繁殖期杂色山雀应激水平的皮质酮浓度 与繁殖投入的关系

皮质酮是鸟类重要的糖皮质激素,在其适应环境变化及压力应激反应中起重要的调节作用。非应激状态时,鸟类血浆皮质酮浓度处于基线水平,当鸟类面对应激刺激时,血浆皮质酮浓度迅速升高,应激水平的皮质酮对鸟类个体生存至关重要。然而,目前繁殖季鸟类血浆应激水平的皮质酮浓度变化及其与繁殖投入关系的研究结果存在种间差异,仍需在不同的物种中进行实验研究。本研究分析了繁殖季杂色山雀（Sittiparus varius）血浆应激水平的皮质酮浓度在繁殖阶段的变化,及育雏期亲鸟血浆应激水平的皮质酮浓度与繁殖参数和亲鸟育雏投入的关系。结果显示,与求偶期相比,育雏期杂色山雀亲鸟血浆应激水平的皮质酮浓度极显著升高（P < 0.001）,雌性与雄性亲鸟之间无显著性差异（P > 0.05）;雌性与雄性亲鸟血浆应激水平的皮质酮浓度与繁殖参数、亲鸟递食投入、巢防卫行为均无显著相关性（P > 0.05）。     

Effects of the winter beechmast crop on bird occurrence in British gardens

Capsule Woodland birds were significantly less likely to occur in gardens in years of high beechmast crop.

Aim To test the hypothesis that woodland species that feed on beechmast will have significantly lower occurrence rates at garden feeders in mast years.

Methods Weekly winter occurrence rates at garden feeders between 1970/71 and 1999/2000 for 40 species were analysed in relation to annual beechmast abundance, classified into low, medium and high years. A repeated-measures logistic regression model was used to assess whether beechmast abundance explained further significant variation additional to underlying seasonal and annual trends.

Results Seven species that commonly feed on beechmast showed significantly lower occurrence in gardens in years of highest beechmast abundance: Great Spotted Woodpecker Dendrocopos major, Woodpigeon Columba palumbus, Great Tit Parus major, Coal Tit Periparus ater, Nuthatch Sitta europaea, Jay Garrulus glandarius and Chaffinch Fringilla coelebs. Blackbird Turdus merula and Siskin Carduelis spinus, which showed similar significant patterns, are likely to take beechmast as elements of their diet. Pied Wagtail Motacilla alba was the only insectivorous species to show significant effects, but occurrence was lowest in years of intermediate beechmast abundance. For the latter species, this may have been due to confounding effects of temperature, but there were no such confounding effects of either temperature, or the number of bird feeders provided in gardens, for the other nine species.

Conclusion Use of artificial food sources by birds in gardens is influenced by resources in the surrounding countryside, suggesting that food provided in gardens may play a significant part in the population dynamics of these species, that population monitoring without consideration of the garden habitat may be deficient, and that volunteer-based garden bird recording may provide data that can be used as an indicator of changes in the wider countryside.     

The effect of flight, fasting and p,p'-DDT on thyroid hormones and corticosterone in Gambel's white-crowned sparrow, Zonotrichia leucophrys gambelli

This study examined the effects of p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), fasting and flight on thyroid hormones and corticosterone in Gambel's White-crowned Sparrows (Zonotrichia leucophrys gambelli). Female sparrows were dosed daily with either 5 mg p,p'-DDT per kg body mass or corn oil vehicle over 3 days. On the fifth day the sparrows were divided into 3 groups: (1) unstressed - non-stressed control sparrows; (2) fasted - sparrows fasted for intervals ranging from 20 min to 9 h; or (3) flown - sparrows flown in a wind tunnel for intervals between 20 min and 2.5 h while fasting. Half the sparrows from each group received DDT (DDT-dosed sparrows) and the other half corn oil vehicle only (vehicle sparrows). Trunk blood plasma was analyzed for thyroxine, triiodothyronine and corticosterone using radioimmunoassay. In the flown group, corticosterone was elevated (DDT-dosed 35.52 ng/ml, P < or = 0.05), and thyroxine was depressed (DDT-dosed 4.09 ng/ml, P < or = 0.05; vehicle 4.33 ng/ml, P < or = 0.05). Elevated corticosterone likely decreased thyroid hormone production through a negative feedback mechanism originating at the hypothalamus. Mean triiodothyronine concentrations did not differ among any of the test groups. Relative to time fasted and flown, thyroxine decreased in flown birds dosed with DDT (P < 0.001) and triiodothyronine decreased in fasted birds dosed with DDT (P = 0.004). The increased rate of hormone diminution may be a result of the ability of DDT to induce microsomal enzyme production.     

