Emberiza Bruniceps Research Articles

Role of differential food treatment on hypothalamic NPY expression and migratory phenology of redheaded bunting (Emberiza bruniceps)

ABSTRACT The present study explores the effect of differential food treatment on the migratory phenology of redheaded bunting (Emberiza bruniceps). Birds were divided into four groups (N = 10 each) on the basis of the food provided. Group I was fed with seeds of Setaria italica (kakuni), while group II was provided with protein-rich diet (combination of; 3 parts egg white and 1 part kakuni seeds). Likewise, group III birds received fat-rich food (i.e. 3 parts sesame seeds and 1 part kakuni seeds). Birds in group IV were provided with all three food items mentioned above separately. The experiment continued until the appearance of 7 cycles of zugunruhe. The results reveal a significant impact of food on locomotor activity and food intake behavior of birds, although the physiological response as demonstrated by a gain in body mass, fat score, and gonadal recrudescence was mainly influenced by the LHS. Besides the behavioral and physiological responses, the hypothalamic expression of neuropeptide Y (NPY) in infundibular complex (INc) was significantly high for group IV, highlighting the importance of “variety” in food intake. Thus, the present study suggests a significant role of food in influencing seasonal responses via hypothalamic NPY stimulation.

Rising global temperatures and its impact on sleep behavior of male redheaded bunting (Emberiza bruniceps).

Anthropogenic global warming is one of the most pervasive threats to nature and biodiversity. The magnitude with which earths' temperature is rising is affecting every lifeform uniquely; however, the studies highlighting the impacts of global warming on avian sleep are scarce. To this end, the present study was aimed at analyzing the impact of global warming on sleep behavior of a nocturnal migrant, Emberiza bruniceps. For this purpose, the birds were divided into two groups (N = 15 each), subjected to high (35 ± 1°C) and low (19 ± 1°C) temperature schedule with concurrent exposure to 8L:16D (short day; SD) photoperiod followed by 13L:11D (long day; LD). The experiment continued till 7 cycles of zugunruhe (LD) in birds. The results reveal significant impact of temperature treatment on initiation and quality of zugunruhe. Temporal distribution of activity and rest varied according to the temperature provided. Focusing on rest and specifically on sleep of birds, high ambient temperatures resulted in greater sleep fragmentation (evident by increased awakenings during night), whereas low temperature created a sleep conducive environment (evident by abundance of back sleep). Besides postural differences, high temperature resulted in reduced sleep duration, sleep onset latency and circulating plasma melatonin levels in comparison with low temperature suggesting the negative impact of high temperature on different sleep attributes. Not only sleep, seasonal physiology of birds such as hyperphagia, gain in body mass, and fat stores showed significant reduction in high temperature condition. Besides behavioral and physiological alterations, high ambient temperature led to elevated expression of temperature sensitive (trpv4, trpm8, hspa8, and hsp70) genes. Enhanced expression of chrm3 (responsible for wakefulness) also affirms sleep fragmentation in response to high temperature. Thus, the study highlights the negative impact of high temperature on birds' sleep behavior and seasonal physiology.

Inter-organ differences in redox imbalance and apoptosis depict metabolic resilience in migratory redheaded buntings

Migration, a bird’s metabolic apex, depends primarily on the liver and muscle for fuel mobilization and endurance flight. In migratory redheaded buntings, adaptive increase in mitochondrial membrane (MM) proton gradient to drive ATP synthesis, measured by MM potential (MMP+) and reactive oxygen species (ROS) response, have been well characterized in the blood but not in the muscle or liver. We assessed MMP+, ROS, and apoptosis in the liver and pectoralis muscle of photosensitive nonmigratory (nMig.) male redheaded buntings photoinduced to migratory (Mig.) states. Relative expression levels of genes associated with energy (ACADM, PEPCK, GOT2, GLUT1, and CS), ROS modulation (SIRT1), mitochondrial free-radical scavengers (SOD1, PRX4, NOS2, GPX1, and GPX4), anti-apoptotic genes (NF-κβ), apoptotic (CASP7), and tissue damage using histology, during migration were assessed. The MMP+ decreased and the ROS concentration increased, due to the metabolic load on liver and pectoralis muscle tissues during Mig. However, percentage of apoptotic cells increased in liver but decreased in muscle, which is of functional significance to migratory passerines. During Mig., in muscle, SIRT1 increased, while an increase in anti-apoptotic NF-κβ aided immune pathway-mediated antioxidant activity and guarded against muscle oxidative damage during migration. Inter-organ differences in metabolism add to our current understanding of metabolic flexibility that supports successful migration in buntings.

