Pair copulation frequency correlates with female reproductive performance in Tree Sparrows Passer montanus

In socially monogamous birds, males benefit from frequent copulations with their partner if this increases their paternity in the brood. By soliciting and accepting copulation attempts, female birds can control pair copulation frequencies. Engaging in copulations can be costly by taking up time and by increasing the risks of predation and pathogen transmission. Current hypotheses propose that high pair-copulation frequencies may compensate for these costs by providing females with direct benefits that can result in higher reproductive success. In this study, I examine in a Tree Sparrow population the prediction that high pair-copulation frequencies are associated with better female reproductive performance. The results show that clutch sizes laid were positively correlated with the pair-copulation frequency. The length of the incubation period was negatively correlated and, as expected, the number of fledglings was positively correlated with pair-copulation frequency. The results are consistent with current hypotheses for the evolution of frequent pair copulations and provide one of the few evidences for a positive relation between pair-copulation frequency and female reproductive performance. This study also suggests that within-pair copulation frequency could be an early expression of the pairs' reproductive ability and might signal their phenotypic quality.     

树麻雀代谢率和器官重量在光周期驯化中的变化

为探讨光周期对树麻雀代谢产热和代谢器官变化的影响,对成年树麻雀 Passer montanus 进行温度为25℃、两种光周期16 L:8 D(LD组)和8 L:16 D(SD组)4周的气候箱驯化后,测定其体重、基础代谢率(BMR)、体脂和水分含量,以及各器官、组织的鲜重和干重.结果 显示,SD组麻雀BMR显著大于LD组,作为代谢活性器官的消化道显著增生是其BMR显著增加的主要原因之一;麻雀通过增加体重和能量储备物脂肪来实现对较长黑暗环境的适应是其成功的生存策略.SD组麻雀体重的显著增加和水分含量显著降低,说明短光照的刺激引起麻雀能量储备的增加和代谢活性器官消化道增生.光周期驯化的结果验证了中心限制假说,即麻雀体内存在着与BMR相关的代谢机器,中心器官(消化道)是改变麻雀BMR的基础之一.     

树麻雀代谢率和器官重量在温度驯化中表型的可塑性变化

为探讨温度对树麻雀基础代谢和代谢器官的表型可塑性变化,以人工气候箱驯养4周的光周期为12L:12D、温度为5℃(实验组)和25℃(对照组)的两组成年树麻雀为研究对象,测定其体重、基础代谢率(BMR)、体脂和水分含量以及各器官、组织的湿重和干重.结果实验组麻雀的BMR显著升高,体脂含量和水分含量以及体重均没有显著变化;肝脏重量和肾脏湿重显著增加,干重增加不显著;总消化管干重、小肠干重、直肠湿重和干重显著降低(P<0.01),胃湿重增加显著(P<0.05).由此提示:环境温度改变引起麻雀各器官结构和功能能力相应的可塑性的调整变化,器官能耗总量的增加很可能是引起BMR升高的主要原因,是麻雀器官能耗与功能能力、摄食量与消化率乃至个体适合度价与环境因素进行能量预算的结果.     

Habitat use of urban Tree Sparrows in the process of urbanization:Beijing as a case study

The Tree Sparrow (Passer montanus) is a dom-inant species in urban bird communities.With the devel-opment of urbanization,the habitats and sources of food for Tree Sparrows are decreasing.Can the urban Tree Sparrow adapt to changes in the urban environment? To answer this question,we studied the habitat use of Tree Sparrows in eight types of urban areas in Beijing.The results show that the number of both breeding and winter-ing Tree Sparrows decreased with increasing urbanization.The habitat use of Tree Sparrows,analyzed using stepwise discriminant analysis,was positively correlated with the number of brick bungalows,coniferous and broad-leaved trees and air conditioners.It was negatively correlated with the area of high buildings and hardened roads,pedestrian and automobile flux.This indicates that the Tree Sparrow had not adapted to rapid urbanization even though it is a generally adaptable species.Urban planning should take birds such as the Tree Sparrow into consideration.     

