Dräktförändring hos en intersex gräsand Anas platyrhynchos över en sexårsperiod

Intersex individuals with a mixture of female and male plumage traits are reported regularly, but at low frequency. Here we describe the changes in plumage in a Mallard Anas platyrhynchos intersex individual over six years (2015–2020), from a mixed female–male phenotype to a predominantly male phenotype. Already at the first observation, typical male characteristics were present, such as greyish-white tail with two central curved black rectrices and a greenish tinge to parts of the head. The bird attained a more male-like plumage with the next moult and maintained that plumage for the rest of the study period. However, presence of female-patterned body feathers continued until 2019, but in reduced frequency, except for the cheeks and ear-coverts, which displayed a variation in colour. The bill remained female-patterned throughout and the bird did not enter eclipse plumage.

Why neotypification of Lophorina superba (Pennant, 1781) (Aves: Paradisaeidae) is justified—and necessary

We review Irestedt et al.’s (2017) neotypification of the senior species name superba Pennant, 1781 in the bird-of-paradise genus Lophorina in response to Elliott et al. (2020) who challenged the resultant shift in name from the small isolate in New Guinea’s Vogelkop to the widespread species in the island’s central cordillera. In nine male plumage traits which differentiate the two species, six of which had been identified as novel by Irestedt et al., we show that the only two figures of the perished male holotype of superba match the central cordillera species more closely than the Vogelkop. We find as well that not only was the trading of bird-of-paradise skins from the central cordillera to coastal ports in the Vogelkop feasible before European contact, but application of superba to the central cordillera species also promotes nomenclatural stability: the name has been used overwhelmingly at species rank for that widespread form throughout post-19th century media. Re-assessment of Irestedt et al.’s point-by-point justification of neotypification under Article 75.3 of the ICZN (1999) Code establishes, furthermore, that their case meets the requirements of every condition specified in the article; the neotypification is thus valid. Elliott et al.’s alternative to fix superba to the Vogelkop isolate by type locality restriction is not Code-compliant, nor is their evidence for interpreting J.R. Forster as the author of the name. In conclusion, we lay out the correct nomenclature for the taxa of Lophorina under the Code.

Rapid speciation via the evolution of pre-mating isolation in the Iberá Seedeater

Behavioral isolation can catalyze speciation and permit the slow accumulation of additional reproductive barriers between co-occurring organisms. We illustrate how this process occurs by examining the genomic and behavioral bases of pre-mating isolation between two bird species (Sporophila hypoxantha and the recently discovered S. iberaensis) that belong to the southern capuchino seedeaters, a recent, rapid radiation characterized by variation in male plumage coloration and song. Although these two species co-occur without obvious ecological barriers to reproduction, we document behaviors indicating species recognition by song and plumage traits and strong assortative mating associated with genomic regions underlying male plumage patterning. Plumage differentiation likely originated through the reassembly of standing genetic variation, indicating how novel sexual signals may quickly arise and maintain species boundaries.

Female and male plumage colour is linked to parental quality, pairing and extra-pair mating in a tropical passerine

ABSTRACTSexual selection has been proposed to drive the evolution of elaborate phenotypic traits in males, which often confer success in competition or mating. However, in many species both males and females display such traits, although studies reporting selection acting in both sexes are scarce. In this study, we investigated whether plumage ornamentation is sexually selected in female and male lovely fairy-wrens Malurus amabilis, a cooperatively breeding songbird. We found that female and male plumage colour was correlated with parental quality but did not incur survival costs. We also found evidence of positive assortative mating based on plumage colour. Microsatellite analyses of paternity indicated that the lovely fairywren has high levels of extra-pair paternity, with 53% of offspring resulting from extra-pair mating. Female and male plumage colour did not predict reproductive success and female proportion of extra-pair offspring in its own nest, but less colourful males obtained higher extra-pair paternity. We argue that plumage colour may be under sex-specific selection, highlighting the importance of looking at both sexes in studies of sexual selection and ornament evolution. The current findings together with previous study, suggest that plumage colour in female and male lovely fairy-wrens appears to be an honest signal relevant in both intra and inter-sexual competition contexts.

