Learn it now,sing it later? Field and laboratory studies on song repertoire acquisition and song use in nightingales

In many bird species, song changes with age. The mechanisms that account for such changes are only partially understood. Common nightingales Luscinia megarhynchos change the size and composition of their repertoire between their first and second breeding season. To inquire into mechanisms involved in such changes, we compared the singing of 1-year-old and older free-living nightingales. Older males have more song types in common than have 1-year olds. Certain song types frequently sung by older birds did not (or only rarely) occur in the repertoire of yearlings (‘mature’ song types). We conducted learning experiments with hand-reared nightingales to address reasons for the lack of mature song types. The acquisition success of mature songs was as good as that of control songs (commonly sung by both age groups). However, the analysis of song type use revealed that all yearlings sang common song types more often than mature types. This indicates that the absence of certain song types in the repertoires of free-living yearlings cannot be accounted for by learning and/or motor constraints during song learning. Moreover, our results suggest that in communication networks, animals may restrict the actual use of their signal repertoire to a certain subset depending on the context.     

哈尔滨市松北区城市湿地水环境分析及针对旅游开发活动的保护措施

随着城市的快速发展建设和开发,城市人口的增加和不断的对城市湿地水环境产生不利的影响,导致了松北区湿地水环境的破坏。文章应用层次分析法对松北区城市湿地的水质监测数据进行了系统的分析,可知松北湿地污染特点是以万宝镇为起点,沿河流为轴,靠水流内外扩散、自然分解和水体自净作用使松北湿地的水质从远及近逐渐改善,这对保护湿地水环境具有重要的意义。     

Songs of two starling species: common traits versus adaptations to the social environment

We analysed, for the first time, songs of the African Red-winged Starling Onychognathus morio and compared their general characteristics with those of the European Starling Sturnus vulgaris. Both species are gregarious during the non-breeding season, but European Starlings tend to nest in colonies, form unstable pair-bonds and are occasionally polygynous, whereas Red-winged Starlings form long-term pair-bonds and occupy exclusive nesting territories. Red-winged Starlings produced the same basic song categories as European Starlings: warbles and whistles. These two categories appeared to be involved in similar social interactions in the two species. However, several aspects of song behaviour differed between the two species: Red-winged Starlings, breeding in isolated nests, preferentially used whistles for long-distance communication and showed a simpler organization of warbling song. Whistles in the Red-winged Starling were mostly shared between birds and, in contrast to the European Starling, were not indicators of individual identity. Also in contrast to the European Starling, female song in Red-winged Starlings appeared very important throughout the breeding period. Our results suggest that some song characteristics in the two species are phylogenetically conserved whereas others are affected by the distinct social systems of the two species.     

Babbling behavior in the sac-winged bat (Saccopteryx bilineata)

Infant babbling in humans and a few other primates plays an important role in allowing the young to practice the adult vocal repertoire during early behavioral development. Vocalizations uttered during babbling resemble, to some degree, the acoustic structure of adult vocalizations and are often produced in long bouts independent of any social context. Similar behavior, termed subsong or plastic song, is known from a variety of songbirds. Here, we show that pups of the sac-winged bat (Saccopteryx bilineata), a species with an unusually large vocal repertoire, produce renditions of all known adult vocalization types during bouts of vocalizations, which appear to be independent of a distinct social context. Babbling occurs in pups of both sexes, even though only adult males, not females, utter all different vocalization types produced in infancy. To our knowledge, this is the first evidence of babbling in a nonprimate mammal and suggests that infant babbling may be necessary for the ontogeny of complex vocal repertoires.     

