Sexual Selection Characteristics Of Birds Based On Plumage Color

The reproductive behavior of birds is related to the survival and extinction of the whole population,and sexual selection is an important part of the reproductive behavior of birds.In sexual selection,females have the initiative.The intensity of sexual selection is different between males and females,which eventuallyleads to the male and female dimorphism.Plumage color has always been one of the important model objects in testing sexual selection.Birds have four types of visual cells,so studies have found that similar feathers in humans are very different in bird vision.Fiber optic spectrometer can help quantifying feather color,and studying the difference of feather color in birds from the perspective of bird vision.From the human visual,the Varied Tit(Sittiparus varius)is a small passerine bird with no obvious sexual dimorphism on plumage color.At present,studies on the feather color of birds with no obvious dimorphism is still limited.For this reason,I took the varied tits in Xianrendong National Nature Reserve of Liaoning Province as the research object,and selected 9 parts of the feather color,explored the difference between male and female tits,and the relationship between feather color and reproductive efficiency and tried to reveal the mechanism of variegated tits' sexual selection based on plumage color.I divide my research into three parts:(1)the phenomena of feather color dimorphism of varied tits in Zhuanghe area of Dalian were systematically studied during the non-breeding season and the breeding season;(2)the mating pairs of reproductive nests were captured by nest box,and the mating mode of varied tits was explored,as well as the preference of female to male mating;(3)the mountain of varied tits in artificial nest box was recorded.To explore the relationship between feather color and reproductive parameters,reproductive efficiency and parental physical parameters of varied tits.The results are as follows:(1)A total of 35 adults(6 females and 29 males)varied tits were ringed in the early breeding season and 43 adults(23 females and 20 males)were banded innest-box during the late breeding season.After comparing the difference of feather color between males and females in 9 parts,the brightness(Br8,prophase: p < 0.01;anaphase: P < 0.05),the chroma(C8,prophase: P < 0.01;anaphase: P < 0.05)and the hue(H8,prophase: P < 0.01;anaphase: P < 0.05)of the flanks of females and males in the two periods showed significant differences.Male feathers were darker than female feathers,with higher hues: dark red feathers on flanks of males.At the same time,the upper back chroma(C2,P < 0.01),jaw chroma(C6,P < 0.05),tail coverts hue(H9,P < 0.01)in pro-breeding season were significantly different between males and females.Late in the reproductive season,the forehead brightness(Br4,P < 0.05),hue(H4,P = < 0.05)and the chroma of tail coverts(C9,P < 0.01)were significantly different between males and females.By analyzing the feather color spectra of the two flanks,it was found that there were significant differences between males and females in the ultraviolet part(early stage: P < 0.01;late stage: P < 0.01).There were also significant differences in blue light(P < 0.01)and green light(P < 0.05)between males and females at the prophase of breeding season.(2)In the late reproductive season,there were 20 mating pairs,the chroma(C8,r = 0.643,P < 0.01)and hue(H8,r = 0.5,P < 0.05)of the flanks color between the pairs were significantly positively related,which showed that the selected mating.Males with stable partner had lower brightness(Br8,t = 3.263,P < 0.01),higher chroma(C8,t = 3.233,P < 0.01),and higher hues(H8,t = 3.003,P < 0.01).That is,the plumage color of the reproductive males are darker and tend to dark red.From the non-breeding season to the breeding season,the male plumage became dark red.(3)The results showed that: the more red of the male varied tits' flanks color,the larger of the clutch size in the nest,and the more chicks they hatched.The more red of the female varied tits' flanks color,the more chicks they hatched.I did not find significant relationship between female flank color and nest reproductive performance(P > 0.05),though male flank color was positively related with fledged young(r = 0.465,P < 0.05)and reproductive success(r = 0.484,P < 0.05).The chroma of flanks(C8)was positively related with beak length(r = 0.514,P < 0.01)and beak width(r = 0.339,P < 0.01),and hue(H8)was positively related with beak length(r = 0.299,P < 0.01).That is,the darker the feathers were,the wider the beak of the males.At the same time,there was a significant positive correlation between the flank color of female varied tit and beak length(P = 0.001,Table 4-13)and beak width(P < 0.05,Table 4-13).That is,the darker the flank cloor,the wider the beak of the females.To sum up: 1.Based on the visual system of birds,there is significant sexual dimorphism in the feathers of the flanks of varied tits,and there are significant differences under the short-wave light,especially under the ultraviolet light.The male feathers are darker than the female feathers,and tend to be dark red.2.The male feathers are darker in the breeding season than in the non-breeding season,and the male with stable spouse have darker plumage than other males.3.Female preference for male pairing is similar to their own feather color phenotype.The mode of mate selection is selective mating.4.The darker the plumage is on both sides of the varied tits,the bigger the tonal value is,the longer and wider the beak is,the larger the clutch size in the breeding nest and the more chicks they hatch.Therefore,I believe that the color of flank feathers can be used as a sexual selective trait for varied tits.Females prefer males with dark red plumage,and the reproductive efficiency of their reproductive nests is higher.