Interference from long-tailed finches constrains reproduction in the endangered Gouldian finch

Abstract

Summary 1.Interspecific interference competition for nest-sites among cavity-nesting birds can have important effects on reproductive fitness and the distribution of competing species. 2. We observed interference at nest-sites in free-living populations of the endangered Gouldian finch (Erythrura gouldiae) and sympatric long-tailed finch (Poephila acuticauda), and also experimentally tested the relative strength and effect of interference at nest-sites in captive populations. 3. Levels of competitive interference at nest-sites in the wild were high for Gouldian, but not long-tailed finches, and interference frequency was inversely related to Gouldian finch reproductive success. High levels of interference conferred reduced fledging success but did not affect offspring condition. 4. Captive experiments corroborated the field data, also demonstrating fitness costs of interspecific competition, and that long-tailed finches dominated resources under standardized conditions. 5. Such asymmetrical competition dynamics are likely to constrain reproduction in Gouldian finch populations, potentially affecting recruitment and hindering the recovery of remaining populations of this endangered species.

Lifetime productivity of tree cavities used by cavity‐nesting animals in temperate and subtropical forests

“…Third, by restricting access of subordinate species to high‐quality cavities, dominant species might reduce cavity‐level richness (again, while maintaining a high number of nests in some cavities; e.g., Renton and Brightsmith , Strubbe and Matthysen , Brazill‐Boast et al. ). We currently lack evidence regarding the relative strength of interspecific competition for cavities in temperate vs. subtropical forests.…”

The hawk–dove game in a sexually reproducing species explains a colourful polymorphism of an endangered bird

“…It is also of interest to note that populations riddled with internal conflict can become weaker interspecific competitors [32,33]. In the Gouldian finch, nest-site competition is intensified by the presence of heterospecific finch competitors [34]. If the presence of heterospecific competitors favours hawk-like behaviours, within-population investment may shift even further away from good parenting, and indeed a recent study confirmed that hawk-like red Gouldians were more competitive against a heterospecific nest-site competitor [5].…”

Three Molecular Markers Show No Evidence of Population Genetic Structure in the Gouldian Finch (Erythrura gouldiae)

“…As part of a larger study to compare breeding ecology of two sympatric hollow-nesting finches, the site at Wyndham was supplemented with nest-boxes and the breeding of Gouldian and long-tailed finches was monitored [15,23,24]. Birds were caught at nests with hand nets when nestlings were more than 14 days old to avoid nest desertion.…”

“…We used 93 breeding individuals from the Wyndham population in 2008 and 2009 [23,24,26] to examine fine-scale genetic structure. All other analyses are based on a random subset of individuals matched to the sample size of the smallest locality (49 individuals), plus an additional six individuals from Chidna in Western Queensland.…”

“…We used this spatial autocorrelation approach to investigate restricted movement at the local scale. Spatial autocorrelation was conducted on individuals nesting in 2008 and 2009 over ~12km in our Wyndham study site [24,26]. Significant autocorrelation (either positive or negative) was determined by 1,000 bootstrap resamples against 1,000 permutations of a null hypothesis constituting no spatial structure [43].…”