In many songbird species,birdsong features phonological syntax,meaning that the units within their vocal se-quences are ordered in a non-random way that adheres to a rule.While such syntactical patterns have been rich...In many songbird species,birdsong features phonological syntax,meaning that the units within their vocal se-quences are ordered in a non-random way that adheres to a rule.While such syntactical patterns have been richly described in many species,comparatively little is known about how those patterns contribute to song achieving its important functions.For each of song’s main functions,territorial defense and mate attraction,evidence of a role for syntax is limited.One species for which syntax has been thoroughly described is the Hermit Thrush(Catharus guttatus),which presents song types from their repertoires in a semi-predictable order and,in doing so,rapidly cycle up and down the frequency spectrum.The objective of the present study was to explore the importance of song syntax in the Hermit Thrush through a within-subject examination of how measures of syntax,such as the predictability of song type order within song sequences,shift over the breeding season.We hypothesized that,if such syntactical characteristics are important to breeding behaviour,they would be most prominent at the start of the breeding season when activity associated with territory establishment and mate attraction is most intense.Analysis revealed that,as predicted,the rigidness of song type ordering within se-quences was highest at the start of the season and declined thereafter.That song type sequences were most predictable at the vitally important early part of the breeding season fit our hypothesis that this aspect of song syntax is important to song’s functions related to territory establishment and/or mate attraction.Future work will clarify whether that role relates to one of song’s two main functions or serves song transmission in some broader way.展开更多
Extra-pair copulation(EPC)can potentially maximize individual reproductive fitness,and this process may involve sexual selection of male and female traits that reflect individual quality.Previous studies have implied ...Extra-pair copulation(EPC)can potentially maximize individual reproductive fitness,and this process may involve sexual selection of male and female traits that reflect individual quality.Previous studies have implied that adult characteristics are associated with the probability of extra-pair paternity(EPP),but it differs between species.Moreover,there are relatively few examples of the adaptive rationale for females’engagement in EPCs based on an examination of these more traditionally recorded traits,in combination with female flight-mediated traits such as wing length.We investigated whether EPP existed in the wild Chestnut Thrush(Turdus rubrocanus)population during three breeding seasons(2019–2021),and whether paternity was related to morphological traits of males and females.Eight highly variable microsatellite loci were used to identify paternity,and generalized linear mixed models were used to analyze the relationship between paternity and morphological traits.We found that EPP existed in the Chestnut Thrush.53.3%(N=41/77)of the broods contained at least one extra-pair offspring(EPO),and 34.6%(N=72/208)of the nestlings were EPO.We also found that male wing length was negatively associated with the probability of EPP and the proportion of EPO.Female body length was positively related to the probability of EPP.Both female body condition and mass were negatively associated with the proportion of EPO.While other traits of male and female did not relate to the probability of EPP or the proportion of EPO.Extra-pair males had better body condition compared to the males they cuckolded.EPO did not differ from their half-siblings in terms of body size or body condition.The results suggest that body size and body condition were associated with EPP in the Chestnut Thrush.This study provides fundamental information for further studies on the evolution and maintenance of EPP in the Chestnut Thrush,and it is also useful for the comparison of EPP among Turdus species.展开更多
Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP)....Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP).However,a rece nt study suggested an alternative hypothesis,con cludi ng that con specific brood parasitism(CBP)selects for egg rejection in thrushes,with IBP as a by-product.In the present study,we used a spectrophotometer to quantify egg coloration and egg mimicry and performed artificial parasitism experiments in the grey?backed thrush(Turdus hortulorum).We showed that individuals of this species rejected 100%of 12 foreign eggs,without IBP or CBP detected.In a review of previous studies,we also discuss possible explanations for the high egg rejection rate in the grey-backed thrush and suggest areas for future study.Altricial birds have evolved advaneed reproductive behavior to in crease the fitn ess of their offspring by buildi ng elaborate structures(i.e.,nests),in which they lay eggs and rear their nestlings(Hansell,2000).Bird nests not only provide a suitable place for nestling development,but also act as a concealed location for safety from predators.Furthermore,bird parents have evolved nest sanitation behavior to clean foreig n objects from their n ests,in eluding feces,eggshells,branches,and leaves,because they induce predation,facilitate microorganism growth,damage eggs,or hurt nestlings during brooding(Guigueno&Sealy,2012).Therefore,nest sanitation has evolved as a general behavior in altricial birds for distinguishing between egg-shaped and non-egg-shaped objects.展开更多
