Petronia

Abstract: In birds, colourful and elaborate feathers are important traits in mate choice. Distinct tail white patches are present in many species of birds, but they remain little studied. Tail markings may indeed have a signal function because in many species males spread the tail offering a good view of these markings to females during courtship behaviour. Here, we investigated whether white tail spots in male rock sparrow, Petronia petronia, play a role in mate choice. In a free-living population of rock sparrows, we found a reduction in white tail spots size as the breeding season progressed due to abrasion, which was expected if tail spots act as a reliable quality indicator (i.e. a handicap). The same reduction was found under captive conditions, and males in worse condition (individuals that lost more weight) abraded a bigger part of white. This suggests that white tail markings are an indicator of male quality. In captivity, we measured female preference for males differing in white patch size in a mate choice experiment. The experimental reduction of the size of the males’ white spots resulted in a lower sexual interest by females. During courtship display, male rock sparrow shows a yellow breast patch (a carotenoid-based, sexually selected ornament) together with the white spots in the tail. The sizes of these two traits are positively correlated, but only the abraded white area in the tail correlates with a surrogate of individual quality (lost of weight). In conclusion, we can assert that the size of the white spots is preferred by female rock sparrows and it is a part of a multiple signal system.

Abstract: We investigated the relationship between male nest defence and female breast patch size in an alpine population of rock sparrow (Petronia petronia)in northern Italy. We presented a mounted weasel (Mustela nivalis), a common nest predator, to 28 pairs breeding in nest boxes, with 12–13-d-old nestlings, and measured the intensity of male and female defence reaction. We measured the frequency of attack flights, intensity of alarm calling and total time spent in view, and then combined these for each individual, in a single defence factor by principal component analysis. All the females arrived to defend the nest while only 21 males arrived, and females defended the nest more intensely than males. We analysed, by stepwise regression, the relationship of male defence factor to female behaviour and phenotype (breast patch size, a measure of quality)and brood properties (size, mass, phenology). Male defence factor was significantly related only to female breast patch size. We argue that male rock sparrows apparently make parental investment decisions according to their mate’s quality, and examine possible alternative hypotheses.

Abstract: Demographic parameters of the polygynous Rock Sparrow Petronia petronia were investigated in a small patchy population in the Italian Alps. The population included two distinct breeding patches that differed in altitude and breeding success. Survival parameters were estimated by capture‐recapture analysis of 170 individually marked animals. At the whole population level (Cormack‐Jolly Seber model), no sex difference in local survival probability was detected. We then used a multisite capture‐recapture approach (Arnason‐ Schwarz model) to investigate patch-specific survival probability and between-patch dispersal rate conditional on survival. Female local survival in the higher-altitude patch (mean ± se: 0.54 ± 0.04) was significantly greater than in the other patch (0.37 ± 0.04), probably because permanent emigration from the study area was greater. In the higheraltitude patch, breeding dispersal was constrained by the altitude limit and breeding movements were directed toward the patch at lower altitude. The probability of changing patch in the next breeding season was significantly higher for females (range 0.16‐0.21) than for males (0.01‐0.03). Breeding success varied between years and patches, being lower in the patch where frequency of polygamy and female local mortality were higher.

Abstract: Secondary sexual characters may provide information about individual quality to a partner, which may use it during parental care to strategically allocate resources to the current breeding attempt (Differential Allocation Hypothesis). Differential allocation by females has been demonstrated for a number of species, while male differential allocation based on female secondary sexual traits has received less attention. Yet females of many species, among birds in particular, are ornamented. We performed a test of male differential allocation based on a female ornament in the rock sparrow ( Petronia petronia ), a monomorphic species in which both sexes have a yellow breast patch, the size of which correlates with individual reproductive quality. We reduced the breast patch in a sample of females and compared the parental care of their partners (chick feeding and nest defence) with the parental care of males paired to sham-manipulated controls. Nest defence was assessed by placing a dummy predator on the nest box. Males of ornament-reduced females defended the nest less but did not feed the chicks less than males paired to control females. Our results only partially support male differential allocation and are in agreement with previous tests of male differential allocation in rock sparrows.