Gen Morimoto

Plumage color as a status signal in male-male interaction in the red-flanked bushrobin, Tarsiger cyanurus

Recent studies have suggested that structural-based coloration is an honest signal of male genetic and/or conditional quality in sexual selection. However, whether structural coloration functions in intrasexual competition is unknown. We examined whether plumage color functions as a status signal during intrasexual interactions in the red-flanked bushrobin Tarsiger cyanurus; adult males have many blue plumes as structural coloration whereas yearling males and females are olive brown with few blue plumages. Blue males did not always dominate olive-brown males. The number of interactions did not differ with the colors of the two birds involved. The interactions of a blue male and an olive-brown male were less aggressive than those of two blue or of two olive-brown males. In this study, we found that structural plumage coloration may serve as a signal of aggressive intent and lower the escalation level of an aggressive interaction in a manner consistent with hypotheses regarding the evolution of delayed plumage maturation.

Numerical study on the structural color of blue birds by a disordered porous photonic crystal model

It has been observationally confirmed that the color of birds, such as kingfisher and red-flanked bluetail, is a structural color owing to the interference of the light within a sponge structure inside a barb. In this study, we consider the air rod photonic crystal to which disorder is introduced into the translation vectors and the radius as a model of the structural color of red-flanked bluetail; the optical property of the model is numerically analyzed and is compared with that of the structural color.

Effect of pre-breeding moult on arrival condition of yearling male Narcissus Flycatchers Ficedula narcissina

Capsule Moult of greater coverts in the wintering area is correlated with a decrease in spring arrival condition but not arrival time of yearling male Narcissus Flycatchers.

Spermiophagy in the Male Reproductive Tract of Some Passerine Birds

In order to elucidate the locus and means of spermiophagy in passerine birds, we examined histologically the entire male reproductive tract of sexually mature birds of three passerine species with different forms of sperm competition, namely, the alpine accentor (Prunella collaris), the redflanked bush robin (Tarsiger cyanurus), and the Bengalese finch (Lonchura striata var. domestica). Spermiophagy occurred consistently and frequently in the epithelial layer of the seminal glomera and ejaculatory duct in each species, which were regularly identified by non-ciliated epithelial cells. The epithelial spermiophagy was occasional or infrequent in other portions of the seminal tract, and spermiophagy by macrophages was uncommon throughout the tract. Quantitative data in the seminal glomera and ejaculatory duct gave no clear answer concerning a possible relationship between the epithelial spermiophagy and different levels of sperm competition among these passerine species. In conclusion, the epithelial lining of the terminal region of the seminal tract is the main site for spermiophagy in the male reproductive tract of these passerine species, which activity serves to maintain the quality of semen by eliminating infertile spermatozoa as well as sperm remaining at the end of the breeding season.

Badge Size of Male Eurasian Tree Sparrows Passer montanus Correlates with Hematocrit During the Breeding Season

Abstract We investigated whether the badge size of the Eurasian Tree Sparrow Passer montanus is correlated with morphological traits and hematocrit during the breeding season in order to elucidate the function of badge size as a potential signal of body size and physiological condition. We found a positive correlation in males between badge size and hematocrit, but not in females. As individuals with larger hematocrit values can transport more oxygen to their tissues or organs, male badge size may be linked with oxygen transport ability. We suggest that male badge size may be a signal of physiological status.