Pycnonotus Sinensis Research Articles

Anthropogenic nesting materials and reproductive performance of Chinese Bulbuls (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China

Urbanization induced by human activities presents both challenges and adaptive opportunities for wildlife. One notable impact of urban sprawl is the vast amount of waste it produces, which has discernible effects on wildlife. Interestingly, an emerging trend has been observed that birds are incorporating anthropogenic materials into their nests. However, the relationship between anthropogenic nesting materials (ANMs) and the reproductive performance of urban birds is unclear. In this study, we investigated the relationship between the incorporation of ANMs into nests and the reproductive performance of Chinese Bulbuls (Pycnonotus sinensis) by monitoring and collecting data on 136 breeding nests in Hangzhou, China. We gathered data on seven reproductive traits of Chinese Bulbuls, including laying date, incubation period, nestling period, clutch size, egg volume, hatching success rate, and fledging success rate. We then calculated the urbanization synthetic index as a measure of the level of urbanization and examined its relationship with the proportion and weight of ANMs. Through examination of nest components, we observed significant increase in the proportion and weight of ANMs with the urbanization synthetic index. Notably, we found a higher hatching success rate of Chinese Bulbuls with an increasing proportion of ANMs. However, the inclusion of ANMs in nests was not correlated with other reproductive traits of Chinese Bulbuls. Overall, the use of ANMs by Chinese Bulbuls seems to be consistent with the adaptive hypothesis and the availability hypothesis. Further studies should use controlled experiments to investigate the impact of ANMs on avian reproductive success.

Expansion of the Range of the Light-Vented Bulbul Pycnonotus sinensis into Mainland Japan

Expansion of the Range of the Light-Vented Bulbul Pycnonotus sinensis into Mainland Japan

Structure and characteristics of the plant-frugivore bird network from the Guilin Botanical Garden.

The interaction between plants and frugivores is crucial to ecosystem function and community diversity. However, little is known about the interaction between plants and frugivorous bird species in urban green spaces. We observed interactions between plants and frugivorous birds in the Guilin Botanical Garden for one year and determined the structure and characteristics of the interaction network. We also analyzed the impact of species traits on their network roles. Interactions between 14 frugivorous birds and 13 fruit plant species were recorded in the study area. Autumn interactions comprised 38.79% of the overall network, and winter interactions comprised 33.15%. The modularity (Q, z-score) of the network was higher in autumn; the weighted nestedness (wNODF, z-score) and interaction evenness (E2 , z-score) of the network were higher in winter; the connectance (C, z-score) and interaction diversity (z-score) of the network were higher in spring; and the specialization (H2', z-score) of the network was higher in summer. The observed network showed lower C, lower interaction H2 , lower E2 , lower wNODF, higher H2' and higher Q when compared to the random networks. The bird species most important to network stability were Hemixos castanonotus, Parus venustulus, and Pycnonotus sinensis. The most important plant species were Alocasia macrorrhiza, Cinnamomum camphora, and Machilus nanmu. Of all the bird and plant traits included in this study, only plant color had a significant impact on species strength, with black fruit having a higher species strength. Our results suggest that interaction networks in urban green spaces can be temporally complex and variable and that a network approach can be an important monitoring tool for detecting the status of crucial ecosystem functions.

Metabolic and microbial changes in light-vented bulbul during recent northward range expansion.