Background: The drivers of intraspecific variation in behavioral plasticity are poorly known. A widely held hypothesis is that brain size is positively correlated with behavioral plasticity.Methods: A total of 71 Ches...Background: The drivers of intraspecific variation in behavioral plasticity are poorly known. A widely held hypothesis is that brain size is positively correlated with behavioral plasticity.Methods: A total of 71 Chestnut Thrushes(Turdus rubrocanus) were caught in the wild population. We quantified behavior plasticity of activity of individuals measured in the same cage across two contexts(common and with a novel object stimulation), using a random regression analysis. We then investigated whether head volume(a proxy for brain size) was associated with behavioral plasticity in activity level using Spearman rank-order correlation.Results: We found no significant evidence that activity plasticity was associated with relative head volume. There was no sex difference in head volume or in variance in head volume.Conclusions: We speculate that the absence of an association between brain volume and activity behavior plasticity may result from the inaccuracy of using external skull measurements to estimate brain size, or from a particular part of the brain being responsible for plasticity in activity level.展开更多
Background: Taxonomic treatment of the Zoothera dauma species complex is highly variable and has been hampered by the absence of song recordings for the Nilgiri Thrush(Zoothera [aurea] neilgherriensis).Methods: I obta...Background: Taxonomic treatment of the Zoothera dauma species complex is highly variable and has been hampered by the absence of song recordings for the Nilgiri Thrush(Zoothera [aurea] neilgherriensis).Methods: I obtained two recordings of the song of neigherriensis from southern Indian. Here I publish sonograms and analyze song recordings for all but one currently described taxon from the Eurasian portion of the geographic range of this species complex. Principal component analyses were used to investigate song differences between taxa.Results: The song of neigherriensis is a highly complex series of strophes remarkably similar to the song of the insular Zoothera major. Vocal analyses across the complex indicate four key groups of taxa differentiated in their songs:(1) simple flat whistled songs which include the northern aurea, toratugumi and the undescribed Taiwan population;(2) eastern populations of dauma(reported here for the first time) which sing like northern birds but with much broader bandwidth,(3) strongly down-slurred, thin whistles of tropical resident imbricata of Sri Lanka and horsfieldi of Indonesia, and(4) highly complex songs of Himalayan dauma, neilgherriensis and major.Conclusions: Zoothera dauma is unlikely to represent a single species given the simple singing populations from its eastern range and highly complex song from the Himalayan portion of its range. neilgherriensis should either be transferred from Zoothera aurea, where it is currently classified as a subspecies, and be placed as a subspecies within Z. dauma from the Himalayas or it should be recognized as a distinct species. Given the small number of songs available for analyses, I suggest the former course until it can be clearly demonstrated that neilgherriensis and Himalayan dauma are vocally distinct.展开更多
Aim: Yearly summaries of the North American Breeding Bird Survey (BBS) indicate that populations of many North American bird species are in decline. Determining the causes of these declines is the focus of much curren...Aim: Yearly summaries of the North American Breeding Bird Survey (BBS) indicate that populations of many North American bird species are in decline. Determining the causes of these declines is the focus of much current research in avian conservation. Forest fragmentation has been linked to declines in populations of many species. In this study, the effects of forest fragmentation and connectivity as well as slope and physiographic features on two migratory bird species are explored. Location: This study area is Virginia, USA. Taxon: The species focused on are Wood Thrush (Hylocichla mustelina) and the Ovenbird (Seiurus aurocapilla). Methods: We used the Markov Chain Monte Carlo Generalized Linear Mixed Models (MCMCglmm) package with a Poisson distribution and a Bayesian data analysis model with a 95% probability interval. Using the Repeated Measures ANOVA, the independent and treatment variables included time at 3 different levels in 2001, 2006 and 2011;three different forest types—Core, Connected and Fragmented;8 slope categories and 5 physiographic regions. Results: Results indicate that forest fragmentation has a significant impact on population sizes of Wood Thrush and Ovenbirds in Virginia and that recent changes in Virginia’s landscape have had negative impacts on the populations of these bird species. Specifically, slope characteristics that influence rates of urbanization are correlated with changes in bird populations. The Coastal Plain region in Virginia contributes significantly to the populations of both the Wood Thrush and Ovenbird currently. Main Conclusions: Core forests areas in Virginia are in decline and this process affects the populations and distributions of Ovenbird and Wood thrush in the state.展开更多
