][8][9] ( Fig. 1a, top; Supplementary Video 1). It has been suggested that hooked tool manufacture may have arisen through the (genetic or cultural) accumulation of innovations 6,9 (for a schematic illustration, see Fig. 1b). Any such cumulative process would require differential efficiency of tool types 10 -an important assumption we set out to test experimentally, addressing a conspicuous gap in our understanding of this avian model system 11 . To determine whether the use of hooks enhances food-intake rates of NC crows, we provided 17 temporarily-captive subjects with a suite of standardised, replicated extractive foraging tasks, and recorded the time taken to obtain embedded 'prey' when using either hooked or non-hooked stick tools (Fig. 1c; Supplementary Video 2). We compared time-toextraction data in a survival-analysis framework, with poor 'survival' of prey indicating a superior tool design. Crows manufactured their own hooked stick tools from fresh stems of the locally-preferred raw material, the perennial shrub Desmanthus virgatus 8 , and in a separate treatment, chose non-hooked stick tools from 100 assorted (non-forked) twigs and leaf petioles that had been collected from forest leaf litter. In each 90-minute trial, subjects were given wooden logs containing 18 extraction tasks, in which one of two prey types was hidden in one of two hole sizes (vermiform prey in narrow holes, vermiform prey in wide holes, and spiders in wide holes).Crow-made hooked stick tools (treatment 1a; solid blue lines in Fig. 1d) were three to thirteen times more efficient than crow-sourced non-hooked tools (treatment 1b; solid red lines), depending on the task (spiders in wide holes, HR = 2.91 [95% confidence interval = 1.62-5.24], z = 3.57, p < 0.001; vermiform prey in wide holes, , z = 5.64, p < 0.001; vermiform prey in narrow holes, .01], z = 6.34, p < 0.001). Although hooked tools were more efficient in all tasks, some tasks were inherently more demanding than others: spiders were acquired more quickly than vermiform prey from wide holes (for treatment 1a, HR = 1.79 [1.26-2.53], z = 3.25, p = 0.001), and vermiform prey more quickly from wide than from narrow holes (for t...

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Section: A -Crow-made Hooked Stick Toolsmentioning

confidence: 99%

Section: Pre-testing Proceduresmentioning

confidence: 99%

Section: A -Crow-made Hooked Stick Toolsmentioning

confidence: 99%

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Trait‐mediated indirect effect involving a chain of learning in agroecosystems

Uehara,

Yusa

2024

Ecosphere

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An increase in predation risk triggers a trait response of prey, which alters the interactions between the prey and other species, ultimately affecting other species in the ecosystem. Such predator‐driven trait‐mediated indirect effects (TMIEs) may have been shaped by long‐term evolutionary processes involving the organisms involved, but learning may also be important, especially in contemporary ecosystems experiencing repeated biological invasions. The apple snail Pomacea canaliculata is an important introduced pest of rice, Oryza sativa. Recently, the carrion crow Corvus corone has been found to prey on this species only in some areas, suggesting that learning is involved in this predation. In addition, apple snails can learn to escape from predators and exhibit predator‐specific responses. Thus, the “chain of learning” by the crow and the snail may shape novel TMIEs in the rice ecosystem. We conducted field and mesocosm experiments to test this hypothesis. In the field experiment, we simulated predation by crows in rice fields and investigated the behavior of apple snails. The snails exhibited escape behaviors in response to the simulated predation, and both the proportion of individuals showing the escape response and the degree of escape response were greater in fields with predation by crows than those without predation. In the mesocosm experiment, apple snails from fields with and without predation by crows were separately introduced into mesocosms simulating rice fields, and the behaviors of the snails and the number of remaining rice plants were recorded for 16 days at three levels of predation risk (daily, every 4 days, or no predation). Both the presence/absence of predation in the collection fields and simulated predation affected the escape responses of the snails. Moreover, damage to rice was more severe in mesocosms containing snails from fields without predation than those containing snails from fields with predation. These results suggest that the “chain of learning” causes TMIEs in agroecosystems.

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Where Does Cumulative Culture Begin? A Plea for a Sociologically Informed Perspective

Haidle

Schlaudt

2020

Biol Theory

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Recent field studies have broadened our view on cultural performances in animals. This has consequences for the concept of cumulative culture. Here, we deconstruct the common individualist and differential approaches to culture. Individualistic approaches to the study of cultural evolution are shown to be problematic, because culture cannot be reduced to factors on the micro level of individual behavior (methodological individualism, “atomism”) but possesses a dynamic that only occurs on the group level and profoundly affects the individuals (“holism”). Naive individuals, as a prerequisite of an atomistic perspective, do not exist. We address the construction of a social approach to (cumulative) culture by introducing an inevitable social embedding of the individual development of social beings. The sociological notion of “habitus” as embodied cultural capital permits us to understand social transmission of behavioral components on a very basic level, resulting in a cumulative effect. Bits of information, movement, handling of material, attitudes, and preferences below distinct functional units are acquired through transfer mechanisms simpler than emulation and imitation such as peering, participation, co-performance, or engagement with a material environment altered by group members. The search for a zero point of cumulative culture becomes as useless as the search for a zero point of culture. Culture is cumulative.

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Strong between-site variation in New Caledonian crows’ use of hook-tool-making materials

Cited by 20 publications

References 30 publications

Hook innovation boosts foraging efficiency in tool-using crows

Hook innovation boosts foraging efficiency in tool-using crows

Trait‐mediated indirect effect involving a chain of learning in agroecosystems

Where Does Cumulative Culture Begin? A Plea for a Sociologically Informed Perspective

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