New Caledonian crows attend to multiple functional properties of complex tools

The ability to attend to the functional properties of foraging tools should affect energy-intake rates, fitness components and ultimately the evolutionary dynamics of tool-related behaviour. New Caledonian crows Corvus moneduloides use three distinct tool types for extractive foraging: non-hooked stick tools, hooked stick tools and tools cut from the barbed edges of Pandanus spp. leaves. The latter two types exhibit clear functional polarity, because of (respectively) a single terminal, crow-manufactured hook and natural barbs running along one edge of the leaf strip; in each case, the ‘hooks’ can only aid prey capture if the tool is oriented correctly by the crow during deployment. A previous experimental study of New Caledonian crows found that subjects paid little attention to the barbs of supplied (wide) pandanus tools, resulting in non-functional tool orientation during foraging. This result is puzzling, given the presumed fitness benefits of consistently orienting tools functionally in the wild. We investigated whether the lack of discrimination with respect to (wide) pandanus tool orientation also applies to hooked stick tools. We experimentally provided subjects with naturalistic replica tools in a range of orientations and found that all subjects used these tools correctly, regardless of how they had been presented. In a companion experiment, we explored the extent to which normally co-occurring tool features (terminal hook, curvature of the tool shaft and stripped bark at the hooked end) inform tool-orientation decisions, by forcing birds to deploy ‘unnatural’ tools, which exhibited these traits at opposite ends. Our subjects attended to at least two of the three tool features, although, as expected, the location of the hook was of paramount importance. We discuss these results in the context of earlier research and propose avenues for future work.

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New Caledonian Crows Learn the Functional Properties of Novel Tool Types

PLoS ONE ◽

10.1371/journal.pone.0026887 ◽

2011 ◽

Vol 6 (12) ◽

pp. e26887 ◽

Cited By ~ 43

Author(s):

Alex H. Taylor ◽

Douglas M. Elliffe ◽

Gavin R. Hunt ◽

Nathan J. Emery ◽

Nicola S. Clayton ◽

...

Keyword(s):

Functional Properties ◽

New Caledonian Crows ◽

Tool Types

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Activity profiles and hook-tool use of New Caledonian crows recorded by bird-borne video cameras

Biology Letters ◽

10.1098/rsbl.2015.0777 ◽

2015 ◽

Vol 11 (12) ◽

pp. 20150777 ◽

Cited By ~ 14

Author(s):

Jolyon Troscianko ◽

Christian Rutz

Keyword(s):

Observation Time ◽

Video Cameras ◽

Video Footage ◽

Video Recordings ◽

In The Wild ◽

Foraging Niche ◽

New Caledonian Crows ◽

Total Observation Time ◽

Total Observation ◽

Tool Types

New Caledonian crows are renowned for their unusually sophisticated tool behaviour. Despite decades of fieldwork, however, very little is known about how they make and use their foraging tools in the wild, which is largely owing to the difficulties in observing these shy forest birds. To obtain first estimates of activity budgets, as well as close-up observations of tool-assisted foraging, we equipped 19 wild crows with self-developed miniature video cameras, yielding more than 10 h of analysable video footage for 10 subjects. While only four crows used tools during recording sessions, they did so extensively: across all 10 birds, we conservatively estimate that tool-related behaviour occurred in 3% of total observation time, and accounted for 19% of all foraging behaviour. Our video-loggers provided first footage of crows manufacturing, and using, one of their most complex tool types—hooked stick tools—under completely natural foraging conditions. We recorded manufacture from live branches of paperbark ( Melaleuca sp.) and another tree species (thought to be Acacia spirorbis ), and deployment of tools in a range of contexts, including on the forest floor. Taken together, our video recordings reveal an ‘expanded’ foraging niche for hooked stick tools, and highlight more generally how crows routinely switch between tool- and bill-assisted foraging.

