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Foraging in nature: contrasting responses to resource heterogeneity at small and large spatial scales.

Citation

Jambhekar, Ravi (2020), Foraging in nature: contrasting responses to resource heterogeneity at small and large spatial scales., Dryad, Dataset, https://doi.org/10.5061/dryad.866t1g1p6

Abstract

A key problem faced by foragers is how to forage when resources are distributed heterogeneously in space. This heterogeneity and associated trade-offs may change with spatial scale. Furthermore, foragers may also have to optimize acquiring multiple resources. Such complexity of decision-making while foraging is poorly understood. We studied the butterfly Ypthima huebneri to examine how foraging decisions of adults are influenced by spatial scale and multiple resources. We predicted that, at a small-spatial scale, the time spent foraging in a patch should be proportional to resources in the patch, but at large-spatial scales, due to limitations arising from large travel costs, this relationship should turn negative. We also predicted that both adult and larval resources should jointly affect foraging butterflies. To test these predictions, we laid eleven plots, and sub-divided them into patches. We mapped nectar and larval resources and measured butterfly behavior in these patches and plots. We found that adult foraging behavior showed contrasting relationships with adult resource density at small versus large-spatial scales. At the smaller-spatial scale, butterflies spent more time feeding in resource-rich patches, whereas at the large-scale, butterflies spent more time feeding in resource-poor plots. Furthermore, both adult and larval resources appeared to affect foraging decisions, suggesting that individuals may optimize search costs for different resources. Overall, our findings suggest that the variation in foraging behavior seen in foragers might result from animals responding to complex ecological conditions, such as, resource heterogeneity at multiple spatial scales and the challenges of tracking multiple resources.

Methods

Details of how the data was collected and processed are in the manuscript "Foraging in nature: contrasting responses to resource heterogeneity at small and large spatial scales."

Usage Notes

### Columns description for the dataset final (Large spatial scale analysis

### File name finalbeh.csv

### Code used to run the models
# Detailed information on models used is available in the analysis section of the manuscript
## Behaviour analysis across plots (Large Spatial scale)
# 1. Sr.no. serial numbers for behavioural follows
# 2. Plot: List of plots with unique names, 11 levels categorical variable
# 3. Weather: Descriptive variable, Not used in analysis
# 4. Date: Date on which behavioural sampling was done
# 5. tot.scans: Total number of observations recorded during an individual follow
# 6. fly: Number of observations when flying activity was seen
# 7. feed: Number of observations when feeding activity was seen
# 8. median: Median value of nectar resources in the study plot
# 9. grass: Mean value of percent grass cover in the plot

# Behaviour analysis within plot (small spatial scale)
## File name rb12_03_2019.csv

### Columns description for the dataset final
# 1. subplot: Unique id name of the subplots located withing each plot,
#             used for the small scale analysis
# 2. Sr.no. serial numbers for behavioural follows
# 3. Basking: Number of observations when basking activity was seen
# 4. Feeding: Number of observations when feeding activity was seen
# 5. Flying: Number of observations when flying activity was seen
# 6. Mating: Number of observations when mating activity was seen
# 7. Ovipositing: Number of observations when oviposition activity was seen
# 8. Resting: Number of observations when resting activity was seen
# 9. Walking: Number of observations when walking activity was seen
# 10. Total:Total of all the behavioural events added up
# 11. Justicia: Total number of flowers in the subplot
# 12. Grass: % Estimate of grass cover in the subplot 
# 13. Plot: List of plots with unique names, 11 levels categorical variable
# 14. tot.scans: Total number of observations recorded during an individual follow
# 15. median: Median value of nectar resources in the study plot

Funding

Rufford Small Grants Foundation, Award: 18470-1

Rufford Small Grants Foundation, Award: 18470-1