Effect of Photoperiod and Illuminance on Daily Activity Patterns, Physiology, and NPY Peptide Expression in Migratory Redheaded Buntings (Emberiza bruniceps)

Introduction: Light is the primary source of energy and regulates seasonal changes in physiology and behavior. The role of photoperiod has been much investigated in several bird species, but the role of illumination in seasonal adaptations of passerine finches is less understood. We, therefore, investigated the effects of photoperiod and illuminance on migratory physiology in a Palearctic-Indian migratory finch, redheaded bunting (Emberiza bruncieps). Methods: Photosensitive buntings maintained under short days (8L:16D) were divided into three groups receiving 5, 25, and 100 lux of white daytime illuminance, respectively. Thereafter, using photoperiodic manipulation three life history states, i.e., nonmigratory (NM), premigratory (PM), and migratory (MIG) states were induced in the buntings. The birds in the MIG state were consecutively perfused after seven nights of Zugunruhe (nighttime migratory restlessness) for neuropeptide Y (NPY)-immunohistochemistry, which is involved in a wide range of functions including energy homeostasis, vision, and fat deposition in birds. Results: We found differential effects of illuminance on locomotor activity and physiology. Photostimulated birds showed intense nighttime activity in the MIG state. We observed premigratory hyperphagia in the birds, with increased food intake in the 100 lux group, which was reflected in the body mass gain in the MIG state. NPY expression on the periphery of the nucleus rotundus suggests its potential role in visual acuity, where the NPY-cell count significantly decreased under 25 lux illumination. Conclusion: We demonstrate that migrating birds may also experience physiological effects from changes in daytime illumination. We observed illuminance-dependent variations in the quantity of food consumed by the birds. It indicates that the illuminance may also impact the encephalic centers that control food intake.

Food monotony compromises photoperiod induced responses in migratory redheaded bunting

Food is one of the key environmental factors affecting an organism’s behavior and physiology on daily and seasonal basis. Over the years, studies regarding human food habits and its subsequent impact on their behavior and physiology have been explored a lot but studies on same line are missing with reference to different animal taxa. Thus, in the present study, we investigated the impact of varied food availability over a monotonous food schedule on birds. We were interested in knowing how this treatment affects the birds’ behavior and physiology? The experiment was performed on migratory passerine finch; redheaded bunting ( Emberiza bruniceps), wherein two groups of bird ( N = 10 each) were taken. Group I (Kakuni group; KG) birds were fed only with seeds of Setaria italica (Kakuni) whereas group II (Mixed Diet group; MG) was provided with seeds of kakuni along with sesame seeds ( Sesamum indicum) and egg white, all three separately in different bowls. Results reveal that behaviorally, MG birds were more active with higher gross food intake when compared with KG. MG birds also had significant gain in body mass and testicular volume during the course of experiment, although, the accumulation of fat remained unchanged between the two groups. Thus, the study clearly demonstrates the motivation to eat and stay active besides being reproductively proficient in presence of varied food availability.

Altered dynamics of mitochondria and reactive oxygen species in the erythrocytes of migrating red-headed buntings.

Background: Blood antioxidants provide propensity to mitigate reactive oxygen species (ROS) apart from other oxidative challenges during a high-energy state of migration in night migratory songbirds. The study investigated the modulation of erythrocytes, mitochondrial abundance, hematocrit changes, and relative expression of fat transport-related genes during migration in red-headed buntings (Emberiza bruniceps). We hypothesized an increase in antioxidants along with the mitigation of mitochondria-related reactive oxygen species elevation and consequential apoptosis occurring during migration. Methods: Male red-headed buntings (n = 6) were placed under short days (8h of light and 16h of dark, 8L:16D)/long days (14L:10D) and photo induced to simulated non-migratory, nMig; pre-migratory, pMig; and migratory, Mig, states. Erythrocyte shape, reactive oxygen species production, mitochondrial membrane potential (MMP), reticulocyte proportion, and apoptosis were analyzed using flow cytometry and relative expression of fat metabolizing and antioxidant genes was measured by using qPCR. Results: There was a significant increase in hematocrit, erythrocyte area, and mitochondrial membrane potential. Reactive oxygen species and apoptotic erythrocyte proportion declined in the Mig state. The changes in antioxidant genes (SOD1 and NOS2), fatty acid translocase (CD36), and metabolic (FABP3, DGAT2, GOT2, and ATGL) genes showed a significant increment during the Mig state. Conclusion: These results suggested that adaptive changes occur in mitochondrial behavior and apoptosis of erythrocytes. The transition in erythrocytes, antioxidant genes, and fatty acid metabolism gene expressions suggested differences in regulatory strategies at the cellular/transcriptional level during different states of simulated migration in birds.