Significant effects of season and bird age on use of coppice woodland by songbirds

Woodland birds have experienced widespread population declines across Europe, resulting partly from a decrease in management practices such as coppicing. Increasing fuelwood demand may reverse the decline of coppicing, making it timely to attempt a fuller understanding of its effects. Here, the impact of coppicing on year‐round habitat use by adults and juveniles of 16 songbird species was quantified from a quasi‐experimental study over 32 years (1978–2009) in Treswell Wood, Nottinghamshire, UK. Habitat use was inferred using capture rates from more than 10 000 h of mist‐netting (> 25 000 captures) and detailed information on coppicing. Capture rates varied with coppice age in different ways: (1) increases as coppice aged (e.g. Marsh Tit Poecile palustris, juvenile Eurasian Treecreepers Certhia familiaris); (2) declines as coppice aged (e.g. Eurasian Blue Tit Cyanistes caeruleus, Great Tit Parus major); (3) peaks in capture rates at intermediate coppice age (i.e. 5–15 years) (e.g. Garden Warbler Sylvia borin, Willow Warbler Phylloscopus trochilus, adult Treecreepers); and (4) a peak at intermediate ages, followed by a decline, before an increase in use again at the oldest coppice ages (i.e. > 20 years) (e.g. Common Blackbird Turdus merula, Eurasian Blackcap Sylvia atricapilla, Eurasian Bullfinch Pyrrhula pyrrhula). Responses to coppice age were similar in different seasons, although Willow Tits Poecile montana showed little preference during breeding but avoided older coppice at other times. Juveniles and adults often differed in their responses to coppice age. The analyses reveal patterns in habitat use that are relevant to woodland management and conservation policy. They suggest that a mosaic of age structures in woodland is beneficial to a wide range of woodland species, and that management should consider the requirements of all age‐classes of birds at different times of year.     

Hormonal, behavioral, and thermoregulatory responses to bacterial lipopolysaccharide in captive and free-living white-crowned sparrows (Zonotrichia leucophrys gambelii)

Exposing vertebrates to pathogenic organisms or inflammatory stimuli, such as bacterial lipopolysaccharide (LPS), activates the immune system and triggers the acute phase response. This response involves fever, alterations in neuroendocrine circuits, such as hypothalamo-pituitary-adrenal (HPA) and -gonadal (HPG) axes, and stereotypical sickness behaviors that include lethargy, anorexia, adipsia, and a disinterest in social activities. We investigated the hormonal, behavioral, and thermoregulatory effects of acute LPS treatment in a seasonally breeding songbird, the white-crowned sparrow (Zonotrichia leucophrys gambelii) using laboratory and field experiments. Captive male and female sparrows were housed on short (8L:16D) or long (20L:4D) day lengths and injected subcutaneously with LPS or saline (control). LPS treatment activated the HPA axis, causing a rapid increase in plasma corticosterone titers over 24 h compared to controls. Suppression of the HPG axis occurred in long-day LPS birds as measured by a decline in luteinizing hormone levels. Instead of a rise in body temperature, LPS-injected birds experienced short-term hypothermia compared to controls. Birds treated with LPS decreased activity and reduced food and water intake, resulting in weight loss. LPS males on long days experienced more weight loss than LPS males on short days, but this seasonal effect was not observed in females. These results paralleled seasonal differences in body condition, suggesting that modulation of the acute phase response is linked to energy reserves. In free-living males, LPS treatment decreased song and several measures of territorial aggression. These studies highlight immune-endocrine-behavior interrelationships that may proximately mediate life-history tradeoffs between reproduction and defense against pathogens.     

The phenology and clutch size of UK Blue Tits does not differ with woodland composition

