DOI: 10.5061/dryad.w9ghx3g0f
title: Good habitat and group living mitigate nest failure from predation and flooding in a riparian bird

description: Reduced nest survival due to anthropogenic changes contributes to bird
 population declines. Understanding the drivers of nest failure can thus
 identify targets for conservation. Nest failure is shaped not only by
 ecology, but also by behaviour, especially in species with complex social
 systems. However, the relative importance of behavioural and ecological
 processes, alone or in interaction, can be hard to quantify, particularly
 when multiple threats to nest survival co-exist. We examined the fates of
 859 nests (31% survived) of Endangered purple-crowned fairy-wrens (Malurus
 coronatus coronatus). This cooperatively breeding species inhabits
 waterways in the monsoonal savanna of northwest Australia and is an
 indicator of the health of threatened but biodiverse riparian ecosystems.
 We determined the effects of habitat quality (density of Pandanus
 aquaticus, the dominant midstorey vegetation in this system), weather, and
 social group size on competing risks to nest survival using a multinomial
 logistic-exposure model (13,179 exposure days over 17 years). High-quality
 habitat correlated with lower predation risk (48.4% of all nests were
 depredated). Furthermore, although proximity to water correlated with a
 greater risk of flooding (15.3% of all nests were flooded), this effect
 was attenuated by habitat quality. Nest abandonment was unrelated to
 ecology or behaviour. Social behaviour also reduced predation risk. Nests
 of larger social groups experienced less predation than those of
 unassisted pairs or smaller groups, especially during the nestling stage.
 This indirectly magnifies the positive effect of habitat quality, as
 higher-quality habitat supports larger groups. Riparian ecosystems in
 tropical savannas are important biodiversity refuges from current and
 future hot and dry conditions. Poor management of fire and grazing reduces
 habitat quality, and we show that poor riparian habitat quality is
 associated with reduced nest survival through predation and flooding. To
 support purple-crowned fairy-wrens and other socially and/or ecologically
 similar species that rely on these ecosystems, conservation management
 actions should aim at improving not only the extent but also the quality
 of riparian habitat and preserving existing areas of high P. aquaticus
 density.
description: # Good habitat and group living mitigate nest failure from predation and
 flooding in a riparian bird
 [https://doi.org/10.5061/dryad.w9ghx3g0f](https://doi.org/10.5061/dryad.w9ghx3g0f) ## Description of the data and file structure Data on nest placement, social group composition, nest fate, and active periods for 859 nests of the purple-crowned fairy-wren *Malurus coronatus coronatus* as part of a long-term study on the species' biology and conservation. Data from 2005–2022; compiled for an analysis of the impacts of ecological and social factors on nest survival. ### Files and variables #### File: nest-data-dryad.xlsx ##### Nests * nID: unique nest identifier * fID: unique identifier of the breeding female * tID: unique identifier of the breeding territory * year: [Austral] year of nest initiation (beginning from 1-July) * l: ordinal day of first egg-laying (1=1-July) * h: ordinal day of hatching (1=1-July) * i: ordinal day of first confirmed observation/activity (first egg-laying for nests found before egg-laying; date found otherwise) (1=1-July) * j: ordinal day of last confirmed nest activity (1=1-July) * k: ordinal day of last nest check (1=1-July) * fate: final nest fate (1=survival, 2=predation, 3=flooding, 4=abandonment) * fAge: age of breeding female (d since hatching at time of egg-laying) * nSub: number of subordinate individuals in the group at the time of hatching (or nest failure, if failed before hatching) * nPairs: number of breeding pairs in the area (north/south Annie or Adcock) during the year of nesting * pIndex: numeric index of the extent and density of *Pandanus* in the territory during the breeding season * river: river catchment (-1=Adcock River, 1=Annie Creek) * toad: presence of cane toads on site (-1=pre-establishment [2005-2016], 1=post-establishment [2017-2022]) * htG: height of the nest above ground (m) * htW: height of the nest above water level when found (m) * distW: horizontal distance of the nest from nearest water when found (m) * help: cumulative marginal log-odds of nest defence by subordinates in the group **Climate** * day: day of year (beginning from 1-July) * rain: daily rainfall (mm) * maxT: maximum daily temperature (°C)