Data from: Effects of age, breeding strategy, population density, and number of neighbors on territory size and shape in Savannah Sparrows
Data files
Jun 03, 2024 version files 29.24 KB
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data_for_Suarez_Sharma_et_al._2024_Ornith.csv
26.53 KB
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README.md
2.71 KB
Abstract
The size and shape of an animal’s breeding territory are dynamic features influenced by multiple intrinsic and extrinsic factors and can have important implications for survival and reproduction. Quantitative studies of variation in these territory features can generate deeper insights into animal ecology and behavior. We explored the effect of age, breeding strategy, population density, and number of neighbors on the size and shape of breeding territories in an island population of Savannah Sparrows (Passerculus sandwichensis). Our dataset consisted of 407 breeding territories belonging to 225 males sampled over 11 years. We compared territory sizes to the age of the male territorial holder, the male’s reproductive strategy (monogamy vs. polygyny), the number of birds in the study population (population density), and the number of immediate territorial neighbors (local density). We found substantial variation in territory size, with territories ranging over two orders of magnitude from 57 to 5727 m2 (0.0057 to 0.57 ha). Older males had larger territories, polygynous males had larger territories, territories were smaller in years with higher population density, and larger territories were associated with more immediate territorial neighbors. We also found substantial variation in territory shape, from near-circular to irregularly-shaped territories. Males with more neighbors had irregularly shaped territories, but the shape did not vary with male age, breeding strategy, or population density. For males that lived two years or longer, we found strong consistent individual differences in territory size across years, but weaker individual differences in territory shape, suggesting that size has high repeatability whereas shape has low repeatability. Our work provides evidence that songbird territories are highly dynamic and that their size and shape reflect both intrinsic factors (age and number of breeding partners) and extrinsic factors (population density and number of territorial neighbors).
README: Effects of age, breeding strategy, population density, and number of neighbors on territory size and shape in Savannah Sparrows
https://doi.org/10.5061/dryad.7d7wm383b
Three attachments are included:
- The dataset is in CSV format.
The analyses in RMD format and in in HTML format
Data for Suarez Sharma et al. 2024 Ornith.csv
Variable list:
- Year: Year of territory data collection
- Male_ID: Unique code for each male in the population. The code format is "SAVS-###"". The numerical values were automatically generated.
- Male age (1, 2, 3, or 4+): SAVS Male ages binned into categories
- "1" = one year old
- "2" = two years old
- "3" = three years old
- "4" = four years old or more
- Breeding strategy: Observed breeding strategy of male SAVS.
- MO = monogamous
- PG = polygynous
- NA = breeding strategy is undetermined
- Population density: The number of territories in the study area for the given year.
- Local density (neighbours within 10m): The total number of territories located 10 meters or less away from a given territory.
- Territory_Area (m2): The area of a territory (m2)
- Territory_Perimeter (m): The perimeter of a territory (m)
- Compactness (0 = irregular shape 1 = perfect circle): A numerical value indicating a territory's degree of circularity. Values range from "0" to "1", with smaller values indicating more irregularly shaped territories. Compactness was calculated using the following formula: (4 π × "Territory_Area")/("Territory_Perimeter")^2
- Territory Size (PC1 from 3-variable PCA): A combination of "Territory_Area" and "Territory_Perimeter" in a single variable, "Territory Size". These variables were combined using a PCA. Large values reflect territories with larger areas and bigger perimeters.
- PC2 from 3-variable PCA (use Compactness instead): A combination of "Compactness" and (**Dan do you remember which one we used?) calculated through a second PCA. This variable was ommitted from our analyses. "Compactness" was used in our "Territory Shape" model instead.
analysis for Suarez Sharma et al. 2024 Ornith.Rmd
The complete R code necessary for the statistical analysis and visualisation associated with the paper.
analysis for Suarez Sharma et al. 2024 Ornith.html
A detailed account of our analyses. We include our linear mixed effect model parameters and diagnostics for "Territory Size" and "Territory Shape". We also communicate our results from both models numerically as a table, and visually as figures.