DOI: 10.5061/dryad.7d7wm383b
title: Data from: Effects of age, breeding strategy, population density, and number of neighbors on territory size and shape in Savannah Sparrows

description: 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).
description: # 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](https://doi.org/10.5061/dryad.7d7wm383b) Three attachments are included: 1. The dataset is in CSV format. 2. 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.