Song rate as a signal for nest site quality in blackcaps (Sylvia atricapilla)

In this study we examine male song output as a measure of nest site quality in blackcaps (Sylvia atricapilla). Song rate, breeding success, predation on nests and reaction to playbacks were investigated in individual males. Habitat features determining nest site and song post quality in terms of vegetation cover were compared between successful nests and nests that had suffered predation. We then related song rate of unmated males to habitat factors in territories and nesting sites in order to examine a possible predictor function of blackcap song for habitat quality. Several habitat features are responsible for variation in nesting success. These features also correlate with song rate of unmated males. The study indicates a potential role of song rate in the advertisement of territory quality. Furthermore, the data suggest that females use song rates rather than territory quality in mating decisions. The information females may gain about male quality in relation to territory quality are also discussed.     

Singing performance,frequency matching and courtship success of long-tailed manakins (Chiroxiphia linearis)

We examined the relationship between song performance and courtship success in the lek-mating long-tailed manakin (Chiroxiphia linearis) of Costa Rica. Teams of male manakins form cooperative partnerships consisting of a dominant alpha male and a beta male partner with a variable number of subordinate affiliates. Each alpha and beta partnership performs a joint song virtually in unison, which attracts females to their lek arena. We quantified four aspects of song performance, including synchrony, degree of consistency in the alpha male's singing, degree of consistency in the beta male's singing, and degree of sound frequency matching between partners. When all four variables were included in a discriminant function analysis, average frequency matching alone was useful in discriminating between teams with high rates of visitation by females and those with low visitation rates. Only frequency matching was correlated with the rate at which females visited display lek arenas. We propose that the degree of frequency matching provides an unambiguous ideal against which dual-male courtship performance can be assessed. This aspect of song performance may provide information useful to females in assesing a potential mate's ability to form a cooperative long-term partnership.     

An “Asymmetric Threat” That Should Have Been Anticipated: Political Discourse on 2007 Wildfires in Greece

This paper examines the pre-election interpretative repertoires employed by the two main political parties in Greece regarding the 2007 summer wildfires, which have been recorded as the worst natural disaster in contemporary Greek history. This involved a discourse analysis of press releases, interviews, and press conference statements. While the New Democracy governing party initially followed a “business-as-usual” scenario, comparing the situation with past wildfires under the administration of PASOK (the biggest opposition party), the increasing number of deaths over time rendered any such comparison invalid. In order to regain momentum, the government launched the interpretative repertoire of “asymmetric threat”, which proved instrumental in helping the government to get re-elected. This political discourse lacked any consideration of broad socioeconomic changes in rural areas in Greece which might have contributed substantially to the severity of the disaster. Implications for wildfire policy are discussed.     

Female and male serins (Serinus serinus) respond differently to derived song traits

We tested if male or female behavior towards manipulated song indicates intra- or inter-sexual selection of two characteristics of serin song that are extreme and evolutionarily derived in this species: high frequency and fast syllable rate. In a first experiment, we monitored vocal responses and attendance to song playbacks. Female behavior indicated a preference for high-frequency song and suggested an aggressive function for fast syllable rates, as fast songs inhibited vocal response. Males did not show discrimination of frequency or syllable rate with this experimental design. The second experiment used a simple approach/no approach design, and in this experiment, males showed stronger discrimination between stimuli than did females. Therefore, sex differences in discrimination appear not to result from differences in perceptual abilities but from differences in the context of stimulus presentation. The second experiment also supported a role of song frequency in female choice, as the effect of frequency was limited to females: males did not respond differently to song frequency and approached high-frequency songs less than females did. Results of this experiment also supported an aggressive function for fast syllable rates, as the effect of fast songs did extend to male behavior. Taken together, our results indicate that the high frequency and fast syllable rate of serin song cannot result from a single selection process: while high frequency may have evolved by inter-sexual selection, syllable rate provokes a pattern of response that is more consistent with intra-sexual selection.     

主成分分析在近年来松花江吉林段水质研究中的应用

本文采取主成分分析法,对2005～2008年松花江吉林江段水质监测数据进行分析,通过分析主要污染物（包括：高锰酸盐指数、生化需氧量、氨氮、石油类、挥发酚、六价铬）确定近年来松花江吉林江段水体主要污染物的种类仍然是以有机污染物物为主,同时存在一定无机污染物和特征污染物。分析过程中选取5个监测断面进进行分析,首先建立5个断面污染物相关系数矩阵,得出特征值,其次确定两个主成分并分析与污染物之间关系;最后利用因子得分确定5个监测断面的水质污染程度,并提出了不同断面的环境管理方法。     

Developmental stress impairs song complexity but not learning accuracy in non-domesticated zebra finches (<Emphasis Type="Italic">Taeniopygia guttata</Emphasis>)