Background:Nestling discrimination and feeding habits during brooding are important factors affecting host selec-tion of parasitic birds.Some host birds can avoid being parasitized by discriminating their nestlings or...Background:Nestling discrimination and feeding habits during brooding are important factors affecting host selec-tion of parasitic birds.Some host birds can avoid being parasitized by discriminating their nestlings or feeding food not suitable for parasitic nestlings.Thrushes are common medium-sized birds with widespread distribution and an open nesting habit,but they are rarely parasitized.It remains controversial whether this is due to feeding habits and/or nestling discrimination.Methods:In this study,we tested the nestling discrimination ability and feeding habits of Chestnut Thrushes(Turdus rubrocanus)which is distributed in China’s multi-cuckoo parasitism system.Their nestling discriminability and feeding habits during brooding were studied by cross-fostering experiments and video recording to examine evolutionary restrictions on nestling discrimination and whether feeding habits are consistent with the growth of cuckoo nestlings.Results:Our results indicate that Chestnut Thrushes using earthworms as the main brooding food can feed and maintain cuckoo nestlings and show no nestling discrimination.Conclusions:The present study confirms that feeding habits cannot be regarded as the main factor affecting Chestnut Thrushes being rarely parasitized by cuckoos but suggests that egg rejection is likely to limit the evolution of nestling discrimination in thrushes.展开更多
In the history of British literature, Hardy is not only an excellent novelist, but also a famous poet. He was regarded as "The Father of Modern Poems". Merryn William thought that only Hardy and Lawrence wer...In the history of British literature, Hardy is not only an excellent novelist, but also a famous poet. He was regarded as "The Father of Modern Poems". Merryn William thought that only Hardy and Lawrence were the real first-class novelists and poets in British literature.[1] Among his more than 1000 poems, The Darkling Thrush is a typical lyric poem. The excellence not only lies in its elegant language, musical rhythms and vivid description of nature, but also lies in the expression of poet's desolate attitude through images. The nature images play an important role in displaying the theme and expressing the complex feeling. They also express people's anxiety, confusion and expectation toward to the turning of the passing century and the coming of the new century. This paper tries to deeply undrestand the theme of the poems by analysing these images.展开更多
Both dusky thrush(Turdus numanni) and Amur corktree ( Phellodendron amurense) are only distributed in East Asia. Dusky thrush pass through or stay at the distribution area of Amur corktree during its migrating or wint...Both dusky thrush(Turdus numanni) and Amur corktree ( Phellodendron amurense) are only distributed in East Asia. Dusky thrush pass through or stay at the distribution area of Amur corktree during its migrating or wintering period. The thrush mainly eat fruits of Amur corktree and disperse the seeds at the same time. A mutualism exists between the bird and the tree. The Amur corktree are dispersed mainly by the thrush. Under natural condition, seeds of Amur corktree can not germinate under the mother tree.展开更多
基金partly funded by an NSERC Discovery Grant received by LS Phillmorea UNB University Research Fund grant received by SP Roach
文摘In many songbird species,birdsong features phonological syntax,meaning that the units within their vocal se-quences are ordered in a non-random way that adheres to a rule.While such syntactical patterns have been richly described in many species,comparatively little is known about how those patterns contribute to song achieving its important functions.For each of song’s main functions,territorial defense and mate attraction,evidence of a role for syntax is limited.One species for which syntax has been thoroughly described is the Hermit Thrush(Catharus guttatus),which presents song types from their repertoires in a semi-predictable order and,in doing so,rapidly cycle up and down the frequency spectrum.The objective of the present study was to explore the importance of song syntax in the Hermit Thrush through a within-subject examination of how measures of syntax,such as the predictability of song type order within song sequences,shift over the breeding season.We hypothesized that,if such syntactical characteristics are important to breeding behaviour,they would be most prominent at the start of the breeding season when activity associated with territory establishment and mate attraction is most intense.Analysis revealed that,as predicted,the rigidness of song type ordering within se-quences was highest at the start of the season and declined thereafter.That song type sequences were most predictable at the vitally important early part of the breeding season fit our hypothesis that this aspect of song syntax is important to song’s functions related to territory establishment and/or mate attraction.Future work will clarify whether that role relates to one of song’s two main functions or serves song transmission in some broader way.
基金supported by the National Natural Science Foundation of China(Project 32070452).
