1. Ecology
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Resource depletion through primate stone technology

  1. Lydia V Luncz  Is a corresponding author
  2. Amanda Tan  Is a corresponding author
  3. Michael Haslam  Is a corresponding author
  4. Lars Kulik  Is a corresponding author
  5. Tomos Proffitt  Is a corresponding author
  6. Suchinda Malaivijitnond  Is a corresponding author
  7. Michael Gumert
  1. University of Oxford, United Kingdom
  2. Nanyang Technological University, Singapore
  3. Max Planck Institute for Evolutionary Anthropology, Germany
  4. Chulalongkorn University, Thailand
  5. National Primate Research Center of Thailand-Chulalongkorn University, Thailand
Research Article
Cite this article as: eLife 2017;6:e23647 doi: 10.7554/eLife.23647
6 figures, 1 table and 2 additional files

Figures

Tool weights of Koram and NomSao Islands.

(A) Comparison between weights of stones used by macaques on Koram and NomSao Islands to open oysters. The plot shows all quantiles and the CIs (grey). (B) Comparison between weights of stones used by macaques on Koram and NomSao Islands to open snails. The plot shows all quantiles and the Cis (grey).

https://doi.org/10.7554/eLife.23647.003
Figure 1—source data 1

Stone tools used.

Shellfish foraging stone tools collected on Koram and NomSao Islands, Thailand.

https://doi.org/10.7554/eLife.23647.004
Location of the two study islands (Koram and NomSao) in Khao Sam Roi Yot National Park, Thailand.
https://doi.org/10.7554/eLife.23647.005
Stones available on Koram and NomSao Islands.

(A) Weight of stones (with bootstrapped 95% confidence intervals) found on Koram and NomSao Islands, separated for oyster bed and tidal. (B) Average stone availability per island, separated for oyster bed and tidal (with bootstrapped 95% confidence intervals over observed plots).

https://doi.org/10.7554/eLife.23647.006
Figure 3—source data 1

Natural stone availability and weight.

The number and weight of stones located in 20 × 20 cm plots on Koram and NomSao Islands, Thailand.

https://doi.org/10.7554/eLife.23647.007
Average snail availability on Koram and NomSao Islands for three species (with bootstrapped 95% confidence intervals over observed plots).
https://doi.org/10.7554/eLife.23647.008
Figure 4—source data 1

Snail availability.

The number of snails located in point transects along the shore of Koram and NomSao Islands, Thailand.

https://doi.org/10.7554/eLife.23647.009
Prey size on Koram and NomSao Islands.

(A) Average size of oysters (with bootstrapped 95% confidence intervals) found on Koram and NomSao Islands. (B) Average snail size (volume) (with bootstrapped 95% confidence intervals) found on Koram and NomSao Islands.

https://doi.org/10.7554/eLife.23647.010
Figure 5—source data 1

Oyster size.

The size of rock oysters measured in width and length on Koram and NomSao Islands, Thailand.

https://doi.org/10.7554/eLife.23647.011
Figure 5—source data 2

Snail size.

The size (length) of three marine snails (N = 100 each) on Koram and NomSao Islands, Thailand.

https://doi.org/10.7554/eLife.23647.012
Long-tailed macaque tool use.

(A) Adult male long-tailed macaque using a stone tool to crack open a snail. (B) Size difference between NomSao and Koram Islands of most commonly harvested snails. (C) Abandoned macaque tool at shellfish cracking site, with prey remains. (D) Recently harvested oysters (white) are clearly distinguishable from older oysters (grey).

https://doi.org/10.7554/eLife.23647.013

Tables

Table 1
Life history information of main prey species.
https://doi.org/10.7554/eLife.23647.014
Factors influencing population resiliencePredictionRock oysterTropical periwinkle
Resource Aggregation/ClusteringHigh aggregation
→ slow recovery
High aggregationHigh aggregation
Size and age at sexual reproductive maturityLarge size at sexual maturity → slow recoveryLarge: first year grows 25 mm
Able to reproduce in the first year
Small: first year grows 14 mm (17.44 mm second year).
Reproduced in second year
Reproductive output
(per individual)
High reproductive output → fast recoveryHigh
(50 to 200 million)
Low
(10.000–100.000)
Only 2% survive until sexual maturity
Larvae stageAttached → slow recoveryUnattached:
Planctonic larvae
Unattached:
Planctonic larvae

Additional files

Source data 1

Koram Island shellfish foraging.

The number of prey items consumed during behavioral observation of daily shellfish foraging on Koram Island, Thailand.

https://doi.org/10.7554/eLife.23647.015
Source data 2

Maturation stages.

The size and maturation stages of the main prey species harvested by tool using macaques on Koram and NomSao Island, Thailand.

https://doi.org/10.7554/eLife.23647.016

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