The attractiveness fragment—AFLP analysis of local adaptation and sexual selection in a caeliferan grasshopper, <Emphasis Type="Italic">Chorthippus biguttulus</Emphasis>

Genetic variability among males is a necessary precondition for the evolution of female choice based on indirect genetic benefits. In addition to mutations and host–parasite cycles, migration of locally adapted individuals offers an explanation for the maintenance of genetic variability. In a previous study, conducting a reciprocal transplant experiment on a grasshopper, Chorthippus biguttulus, we found that environmental conditions significantly influenced not only body condition but also an important trait of male calling song, the amplitude of song. Although not significant, all other analysed physical and courtship song traits and attractiveness were superior in native than in transferred males. Thus, we concluded that local adaptation has a slight but consistent influence on a range of traits in our study populations, including male acoustic attractiveness. In our present study, we scanned male grasshoppers from the same two populations for amplification fragment length polymorphism (AFLP) loci connected with acoustic attractiveness to conspecific females. We found greater differences in allele frequencies between the two populations, for some loci, than are expected from a balance between drift and gene flow. These loci are potentially connected with locally adapted traits. We examined whether these alleles show the proposed genotype environment interaction by having different associations with attractiveness in the two populations. One locus was significantly related to sexual attractiveness; however, this was independent of the males’ population affiliation. Future research on the evolution of female choice will benefit from knowledge of the underlying genetic architecture of male traits under intraspecific sexual selection, and the ‘population genomics’ approach can be a powerful tool for revealing this structure.     

Free-flight phonotaxis in a parasitoid fly: behavioural thresholds, relative attraction and susceptibility to noise

 The phonotactic capacity of tachinid flies to acoustically detect and localize a sound source simulating their cricket host was investigated in a large flight room. Acoustic measurements were performed to estimate the actual stimulus delivered to the flies, revealing highly heterogeneous sound fields. When presented with a simulated cricket song in red or infrared light conditions, the flies readily flew to the sound source and landed on it. Behavioural phonotactic thresholds were established as a function of carrier frequency and were found to coincide well with the frequency of the host's natural song (4.5–5.2 kHz). Experiments revealed that the same range of frequencies is preferentially attractive to the free-flying flies, and that the reliability of signal detection in the presence of noise is best at behaviourally relevant frequencies. Received: 23 February 2000 / Accepted in revised form: 6 June 2000     

Ignoring the irrelevant: auditory tolerance of audible but innocuous sounds in the bat-detecting ears of moths

Noctuid moths listen for the echolocation calls of hunting bats and respond to these predator cues with evasive flight. The African bollworm moth, Helicoverpa armigera, feeds at flowers near intensely singing cicadas, Platypleura capensis, yet does not avoid them. We determined that the moth can hear the cicada by observing that both of its auditory receptors (A1 and A2 cells) respond to the cicada's song. The firing response of the A1 cell rapidly adapts to the song and develops spike periods in less than a second that are in excess of those reported to elicit avoidance flight to bats in earlier studies. The possibility also exists that for at least part of the day, sensory input in the form of olfaction or vision overrides the moth's auditory responses. While auditory tolerance appears to allow H. armigera to exploit a food resource in close proximity to acoustic interference, it may render their hearing defence ineffective and make them vulnerable to predation by bats during the evening when cicadas continue to sing. Our study describes the first field observation of an eared insect ignoring audible but innocuous sounds.     

Nutritional correlates and mate acquisition role of multiple sexual traits in male collared flycatchers

The information content of a sexual signal may predict its importance in a multiple signal system. Many studies have correlated sexual signal expression with the absolute levels of nutrient reserves. In contrast, the changes of nutrient reserves associated with signal expression are largely unknown in the wild due to technical limitations although they are important determinants of signal information content. We compared two visual and eight acoustic sexual traits in male collared flycatchers to see whether the nutritional correlates of expression predict the role of the signal in sexual selection. We used single point assays of plasma lipid metabolites to estimate short-term changes in nutritional state in relation to sexual trait expression during courtship. As a measure of sexual selection, we estimated the relationship with pairing latency after arrival in a 4-year dataset. Males which found a mate rapidly were characterized by large wing and forehead patches, but small song strophe complexity and small figure repertoire size. Traits more strongly related to pairing latency were also more closely related to changes in nutrient reserves. This indicates a link between signal role and information content. Small wing patches and, surprisingly, complex songs seemed to indicate poor phenotypic quality and were apparently disfavoured at mate acquisition in our population. Future studies of the information content of sexual traits, especially dynamic traits such as song, may benefit from the use of plasma metabolite profiles as non-invasive indicators of short-term changes in body condition.     