Photoperiod-driven concurrent changes in hypothalamic and brainstem transcription of sleep and immune genes in migratory redheaded bunting.

The molecular regulation of sleep in avian migrants is still obscure. We thus investigated this in migratory redheaded buntings, where four life-history states (LHS; i.e. non-migratory, pre-migratory, migratory and refractory states) were induced. There was increased night-time activity (i.e. Zugunruhe) during the migratory state with reduced daytime activity. The recordings of the sleep-wake cycle in buntings showed increased night-time active wakefulness coupled with drastically reduced front and back sleep during migratory phase. Interestingly, we found the buntings to feed and drink even after lights-off during migration. Gene expression studies revealed increased hypothalamic expression of glucocorticoid receptor (nr3c1), and pro-inflammatory cytokines (il1b and il6) in pre-migratory and migratory states, respectively, whereas in brainstem Ca2+/calmodulin-dependent protein kinase 2 (camk2) was upregulated during the migratory state. This suggested a heightened pro-inflammatory state during migration which is a feature of chronic sleep loss, and a possible role of Ca2+ signalling in promoting wakefulness. In both the hypothalamus and brainstem, the expression of melatonin receptors (mel1a and mel1b) was increased in the pre-migratory state, and growth hormone-releasing hormone (ghrh, known to induce sleep) was reduced during the migratory state. The current results demonstrate key molecules involved in the regulation of sleep-wake cycle across LHS in migratory songbirds.

Photoperiodic modulation of melatonin receptor and immune genes in migratory redheaded bunting

The transcriptional regulation of innate immune function across annual life history states (LHS) remains obscure in avian migrants. We, therefore, investigated this in a migratory passerine songbird, redheaded bunting (Emberiza bruniceps), which exhibits long-distance vernal migration from India to Central Asia. We exposed the birds (N = 10) to differential photoperiodic conditions to induce a non-migratory (NM), pre-migratory (PM), migratory (MIG), and refractory (REF) state, and performed gene expression assays of melatonin receptors (MEL1A and MEL1B), and innate immunity-linked genes (IL1B, IL6, TLR4, and NFKB) in spleen and blood. We found a significant reduction in splenic mass and volume, and a parallel increase in fat accumulation, and testicular growth in birds under migratory state. The gene expression assay revealed an upregulation of MEL1A and MEL1B mRNA levels in both the tissues in MIG. Additionally, we found a nocturnal increase of splenic IL1B expression, and IL1B, IL6, and TLR4 expression in the blood. The mRNA expression of melatonin receptors and proinflammatory cytokine showed a positive correlation. These results suggest that melatonin relays the photoperiodic signal to peripheral immune organs, which shows LHS-dependent changes in mRNA expression of immune genes.

Morphology and morphometry of two hybridizing buntings at their hybrid zone in northern Iran reveal intermediate and transgressive morphotypes

The closely related Black-headed Bunting (Emberiza melanocephala, a western Palearctic lineage) and Red-headed Bunting (Emberiza bruniceps, an eastern Palearctic lineage) hybridize and replace each other south of the Caspian Sea. The parental species have distinct phenotypes and therefore morphology is useful for assessing hybridization in the contact zone. In the years of 1940 and 1977, quite a few hybrids were collected and studied morphologically. Since then, the hybrid zone appears to have expanded westwards, but there has been a time gap in the collection of morphological data. Here we reanalyze bunting specimens morphologically and compare the historical data with recent data. Morphometric and phenotypic traits from three time periods (1940, 1977 and recent) were studied to assess phenotypic variation of hybrids, pattern of hybridization, and transgressive traits in the hybrid zone. Our results show that most of the birds in the hybrid zone exhibit intermediate phenotypes (both colors and morphometric characters), ranging from the pure phenotype of either of the parental species. However, hybridization has also produced novel phenotypes not seen in any of the parents. Using a canonical discriminant function analysis, the morphometric characters separated each parental species and the hybrids quite well. Our results showed morphometric intermediacy of hybrids in accordance with phenotypes. We observe a time trend in which recent hybrids are more similar to Red-headed Buntings phenotypically compared to historical samples. This pattern is likely a signature of a westward expansion of the Red-headed Bunting into the breeding range of the Black-headed Bunting.