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Context-dependent ‘safekeeping’ of foraging tools in New Caledonian crows

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.0278 ◽

2015 ◽

Vol 282 (1808) ◽

pp. 20150278 ◽

Cited By ~ 13

Author(s):

Barbara C. Klump ◽

Jessica E. M. van der Wal ◽

James J. H. St Clair ◽

Christian Rutz

Keyword(s):

Animal Species ◽

Crack Open ◽

Important Constraint ◽

In The Wild ◽

New Caledonian Crows ◽

Context Dependent ◽

Time And Energy

Several animal species use tools for foraging, such as sticks to extract embedded arthropods and honey, or stones to crack open nuts and eggs. While providing access to nutritious foods, these behaviours may incur significant costs, such as the time and energy spent searching for, manufacturing and transporting tools. These costs can be reduced by re-using tools, keeping them safe when not needed. We experimentally investigated what New Caledonian crows do with their tools between successive prey extractions, and whether they express tool ‘safekeeping’ behaviours more often when the costs (foraging at height), or likelihood (handling of demanding prey), of tool loss are high. Birds generally took care of their tools (84% of 176 prey extractions, nine subjects), either trapping them underfoot (74%) or storing them in holes (26%)—behaviours we also observed in the wild (19 cases, four subjects). Moreover, tool-handling behaviour was context-dependent, with subjects: keeping their tools safe significantly more often when foraging at height; and storing tools significantly more often in holes when extracting more demanding prey (under these conditions, foot-trapping proved challenging). In arboreal environments, safekeeping can prevent costly tool losses, removing a potentially important constraint on the evolution of habitual and complex tool behaviour.

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Social transmission in the wild can reduce predation pressure on novel prey signals

Nature Communications ◽

10.1038/s41467-021-24154-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Liisa Hämäläinen ◽

William Hoppitt ◽

Hannah M. Rowland ◽

Johanna Mappes ◽

Anthony J. Fulford ◽

...

Keyword(s):

Evolutionary Dynamics ◽

Parus Major ◽

Predation Pressure ◽

Social Transmission ◽

Blue Tit ◽

Cyanistes Caeruleus ◽

Novel Approach ◽

Transmission Of Information ◽

In The Wild ◽

Animal Communities

AbstractSocial transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences. Using artificial prey and a novel approach in statistical analyses of social networks, we find that blue tit (Cyanistes caeruleus) and great tit (Parus major) predators learn about prey defences by watching others. This shifts population preferences rapidly to match changes in prey profitability, and reduces predation pressure from naïve predators. Our results may help resolve how costly prey defences are maintained despite influxes of naïve juvenile predators, and suggest that accounting for social transmission is essential if we are to understand coevolutionary processes.

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New Caledonian crows show behavioural flexibility when manufacturing their tools

Behaviour ◽

10.1163/1568539x-00003411 ◽

2017 ◽

Vol 154 (1) ◽

pp. 65-91 ◽

Cited By ~ 7

Author(s):

Brenna Knaebe ◽

Alex H. Taylor ◽

Douglas M. Elliffe ◽

Russell D. Gray

Keyword(s):

Behavioural Flexibility ◽

Tool Manufacture ◽

In The Wild ◽

New Caledonian Crows ◽

Do So

New Caledonian crows have demonstrated flexible behaviour when using tools and solving novel problems. However, we do not know whether this flexibility extends to tool manufacture. Here, we show that these crows respond to different tool-using problems by altering the length of the tools that they manufacture; on average, crows made shorter tools for tasks requiring short tools and longer tools for tasks requiring long tools. They continued to do so when they could not simultaneously see the tool-manufacturing material and the apparatus requiring the use of a tool. Despite altering the length of their tools, the crows frequently did not make tools short or long enough to reliably extract the bait, though this may have been due to shortcomings in the task presented to them. Our results demonstrate that these crows have a degree of behavioural flexibility when making tools, which may be used in the wild during foraging.