Evolution and function of auditory systems in insects

While the sensing of substrate vibrations is common among arthropods, the reception of sound pressure waves is an adaptation restricted to insects, which has arisen independently several times in different orders. Wherever studied, tympanal organs were shown to derive from chordotonal precursors, which were modified such that mechanosensitive scolopidia became attached to thin cuticular membranes backed by air-filled tracheal cavities (except in lacewings). The behavioural context in which hearing has evolved has strongly determined the design and properties of the auditory system. Hearing organs which have evolved in the context of predator avoidance are highly sensitive, preferentially in a broad range of ultrasound frequencies, which release rapid escape manoeuvres. Hearing in the context of communication does not only require recognition and discrimination of highly specific song patterns but also their localisation. Typically, the spectrum of the conspecific signals matches the best sensitivity of the receiver. Directionality is achieved by means of sophisticated peripheral structures and is further enhanced by neuronal processing. Side-specific gain control typically allows the insect to encode the loudest signal on each side. The filtered information is transmitted to the brain, where the final steps of pattern recognition and localisation occur. The outputs of such filter networks, modulated or gated by further processes (subsumed by the term motivation), trigger command neurones for specific behaviours. Altogether, the many improvements opportunistically evolved at any stage of acoustic information-processing ultimately allow insects to come up with astonishing acoustic performances similar to those achieved by vertebrates.     

漫游峨眉山

峨眉山位于成都西南约130km，主峰3099m，矗立在海拔不到500m的峨眉平原上。2600多米的高差造就了“一山有四季，十里不同天”的气候垂直分带。这使峨眉山有着非常丰富的动、植物资源，拥有3200多种植物，享有“植物王国”、“绿色宝库”的美称；拥有2300多种动物。这造成了峨眉山优美、秀丽的景色。峨眉山是中国佛教胜地的四大名山之一。孕育了悠久、灿烂的佛教文化。“蜀国多仙山，峨眉邈难四”。漫游雄、秀、幽、奇的峨眉山，足聆听一曲雄浑、优美的祖国颂歌。     

Release from bats: genetic distance and sensoribehavioural regression in the Pacific field cricket, Teleogryllus oceanicus

The auditory thresholds of the AN2 interneuron and the behavioural thresholds of the anti-bat flight-steering responses that this cell evokes are less sensitive in female Pacific field crickets that live where bats have never existed (Moorea) compared with individuals subjected to intense levels of bat predation (Australia). In contrast, the sensitivity of the auditory interneuron, ON1 which participates in the processing of both social signals and bat calls, and the thresholds for flight orientation to a model of the calling song of male crickets show few differences between the two populations. Genetic analyses confirm that the two populations are significantly distinct, and we conclude that the absence of bats has caused partial regression in the nervous control of a defensive behaviour in this insect. This study represents the first examination of natural evolutionary regression in the neural basis of a behaviour along a selection gradient within a single species.     

Verhalten und Neurobiologie von stimmbegabten Insekten

Crickets, tettigoniids (bush crickets or long-horned grasshoppers) and acridids (short-horned grasshoppers) are well-suited animals to study acoustically mediated behavior and to search for the underlying sensory, nervous, and effector mechanisms. Several behavioral tactics are described which improve reproductive success, serve to avoid predators such as bats, or have been developed for defence against parasitic insects. Phonotactic orientation of female crickets toward the calling male was chosen, since for this behavior the underlying sensory and nervous mechanisms have been intensively studied. Song recognition was found to be based on one critical parameter of the song, thesyllable period, and the females show abandpass behavior for which a correlate exists inlocal brain neurons. Sound orientation is based on apressure gradient mechanism in each ear, and it needs abinaural intensity comparison within the central nervous system. With intracellular recordings from auditory interneurons during phonotactic orientation and their manipulation, a cellular correlate could be found which obeys the rule “turn to the side most strongly stimulated”.     