文摘Extra-pair copulation(EPC)can potentially maximize individual reproductive fitness,and this process may involve sexual selection of male and female traits that reflect individual quality.Previous studies have implied that adult characteristics are associated with the probability of extra-pair paternity(EPP),but it differs between species.Moreover,there are relatively few examples of the adaptive rationale for females’engagement in EPCs based on an examination of these more traditionally recorded traits,in combination with female flight-mediated traits such as wing length.We investigated whether EPP existed in the wild Chestnut Thrush(Turdus rubrocanus)population during three breeding seasons(2019–2021),and whether paternity was related to morphological traits of males and females.Eight highly variable microsatellite loci were used to identify paternity,and generalized linear mixed models were used to analyze the relationship between paternity and morphological traits.We found that EPP existed in the Chestnut Thrush.53.3%(N=41/77)of the broods contained at least one extra-pair offspring(EPO),and 34.6%(N=72/208)of the nestlings were EPO.We also found that male wing length was negatively associated with the probability of EPP and the proportion of EPO.Female body length was positively related to the probability of EPP.Both female body condition and mass were negatively associated with the proportion of EPO.While other traits of male and female did not relate to the probability of EPP or the proportion of EPO.Extra-pair males had better body condition compared to the males they cuckolded.EPO did not differ from their half-siblings in terms of body size or body condition.The results suggest that body size and body condition were associated with EPP in the Chestnut Thrush.This study provides fundamental information for further studies on the evolution and maintenance of EPP in the Chestnut Thrush,and it is also useful for the comparison of EPP among Turdus species.
基金supported by the National Natural Science Foundation of China(31672303 to C.Y.,31660617 to L.W.and 31472013 and 31772453 to W.L.)
文摘Several previous studies have indicated that nest sanitation behavior is a general adaptation in altricial birds,with egg recog nition capacity evolvi ng as a specific response to in terspecific brood parasitism(IBP).However,a rece nt study suggested an alternative hypothesis,con cludi ng that con specific brood parasitism(CBP)selects for egg rejection in thrushes,with IBP as a by-product.In the present study,we used a spectrophotometer to quantify egg coloration and egg mimicry and performed artificial parasitism experiments in the grey?backed thrush(Turdus hortulorum).We showed that individuals of this species rejected 100%of 12 foreign eggs,without IBP or CBP detected.In a review of previous studies,we also discuss possible explanations for the high egg rejection rate in the grey-backed thrush and suggest areas for future study.Altricial birds have evolved advaneed reproductive behavior to in crease the fitn ess of their offspring by buildi ng elaborate structures(i.e.,nests),in which they lay eggs and rear their nestlings(Hansell,2000).Bird nests not only provide a suitable place for nestling development,but also act as a concealed location for safety from predators.Furthermore,bird parents have evolved nest sanitation behavior to clean foreig n objects from their n ests,in eluding feces,eggshells,branches,and leaves,because they induce predation,facilitate microorganism growth,damage eggs,or hurt nestlings during brooding(Guigueno&Sealy,2012).Therefore,nest sanitation has evolved as a general behavior in altricial birds for distinguishing between egg-shaped and non-egg-shaped objects.
基金supported by the National Natural Science Foundation of China (Grant No.31472012)
文摘Background: The drivers of intraspecific variation in behavioral plasticity are poorly known. A widely held hypothesis is that brain size is positively correlated with behavioral plasticity.Methods: A total of 71 Chestnut Thrushes(Turdus rubrocanus) were caught in the wild population. We quantified behavior plasticity of activity of individuals measured in the same cage across two contexts(common and with a novel object stimulation), using a random regression analysis. We then investigated whether head volume(a proxy for brain size) was associated with behavioral plasticity in activity level using Spearman rank-order correlation.Results: We found no significant evidence that activity plasticity was associated with relative head volume. There was no sex difference in head volume or in variance in head volume.Conclusions: We speculate that the absence of an association between brain volume and activity behavior plasticity may result from the inaccuracy of using external skull measurements to estimate brain size, or from a particular part of the brain being responsible for plasticity in activity level.
基金provided by an NSERC Postdoctoral fellowship,NSERC Discovery Grant(06538)and Accelerator Grant(492890)to JTWNSF grant to Trevor Price
文摘Background: Taxonomic treatment of the Zoothera dauma species complex is highly variable and has been hampered by the absence of song recordings for the Nilgiri Thrush(Zoothera [aurea] neilgherriensis).Methods: I obtained two recordings of the song of neigherriensis from southern Indian. Here I publish sonograms and analyze song recordings for all but one currently described taxon from the Eurasian portion of the geographic range of this species complex. Principal component analyses were used to investigate song differences between taxa.Results: The song of neigherriensis is a highly complex series of strophes remarkably similar to the song of the insular Zoothera major. Vocal analyses across the complex indicate four key groups of taxa differentiated in their songs:(1) simple flat whistled songs which include the northern aurea, toratugumi and the undescribed Taiwan population;(2) eastern populations of dauma(reported here for the first time) which sing like northern birds but with much broader bandwidth,(3) strongly down-slurred, thin whistles of tropical resident imbricata of Sri Lanka and horsfieldi of Indonesia, and(4) highly complex songs of Himalayan dauma, neilgherriensis and major.Conclusions: Zoothera dauma is unlikely to represent a single species given the simple singing populations from its eastern range and highly complex song from the Himalayan portion of its range. neilgherriensis should either be transferred from Zoothera aurea, where it is currently classified as a subspecies, and be placed as a subspecies within Z. dauma from the Himalayas or it should be recognized as a distinct species. Given the small number of songs available for analyses, I suggest the former course until it can be clearly demonstrated that neilgherriensis and Himalayan dauma are vocally distinct.
