Table 2. List of the environmental and anthropogenic features and nest attributes measured in this study.

Measured features and attributes	Units	Description	Reference
Environmental features
Slope of subaerial beach and dune face	Degrees	Subaerial beach slope was measured between the observed high-water line and the dune toe perpendicular to the nest sites. Dune slope was measured between the dune toe and the dune crest perpendicular to the nest sites. All distance and elevation were measured using ArcGIS10.2.	Zevenbergen & Thorne (1987), ESRI (2013)
Beach profile curvature	Radians per m	Curvature is the second derivative of elevation (i.e., the slope of the slope) calculated using the SfM-DEM. Profile curvature is the curvature intersecting with the plane defined by the Z-axis and maximum gradient direction. Positive values describe convex profile curvature; negative values concave profile and zero values flat surface. Calculated using SAGA GIS 2.1 as implemented in the Morphometry Features tool using a 5 ×5 m window.	Wood, Bjorndal & Ross (2000); Romstad & Etzelmüller (2012)
Terrain ruggedness	Standardised index	Terrain ruggedness was calculated using the vector ruggedness measure (VRM), a parameter that minimizes correlation with slope, based on the SfM-DEM. The dimensionless ruggedness number ranges from 0 (flat) to 1 (most rugged). Calculated in SAGA GIS as implemented in the Morphometry Features tool using a 5 ×5 m window.	Sappington, Longshore & Thompson (2007)
Width of the Subaerial beach and dune	m	The subaerial beach was defined between the observed high-water line and the dune toe perpendicular to nest sites. The dune face was defined between the dune toe and dune crest perpendicular to nest sites. Measured using ArcGIS 10.2	ESRI (2013)
Distance of nest from dense vegetation	m	The Euclidean distance from the nearest digitized dense vegetation cover to the nest as implemented in ArcGIS 10.2.	Hunt et al. (2005); ESRI (2013)
Distance of nest from sparse vegetation	m	The Euclidean distance from the nearest digitized sparse vegetation cover to the nest as implemented in ArcGIS 10.2.	Hunt et al. (2005); ESRI (2013)
Anthropogenic features
Distance to urban areas	m	Euclidean distance from nearest urban area (i.e., contiguous land cover/land composed of relatively dense coverage of impervious surfaces that include housing and other anthropogenic infrastructure) as implemented in ArcGIS 10.2.	ESRI (2013)
Exposure to artificial light	(mcd m2)	Manual light measurements using a hand-held night sky brightness photometer, Unihedron Sky Quality Meter-L. Light was measured as magnitudes per square arcsecond (mag/arcsec2) and converted to milicandelea per square meter (mcd m2).	Cinzano & Falchi (2014)