Endotherms recently expanding to cold environments generally exhibit strong physiological acclimation to sustain high body temperature. During this process, gut microbes likely play a considerable role in host physiological functions, including digestion and thermogenesis. The light-vented bulbul Pycnonotus sinensis represents one such species. It used to be restricted to the Oriental realm but expanded its distribution range north to the Palearctic areas during the past few decades. Here, we explored the seasonal dynamics of the resting metabolic rate (RMR) and microbiota for local and newly colonized populations of the species. Our results showed that the mass-adjusted RMR and body mass were positively correlated with latitude variations in both seasons. Consistently, the gut microbiota showed a corresponding variation to the northern cold environments. In the two northern populations, the alpha diversity decreased compared with those of the two southern populations. Significant differences were detected in dominant phyla, such as Firmicutes, Bacteroidetes, Proteobacteria, and Desulfobacterota in both seasons. The core microbiota showed geographic differences in the winter, including the elevated relative abundance of 5 species in northern populations. Finally, to explore the link between microbial communities and host metabolic thermogenesis, we conducted a correlation analysis between microbiota and mass-adjusted RMR. We found that more genera were significantly correlated with mass-adjusted RMR in the wintering season compared to the breeding season (71 vs. 23). These results suggest that microbiota of the lighted-vented bulbul linked with thermogenesis in diversity and abundance under northward expansion.

Variation in reproductive life-history traits of Chinese Bulbuls (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China

Urbanization brings new selection pressures to wildlife living in cities, and changes in the life-history traits of urban species can reflect their responses to such pressures. To date, most of the studies investigating the impacts of urbanization on avian life-history traits are conducted in Europe and North America, while such studies are often lacking in quickly developing countries in Asia (e.g., China). In this study, we examined the variations in reproductive life-history traits of Chinese Bulbuls (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China. We detected 234 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013. We collected data on seven life-history traits (laying date, incubation period, nestling period, clutch size, egg volume, hatching success rate, and fledging success rate). We used infrared cameras to record the number of feedings per hour as the measure of food resources for the nestlings. We measured nest predation pressure by monitoring 148 natural breeding nests during breeding seasons and 54 artificial nests immediately after breeding seasons. We then calculated the urbanization synthetic index (USI) as a measure of the level of urbanization and examined its relationship with the seven life-history traits. We found that Chinese Bulbuls laid eggs significantly earlier with increasing USI. However, the other six life-history traits did not vary significantly with the USI. Moreover, the feeding frequency of chicks increased significantly with the USI, but the nest predation pressure of Chinese Bulbuls decreased significantly with the USI. Increased food resources and reduced nest predation pressure in cities may lead to earlier laying date of Chinese Bulbuls. Further study should test whether the earlier laying date of Chinese Bulbuls is the result of phenotypic plasticity or genetic change.

Eating More and Fighting Less: Social Foraging Is a Potential Advantage for Successful Expansion of Bird Source Populations.

Simple SummaryUnderstanding why some animal species expand their distributions but others do not under the same global climatic fluctuations and habitat changes is essential to determine expansion mechanisms and predict alien species invasion. However, whether the source population of an expansive species has the potential to survive in a new environment after expansion is rarely evaluated. Social foraging is considered beneficial in obtaining food and increasing population establishment. However, competition will increase under the social context of group foraging. In this laboratory research, whether social foraging could promote individuals to consume more novel food in an unfamiliar environment, which can facilitate survival and population establishment, was tested in a source population of a successful expansive bird, the Light-vented Bulbul (Pycnonotus sinensis). Compared with the sympatric, nonexpansive relative species Collared Finchbill (Spizixos semitorques), bulbuls had longer latencies to consume novel food, but they increased eating times when transferred from solitary to group status and had higher possibilities of eating with their companions. In addition, more than two individuals eating together is significantly more frequent in bulbuls than finchbills. Therefore, social foraging can be a critical species-specific trait that is a potential advantage for expansion because it weakens competition among individuals. This study provides testable hypotheses to explain mechanisms of successful expansions and to predict alien species expansion and possibilities for control.Animals can expand distributions in response to climatic and environmental changes, but the potential expansive ability of a source population is rarely evaluated using designed experiments. Group foraging can increase survival in new environments, but it also increases intraspecific competition. The trade-off between benefit and conflict needs to be determined. The expanding Light-vented Bulbul Pycnonotus sinensis was used as a model to test mechanisms promoting successful expansion. Social foraging and its advantages were evaluated using lab-designed feeding trials. Consuming novel foods was compared between bulbuls and a sympatric, nonexpansive relative species, the finchbill Spizixos semitorques, from native areas at both solitary and social levels. Bulbuls increased their eating times when transferred from solitary to group, whereas social context did not affect finchbills. Bulbuls were significantly more likely to eat with their companions than finchbills when in a group. Thus, exploring food resources in a bulbul source population was facilitated by social context, indicating that social foraging is an important means by which birds successfully expand and respond to environmental changes. This research increases understanding of successful expansion mechanisms and will consequently help predict invasive potentials of alien species.