Habitat use of urban Tree Sparrows in the process of urbanization: Beijing as a case study

The Tree Sparrow (Passer montanus) is a dominant species in urban bird communities. With the development of urbanization, the habitats and sources of food for Tree Sparrows are decreasing. Can the urban Tree Sparrow adapt to changes in the urban environment? To answer this question, we studied the habitat use of Tree Sparrows in eight types of urban areas in Beijing. The results show that the number of both breeding and wintering Tree Sparrows decreased with increasing urbanization. The habitat use of Tree Sparrows, analyzed using stepwise discriminant analysis, was positively correlated with the number of brick bungalows, coniferous and broad-leaved trees and air conditioners. It was negatively correlated with the area of high buildings and hardened roads, pedestrian and automobile flux. This indicates that the Tree Sparrow had not adapted to rapid urbanization even though it is a generally adaptable species. Urban planning should take birds such as the Tree Sparrow into consideration. __________ Translated from Biodiversity Science, 2006, 14(5): 372–381 [译自:生物多样性]     

Photoperiodic control of the termination of breeding and the induction ofmoult in House Sparrows Passer domesticus

Two photoperiodic mechanisms controlling gonadal regression in birds have been identified: absolute photorefractoriness, typical of species with short breeding seasons, where gonadal regression occurs spontaneously during long days, and relative photorefractoriness, where a decrease in daylength is required to induce regression. An experiment was designed to test whether these simply represent extremes of one underlying mechanism. Three groups of male House Sparrows Passer domesticus were transferred from a short photoperiod, 8 h of light: 16 h of darkness per day (8L:16D) to long photoperiods of either 18L:6D, 16L:8D or 13L:11D. Gonadal maturation rates were similar in all three groups; gonadal regression and moult began latest in the 13L:11D group. Four additional groups of sparrows were transferred from 8L:16D to 18L:6D and then transferred to either 13L: 11D or 16L:8D prior to, or shortly after, the onset of gonadal regression. The decrease in daylength prior to regression had no effect on the timing of regression but did advance the onset of moult. Decrease in daylength after the onset of regression increased the rate of regression and the rate of moult. Because a decrease in daylength did not affect the timing of regression, the data do not support the hypothesis that absolute and relative photorefractoriness represent extremes of a single underlying photoperiodic control mechanism. The adaptive significance of the effects of decreasing daylength on the rate of regression and moult is discussed.     

The diet of Eurasian Tree Sparrow Passer montanus nestlings in relation to agri-environment scheme habitats

It has been suggested by some authors that the UK agri-environment ‘wild bird seed’ option negatively impacts Tree Sparrow populations in the UK. Here we provide evidence for a change in nestling diet with increasing wild bird seed coverage and propose a possible mechanism for its negative impact on population trends.     

Muscle protein loss in laying House Sparrows Passer domesticus

In a study of female House Sparrows Passer domesticus , it was established that almost all of the lean dry material lost from the flight muscles during the period of egg formation and laying was protein. The two large fractions of muscle protein, the sarcoplasmic and myofibrillar fractions, were measured biochemically. Protein in the myofibrillar fraction, which formed the greater part of the total protein, decreased during the study period. There was no evidence to support the proposal that sarcoplasm in muscle acts as the main reserve of proteins.     

Seasonal plasticity of duodenal morphology and histology in Passer montanus

When facing seasonal environmental changes, flying birds and small mammals may develop adaptive gastrointestinal changes to optimize their digestive and absorptive strategies to meet the changing of physiologic needs. As a main component of gastrointestinal tract, small intestine is extraordinarily sensitive to food abundance, food quality, and other environmental factors. However, the detailed morphological adaptations of the small intestine during seasonal changes are largely unknown. Here, we studied the morphological and histological dynamics of duodenum from Passer montanus in Zhalong Nature Reserve in China during seasonal changes. The luminal and wall cross-section area were greater in spring and autumn than that in summer. Villus height and width went up to peak values in winter and showed similar seasonal dynamic changes with that of mucosal thickness, while villus atrophy accompanied by the deepest crypt depth was easily detected in summer. Epithelium thickness was coincident with villus atrophy except a sharp increase in summer. Submucosal thickness was negatively correlated with that of mucosa, while the size, but not total number, of duodenal glands was altered to reflect to seasonal changes. Neither the inner circular nor the outer longitudinal muscle showed seasonal morphological changes, indicating the relatively stable plasticity of intestine muscle structures. Taken together, we propose that phenotypic flexibility in digestive morphology and histology enables small birds to cope with remarkable seasonal changes.     

Field observation of predation on adult lepidopterans by the tree sparrow Passer montanus saturatus

Many studies have examined defensive strategies of adult lepidopterans against bird predation. However, detailed field observations that describe how lepidopterans are hunted by wild birds are quite limited. I observed foraging behavior of wild tree sparrows on adult lepidopterans from May to June 2006 at Mt Yoshida, Kyoto, Japan. A total of 253 foraging attempts on at least 14 species of lepidopterans were observed. The tree sparrows attacked both resting and flying lepidopterans. When a tree sparrow approached a resting lepidopteran, the lepidopteran frequently flew to escape predation. The number of feeding attempts for resting and flying lepidopterans was 215 and 38, respectively. This result indicates that resting lepidopterans are the main target of predation by the tree sparrow. It is therefore considered that reducing the risk of detection is important for lepidopterans to avoid predation by the tree sparrow. Coloration as crypsis is probably effective in this respect.     

