ABUNDANCE AND CONSERVATION STATUS OF AVIFAUNA IN LIMBOTO LAKE, GORONTALO

Altitudinal gradients create environmental variation that can strongly affect avian life history strategies. To fully understand this issue, a comparison of the demography of populations of the same species over large altitudinal differences is required. Here, we investigated the breeding ecology of two populations of Eurasian tree sparrow (Passer montanus), one in the temperate zone of central China at an altitude of 30 m and another in the alpine zone of the northeastern Tibetan plateau at an altitude of 3430 m. The breeding ecology of this species was rarely studied at such a high altitude before. Our result revealed that high-altitude tree sparrows started breeding later, had a shorter breeding period (80 versus 140 days), produced smaller broods (1.2 versus 2.5 chicks) and had significantly smaller clutches (4.0 versus 4.9 eggs) but larger eggs (4272 versus 3443 mm3) when compared with their low-altitude counterparts. Besides, tree sparrows at our high-altitude site had longer nestling periods (14.5 versus 13.4 days) than those at the low-altitude site. High-altitude tree sparrows tend to have reduced fecundity but allocate more energy into each offspring to confront the stressful conditions at high altitudes. The observed patterns are consistent with adaptive life history strategies.

In vertebrates, myoglobin (Mb) and cytoglobin (Cygb) are closest relatives in the family of globins, which are heme-containing proteins that can bind gaseous molecules. Mb acts not only as an O2 transporter but also a nitric oxide (NO) scavenger in cardiac and striated muscle. Cygb has been suggested to play important functions in lipid-based signaling processes, defense against reactive oxygen species (ROS), and nitric oxide (NO) metabolism, and it is present in a variety of cell types. However, little information about the structures and functions of Mb and Cygb is known in birds. Here, we cloned the full-length open reading frames (ORFs) of the two globins in Eurasian Tree Sparrow (Passer montanus). The Mb ORF cDNA contains 465 base pairs (bp) encoding 154 amino acids (aa), and the Cygb ORF cDNA contains 540 bp encoding 179 aa. Our results show that the amino acid sequences and three-dimensional (3D) structures of Mb and Cygb are highly conserved in vertebrate species. Interestingly, two specific substitutions were detected in Cygb compared with other vertebrates, which resulted in slight variation of the 3D conformation (e.g., distance between Tyr H16 and Lys G8, the strength of hydrogen bonds, and angles between the G–H helices). Our results may contribute to further understanding the structures, properties, and functions of Mb and Cygb as well as the potential mechanisms of oxygen utilization pathways in vertebrates.

Global warming has become an undeniable fact, and the frequent occurrence of extremely hot weather is a serious challenge to the survival of animals. As one of the most active components of the ecosystem, birds are sensitive to the constant changes in the climate and environment. To investigate the physiological responses of Eurasian tree sparrows (Passer montanus) to acute heat stress, various thermogenic parameters of the birds, which included resting metabolic rate (RMR), body mass, body temperature, water intake, and liver cellular metabolic capacity, were measured after exposure to 42°C for different times. The antioxidant response of Eurasian tree sparrows to heat stress was investigated by measuring the lipid oxidation indexes and related antioxidant oxidase activities in the serum and liver. Body temperature and water intake were significantly increased after 2 h of heat stress and lasted until the end of the heat stress (12 h). In contrast, RMR was significantly decreased after 2 h of heat stress. At the cellular level, liver COX activity was significantly increased during heat stress from 2 h to 6 h. Additionally, there was a significant increase in MDA content and superoxide dismutase (SOD) and catalase (CAT) activity levels in the serum. The glutathione peroxidase (GSH-PX) activity in the liver was significantly decreased after 2 h of heat stress. Our results indicated that heat production decreased while heat dissipation increased in Eurasian tree sparrows exposed to acute heat stress. At the same time, the internal antioxidant defense system of the birds was activated to counteract the damage caused by high temperatures. Therefore, it was reasonable to speculate that Eurasian tree sparrows might be resistant to high temperatures to the extent that they can maintain normal life activities through the regulation of thermogenic and antioxidant systems under acute heat stress.

