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.     

珠颈斑鸠繁殖期占据领域鸣声特征及行为

2003年4～6月,在四川省南充市通过野外观察、录音、室内计算机处理及声谱分析对珠颈斑鸠繁殖期占据领域鸣声特征及行为做了研究。结果表明：珠颈斑鸠有一般占据和召唤配偶共同占据两类鸣声,两类鸣声雌雄不同,但均由3音节组成;其鸣唱具有应答性,且每次在各栖位点的鸣唱顺序大致相同;日鸣唱频次变化大,具3个高峰期;繁殖各时期鸣唱频次变化亦大。     

Location of neurons projecting to the hypophysial stalk — median eminence in ring doves (Streptopelia roseogrisea)

The median eminence/pituitary stalk represents the final common pathway for fibers from neurons that project to the pituitary gland. We have used the lipophilic fluorescent tracer 1,1-dioctadecyl-3,3,3,3-tetramethylindocarbocyanine perchlorate (DiI) to determine the location of neurons projecting to the median eminence/pituitary stalk in ring doves. The tracer can be precisely applied to fixed tissue, in areas to which it is otherwise difficult to gain access. Follwwing application of DiI to the median eminence/pituitary stalk, labeled neurons were detected in six distinct regions: the ventromedial hypothalamic nucleus, paraventricular nucleus, supraoptic nucleus, in and ventral to the lateral forebrain bundle, preoptic area, and lateral septum. Labeled fibers branched extensively in the diencephalon, particularly along the third ventricle and in the septal-preoptic area. Sparse fiber labeling occurred caudal to the tuberal hypothalamus, even though these regions were close to the application site of the tracer. Labeled cerebrospinal-fluid-contacting cells were seen in the paraventricular region of the third ventricle. The results indicate that the avian neuronal system that projects to the median eminence and neural lobe occurs in diffuse clusters largely along the midline region of the hypothalamic septal-preoptic area. The paucity of fiber staining caudal to the tuberal hypothalamic region indicates that cells of these regions do not project to the median eminence/pituitary.     

Optimal brood size and its limiting factors in the Rufous Turtle DoveStreptopelia orientalis

Optimal brood size and its limiting factors of the Rufous Turtle Dove,Streptopelia orientalis, were studied at the campus of the University of Tsukuba, Japan, during the breeding season in 1990–92. The dove usually lays two eggs in a nest. I made nests of a brood size of one and three by transferring a hatchling from one nest to the other, and compared their fledging success, factors of breeding failure, weight and tarsus length at fledging, growth rate and nestling period with those of a brood of two. The index of fitness (fledgling weight multiplied by average number of fledglings per nest) was almost the same in broods of two and three. However, the highest variation in fledging weight within the brood and the extension of nestling period were observed in broods of three, which caused the extension of inter-brood interval and consequently the smaller number of broods in the total breeding season. Therefore, broods of three would not have an advantage in producing more offspring than broods of two. Crop milk production had an effect on the growth of nestlings in the early phase of the nestling period, but the rapid growth in the granivorous phase compensated for the growth delay of the smallest nestling in broods of three. Small brood size and a large number of broods in a season would also be more effective under high predation pressure.     

Spatial dynamics of an invasive bird species assessed using robust design occupancy analysis: the case of the Eurasian collared dove (Streptopelia decaocto) in France

Aim The study of the spatial dynamics of invasive species is a key issue in invasion ecology. While mathematical models are useful for predicting the extent of population expansions, they are not suitable for measuring and characterizing spatial patterns of invasion unless the probability of detection is homogeneous across the distribution range. Here, we apply recently developed statistical approaches incorporating detection uncertainty to characterize the spatial dynamics of an invasive bird species, the Eurasian collared dove (Streptopelia decaocto). Location France. Methods Data on presence/absence of doves were recorded from 1996 to 2004 over 1045 grid cells (28 × 20 km) covering the entire country. Each grid cell included five point counts spaced along a route, which was visited twice a year, allowing for an estimation of detection probability. Each route was assigned to one of six geographical regions. We used robust design occupancy analysis to assess spatial and temporal variation in parameters related to the spatial dynamics of the species. These parameters included occupancy rate, colonization and local extinction probabilities. Our inference approach was based on the selection of the most parsimonious model among competitive models parametrized with conditional probabilities. Results The probability of detecting the presence of doves on a given route was high. However, we found evidence to incorporate detection uncertainty in inference processes about spatial dynamics, since detection probability was neither perfect (i.e. it was < 1), nor constant over space and time. Results showed a clear positive trend in occupancy rate over the study period, increasing from 55% in 1996 to 76% in 2004. In addition, occupancy rate differed among regions (range: 37–79%) and further analysis showed that colonization probability by region was positively related to occupancy rate. Finally, local extinction probability was lower than colonization probability and showed a tendency to decrease over the study period. Main conclusions Our results emphasize the importance of estimating detection probabilities in order to draw proper inferences about the spatial and temporal dynamics of the invasion pattern of the collared dove. In contrast to the perceived spatial dynamics from national atlas surveys, we provide evidence that the range of this species is currently increasing in France. Other results, such as regional specificity in colonization probabilities and time variation in local extinction are consistent with expectations from invasion and metapopulation theory.     

