The inheritance of patterns on avian eggshells is central to understanding the evolution of traits such as egg mimicry (e.g. in cuckoos). Yet little is known about the inheritance, or indeed function, of eggshell patterns. It has long... more
The inheritance of patterns on avian eggshells is central to understanding the evolution of traits such as egg mimicry (e.g. in cuckoos). Yet little is known about the inheritance, or indeed function, of eggshell patterns. It has long been believed that the evolution of eggshell pattern mimicry required that patterns be determined by genes situated on the female-speci¢c W chromosome. However, it has never been demonstrated for any bird that egg pattern traits (rather than ground colour) are female sex linked, or indeed that they are inherited.We studied the inheritance of three measures of egg-pigment patterns in a wild great tit population. Egg patterns were female speci¢c but unrelated to female attributes such as age or condition and showed only weak environmental e¡ects. Eggs of daughters resembled those of both their mothers and maternal grandmothers, but not of their paternal grandmothers.We conclude that this is the ¢rst demonstration of female sex-linked inheritance of avian...
Changes in mass during moult were investigated by analysis of data recorded on standard moult cards by members of the British Trust for Ornithology Ringing Scheme. In the analysis of post juvenile moult, all available cards that presented... more
Changes in mass during moult were investigated by analysis of data recorded on standard moult cards by members of the British Trust for Ornithology Ringing Scheme. In the analysis of post juvenile moult, all available cards that presented wing length, mass and time of capture were used. The analysis of adult post-nuptial moult was restricted to cards from a single year. Juvenile mass correlated strongly with body size, time of day and the number of greater coverts being replaced. After controlling for the effects of size and time of day, mass was found to increase with date except in those individuals in which all juvenile greater coverts were retained. In these birds residual mass declined with date. In adult males, mass increased with both date and moult scores of primary, secondary and tertial remiges and of rectrices but because of the strong correlations between moult scores and date, the true relationship was not clear. In adult females, mass declined with date before increasing again. Unlike the males, female moult scores did not predict body mass. However, the timing of moult was a strong predictor of body mass. The differences between age and sex groups are discussed in relation to the nutritional demands of moult.
