In brood-parasitic Cuculus cuckoos,male vocalizations are species-specific and easily distinguishable,whereas female calls are remarkably similar across species,making species identification challenging.In this study,...In brood-parasitic Cuculus cuckoos,male vocalizations are species-specific and easily distinguishable,whereas female calls are remarkably similar across species,making species identification challenging.In this study,we examined the structural characteristics and variability of female bubbling calls among four Cuculus species(Common Cuckoo C.canorus,Oriental Cuckoo C.optatus,Indian Cuckoo C.micropterus,and Lesser Cuckoo C.poliocephalus)breeding in South Korea.Comprehensive acoustic analyses of seven call parameters,using recordings from 2021 to 2023,were conducted to quantify the characteristics of their calls and compare withinand between-individual variability across species.Significant differences were found across all call parameters,with the Common Cuckoo producing the highest number of notes and the Oriental Cuckoo the lowest-frequency calls.Despite these differences,the overall structure of the calls remained acoustically similar,with overlapping characteristics across species.Furthermore,female Common Cuckoos exhibited greater within-individual variability in their calls,while the other species showed higher between-individual variability,which may further complicate species identification based vocalization alone.These findings highlight the complexities of female vocalizations in Cuculus cuckoos and suggest that ecological,social,and evolutionary factors may contribute to this vocal variability.展开更多
Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,...Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,vascularization,and edema.However,little is known about whether avian brood parasites that do not incubate their eggs exhibit brood patch development during the breeding season.In this study,we measured the size of the ventral apterium in 114 Common Cuckoos(Cuculus canorus)captured in the field throughout the breeding season and examined the appearance of the ventral apterium to confirm the development of brood patches.We also examined whether morphological traits and various factors correlated with the size of the ventral apterium(sternal apterium and abdominal apterium)and how it changed during the breeding season.We found no clear signs of brood patch development in Common Cuckoos captured throughout the breeding season,indicating that they likely did not develop brood patches on the ventral apterium during this period.We also found that ventral apterium size was positively correlated with wing length and body weight.In addition,Common Cuckoos with newly growing feathers on the boundary of the ventral apterium with pteryla were frequently observed as seasons progressed to the end.In conclusion,Common Cuckoos exhibit neither brood patch development nor the vestigial characteristics of ancestral brood patches,except for the growth of feathers on boundary the ventral apterium.Further studies examining brood patches across different groups of avian brood parasites are valuable for enhancing our understanding of the developmental and physiological adaptations of avian brood parasites.展开更多
Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky ...Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by The Ministry of Education(NRF-2020R1I1A2063567)。
文摘In brood-parasitic Cuculus cuckoos,male vocalizations are species-specific and easily distinguishable,whereas female calls are remarkably similar across species,making species identification challenging.In this study,we examined the structural characteristics and variability of female bubbling calls among four Cuculus species(Common Cuckoo C.canorus,Oriental Cuckoo C.optatus,Indian Cuckoo C.micropterus,and Lesser Cuckoo C.poliocephalus)breeding in South Korea.Comprehensive acoustic analyses of seven call parameters,using recordings from 2021 to 2023,were conducted to quantify the characteristics of their calls and compare withinand between-individual variability across species.Significant differences were found across all call parameters,with the Common Cuckoo producing the highest number of notes and the Oriental Cuckoo the lowest-frequency calls.Despite these differences,the overall structure of the calls remained acoustically similar,with overlapping characteristics across species.Furthermore,female Common Cuckoos exhibited greater within-individual variability in their calls,while the other species showed higher between-individual variability,which may further complicate species identification based vocalization alone.These findings highlight the complexities of female vocalizations in Cuculus cuckoos and suggest that ecological,social,and evolutionary factors may contribute to this vocal variability.
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by The Ministry of Education(NRF-2020R1I1A2063567)。
文摘Many birds develop brood patches on their ventral apterium under hormonal regulation to effectively transmit body heat to eggs during incubation.The developed patch has several characteristics,including de-feathering,vascularization,and edema.However,little is known about whether avian brood parasites that do not incubate their eggs exhibit brood patch development during the breeding season.In this study,we measured the size of the ventral apterium in 114 Common Cuckoos(Cuculus canorus)captured in the field throughout the breeding season and examined the appearance of the ventral apterium to confirm the development of brood patches.We also examined whether morphological traits and various factors correlated with the size of the ventral apterium(sternal apterium and abdominal apterium)and how it changed during the breeding season.We found no clear signs of brood patch development in Common Cuckoos captured throughout the breeding season,indicating that they likely did not develop brood patches on the ventral apterium during this period.We also found that ventral apterium size was positively correlated with wing length and body weight.In addition,Common Cuckoos with newly growing feathers on the boundary of the ventral apterium with pteryla were frequently observed as seasons progressed to the end.In conclusion,Common Cuckoos exhibit neither brood patch development nor the vestigial characteristics of ancestral brood patches,except for the growth of feathers on boundary the ventral apterium.Further studies examining brood patches across different groups of avian brood parasites are valuable for enhancing our understanding of the developmental and physiological adaptations of avian brood parasites.
基金financially supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by The Ministry of Education(NRF2020R1I1A2063567)。
文摘Sperm competition has been studied in numerous species as a representative example of postcopulatory sexual selection,where sampling sperm from male is the most basic and important step.Sperm collection can be tricky in birds,however,because unlike mammals,the genitals of birds are generally latent in the cloacal region and their characteristics vary among species.Various methods to collect sperm from different birds have been tested,such as cloacal massage,feces collection,and electro-stimulation,but their applicability varies depending on species.In this study,we introduced the urodeum stimulation method(UroS method)to collect sperm from Cuculus cuckoos,such as the Common Cuckoo(C.canorus).These species are expected to have interesting patterns of pair bonding and sperm competition because of their unique breeding strategy called brood parasitism;however,it remains unexplored.In this study,we described the application of our new method to expel semen from male common cuckoos,measured the volume of semen collected,checked the presence of sperm in the semen sample,and finally estimated its success rate among 82 males.Samples were successfully collected from 76 cuckoos(approximately 93%)and the colors and volumes of the samples were very diverse.Sperm was present in 43 of these samples(57%),showing a sperm observation rate approximately twice as high as that of the conventional cloacal massage method.We believe that this novel method will contribute to a better understanding of postcopulatory sexual selection in avian brood parasites and facilitate the process of sperm collection and artificial insemination in other medium-sized birds.
