Background:The vocalizations of birds are dynamic traits that often vary in output with time of day and time of year.By quantifying patterns of diel and seasonal variation in vocal output,we can gain insight into the ...Background:The vocalizations of birds are dynamic traits that often vary in output with time of day and time of year.By quantifying patterns of diel and seasonal variation in vocal output,we can gain insight into the ecology and evolution of birds and the function of their vocalizations.In this investigation,we quantified diel and seasonal variation in song output by studying a breeding population of Savannah Sparrows (Passerculus sandwichensis).Methods:We used autonomous recorders to collect extensive recordings across the breeding season in a long-term, colour-marked study population of Savannah Sparrows in eastern Canada.We described diel and seasonal variation across five different breeding stages based on recordings of more than 50,000 songs from 34 males.Results:During the pre-breeding stage, prior to female arrival, males sang a pronounced dawn chorus with a peak in song output during the early morning.During the breeding stage,in contrast,the dawn chorus was diminished and males instead exhibited a pronounced dusk chorus with a peak in song output during the evening.Across the breeding season,the highest levels of song output occurred in late April and early May,soon after males arrived on the breeding grounds,and the lowest levels occurred in August,prior to the departure of birds for the wintering grounds.Conclusions:These patterns suggest that Savannah Sparrows' early-season dawn choruses are directed at males and serve a territorial defense function.Later-season dusk choruses,in contrast, appear to play a role in attracting mates and possibly acoustic mate guarding.展开更多
The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis.Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages.However,only a few st...The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis.Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages.However,only a few studies have examined the temporal trend of hormone levels among different reproductive stages in multiple brooded species.We investigated the changes in plasma luteinizing hormone(LH)and prolactin(PRL)concentrations during different reproductive stages of the facultative double-brooded Great Tit(Parus major).We found that the concentrations of LH and PRL in females were significantly higher than those in males.Females had significantly higher LH and lower PRL concentrations in the pre-breeding period than in the first/second brooding periods,and there were no significant changes between the first and second brooding periods.The concentrations of LH and PRL in males had no significant difference between the pre-breeding period and the first brooding periods,while LH and PRL concentrations in the second brooding period were significantly higher than those in the first brooding period.We conclude that there are sex-based differences between LH and PRL at different stages of reproduction.The changes in LH and PRL in both males and females should be related to their physiological functions.Especially for males,individuals with higher levels of LH and PRL are more likely to maintain second clutches.展开更多
基金the Natural Sciences and Engineering Research Council of Canada NSERC for ongoing financial support to SMD,AEM,DRN,and DJM
文摘Background:The vocalizations of birds are dynamic traits that often vary in output with time of day and time of year.By quantifying patterns of diel and seasonal variation in vocal output,we can gain insight into the ecology and evolution of birds and the function of their vocalizations.In this investigation,we quantified diel and seasonal variation in song output by studying a breeding population of Savannah Sparrows (Passerculus sandwichensis).Methods:We used autonomous recorders to collect extensive recordings across the breeding season in a long-term, colour-marked study population of Savannah Sparrows in eastern Canada.We described diel and seasonal variation across five different breeding stages based on recordings of more than 50,000 songs from 34 males.Results:During the pre-breeding stage, prior to female arrival, males sang a pronounced dawn chorus with a peak in song output during the early morning.During the breeding stage,in contrast,the dawn chorus was diminished and males instead exhibited a pronounced dusk chorus with a peak in song output during the evening.Across the breeding season,the highest levels of song output occurred in late April and early May,soon after males arrived on the breeding grounds,and the lowest levels occurred in August,prior to the departure of birds for the wintering grounds.Conclusions:These patterns suggest that Savannah Sparrows' early-season dawn choruses are directed at males and serve a territorial defense function.Later-season dusk choruses,in contrast, appear to play a role in attracting mates and possibly acoustic mate guarding.
基金supported by the National Natural Science Foundation of China (No.31770419 and 31971402 to HW,32001094 and 31870368 to JY)
文摘The reproductive behaviors of birds are mainly controlled by the hypothalamus-pituitary-gonad axis.Many studies have shown that reproductive hormones are tightly linked to the breeding sub-stages.However,only a few studies have examined the temporal trend of hormone levels among different reproductive stages in multiple brooded species.We investigated the changes in plasma luteinizing hormone(LH)and prolactin(PRL)concentrations during different reproductive stages of the facultative double-brooded Great Tit(Parus major).We found that the concentrations of LH and PRL in females were significantly higher than those in males.Females had significantly higher LH and lower PRL concentrations in the pre-breeding period than in the first/second brooding periods,and there were no significant changes between the first and second brooding periods.The concentrations of LH and PRL in males had no significant difference between the pre-breeding period and the first brooding periods,while LH and PRL concentrations in the second brooding period were significantly higher than those in the first brooding period.We conclude that there are sex-based differences between LH and PRL at different stages of reproduction.The changes in LH and PRL in both males and females should be related to their physiological functions.Especially for males,individuals with higher levels of LH and PRL are more likely to maintain second clutches.