呼和浩特市鸟类种的新记录——珠颈斑鸠

2004年4月4日笔者在呼和浩特市第三苗圃(40°48.445′N,111°433.49′E)进行鸟类资源调查时,于15:40左右在东侧靠近东墙的灌丛中发现两只体长约30cm的类似灰斑鸠的鸟,在距其约8m的地方,通过8×40倍双目望远镜观察发现:通体粉褐色,头部灰褐色;后颈具宽阔的黑色领圈,其上杂以珍珠     

Haemolytic and bactericidal activity of serum from the ring dove (Streptopelia risoria) after treatment with exogenous prolactin

The purpose of this study was to elucidate the effect of exogenous prolactin on the haemolytic and bactericidal capacity of serum obtained from ring doves (Streptopelia risoria) previously injected with either bovine serum albumin or saline solution. Haemolytic activity was measured in CH-50 units (which represents the capacity of serum complement to lyse 50% of sheep red blood cells in the presence of specific antibody) and the bactericidal activity was estimated from the number of colony-forming units ofStaphylococcus aureus which survived after 24 h of incubation in the presence of serum. The results indicated that: (1) bovine serum albumin stimulated both haemolytic and bactericidal activity, the highest values occurring 24 h and 4 days after administration, respectively. (2) Prolactin induced an increase in the haemolytic activity of complement. (3) The administration of bovine serum albumin to animals previously treated with prolactin produced a greater stimulation than either bovine serum albumin or prolactin alone.Abbreviations BSA bovine serum albumin - CFT complement fixation test - CFU colony-forming units - CH-50 units, the reciprocal of the complement dilution with 50% lysis of the hemolysin-treated erythrocytes - IU international units - PBS phosphate-buffered saline solution - SS saline solution     

Distribution shifts in wintering Golden Plover Pluvialis apricaria and Lapwing Vanellus vanellus in Britain

Capsule The winter distribution of Golden Plover and Lapwing has shifted east since the mid-1980s, perhaps in response to climate change.

Aims To combine analyses of winter trends on wetlands and flocks on farmland to assess the current status of Golden Plover and Lapwing in one of their main wintering regions.

Methods Winter trends were derived from monthly counts on estuaries and wetlands for the period 1974–2002 (the Wetland Bird Survey). Winter distribution on farmland was assessed using casual records of large flocks and surveys of a stratified random sample of 1-km squares (the Winter Farmland Bird Survey).

Results Regional trends showed a pronounced increase in numbers of both species since 1974 on the east coast, with a smaller increase on the south coast. Numbers in the west and north tended to decline. Flocks on farmland were concentrated in eastern Britain unlike the situation in the 1980s.

Conclusions The winter distribution of Golden Plover and Lapwing has shifted to the east, resulting in large numbers on the east coast and in the arable east of Britain. The implications of this shift, especially in relation to known habitat associations, are discussed.     

Method learning caused a first‐time observer effect in a newly started breeding bird survey

Capsule A first‐time observer effect in the new French breeding bird survey (BBS) was found to result from new observers learning how to use the point count method on randomly selected sites.

Aims To estimate the first‐year effect in a newly started BBS, to look for correlates and test for a temporal trend in learning.

Methods Trends of 105 species were estimated using data from 2001–2007 obtained by 1100 observers conducting point counts over 1535 randomly selected squares. I estimated the average increase in detected numbers between the first and all subsequent years of survey at a site.

Results Observers counted 4.3% more birds in subsequent years than during the initial year of survey. This first‐year effect decreased from 2001 to 2007 (by an average of 2% per year). It was not related to most variables known to influence species detection probability. Only species with songs of lower sound frequencies (ranging from 0.5 to 8 kHz here) displayed a greater increase in locally detected numbers.

Conclusion The detected first‐year effect was the result of method learning by new observers who had not previously conducted point counts or visited randomly selected sites. The learning effect was larger for species with songs of lower sound frequency which are harder to hear during the dawn chorus.