Breeding biology and life-history traits of an Australasian tropical granivore, the Crimson Finch (Neochmia phaeton)

The evolutionary basis of the latitudinal gradient in clutch-size is a major, unresolved question in life-history theory, the resolution of which is hampered by the lack of proportionate study of southern passerines. Here, we present detailed data on breeding biology and life history for an Australasian tropical granivore, the Crimson Finch (Neochmia phaeton), emphasising aspects of their life history that are atypical of southern passerines. We collected data over three breeding seasons at Mornington Wildlife Sanctuary in north-western Australia. Apparent annual survival of adults was high, at 7096%. Crimson Finches were multi-brooded and laid 5.080.07 eggs per clutch. The rate of nest predation was high, with 59.7% of clutches lost to predation. Thus, Crimson Finch life history contradicts the leading explanation of the clutch-size gradient that higher rates of nest predation and higher adult survival in southern species select for smaller clutch-sizes. Our findings are more consistent with other explanations of the clutch-size gradient, specifically those involving post-fledging parental care, diet, seasonality and phylogeny. Exploring life histories that differ from the norm may be particularly helpful in understanding latitudinal differences in these strategies.