Изменение структуры населения птиц под воздействием антропогенных факторов в долине р. Угам (Западный Тянь-Шань)

The article addresses the issues of changes in the species composition and number of birds in the middle part of the valley of the Ugam River. The valley has been mastered by humans since ancient times, but due to its geographical location, the possibilities for conducting economic activities in it have always been limited, and its intensity has its own characteristics. Here, the location of the only settlement changed, orchards were planted and cut down, cattle were grazed everywhere or in the vicinity of the village, hayfields were mowed or abandoned, and field roads were laid and overgrown. The inclusion of the territory in the Sairam-Ugam National Park has reoriented human activities. The construction of tourist facilities has begun and continues here, which has led to an increase in the number of lovers of outdoor recreation. All this was reflected in the birds of the valley, which are very sensitive to environmental changes. This is especially noticeable in mountainous conditions, where the concentration of nesting species is not high, the main routes of migrants go along the foothills, and wintering conditions are not favorable. The first data on the avifauna of this section of the valley were obtained by M.N. Korelov in the summer and autumn of 1949 and later collected by the author in May 2003, July 2011, and 2022, which made it possible to analyse its species-specific variation. Over 70 years of observations, 127 bird species were encountered here, of which 114 were in 1949, 53 were in 2003, 54 were in 2011, and 44 were in 2022. The structure of the bird population in the valley also changed. This is especially noticeable in July 2003 and 2022, when the studies were carried out on the same days. In the first year, human activity was limited to the outskirts of the village, and in the second year, it was carried out throughout the entire section of the valley. In the first year, 617 individuals were encountered in 4 days; in the second year, 307, i.e., twice as small. In 2003, the main bird populations were Corvus corone (11.4% of the number of birds encountered), Pica pica (11.2%), Emberiza bruniceps (9.4%), Acridotheres tristis (7.3%), Emberiza cia (6.6%), Lanius minor (5.7%) and Carduelis caniceps (5.3%), and in 2022, Chloris chloris (12.4%), Ac. tristis (12.1%), C. caniceps (11.4%), Streptopelia orientalis (6.6%), C. corone (4.5%), P. pica and Em. bruniceps (3.8% each). With the development of the valley by humans, the species ratio of birds also changed. In 1949, species whose life is exclusively associated with humans were not recorded here; in 2003, 2011, and 2022, they included 5 species (Columba livia, Streptopelia senegalensis, Hirundo rustica, H. daurica, and Acridotheres tristis), which accounted for 14.2, 29.0, and 10.3% of the number of individuals encountered, respectively. The number of species indifferent to the place of residence, but preferring natural biotopes, has been stable over the years - 16, 17, 15 and 16, but changed quantitatively (50.0, 31.1 and 45.7% in 2003, 2011 and 2022). During the same period, the diversity of species living in natural biotopes also decreased (32, 27, and 25). All these and other issues are discussed in the analysis of each bird species, and it is shown that the increased anthropotization of the valley leads to a reduction in species diversity, the number of birds living here and to the loss of its uniqueness.

О некоторых консортивных связях птиц и растений-эфемероидов

The use of ephemeroids in feeding and as nest material by birds is assessed in this report. The consumption of 18 species of plants by Alectoris chukar and Phasianus colchicus both in nature (Trans Ili Alatau) as well as in culture (collection of the Botanical Garden of Almaty) was noted. In the Western Tien Shan, Passer hispaniolensis and Emberiza bruniceps utilized seven species of ephemeroids for nest building, most often Gymnospermium alberti, Ranunculus regelianus and Poa bulbosa. In the nests of six other passerine species, individual parts of such plants are less common and are used only as an admixture.