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Predators as Agents of Selection and Diversification

Diversity ◽

10.3390/d12110415 ◽

2020 ◽

Vol 12 (11) ◽

pp. 415

Author(s):

Jerald B. Johnson ◽

Mark C. Belk

Keyword(s):

Natural Selection ◽

Empirical Evidence ◽

Mortality Rates ◽

Predator Species ◽

Natural Systems ◽

Evolutionary Diversification ◽

Multiple Predator Species ◽

In The Wild ◽

Taxonomic Groups ◽

Future Work

Predation is ubiquitous in nature and can be an important component of both ecological and evolutionary interactions. One of the most striking features of predators is how often they cause evolutionary diversification in natural systems. Here, we review several ways that this can occur, exploring empirical evidence and suggesting promising areas for future work. We also introduce several papers recently accepted in Diversity that demonstrate just how important and varied predation can be as an agent of natural selection. We conclude that there is still much to be done in this field, especially in areas where multiple predator species prey upon common prey, in certain taxonomic groups where we still know very little, and in an overall effort to actually quantify mortality rates and the strength of natural selection in the wild.

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CAM Software Development for Laminated Tooling: Lamination Cutting Trajectory Algorithms

10.1115/imece2000-1828 ◽

2000 ◽

Author(s):

Yong-Tai Im ◽

Daniel F. Walczyk

Keyword(s):

Line Of Sight ◽

Tool Orientation ◽

Cutting Machine ◽

Tool Shape ◽

G Code ◽

Sharp Edges ◽

Profiled Edge Lamination ◽

Future Work ◽

Awj Cutting ◽

Cam Software

Abstract This paper addresses the research and development of a Computer-Aided Manufacturing (CAM) software package used for fabricating Profiled-Edge Lamination (PEL) tooling. Background research in PEL tooling is reviewed and possible applications for PEL tooling in seven different manufacturing processes are examined. The general PEL tooling process is outlined and the fundamental role that the CAM software plays in this process are discussed. The CAM software is used to create and simulate appropriate line-of-sight cutting trajectories for an Abrasive Water Jet (AWJ) cutting machine. Using this CAM software, PEL cutting trajectories and the resulting PEL tool shape can be compared with the original CAD tool shape. After the tool shape is evaluated, the CAM software exports CNC G-code to an AWJ cutting machine for cutting individual laminations. Four algorithms have been developed to create suitable cutting trajectories for PELs. Each algorithm is evaluated through simulation using the benchmark tool shape. As a result of this evaluation, one particular algorithm was found to be the most promising because it 1) successfully produces sharp edges with no loss of original shape, 2) allows unlimited tool orientation, and 3) better handles complicated tooling geometries. Finally, future work to validate the cutting trajectory algorithms is outlined.

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Functional and evolutionary trade-offs co-occur between two consolidated memory phases in Drosophila melanogaster

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2012.1457 ◽

2012 ◽

Vol 279 (1744) ◽

pp. 4015-4023 ◽

Cited By ~ 14

Author(s):

Fabrice Lagasse ◽

Celine Moreno ◽

Thomas Preat ◽

Frederic Mery

Keyword(s):

Evolutionary Dynamics ◽

Functional Relationship ◽

Learning Task ◽

Long Term Memory ◽

Phenotypic Traits ◽

Trade Offs ◽

Memory Phase ◽

Fitness Benefits ◽

Benefits And Costs

Memory is a complex and dynamic process that is composed of different phases. Its evolution under natural selection probably depends on a balance between fitness benefits and costs. In Drosophila , two separate forms of consolidated memory phases can be generated experimentally: anaesthesia-resistant memory (ARM) and long-term memory (LTM). In recent years, several studies have focused on the differences between these long-lasting memory types and have found that, at the functional level, ARM and LTM are antagonistic. How this functional relationship will affect their evolutionary dynamics remains unknown. We selected for flies with either improved ARM or improved LTM over several generations, and found that flies selected specifically for improvement of one consolidated memory phase show reduced performance in the other memory phase. We also found that improved LTM was linked to decreased longevity in male flies but not in females. Conversely, males with improved ARM had increased longevity. We found no correlation between either improved ARM or LTM and other phenotypic traits. This is, to our knowledge, the first evidence of a symmetrical evolutionary trade-off between two memory phases for the same learning task. Such trade-offs may have an important impact on the evolution of cognitive capacities. On a neural level, these results support the hypothesis that mechanisms underlying these forms of consolidated memory are, to some degree, antagonistic.

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