文摘Aim: Yearly summaries of the North American Breeding Bird Survey (BBS) indicate that populations of many North American bird species are in decline. Determining the causes of these declines is the focus of much current research in avian conservation. Forest fragmentation has been linked to declines in populations of many species. In this study, the effects of forest fragmentation and connectivity as well as slope and physiographic features on two migratory bird species are explored. Location: This study area is Virginia, USA. Taxon: The species focused on are Wood Thrush (Hylocichla mustelina) and the Ovenbird (Seiurus aurocapilla). Methods: We used the Markov Chain Monte Carlo Generalized Linear Mixed Models (MCMCglmm) package with a Poisson distribution and a Bayesian data analysis model with a 95% probability interval. Using the Repeated Measures ANOVA, the independent and treatment variables included time at 3 different levels in 2001, 2006 and 2011;three different forest types—Core, Connected and Fragmented;8 slope categories and 5 physiographic regions. Results: Results indicate that forest fragmentation has a significant impact on population sizes of Wood Thrush and Ovenbirds in Virginia and that recent changes in Virginia’s landscape have had negative impacts on the populations of these bird species. Specifically, slope characteristics that influence rates of urbanization are correlated with changes in bird populations. The Coastal Plain region in Virginia contributes significantly to the populations of both the Wood Thrush and Ovenbird currently. Main Conclusions: Core forests areas in Virginia are in decline and this process affects the populations and distributions of Ovenbird and Wood thrush in the state.
基金funded by the National Natural Science Foundation of China(Nos.31772453 and 31970427 to WL,and 31472012 to Y-HS)。
文摘Background:Nestling discrimination and feeding habits during brooding are important factors affecting host selec-tion of parasitic birds.Some host birds can avoid being parasitized by discriminating their nestlings or feeding food not suitable for parasitic nestlings.Thrushes are common medium-sized birds with widespread distribution and an open nesting habit,but they are rarely parasitized.It remains controversial whether this is due to feeding habits and/or nestling discrimination.Methods:In this study,we tested the nestling discrimination ability and feeding habits of Chestnut Thrushes(Turdus rubrocanus)which is distributed in China’s multi-cuckoo parasitism system.Their nestling discriminability and feeding habits during brooding were studied by cross-fostering experiments and video recording to examine evolutionary restrictions on nestling discrimination and whether feeding habits are consistent with the growth of cuckoo nestlings.Results:Our results indicate that Chestnut Thrushes using earthworms as the main brooding food can feed and maintain cuckoo nestlings and show no nestling discrimination.Conclusions:The present study confirms that feeding habits cannot be regarded as the main factor affecting Chestnut Thrushes being rarely parasitized by cuckoos but suggests that egg rejection is likely to limit the evolution of nestling discrimination in thrushes.
文摘In the history of British literature, Hardy is not only an excellent novelist, but also a famous poet. He was regarded as "The Father of Modern Poems". Merryn William thought that only Hardy and Lawrence were the real first-class novelists and poets in British literature.[1] Among his more than 1000 poems, The Darkling Thrush is a typical lyric poem. The excellence not only lies in its elegant language, musical rhythms and vivid description of nature, but also lies in the expression of poet's desolate attitude through images. The nature images play an important role in displaying the theme and expressing the complex feeling. They also express people's anxiety, confusion and expectation toward to the turning of the passing century and the coming of the new century. This paper tries to deeply undrestand the theme of the poems by analysing these images.
文摘Both dusky thrush(Turdus numanni) and Amur corktree ( Phellodendron amurense) are only distributed in East Asia. Dusky thrush pass through or stay at the distribution area of Amur corktree during its migrating or wintering period. The thrush mainly eat fruits of Amur corktree and disperse the seeds at the same time. A mutualism exists between the bird and the tree. The Amur corktree are dispersed mainly by the thrush. Under natural condition, seeds of Amur corktree can not germinate under the mother tree.