成都市区麻雀夜宿规律初步观察

2002年10月～2003年10月,对成都市区内一观察点麻雀的夜宿规律进行了观察。发现麻雀夜宿归巢时间、高峰时间、结束时间和清晨飞离时间有较强的规律,认为这是麻雀的生物节律决定的。     

Seasonal acclimatization of metabolism in Eurasian tree sparrows (Passer montanus)

Acclimatization to winter conditions is an essential prerequisite for survival of small passerines of the northern temperate zone. Changes in photoperiod, ambient temperature and food availability trigger seasonal acclimatization in physiology and behavior of many birds. In the present study, seasonal adjustments in several physiological, hormonal, and biochemical markers were examined in wild-captured Eurasian tree sparrows (Passer montanus) from the Heilongjiang Province in China. In winter sparrows had higher body mass and basal metabolic rate (BMR). Consistently, the dry mass of liver, heart, gizzard, small intestine, large intestine and total digestive tract were higher in winter than in that in summer. The contents of mitochondrial protein in liver, and state-4 respiration and cytochrome c oxidase (COX) activity in liver and muscle increased significantly in winter. Circulating level of serum triiodothyronine (T₃) was significantly higher in winter than in summer. Together, these data suggest that tree sparrows mainly coped with cold by enhancing thermogenic capacities through increased organ masses and heightened activity of respiratory enzymes activities. The results support the view that prominent winter increases in BMR are manifestations of winter acclimatization in tree sparrows and that seasonal variation in metabolism in sparrows is similar to that in other small temperate-wintering birds.     

Female Choice for Male Morphological Traits in House Sparrows,Passer domesticus

Female mate choice for male morphological traits was examined in captive house sparrows in New Mexico, USA. A study of house sparrows in Denmark indicated that male bib size is important in female choice (Moller 1988, 1989). To examine this issue further, and to compare the selective pressures on male morphological traits between the two populations, bibs of males were manipulated to one of four standard sizes and females were allowed to choose from four males, one of each bib size. The amount of time the female spent with each male was recorded for 40 trials. Males were then ranked in each trial, with a rank of 4 given to the male the female spent the most time with. The ranks a male obtained were then averaged to provide an indication of a male's attractiveness to females. Data from 23 different males indicated that bib size was not correlated with a male's average rank, even when the effects of other traits were controlled statistically. In addition, the size of the original (unaltered) bib was not correlated with male average rank. Bill depth was the only trait significantly correlated with a male's average rank. Differences in the populations studied or the methodologies used may have led to differences between the results obtained in this study and that of Moller (1988).     

Habitat use of breeding birds in Central European reed beds

Wetlands Ecology and Management - To date, there have been few comprehensive studies on habitat preferences of wetland bird communities focusing on European reed bed avifauna. During the years...     

Dynamics of West Nile Virus Persistence in House Sparrows (Passer domesticus)

West Nile Virus (WNV) is now endemic throughout North America, with annual recurrence dependent upon successful overwintering when cold temperatures drive mosquito vectors into inactivity and halt transmission. To investigate whether avian hosts may serve as an overwintering mechanism, groups of eight to ten House Sparrows were experimentally infected with a WN02 genotype of WNV and then held until necropsy at 3, 5, 7, 9, 12, 15, or 18 weeks post-infection (pi) when they were assessed for the presence of persistent infection. Blood was collected from all remaining birds every two weeks pi, and sera tested for WNV RNA and WNV neutralizing antibodies. West Nile virus RNA was present in the sera of some birds up to 7 weeks pi and all birds retained neutralizing antibodies throughout the experiment. The detection of persistently infected birds decreased with time, from 100% (n = 13) positive at 3 weeks post-infection (pi) to 12.5% (n = 8) at 18 weeks pi. Infectious virus was isolated from the spleens of birds necropsied at 3, 5, 7 and 12 weeks pi. The current study confirmed previous reports of infectious WNV persistence in avian hosts, and further characterized the temporal nature of these infections. Although these persistent infections supported the hypothesis that infected birds may serve as an overwintering mechanism, mosquito-infectious recrudescent viremias have yet to be demonstrated thereby providing proof of principle.