Morphological and physiological correlates of among- individual variation in basal metabolic rate in two passerine birds

Basal metabolic rate (BMR) has been shown to be a highly phenotypic flexibility trait within species. A significant proportion of an individual's energy budget is accounted for by BMR, hence among-individual variation in this trait may affect other energetic processes, as well as fitness. In this study, we measured BMR, organ mass, mitochondrial respiration capacities and cytochrome c oxidase (COX) activities in muscle and liver and circulating levels of plasma triiodothyronine (T3) in Chinese bulbuls (Pycnonotus sinensis) and Eurasian tree sparrows (Passer montanus). Our results showed that heart and kidney mass was positively correlated with BMR in Chinese bulbuls, whereas liver and kidney mass was positively correlated with BMR in Eurasian tree sparrows. Regarding metabolic biochemical markers of tissues, state 4 respiration and COX activity in the muscles of the Chinese bulbuls was correlated with BMR, while state 4 respiration in the muscle and liver was correlated with BMR in Eurasian tree sparrows. T3 was significantly and positively correlated with BMR in Chinese bulbuls and Eurasian tree sparrows. Consistent with the above results, our findings suggest that T3 levels play an important role in modulating BMR in Chinese bulbuls and Eurasian tree sparrows. Moreover, individual variation in BMR can be explained partly by morphological and physiological mechanisms.

Nest predation pressure on Chinese Bulbuls decreases along the urbanization gradient in Hangzhou, China

Nest predation is an essential factor affecting bird population density, reproductive ecology and life cycle. However, there are still contradictory results about how nest predation pressure changes with urbanization. One of the reasons for the controversy is that previous studies often use artificial nests to investigate nest predation, but the result of artificial nests is often biased and contrary to that of natural nests. Therefore, it is important to perform nest predation experiments simultaneously with both natural and artificial nests. In this study, we examined the change of nest predation pressure on the Chinese Bulbul (Pycnonotus sinensis) along the urbanization gradient in Hangzhou, China. We detected 148 natural nests of Chinese Bulbuls and continuously monitored them in two continuous breeding seasons from 2012 to 2013. After the breeding season, we placed artificial eggs in natural nests of Chinese Bulbuls to investigate the changes in nest predation pressure and used infrared cameras to record the predators. We then calculated the urbanization synthetic index (USI) as the measure of the degree of urbanization and examined its relationship with nest predation pressure. We found that no matter whether natural nests or artificial eggs were used, the nest predation pressure always decreased significantly with the degree of urbanization. The average height of shrubs within 10 ​m of the nest differed significantly between the predated and unpredated nests, which also affected the risk of nest predation. Our study highlights the importance of using natural and artificial nests simultaneously to conduct nest predation experiments, which can reduce the bias or errors caused by only using artificial nests. We also recommend the use of infrared cameras in future nest predation studies, which has obvious advantages in monitoring and identifying potential predators.

The function of avian mobbing: an experimental test of ‘attract the mightier’ hypothesis

Various avian species give mobbing calls that draw conspecific and heterospecific individuals to react against the potential predator. According to the ‘attract the mightier’ hypothesis, when predators appear, prey will produce mobbing calls to attract superior predators to repel or kill the primary predator. To test this hypothesis, we broadcast calls from light-vented bulbuls, Pycnonotus sinensis (the prey) in the vicinity of a taxidermy model of a collared scops owl, Otus lettia (the primary predator). Three call types were used: the typical call (TC, the control treatment), a mobbing call to a collared scops owl (the MtO treatment) and a mobbing call to a crested goshawk, Accipiter trivirgatus (the superior predator; the MtH treatment). Our results showed that crested goshawks appeared and attacked the taxidermy model during the MtO treatment, but not during the control or MtH treatment. The difference between the MtO and other treatments was significant. Our results, therefore, provide strong evidence for the hypothesis that mobbing calls to primary predators can successfully attract superior predators to harm primary predators.