Seasonal changes in adrenocortical responses to acute stress in Eurasian tree sparrow ( Passer montanus) on the Tibetan Plateau: Comparison with house sparrow ( P. domesticus) in North America and with the migratory P. domesticus in Qinghai Province

Seasonal transitions in avian reproductive cycles are governed by neuroendocrine adaptability. The molecular mechanisms behind seasonal regulation are still not fully understood in many species and remain an important area of ongoing research. Despite recognizing the importance of regulatory genes, gaps persist in comprehending the exact molecular processes that control the transitions between different reproductive phases. We investigated the expression patterns of Tsh-β (Thyroid-stimulating hormone subunit beta), Dio2 (Iodothyronine deiodinase 2), Dio3 (Iodothyronine deiodinase 3), and GnRH-I (Gonadotropin-releasing hormone I) mRNAs in regulating reproduction in both sexes of the Eurasian tree sparrow (Passer montanus). Adult tree sparrows (n = 4 for each sex) were procured from the wild, and mRNA expression of Tsh-β, Dio2, Dio3, and GnRH-I, along with gonadal size and body weight, was examined on a monthly basis for 1 year. Results revealed distinct annual cycles of Tsh-β, Dio2, Dio3, and GnRH-I mRNA expression and gonadal size in both sexes. Significantly higher expressions of Tsh-β, Dio2, and GnRH-I mRNA were observed during the breeding phase (April-May), while Dio3 expression was reported higher during the non-breeding phase. The synchronization in the pattern of increase in the Tsh-β, Dio2, and GnRH-I during the breeding phase is associated with gonadal growth, suggesting their potential involvement in regulating seasonal reproduction in tree sparrows. Thus, the control of the reproductive cycle in tree sparrows involves the actions of Tsh-β and Dio2/Dio3 leading to the activation and deactivation of GnRH-I via the HPG (hypothalamic-pituitary-gonadal) axis.

Stress responses of testosterone and corticosterone-binding globulin in a multi-brooded species, Eurasian Tree Sparrows (Passer montanus): Does CBG function as a mediator?

BackgroundSmall birds in temperate habitats must either migrate, or adjust aspects of their morphology, physiology and behavior to cope with seasonal change in temperature and photoperiod. It is, however, difficult to accurately measure how seasonal changes in temperature and photoperiod affect physiological processes such as basal metabolic rate (BMR) and metabolic activity. To address this problem, we collected data in each month of the year on body mass (Mb) and BMR, and conducted a series of experiments to determine the effect of temperature and photoperiod on Mb, BMR and physiological markers of metabolic activity, in the Eurasian Tree Sparrow (Passer montanus).MethodsIn one experiment, we measured monthly change in Mb and BMR in a captive group of birds over a year. In another experiment, we examined the effects of acclimating birds to two different temperatures, 10 and 30 °C, and a long and a short photoperiod (16 h light:8 h dark and 8 h light:16 h dark, respectively) for 4 weeks.ResultsWe found that these treatments induced sparrows to adjust their Mb and metabolic rate processes. Acclimation to 30 °C for 4 weeks significantly decreased sparrows’ Mb, BMR, and energy intake, including both gross energy intake and digestible energy intake, compared to birds acclimated to 10 °C. The dry mass of the liver, kidneys and digestive tract of birds acclimated to 30 °C also significantly decreased, although their heart and skeletal muscle mass did not change significantly relative to those acclimated to 10 °C. Birds acclimated to 30 °C also had lower mitochondrial state-4 respiration (S4R) and cytochrome c oxidase (COX) activity in their liver and skeletal muscle, compared to those acclimated to 10 °C. Birds acclimated to the long photoperiod also had lower mitochondrial S4R and COX activity in their liver, compared to those acclimated to the short photoperiod.ConclusionsThese results illustrate the changes in morphology, physiology, and enzyme activity induced by seasonal change in temperature and photoperiod in a small temperate passerine. Both temperature and photoperiod probably have a strong effect on seasonal variation in metabolic heat production in small birds in temperate regions. The effect of temperature is, however, stronger than that of photoperiod.

The effects of artificial light at night on Eurasian tree sparrow (Passer montanus): Behavioral rhythm disruption, melatonin suppression and intestinal microbiota alterations