Food restrictions early in life can have adverse effects on the development of adult avian song structure. Nutritional deficiencies during brain development are thought to impair the growth of neural circuits responsible for learning and production of song in adulthood. Thus, the quality of song may reflect the quality of the singer due to the costs associated with neural development early in life. Recent investigations have focused on domesticated laboratory strains of zebra finches where early dietary deficiencies have significantly reduced the complexity of song and its sexual attractiveness. Domesticated zebra finches may be more sensitive to the early effects of moderate under-nutrition on song complexity than their non-domesticated counterparts. In an aviary experiment with non-domesticated zebra finch stock, we found that song complexity when measured by a linear combination of six variables was reduced in food-restricted birds, with syllable rate and maximum syllable frequency as the principal variables affected. The restriction had no effect on learning accuracy when song phrases of experimental birds were compared to those of their fathers.This result demonstrates that early nutrition may differentially affect the development of neural processes that influence learning accuracy and song complexity. While the finding of negative effects of dietary restriction on song complexity is robust for zebra finches and is not an artefact of domestication, it does not explain why some nutritionally stressed populations of wild zebra finches have more complex songs than those from other regions of Australia characterised by greater food availability.     

宋至清荆江南岸分流四口的演变

在历史时期荆江地区的经济开发与江湖关系的演变历程中,分流诸口是极其重要的影响因素。以宋至清的志书为主要资料,立足于历史学的实证方法,以今荆江南岸存在的4个分流穴口,即虎渡口、调弦口、藕池口和松滋口为主要对象,考察四口在宋元明清时期的分塞情况,并对今人存在的一些认识进行了辨析。其中,虎渡河的形成时间说法不一,南宋以后,虎渡口逐渐形成稳定分流。调弦口自元代大德年间开浚后时开时塞,直至清朝才基本保持分流,1958年调关设置后此口渐废。藕池口早在五代时即已存在,北宋以后湮塞,直至1852年藕池堤溃不筑,藕池河再次形成。松滋河则在1869年以前由于黄家埠堤溃决而形成。研究表明,宋代以降,四口的分塞情况较为复杂,因此,考察荆江穴口分流与湮塞的历史变迁,厘清以往的相关歧见,将有助于更正确、客观地理解今天的人地关系、江湖关系的格局及其走向。     

Testosterone and the allocation of reproductive effort in male house finches (Carpodacus mexicanus)

Testosterone has been proposed to serve as the mediator that controls the relative effort that an individual male bird will devote to mating effort versus parental effort. Here, we demonstrate a testosterone-influenced trade-off between parental and mating efforts in male house finches. Male house finches with experimentally elevated testosterone fed nestlings at a significantly lower rate, but sang at a higher rate than males without manipulated testosterone levels. Females mated to testosterone-implanted males fed nestlings at a significantly higher rate than females mated to males without testosterone implants, resulting in similar feeding rates for both treated and untreated pairs. The effects of testosterone on male house finches, however, were not as dramatic as the effects of testosterone observed in some other socially monogamous species of birds. Because extra-pair copulations are uncommon in house finches and males provide substantial amounts of parental care, these more modest effects may be due to differences in how the allocation of reproductive effort affects the costs and benefits of different reproductive behaviors. Received: 6 June 2000 / Accepted: 17 July 2000     

Song type variants and aggressive context

We asked whether switching among song type variants functions as a graded signal of aggression in song sparrows (Melospiza melodia). Song type variants are different versions of a given song type and are defined by much smaller acoustic differences than those defining separate song types. The principal evidence that switching between song types functions as an aggressive signal, in song sparrows and other species, is that song type switching frequencies increase during aggressive contexts, for example during simulated territorial intrusions. We tested whether variant switching frequencies change in the same way, using playback of conspecific song to simulate intrusions. Male song sparrows showed a significant increase in variant switching frequencies during intrusion relative to before intrusion. After intrusions, variant switching frequencies returned to pre-intrusion levels. These results are consistent with the hypothesis that variant switching is a graded aggressive signal, but other interpretations are possible, for example, that variant switching is a signal of submission or represents simple production error. Received: 20 January 2000 / Revised: 15 July 2000 / Accepted: 30 July 2000     

Individual recognition of neighbors by song in a suboscine bird, the alder flycatcher Empidonax alnorum

The ability of territorial males to discriminate between songs of their neighbors and songs of strangers has been demonstrated in 27 species of songbirds. Such experiments test only the ability of a subject to discriminate between two classes of stimuli, familiar (neighbors) and unfamiliar (strangers) songs. Individual recognition of neighbors is a finer, more complex type of discrimination. The ability of territorial males to recognize individual neighbors by song has been documented in 12 species of oscine passerines (Passeriformes, Passeri), but has never been demonstrated in suboscine passerines (Tyranni). We investigated recognition of songs of individual neighbors in a suboscine, the alder flycatcher (Empidonax alnorum). We performed a series of song playback experiments and recorded responses of territorial males to songs of neighbors and songs of strangers broadcast from two locations, the neighbor boundary and an opposite boundary. Subjects responded more aggressively to songs of a neighbor when played from the opposite boundary than when played from the neighbor boundary. They responded with equal aggression to songs of strangers regardless of location of playback. The difference in response to neighbor songs between speaker locations and the lack of a difference in response to stranger songs indicate that territorial males associate a particular song with a particular location (territory), and thus recognize individual neighbors.Communicated by I. Hartley