Flush early and avoid the rush? It may depend on where you stand

AbstractOptimal escape theory predicts that animals should flee at an optimal distance from the approaching predator (flight initiation distance, FID). However, FID usually increases with increasing alert distance (AD) or starting distance (SD). As an explanation for this pattern, the “flush early and avoid the rush” (FEAR) hypothesis states that prey should escape soon after detecting an approaching predator due to the cost of continuously monitoring risk. However, the positive relationship observed may also result from a mathematical artefact. Meanwhile, it is unknown whether animals would consistently follow this rule in different environmental contexts. We explored escape behaviours in light‐vented bulbuls (Pycnonotus sinensis) perched at different heights. FID generally increased with increasing AD and decreasing perch height. The positive relationships between AD and FID were outside the 95% confidence levels of simulated slopes from Monte Carlo simulations, suggesting that the relationships observed reflect biological effects rather than merely a mathematical artefact. Increasing perch height was also associated with longer buffer distance (defined as FID minus AD or SD), suggesting that the birds tend to delay their flush after detecting an approaching predator when perched high. The effects of environmental contexts (and the associated predation risk) on the AD‐FID relationship should be considered when performing inter‐specific comparisons or meta‐analyses.

Nest site selection for five common birds and their coexistence in an urban habitat

Many species of birds gradually adapt to urbanization and colonize cities successfully. However, their nest site selection and competitive relationship in an urban community remain little known. Understanding the impact of urbanization on birds and the competitive relationship has important implications for the conservation and management of wildlife in urban ecosystems. Here, we undertook a systematic study to quantify nests in all species of birds in an urbanizing area of Nanchang, China. A total of 363 nests were detected in surveys including 340 nests of 16 bird species and 23 unidentified species nests. We mainly analyzed 5 dominant breeding birds with a sample size of >10 during the two breeding seasons (From April to July in 2016 and 2017), which included the light-vented bulbul, Chinese blackbird, scaly-breasted munia, spotted dove and grey-capped greenfinch. Most birds (93.66%) nested in the tree of artificial green belts, which seems to be the best breeding habitat for urban birds. Our results suggested that birds' breeding success relies on the trade-off between the benefit and the expense of specific stresses from habitats. The nest site selection of birds is also affected by the life habit of urban predators. Furthermore, competition among species can influence their distributions and utilization of environmental resources when birds nest in cities. We confirmed that the niche differentiation of five bird species in an urban environment makes them coexist successfully by utilizing various resources.

플라스틱 유색가락지에 의한 흰배지빠귀(Turdus pallidus)와 검은이마직박구리(Pycnonotus sinensis)의 발가락 끼임과 부상

플라스틱 유색가락지는 수많은 생태학 및 조류학 현장 연구에 흔히 사용되고 있으나, 참새목 조류에서 유색가락지로 인한 부상에 대한 기록은 드문 실정이다. 본 연구는 전남 신안군 홍도에서의 가락지 부착조사 과정에서 최초 포획된 날로부터 596일 후 재포획된 흰배지빠귀(Turdus pallidus)가 분할식 다빅(Darvic) 유색가락지로 인해 발가락이 소실되었음을 확인하고 이를 처음으로 보고한다. 또 인접한 흑산도에서는 포획된 지 135일 후에 재관찰된 검은이마직박구리(Pycnonotus sinensis)의 왼쪽 뒷발가락이 유색가락지 안쪽에 끼어있는 사례도 함께 확인하였다. 유색가락지를 부착한 산새류 1,900여 개체에서 확인된 두 사례를 바탕으로, 향후 유색가락지의 사용과 부착에 있어서 일반적인 유색가락지 부착지침을 따르는 신중한 접근법을 강조한다.