Urban planning and management need long-term population level studies for evaluating how urbanization influences biodiversity. Firstly, we reviewed the current population trends of the House Sparrow (Passer domesticus) and the Eurasian Tree Sparrow (Passer montanus) in Europe, and evaluated the usefulness of citizens’ science projects to monitor these species in Finland. Secondly, we conducted a long-term (1991–2020) winter field study in 31 urban settlements along a 950 km north–south extent in Finland to study how latitude, weather and urbanization influence on sparrow’s growth rates. The House Sparrow is declining in 15 countries, and increasing in 5, whereas the Eurasian Tree Sparrow is declining in 12 and increasing in 9 European countries. The trend of the House Sparrow was significantly negative in continental Europe. However, the trend of the Eurasian Tree Sparrow was not significant. Both species have declined simultaneously in six countries, whereas in four countries, their trends are opposite. Citizen-based, long-term (2006–2020) winter season project data indicated that House Sparrow has decreased, whereas Eurasian Tree Sparrow has increased in Finland. However, the short-term (2013–2020) breeding season citizen-based project data did not indicate significant changes in the occupation rate of sparrows. Our long-term (1991–2020) field study indicated that wintering populations of the House Sparrow have decreased, whereas the Eurasian Tree Sparrows have both expanded their wintering range and increased their population size. Based on our winter count data, latitude and weather did not significantly influence the growth rates of sparrows. When the human population increased within the study plot, House Sparrow populations decreased, and vice versa. There was also a trend that a decreasing number of feeding sites has decreased the House Sparrow numbers. Urban-related factors did not influence the growth rate of the Eurasian Tree Sparrow. Our results indicate that the colonization of a new, even closely related species does not influence negatively on earlier urbanized species. It is probable that the niches of these sparrow species are different enough for allowing them to co-occur. The House Sparrow mainly nests on buildings, whereas the Eurasian Tree Sparrow can easily accept, e.g., nest boxes. Urban planning should take care of both the food availability and nest sites availability for both sparrow species.

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

Occurrence and biomagnification of organohalogen pollutants in two terrestrial predatory food chains

Rewriting The Ugly Duckling Tale: a Eurasian tree sparrow reared among great tits. Competitive relationships between hole-nesting passerine bird species can lead to mixed broods when two or more species lay their eggs in the same nest. On 5 May 2023, during a routine inspection of nest boxes in orange plantations in Sagunto, Eastern Spain, we found a Eurasian tree sparrow (Passer montanus) egg dumped among nine great tit (Parus major) eggs. From this clutch, six great tits and the Eurasian tree sparrow hatched, and four great tits and the sparrow fledged. Using a video camera inside the nest box, we observed that the nestlings, including the sparrow, were fed only by great tit adults. The adults brought caterpillars, moths and spiders, a typical great tit nestling diet in this habitat. To date, great tit eggs have been found in Eurasian tree sparrow nests, but to our knowledge this is the first report of a Eurasian tree sparrow chick successfully raised by great tits.

Growth of the human crystalline lens in childhood

The threat of predation is the main cause of bird nest abandonment, with such behaviour imposing considerable energetic costs on breeding birds. However, for several species, nest abandonment can be a less costly alternative to complete brood failure. In this study, we examined nest abandonment among Eurasian Tree Sparrows (Passer montanus) by surveying 71 Tree Sparrow nests with various types of entry holes and conducted artificially manipulating some of the entrance shapes. We found that nest abandonment was caused by changes to the nest entry shape in seven cases and by human interference in two cases. Nest abandonments occurred throughout the breeding season, and breeding pairs attempted to breed again immediately after nest abandonment. The results of the artificial nest entry shape manipulation experiment showed that nine of twelve nests (75.0%) were abandoned where the nest entrance holes were widened, and six of eleven nests (54.5%) were abandoned where the nest entrance holes were narrowed. However, none of the nests were abandoned where the entry shape was unchanged. Thus, nest abandonment by Tree Sparrows is correlated with nest entry shape manipulation and is more likely to occur when the energy cost of breeding again is less than that of abandoning the nest.

In free-living animals, it has been well demonstrated that the intensity of the adrenocortical response to acute restraint stress can vary with reproductive investment during breeding. The parental care hypothesis posits that the stress response is negatively correlated with parental investment in avian species. To further test this hypothesis, we examined changes in both free and total corticosterone (CORT) at baseline and stress-induced levels (maximal CORT) and corticosteroid-binding globulin (CBG) capacities, in both sexes of a multi-brooded Eurasian tree sparrows (Passer montanus), during the nest building, the early nestling, the later egg-laying, and the later nestling stages. Our results showed Eurasian tree sparrows did not exhibit any differences between sexes in CORT and CBG levels during the egg-laying or nestling stages. Both sexes had lowered CBG capacities and females exhibited lower maximal CORT during the early compared to later nestling stages. In addition, both sexes had lower maximal free CORT levels during the nest building stage than those of the early nestling stages, and males expressed higher total maximal CORT levels than females during nest building stage. The variation in CORT response and CBG levels during different breeding sub-stages in Eurasian tree sparrow may correlate with their energetic situations and parental investments. J. Exp. Zool. 325A:75-83, 2016. © 2015 Wiley Periodicals, Inc.