A plumage patch signaling occupancy is shaped by social environment

The cliff swallow (Petrochelidon pyrrhonota) is a colonial bird that nests in groups of different sizes. Adult cliff swallows have a prominent white forehead patch that we hypothesize functions as a signal of nest occupancy to mitigate costly nest intrusions, especially in crowded nesting colonies. To test this hypothesis, we measured variation in forehead patch area and brightness relative to sex, colony size, and date of collection for 241 preserved specimens collected over 43 years. Additionally, we experimentally tested signal function by darkening the foreheads of nesting birds and observing intraspecific interactions. Consistent with a signaling role, we found that females had larger patches than males, patch area increased with colony size, and nests of birds with darkened forehead patches attracted significantly more visits from transient cliff swallows than did nests with no darkened owners. These results suggest that variation in social environment, both in space and time, as ..., , # A plumage patch signaling occupancy is shaped by social environment

Dataset DOI: [10.5061/dryad.37pvmcvz1](10.5061/dryad.37pvmcvz1)

## Description of the data and file structure

Cliff swallows exhibit a distinct patch of white plumage on their foreheads, which we investigate as a potential visual signal of occupancy. This study utilizes museum specimens collected in 1982-2024. Enclosed data details various aspects of bird specimens and their patches, for use in modeling key relationships. 

### Files and variables

#### File: 5NovPatchData.csv

**Description:** Dataset used for the main study findings (See StatsOverview.Rmd), details information collected for each bird specimen. 

##### Variables

* Year: The year the bird was collected.
* Date: The day of the year the bird was collected, 1-365 (or 1-366 in leap years)
* ID: Bird identification code
* Area: The area of the forehead patch, measured in mm^2^. Measurements made in Fiji 

using color thresholding, or the lasso tool w...,