Food restriction decreases BMR, body and organ mass, and cellular energetics, in the Chinese Bulbul (Pycnonotus sinensis)

BackgroundFood is an important environmental factor that affects animals’ energy metabolism and food shortage has significant effects on animals’ behavior, physiology and biochemistry. However, to date few studies have focused on the thermogenesis and its effects on the body condition of birds. In this study, we examined the effects of food restriction on the body mass, basal metabolic rate (BMR) and body composition, and several physiological, biochemical and molecular markers potentially related to thermogenesis, in the Chinese Bulbul (Pycnonotus sinensis).MethodsBirds in the control group were provided with food ad libitum whereas those in the food restriction group were provided with one-half of the usual quantity of food for 12 days. Oxygen consumption was measured using an open-circuit respirometry system. Mitochondrial state 4 respiration and cytochrome c oxidase (COX) activity in the liver and pectoral muscle were measured with a Clark electrode. Avian uncoupling protein (avUCP) mRNA expression was determined in pectorals muscle with quantitative Real-time PCR.ResultsChinese Bulbuls in food restriction group decreased in body mass, BMR and internal organ (heart, kidneys, small intestine and total digestive tract) mass compared with the control group over the 12-day period of food restriction. Bulbuls in the food restriction group also had lower levels of state-4 respiration, COX activity in the liver and muscle, and mitochondrial avUCP gene expression in muscle compared to the control group. BMR was positively correlated with body mass, state 4 respiration in the liver and COX activity in the muscle.ConclusionsOur data indicate that Chinese Bulbuls not only sustain food shortage through simple passive mechanisms, such as reducing body and organ mass and energy expenditure, but also by reducing energetic metabolism in the liver and muscle.

Arsenic concentrations and speciation in wild birds from an abandoned realgar mine in China

Birds are at a higher level in the food chain; however, the potential bioaccumulation and biotransformation of arsenic (As) in birds in As mines has rarely been studied. In this study, four passerine bird species (tree sparrow [Passer montanus], light-vented bulbul [Pycnonotus sinensis], Garrulax canorus [Leucodioptron canorus], and magpie [Pica pica]) were collected from an abandoned As mine in China. The highest recorded As concentrations were 4.95 mg/kg and 51.65 mg/kg in muscles and feathers, respectively. Detection using high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS) revealed six As species, including arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenobetaine (AsB) and arsenocholine (AsC), with the former three species as the dominant (>92%) and the latter three as the minor As species (<6.17%). Further analysis of the selected bird samples using the X-ray absorption near edge structure (XANES) technique revealed the existence of As(III)-tris-glutathione (As(III)-GSH), which can be regarded as equivalent to the non-extractable and unidentified As form in the HPLC-ICP-MS data. Both methods revealed similar patterns of As species in the birds from the As mine, with muscles containing mainly inorganic As and DMA and feathers containing mainly inorganic As. The results of this study contribute to the knowledge regarding As accumulation and speciation in terrestrial organisms.

Temperature and photoperiod as environmental cues affect body mass and thermoregulation in Chinese bulbuls, Pycnonotus sinensis.