Hypothalamic molecular correlates of photoperiod-induced spring migration in intact and castrated male redheaded buntings

This study investigated the molecular changes associated with neural plasticity in photoperiodic induction of spring migration in intact and castrated redheaded bunting, Emberiza bruniceps. We measured the hypothalamic mRNA expression of genes in birds that were photostimulated into winter non-migratory and spring (vernal) migratory phenotypes under short and long photoperiods, respectively. These included genes associated with the appetitive phase of reproduction (spring migration drive, th and ddc genes encoding for tyrosine hydroxylase and dopamine decarboxylase enzymes, respectively), sleep/awake state (pmch gene encoding for pro-melanin concentrating hormone; hcrt and hcrtr2 encoding for the hypocretin/orexin and its receptor, respectively) and neurogenesis (dcx and neuN coding for doublecortin and neuronal nuclear proteins, respectively). Higher th mRNA levels suggested an upregulated dopamine synthesis in the hypothalamus of spring migrants. Similarly, elevated hcrt and hcrtr2 mRNA levels suggested an increased wakefulness, and those of dcx and neuN genes suggested an enhanced neurogenesis during the spring migration state. Further, compared to intact birds, the lower th and pmch, and higher hcrtr2 and neuN mRNA levels in castrates suggested a role of testicular steroids in modulation of the appetitive phase of reproduction, sleep and awake states, and neurogenesis during spring migration period. These results provide insights into molecular changes linked with important hypothalamic molecular pathways and steroidal influence in the photoperiodic induction of spring migration in obligate migratory songbirds.

Circadian activity in different photoperiod (12L: 12 D) and (8L: 16D) in passerine finches

Circadian rhythms are more synchronized in birds than mammals. Circadian clock functions as a timing reference allow organisms fluctuations in their environments and are the basis for the transduction of seasonality from photoperiod. The present study was performed to determine the effect of constant dim and bright light illumination on circadian behavior of baya weaver bird ( Ploceus philippinus), black-headed munia ( Lonchura malaca malaca), and red-headed bunting ( Emberiza bruniceps). It analyzed the data of locomotors activity of these under the effect of different photoperiods (12L: 12D and 8L: 16D) for a period of 30 days. In the captivity, birds were acclimatized for 4 weeks and were subjected to photoperiodic chambers (60×45×35 cm3) providing short-day conditions (8h light: 16h darkness; 8L:16D). Total activity profile was observed for 30 days under 12L: 12D and 8L: 16D photoperiod. Under 12 L: 12D photoperiod, significant response was observed in two of the four birds in daily profile of baya weaver bird and also in black-headed munia but the marginal significant response noticed in one of the four birds under 8L: 16D. The comparison of day and night total activity count in baya weaver bird and black-headed munia showed the maximum activity in weaver bird under 12L: 12D photoperiod.

Distribution modeling of the hybrid sister taxa in red-headed bunting and black-headed bunting, Order Passeriformes