Pre- and post-copulatory traits working in concert: sexual dichromatism in passerines is associated with sperm morphology

Passerine birds produce costly traits under intense sexual selection, including elaborate sexually dichromatic plumage and sperm morphologies, to compete for fertilizations. Plumage and sperm traits vary markedly among species, but it is unknown if this reflects a trade-off between pre- and post-copulatory investment under strong sexual selection producing negative trait covariance, or variation in the strength of sexual selection among species producing positive covariance. Using phylogenetic regression, we analysed datasets describing plumage and sperm morphological traits for 278 passerine species. We found a significant positive relationship between sperm midpiece length and male plumage elaboration and sexual dichromatism. We did not find a relationship between plumage elaboration and testes mass. Our results do not support a trade-off between plumage and sperm traits, but may be indicative of variance among species in the strength of sexual selection to produce both brightly coloured plumage and costly sperm traits.

Plumage coloration and social context influence male investment in song

Animals use multiple signals to attract mates, including elaborate song, brightly coloured ornaments and physical displays. Female birds often prefer both elaborate male song and intense carotenoid-based plumage coloration. This could lead less visually ornamented males to increase song production to maximize their attractiveness to females. We tested this possibility in the highly social and non-territorial house finch ( Haemorhous mexicanus ), in which females discriminate among males based on both song and on the intensity of red carotenoid-based plumage coloration. We manipulated male plumage coloration through carotenoid supplementation during moult, so that males were either red or yellow. Males were then housed under three social environments: (i) all red birds, (ii) all yellow birds or (iii) a mixture of red/yellow birds. We recorded song after presentation of a female. Red males produced more song than yellow males. But when yellow males were housed with red conspecifics, they produced more song relative to yellow males housed with equally unattractive yellow males. This study provides novel evidence that a male's plumage coloration and the plumage colour of his social competitors influence investment in song.

Plumage Colouration and the Provisioning Behaviour of Male and Female Eastern Phoebes

Many factors, including nestling age, brood size, and mate quality, can influence the provisioning behaviour of adult birds. Mate quality may affect provisioning behaviour because high-quality individuals may be ‘good parents’ and provision at higher rates. Alternatively, individuals paired to high-quality mates may provision at higher rates because the benefits provided by such mates ( e.g. good genes) increase the likelihood of reproductive success. We examined variation in the plumage colour of male and female Eastern Phoebes ( Sayornis phoebe) and the possible relationship between such variation and provisioning behaviour. During the 2006–2007 breeding seasons, we captured, banded, and measured adult Eastern Phoebes and collected belly feathers for spectral analyses. We also videotaped nests to quantify provisioning behaviour. Male Eastern Phoebes were larger than females, but the plumage (belly feathers) of males and females did not differ in brightness, hue, and carotenoid chroma (all P ≥ 0.37). Females provisioned nestlings at higher rates than males ( P = 0.009), but we found no significant relationship between provisioning rates of males and females and plumage colour. However, relationships between female provisioning rates and the brightness and carotenoid chroma of their mates’ belly feathers approached significance ( P ≤ 0.08). The larger size of male Eastern Phoebes suggests there is male–male competition for access to resources ( e.g. nest sites and mates), with larger size conferring a selective advantage. However, the absence of intersexual differences in plumage colour suggests limited sexual selection driven by female choice for extra-pair partners. Differences in provisioning rates of males and females may be due to male uncertainty of paternity status or to intersexual differences in foraging behaviour. The relationship between female provisioning rates and male plumage quality suggests that females may invest more in reproduction if male Eastern Phoebes with brighter, carotenoid-rich belly plumage are better able to provide quality nest sites and territories or, perhaps, high-quality genes that can potentially enhance female fitness (differential-allocation hypothesis).