The deciduous tree-herbivorous caterpillar-insectivorous bird food chain is a well-studied system for investigating the impacts of climate change across trophic levels. To date, across Europe, most attention has focused on the impacts of increasing spring temperature on changes to phenology in Oak-dominated (Quercus spp.) woodlands. Paridae species and Pied Flycatcher Ficedula hypoleuca are the most studied secondary consumers, all of which demonstrate an advancement in reproductive phenology with increases in spring temperature. Shifts in climate and phenology may also impact on reproductive investment in clutch size, and the effects of climate on phenology and clutch size may vary depending on woodland composition. To date, the effects of among-habitat variation in phenology and reproductive investment have received little attention. Insectivorous birds inhabiting woodlands that differ in tree composition may differ in the timing of breeding, due to local tree leafing phenology acting as a cue for egg-laying date and/or clutch size. Moreover, for most insectivorous birds, woodland composition within a territory is likely to be the main determinant of food availability for both adults and chicks. Consequently, if warming springs affect the temporal patterns of food availability differently across different woodland compositions, this may affect the optimal average local phenology for nesting birds. Here, using data from 34 long-term (mean 15 years) nest monitoring sites across the UK, we investigate the effect of woodland tree composition and temperature on Blue Tit Cyanistes caeruleus first egg date (FED) and clutch size. We supplemented the nest monitoring data by quantifying woodland composition, at a site level, through modified point counts. We predict that birds breeding in woodlands with greater proportions of late-leafing species, such as Oak and Ash Fraxinus excelsior, will breed later than those breeding in woodlands with greater proportions of early-leafing species, such as Birch Betula spp. and Beech Fagus sylvatica. We found no evidence for differences in Blue Tit FED or clutch size in relation to the proportion of any of the tree species investigated, after controlling for temperature and latitude (FED: −3.4 and 2.2, clutch size: −0.4 and − 0.2 eggs for one-unit increase in temperature and latitude, respectively). In recent decades and across all sites, clutch size has decreased as spring temperatures have increased, a strategy which could allow birds flexibly to adjust their breeding phenology such that nestling demand coincides with peak food availability. The lack of an effect of woodland composition on Blue Tit phenology suggests Blue Tits do not fine-tune their reproductive phenology to the local tree composition. Whether this lack of evidence for phenological divergence is due to an absence of divergent selection on breeding phenology and clutch size or to gene flow is not clear.     

新疆北部白冠攀雀的巢与巢址选择

2008年4—7月,在新疆北部对白冠攀雀巢址选择进行了研究。白冠攀雀的营巢习性特殊,巢呈囊袋状,结构甚为精致。对于白冠攀雀巢的研究,采用总面积调查法,进行地毯式的搜寻,并结合标图法对其进行标记,绘制分布图。研究结果共发现巢125个,营巢位于于临近湖泊、河流等水域附近的柳树、杨树、桦树等阔叶树上。营巢树种以柳树为主,占68.80%。巢的高度平均为(5.3±2.5)m,营巢于乔木的中下部（约1/3处）,约70%的巢离河边不足30 m。对于巢址选择的研究,将原始记录中与巢址选择有关的特征变量进行主成分分析,分析表明,影响白冠攀雀巢址选择的主要因素有4种,依次为：郁闭度因素（包括营巢树胸径、巢上郁闭度）、营巢树种因素(包括营巢树种、树高、巢位高度和乔木种类)、方位因素（包括距河边距离和巢向）、食物与巢材因素。     

A simple tool for calculating egg shape,volume and surface area from digital images

The geometrical properties of eggs – such as volume and surface area – have uses ranging from ecological, physiological and morphological studies in birds, to predictions of chick condition in the poultry industry. Although measurements of an egg's length and breadth can be used to approximate its geometry, the coefficients used in these models are specific to the original test population, and intraspecific variation in egg shape means these methods cannot be used reliably beyond that population. Here I present a novel mathematical formula to describe the curvature of a bird's egg that can be used to calculate the shape, volume and surface area of an egg precisely from digital images. Using data from several species I demonstrate that the model has a greater level of accuracy than length‐ and breadth‐based methods, and release the user‐friendly tool for others to use for measuring eggs from digital images.     

瓦屋山2种山雀的生态位分化和共存

黑冠山雀(Parus rubidiventris)和煤山雀(P.ater)在瓦屋山同域分布,生态位相似,是潜在的竞争者。在垂直分布上,煤山雀的生态位宽度为5.237,显著高于黑冠山雀的2.792,而在水平分布和活动基质2个维度上,二者的生态位宽度值相当。尽管3个维度上2种山雀生态位重叠值均大于0.7,但是它们对3个维度上的资源利用分别存在不同的偏好和侧重。2种山雀的身体量度除了喙宽外均有极显著差异,这应该是2种山雀对环境适应的结果。这2种山雀在巢址选择上各项参数差异均不显著,表明适宜的洞巢可能是它们种间竞争的主要对象。2种山雀的种群数量可能与居留类型有关。空间生态位或食物生态位的分离及适宜的种群数量和比例是它们得以共存的几个重要因素。     

The ultrastructure of the cells of Leydig in the white-crowned sparrow (Zonotrichia leucophrys gambelii) in relation to plasma levels of luteinizing hormone and testosterone

In male White-crowned Sparrows subjected to 20 h daily photoperiods there is an approximately 3-fold increase in the plasma concentration of luteinizing hormone (LH) on the first long day after which a quasi-stable level is maintained for at least 42 days. This increase is followed by an increase in numbers of cells of Leydig and an enhancement of their steroidogenic features, a decrease in transitional interstitial cells, and an increase in plasma level of testosterone. With the decline in plasma LH, as photorefractoriness develops, the steroidogenic features of the cells of Leydig undergo disorganization. For as yet unexplainable reasons the plasma levels of testosterone decline before the decrease in plasma LH and before the degeneration of the steroidogenic features of the cells of Leydig.