سابقه و هدف: جدایی گونه ها بر مبنای نتایج فیلوژنی می تواند با مدل سازی هایی که ورودی آنها داده های زیستگاهی هستند، پشتیبانی شود. در مطالعه حاضر دو آرایه خواهری که براساس مستندهای مولکولی جدا از هم هستند، از نظر عامل های تأثیرگذار زیستگاهی که احتمالا در این جدایی دخیل بوده اند و همچنین از نظر پراکنش در برهه تاریخی گذشته و آینده، مورد بررسی قرار گرفته اند. گونه ها ی مورد مطالعه شامل زردپره سرسرخ و زردپره سرسیاه از راسته گنجشک سانان هستند.موا د و روش ها: در راستا ی مدل سازی توزیع گونه ها ، متغیرهای زیست اقلیمی از پایگاه داده CHELSA به همراه متغیرهای ارتفاع، شیب و سنجه پوشش گیاهی به عنوان داده های زیستگاهی برای ورود به مدل مورد استفاده قرار گرفتند. همچنین نقاط حضور گونه ها پس از جمع آوری در بازه تولیدمثلی غربالگری شد ه و به عنوا ن داده تعلیمی به مدل ها اضافه شد. در این مطالعه جهت مدل سا زی از پکیج sdm شامل 8 مدل ( GLM ، GAM ، BRT ، RF ، CART ، SVM ، MaxEnt و MARS ) در محیط نرم افزار R استفاده گردید. مدل سازی توزیع گونه ها در برهه زمانی آخرین دوره یخبندان، حال حاضر ( 1997 - 2013 ) و سال 2050 انجام شد.نتایج و بحث: نتایج جدایی پردازه اکولوژیکی، گونه ها را تحت تأثیر متغیرهای محیطی نشان داد. مطابق نتایج ارزیابی صحت، معتبرینمدل از نظر سنجه TSS و AUC ، مدل جنگل تصادفی برآورد شد. همچنین بنابر نتایج، در سال 2050 زیستگاه ها ی مطلوب برای گونهزردپره سرسرخ محدو د به شمال شرق کشور و برای گونه زردپره سرسیاه مطلوبیت محدود به منطقه ها یی در جنوب رشته کوه البرز، شمال غرب و غرب ایران خواهد بود. مطابق با نتایج، وسعت زیستگاه های مطلوب برای گونه زردپره سرسیاه در غرب نسبت به امروز کمتر بوده است که بنابر مطالعات صورت گرفته ظاهرا عامل های درونی و اقلیمی هردو در تغییرات محدوده پراکنش دو گونه تأثیرگذار بوده اند. نتایج تحقیق گویای کاهش مطلوبیت زیستگاه برای گونه های مورد مطالعه در هر دو بازه زمانی (آخرین عصر یخبندان تا حال حاضر و حال حاضر تا سال 2050) می باشد.نتیجه گیری: شناخت عامل های تأثیرگذار بر تعیین مطلوبیت زیستگاه های حیات وحش ضروری است. برخی تغییرات ناشی از دستکاریاکوسیستم به شدت د ر محدوده پراکنش گونه ها اثر گذاشته است . پیش بینی کاهش مطلوبیت زیستگاه در آینده و ادامه روند از بین رفتن آن، پایش مستمر نواحی متمرکز پراکنش و اجرای تمهیدهای پیشگیری از تخریب این زیستگاه ها را می طلبد. همینطور منطقه های مستعد برای دورگه زایی گونه های خواهری که از استعداد ذاتی برای دورگه زایی برخوردارند، باید بیشتر مورد توجه و دقت قرار گیرند و تغییرات آنها تحت تأثیر شرایط اقلیمی آینده با حساسیت بیشتری مورد نظارت پیوسته قرار گیرد .

Short term effects of restricted food availability and peripheral leptin injections in redheaded bunting, Emberiza bruniceps

Migratory birds need continued food supply and efficient metabolic machinery to meet high energy demands of the magnanimous feat of flight. Two questions are important i.e. as to 1) how a bird adapts to a temporary food constrain on a daily basis, and 2) how peripheral leptin, an anorectic hormone, impacted feeding and migratory behaviour in buntings? The aim of this study was to induce a non-photoperiodic tweak in the physiology of redheaded buntings through exogenous leptin administration and study its effect on their food intake and migratory behaviour. Groups of male redheaded buntings, Emberiza bruniceps (n=17) were transferred from short (8L: 16D) to long (16L: 8D) days and presented with food only either for first (morning food presence, MFP) or second (evening food presence, EFP) half of the 16h lighted phase, while control group received food ad libitum. Total daily food intake (FI) did not differ significantly between the MFP, EFP and controls, but hourly FI in MFP and EFP indicated increased activity differences based on time of food availability and bird’s tendency to cache food/ recompense for food scarcity during migration. In another experiment, a chemical tweak in bird’s FI was induced by peripheral administration of leptin, to add to current understanding of transition in buntings’ metabolic efficiency during high energy demanding migratory journey. Exogenous leptin appeared to safeguard cadaveric effect of exogenous injection in migrating buntings through promoting blood cholesterol and reduced liver fibrosis. Food restriction in the morning was better responded by buntings than that in evening. Therefore, migratory buntings exhibited diurnal variation in response to food scarcity.