Seasonal changes in temperature and photoperiod are important environmental cues used by small birds to adjust their body mass (Mb) and thermogenesis. However, the relative importance of these cues with respect to seasonal adjustments in Mb and thermogenesis is difficult to distinguish. In particular, the effects of temperature and photoperiod on energy metabolism and thermoregulation are not well known in many passerines. To address this problem, we measured the effects of temperature and photoperiod on Mb, energy intake, resting metabolic rate (RMR), organ mass and physiological and biochemical markers of metabolic activity in the Chinese bulbul (Pycnonotus sinensis). Groups of Chinese bulbuls were acclimated in a laboratory to the following conditions: (1) warm and long photoperiod, (2) warm and short photoperiod, (3) cold and long photoperiod, and (4) cold and short photoperiod, for 4 weeks. The results indicate that Chinese bulbuls exhibit adaptive physiological regulation when exposed to different temperatures and photoperiods. Mb, RMR, gross energy intake and digestible energy intake were higher in cold-acclimated than in warm-acclimated bulbuls, and in the short photoperiod than in the long photoperiod. The resultant flexibility in energy intake and RMR allows Chinese bulbuls exposed to different temperatures and photoperiods to adjust their energy balance and thermogenesis accordingly. Cold-acclimated birds had heightened state-4 respiration and cytochrome c oxidase activity in their liver and muscle tissue compared with warm-acclimated birds indicating the cellular mechanisms underlying their adaptive thermogenesis. Temperature appears to be a primary cue for adjusting energy budget and thermogenic ability in Chinese bulbuls; photoperiod appears to intensify temperature-induced changes in energy metabolism and thermoregulation.

Dispersal of invasive Phytolacca americana seeds by birds in an urban garden in China

Although seed dispersal is a key process determining the regeneration and spread of invasive plant populations, few studies have explicitly addressed the link between dispersal vector behavior and seedling recruitment to gain insight into the invasion process within an urban garden context. We evaluated the role of bird vectors in the dispersal of pokeweed (Phytolacca americana), a North American herb that is invasive in urban gardens in China. Fruiting P. americana attracted both generalist and specialist bird species that fed on and dispersed its seeds. The generalist species Pycnonotus sinensis and Urocissa erythrorhyncha were the most frequent dispersers. Seedling numbers of P. americana were strongly associated with the perching behavior of frugivorous birds. If newly recruited bird species use seedling-safe perching sites, the P. americana will regenerate faster, which would enhance its invasive potential. Based on our observations, we conclude that the 2 main bird vectors, P. sinensis and U. erythrorhyncha, provide potential effective dispersal agents for P. americana. Our results highlight the role of native birds in seed dispersal of invasive plants in urban gardens.

Effects of temperature and photoperiod on body mass, energy budget and digestive tract morphology in Pycnonotus sinensis.

Temperature and photoperiod are proximate environmental factors that have an important influence on the morphological, physiological and behavioral adjustments animals performance du-ring seasonal acclimatization. In this study, the effects of temperature and photoperiod on phenotypic flexibility in body mass, energy budget and digestive tract morphology in the Chinese bulbul (Pycnonotus sinensis) were examined, and the relationship between energy budget and digestive tract morphology was analyzed. Twelve male and sixteen female Chinese bulbuls were randomly assigned into 4 experimental groups so that each group was comprised of three males and four females. The groups were: 1) a warm and long photoperiod (30 ℃, 16 light: 8 dark) group, 2) a warm and short photoperiod (30 ℃, 8 light: 16 dark) group, 3) a cold and long photoperiod (10 ℃, 16 light:8 dark) group, and 4) a cold and short photoperiod (10 ℃, 8 light: 16 dark) group. Each group was acclimated to its respective temperature and photoperiod for 4 weeks. Birds in the cold temperature and short photoperiod group underwent a significant increase in body mass, gross energy intake (GEI) and digestible energy intake (DEI) compared to the other three groups, and there was a significant interaction between temperature and photoperiod on gross energy intake and diges-tible energy intake. The mass of the stomach, small intestine, rectum, and total digestive tract, all increased significantly in cold temperature treatment groups compared to those acclimated to a relatively warm temperature. There was a significant, positive correlation between GEI and DEI resi-duals and those of the length and dry mass of the small intestine and total digestive tract. These results suggested that the Chinese bulbul met the increased energy demands of winter (colder tempe-ratures and reduced foraging time due to shorter day-length) by increasing its body mass, digestible energy intake and digestive tract size.

