DOI: 10.5061/dryad.vhhmgqnsq
title: Data from: Sex-specific contributions to nest building in birds

description: The causes and consequences of interspecific variation in sex-specific
 contributions to animal parental care are relatively well understood
 during pregnancy or incubation and during offspring provisioning, but
 comparative patterns of sex-biased investment during nest-, den-, or other
 shelter-building have been almost completely overlooked. This is
 surprising because birthing shelter properties have important fitness
 consequences for both parents and offspring. Here, we address this gap in
 our knowledge by testing predictions concerning sex-specific contributions
 to avian nest building in more than 500 species of Western Palearctic
 birds in relation to the time available to breed and sex-specific
 reproductive effort, whilst also examining correlates with nesting site
 and nest structure. Using multivariate phylogenetic comparative and path
 analysis approaches, we found that species in which females build nests
 alone have shorter breeding seasons and breed at higher latitudes. In
 addition, species in which females lay larger clutch sizes and incubate
 eggs alone are more likely to have nests built by females alone, implying
 that reproductive contributions are not traded-off between the sexes.
 Finally, sex-specific nest building contributions were related to nest
 site and structure, as species in which females built nests alone were
 more likely to have open cup nests relative to domed nests of species in
 which both parents build. Our study provides important new insights, and
 generates several new questions for experimental research into the
 adaptive dynamics of sex-specific contributions prior or at the onset of
 breeding.
description: We quantified nest building contributions and several life
 history and ecological traits for 521 bird species. Nest building
 contributions were classified by coding the species’ descriptions in the
 Birds of the Western Palearctic book series and were classified as being
 ‘neither’ if no birds collected materials, ‘male’ if males build the nest
 alone, ‘female’ if females build the nest alone and ‘both’ if males and
 females build the nest together. Nest sites were classified as being
 grass/reed, ground, ground hole/cavity, ledge, tree/bush, tree
 hole/cavity, wall or water. Nest complexity/structure was classified
 following the approach of Hall et al. (2013), although we added an extra
 ‘dome’ category to separate the domed nests from the cup nests of species.
 We defined clutch sizes as the means of the upper and lower average values
 of the published clutch sizes. The sex that incubates was defined as being
 ‘male’, ‘female’ or ‘both’. The duration of breeding was classified as the
 number of months between the first and last month of breeding. We used the
 mean average of the maximum and minimum breeding ranges for measuring
 species' mean breeding latitude values.
description: Variable names
 and descriptions Species - scientific name of bird
 species<br> Nest_builder - nest builder sex (both, female, male,
 neither)<br> Nest_site - nest site (grass_reed, ground,
 ground_hole_cavity, ledge, tree_bush, tree_hole_cavity, wall,
 water)<br> Nest_structure - nest complexity/structure (cup, dome, no
 nest, platform)<br> Clutch_size_mean - average clutch size<br>
 Incubating_sex - incubating sex (both, female, male)<br>
 Length_breeding - length of the breeding season<br> Latitude_mean -
 mean breeding latitude