Impact of Light at Night Is Phase Dependent: A Study on Migratory Redheaded Bunting (Emberiza bruniceps)

Artificial light at night (LAN) alters the physiology and behavior of an organism; however, very little is known about phase-dependent effects of LAN, particularly, in night migratory songbirds. Therefore, in this study, we investigated whether the effects of LAN on daily activity and photoperiodic responses in the Palearctic Indian migratory songbird, redheaded buntings (Emberiza bruniceps), is dependent on the different phases of the night. Male buntings maintained under short photoperiod (8L:16D; L = 100 lux, D < 0.1 lux) in individual activity cages were exposed to LAN (2 lux) for 6 weeks either in 4 h bin given at the different phases of 16 h night (early, mid, or late at ZT 08–12, ZT 14–18, or ZT 20–24, respectively; n = 9 each group) or throughout 16 h night (all night light, n = 6, ZT 08–24, the time of lights ON was considered as Zeitgeber time 0, ZT 0). A group (n = 6) with no LAN served as control. The results showed that LAN at the different phases of night induced differential effects as shown by an intense activity during the night, altered melatonin and temperature rhythms, and showed an increase in body mass and body fattening, food intake, and gonadal size. Midnight light exposure has a greater impact on migration and reproduction linked phenotypes, which is similar to the ones that received light throughout the night. The highlights of this study are that (i) LAN impacts day-night activity behavior, (ii) its continuity with the day alters the perception of day length, (iii) birds showed differential sensitivity to LAN in a phase-dependent manner, (iv) the direction of placing LAN affects the daily responses, e.g., LAN in the early night was “accepted” as extended dusk but the late night was considered as early dawn, and (v) midnight LAN was most effective and induced similar responses as continuous LAN. Overall, LAN induces long day responses in short days and shows differential sensitivity of the different phases of the night toward the light. This information may be valuable in adopting a part-night lighting approach to help reduce the physiological burden, such as early migration and reproduction, of artificial lighting on the nocturnal migrants.

Daytime light spectrum affects photoperiodic induction of vernal response in obligate spring migrants

It is not well understood how the spectral composition (wavelength) of daylight that varies considerably during the day and seasons affects photoperiodic responses in a seasonal species. Here, we investigated the molecular underpinnings of wavelength-dependent photoperiodic induction in migratory redheaded buntings transferred to 13 h long days in neutral (white), 460 nm (blue), 500 nm (green) or 620 nm (red) wavelength that were compared with one another, and to short day controls for indices of the migratory (body fattening and weight gain, and Zugunruhe) and reproductive (testicular maturation) responses. Buntings showed wavelength-dependent photoperiodic response, with delayed Zugunruhe and slower testis maturation under 620 nm red light. Post-mortem comparison of gene expressions further revealed wavelength-dependence of the photoperiodic molecular response. Whereas there were higher retinal expressions of opn2 (rhodopsin) and opn5 (neuropsin) genes in red daylight, and of rhodopsin-like opsin (rh2) gene in green daylight, the hypothalamic opn2 mRNA levels were higher in blue daylight. Similarly, we found in birds under blue daylight an increased hypothalamic expression of genes involved in the photoperiodic induction (thyroid stimulating hormone subunit beta, tshb; eye absent 3, eya3; deiodinase type 2, dio2) and associated neural responses such as the calcium signaling (ATPase sarcoplasmic/endoplasmic reticulum Ca2+ transporting 2, atp2a2), dopamine biosynthesis (tyrosine hydroxylase, th) and neurogenesis (brain-derived neurotrophic factor, bdnf). These results demonstrate transcriptional changes in parallel to responses associated with migration and reproduction in buntings, and suggest a role of daylight spectrum in photoperiodic induction of the vernal response in obligate spring avian migrants.

Molecular changes associated with migratory departure from wintering areas in obligate songbird migrants.

Day length regulates the development of spring migratory and subsequent reproductive phenotypes in avian migrants. This study used molecular approaches, and compared mRNA and proteome-wide expression in captive redheaded buntings that were photostimulated under long-day (LD) conditions for 4 days (early stimulated, LD-eS) or for ∼3 weeks until each bird had shown 4 successive nights of Zugunruhe (stimulated, LD-S); controls were maintained under short days. After ∼3 weeks of LD, photostimulated indices of the migratory preparedness (fattening, weight gain and Zugunruhe) were paralleled with upregulated expression of acc, dgat2 and apoa1 genes in the liver, and of cd36, fabp3 and cpt1 genes in the flight muscle, suggesting enhanced fatty acid (FA) synthesis and transport in the LD-S state. Concurrently, elevated expression of genes involved in the calcium ion signalling and transport (camk1 and atp2a2; camk2a in LD-eS), cellular stress (hspa8 and sod1, not nos2) and metabolic pathways (apoa1 and sirt1), but not of genes associated with migratory behaviour (adcyap1 and vps13a), were found in the mediobasal hypothalamus (MBH). Further, MBH-specific quantitative proteomics revealed that out of 503 annotated proteins, 28 were differentially expressed (LD-eS versus LD-S: 21 up-regulated and 7 down-regulated) and they enriched five physiological pathways that are associated with FA transport and metabolism. These first comprehensive results on gene and protein expression suggest that changes in molecular correlates of FA transport and metabolism may aid the decision for migratory departure from wintering areas in obligate songbird migrants.