Contaminants of legacy and emerging concern in terrestrial passerines from a nature reserve in South China: Residue levels and inter-species differences in the accumulation

Knowledge is limited about the bioaccumulation of persistent halogenated compounds (PHCs) in terrestrial wildlife. Several PHCs, including dichlorodiphenyltrichloroethane (DDT) and its metabolites (designated as DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenylethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and stable isotopes (δ15N and δ13C) were analyzed in the muscle of four terrestrial passerines, Parus major, Copsychus saularis, Pycnonotus sinensis and Pycnonotus jocosus, from a nature reserve in South China. P. major had the highest PHC concentrations, with median values of 1060, 401, 92, 25 and 0.3 ng/g lipid weight for DDTs, PCBs, PBDEs, DBDPE and BTBPE, respectively. Fractions of DDT in P. jocosus and PCBs 153, 118 and 180 in C. saularis were higher compared with the other species. The inter-species differences in PHC concentrations and profiles could be attributed to the differences in trophic level, diet, living habits and metabolic capacity among the birds.

Effect of food restriction on the energy metabolism of the Chinese bulbul (Pycnonotus sinensis).

Food resources play an important role in the regulation of animals' physiology and behavior. We investigated the effect of short-term food restriction on metabolic thermogenesis of Chinese bulbuls (Pycnonotus sinensis) by measuring changes in body mass, body fat, basic metabolic rate (BMR), and organ mass of wild-caught Chinese bulbuls from Wenzhou, China. Short-term food restriction induced a significant decrease in body mass and body fat but body mass returned to normal levels soon after food was no longer restricted. Food restriction caused a significant reduction in BMR after 7 days (P<0.05), which returned to normal levels after food restriction ceased. Log total BMR was positively correlated with log body mass (r(2)=0.126, P<0.05). The dry masses of livers and the digestive tract were higher in birds that had been subject to temporary food restriction than in control birds and those subject to continual food restriction (P<0.001 and P<0.05, respectively). There was also significant differences in the dry mass of the lungs (P<0.05), heart (P<0.01), and spleen (P<0.05) in birds subject to short-term food restriction compared to control birds and those subject to continual food restriction. BMR was positively correlated with body and organ (heart, kidney and stomach) mass. These results suggest that the Chinese bulbul adjusts to restricted food availability by utilizing its energy reserves, lowering its BMR and changing the weight of various internal organs so as to balance total energy requirements. These may all be survival strategies that allow birds to cope with unpredictable variation in food abundance.

Accumulation of Dechlorane Plus flame retardant in terrestrial passerines from a nature reserve in South China: The influences of biological and chemical variables

Although a number of studies have addressed the bioaccumulation of Dechlorane Plus (DP) flame retardant in wildlife, few data are available on terrestrial organisms. This study examined the presence of DP isomers in the muscle tissue of seven terrestrial resident passerine species, i.e., the great tit (Parus major), the oriental magpie-robin (Copsychus saularis), the red-whiskered bulbul (Pycnonotus jocosus), the light-vented bulbul (Pycnonotus sinensis), the streak-breasted scimitar babbler (Pomatorhinus ruficollis), the long-tailed shrike (Lanius schach), and the orange-headed thrush (Zoothera citrina), from a national nature reserve located in South China. The ∑DP (sum of syn-DP and anti-DP) concentrations ranged from 1.2 to 104ng/g lipid weight, with significantly higher levels in insectivorous birds than in omnivorous birds. The overall exposure to DP isomers of the current passerines may be attributed to the intensive release of this pollutant from electronic waste recycling sites and industrial zones in the vicinity of the nature reserve. Species-specific DP isomeric profiles were also found, with significantly greater fanti values (the isomer fractions of anti-DP) in the red-whiskered bulbul and the oriental magpie-robin. Additionally, the fanti values were significantly negatively correlated to ∑DP concentrations for the individual bird samples, suggesting the influence of DP concentrations on the isomeric profiles.