Magnetic Compass Orientation in a Palaearctic-Indian Night Migrant, the Red-Headed Bunting.

Simple SummaryThe earth’s magnetic field, celestial cues, and retention of geographical cues en route provide birds with compass knowledge during migration. The magnetic compass works on the direction of the magnetic field, specifically, the course of the field lines. We tested Red-headed Buntings in orientation cages in the evening during spring migration. Simulated overcast testing resulted in a northerly mean direction, while in clear skies, birds oriented in an NNW (north–northwest) direction. Buntings were exposed to 120° anticlockwise shifted magnetic fields under simulated overcast skies and responded by shifting their orientation accordingly. The results showed that this Palaearctic night migrant possesses a magnetic compass, as well as the fact that magnetic cues act as primary directional messengers. When birds were exposed to different environmental conditions at 22 °C and 38 °C temperatures under simulated overcast conditions, they showed a delay in Zugunruhe (migratory restlessness) at 22 °C, while an advance migratory restlessness was observed under 38 °C conditions. Hot and cold weather clearly influenced the timing of migrations in Red-headed Buntings, but not the direction.Red-headed Buntings (Emberiza bruniceps) perform long-distance migrations within their southerly overwintering grounds and breeding areas in the northern hemisphere. Long-distance migration demands essential orientation mechanisms. The earth’s magnetic field, celestial cues, and memorization of geographical cues en route provide birds with compass knowledge during migration. Birds were tested during spring migration for orientation under natural clear skies, simulated overcast skies at natural day length and temperature, simulated overcast at 22 °C and 38 °C temperatures, and in the deflected (−120°) magnetic field. Under clear skies, the Red-headed Buntings were oriented NNW (north–northwest); simulated overcast testing resulted in a northerly mean direction at local temperatures as well as at 22 °C and 38 °C. The Buntings reacted strongly in favor of the rotated magnetic field under the simulated overcast sky, demonstrating the use of a magnetic compass for migrating in a specific direction.

Concurrent changes in photoperiod-induced seasonal phenotypes and hypothalamic CART peptide-containing systems in night-migratory redheaded buntings.

This study tested the hypothesis whether hypothalamic cocaine-and amphetamine-regulated transcript (CART)-containing systems were involved in photoperiod-induced responses associated with spring migration (hyperphagia and weight gain) and reproduction (gonadal maturation) in migratory songbirds. We specifically chose CART to examine neural mechanism(s) underlying photoperiod-induced responses, since it is a potent anorectic neuropeptide and involved in the regulation of changes in the body mass and reproduction in mammals. We first studied the distribution of CART-immunoreactivity in the hypothalamus of migratory redheaded buntings (Emberiza bruniceps). CART-immunoreactive neurons were found extensively distributed in the preoptic, lateral hypothalamic (LHN), anterior hypothalamic (AN), suprachiasmatic (SCN), paraventricular (PVN), dorsomedialis hypothalami (DMN), inferior hypothalamic (IH), and infundibular (IN) nuclei. Then, we correlated hypothalamic CART-immunoreactivity in buntings with photostimulated seasonal states, particularly winter non-migratory/non-breeding (NMB) state under short days, and spring premigratory/pre-breeding (PMB) and migratory/breeding (MB) states under long days. There were significantly increased CART-immunoreactive cells, and percent fluorescent area of CART-immunoreactivity was significantly increased in all mapped hypothalamic areas, except the SCN, PVN, AN, and DMN in photostimulated PMB and MB states, as compared to the non-stimulated NMB state. In particular, CART was richly expressed in the medial preoptic nucleus, LHN, IH and IN during MB state in which buntings showed reduced food intake and increased night-time activity. These results suggest that changes in the activity of the CART-containing system in different brain regions were associated with heightened energy needs of the photoperiod-induced seasonal responses during spring migration and reproduction in migratory songbirds.