Ultrasonic courtship song in the Asian corn borer moth, Ostrinia furnacalis

Although sex pheromone communication in the genus Ostrinia (Lepidoptera: Crambidae) has been studied intensively, acoustic communication in this genus has not been explored. In this study, we report that male-produced ultrasound serves as a courtship song in the Asian corn borer moth, O. furnacalis. Upon landing close to a pheromone-releasing female, a male showed a series of courtship behaviors involving emission of ultrasound. The sounds were produced when the wings were vibrated quickly in an upright position. The male song was composed of chirps, i.e., groups of pulses (duration of a chirp = 58.9 ms, 8.8 pulses/chirp), with a broadband frequency of 25–100 kHz. In flight tunnel experiments, deaf and hearing females showed a significant difference in the incidence of three behavioral responses to courting males, i.e., immediate acceptance, acceptance after walking, and rejection. Deaf females showed more ‘rejection’ and less ‘acceptance after walking’ than hearing females, indicating that the detection of male-produced ultrasound plays an important role in the acceptance of a male. The findings are discussed in the context of exploitation of receiver bias and mate choice.     

The effect of female wings on male courtship behavior in the cricket Gryllus bimaculatus

Sexual dimorphism exists in the shape and the structure of the forewings of the cricket (Gryllus bimaculatus). However, the functional significance of the wings in the G. bimaculatus female has been unclear. In common blue butterflies (Polyommatus icarus), wings in females have been suggested as being important for attracting males. To test whether female crickets need wings for conspecific males to recognize them and initiate mating behavior, we removed all wings from females and observed the behavior of males towards them. Most males (87.5%) showed mating behavior towards the wingless females: they produced courtship song and transferred spermatophores to the wingless females. Similarly, 88.5% of the males showed mating behavior towards intact females. When males were placed with both a wingless female and an intact female, no significant difference was detected in male mate choice. The findings demonstrate that the wing of the G. bimaculatus female is not necessary for female recognition by conspecific males and the initiation of male mating behavior, and that it is not important in male mate choice.     

承德市室内环境质量污染现状调查与研究

对承德市160家宾馆、饭店、歌舞厅等公共场所,80个民用建筑工程项目,80余家个人家庭装修进行室内环境检测,发现不同场所室内主要超标污染物不同,新建公共场所主要超标污染物为挥发性有机物、甲醛;已建成的重点公共场所空气超标污染物主要为茵落总数和CO2;民用建筑工程超标污染物主要为氨、甲醛;个人家装超标污染物主要为总挥发性有机物,甲醛。     

Acoustic orientation via sequential comparison in an ultrasonic moth

Orientation of female lesser wax moths (Achroia grisella) to male calling song was tested on a locomotion-compensator device that withheld all inter-aural acoustic differences from the insect. Under these circumstances, females remained longer in the vicinity of the sound source if they experienced a variable sound level that increased when approaching the source rather than a level that remained constant at all times. Analyses of orientation paths revealed that greater retention near the source was achieved by enhanced turning when the perceived sound level remained unchanged or decreased but retaining the previous heading when the level increased. These findings suggest that acoustic orientation can be supplemented by mechanisms based on sequential, as opposed to instantaneous, comparison of auditory input. Such mechanisms may be valuable when binaural hearing is impaired or asymmetric or in environments where acoustic differences at the two ears are unreliable indications of direction to the sound source.     

Response to displaced neighbours in a territorial songbird with a large repertoire

Neighbour recognition allows territory owners to modulate their territorial response according to the threat posed by each neighbour and thus to reduce the costs associated with territorial defence. Individual acoustic recognition of neighbours has been shown in numerous bird species, but few of them had a large repertoire. Here, we tested individual vocal recognition in a songbird with a large repertoire, the skylark Alauda arvensis. We first examined the physical basis for recognition in the song, and we then experimentally tested recognition by playing back songs of adjacent neighbours and strangers. Males showed a lower territorial response to adjacent neighbours than to strangers when we broadcast songs from the shared boundary. However, when we broadcast songs from the opposite boundary, males showed a similar response to neighbours and strangers, indicating a spatial categorisation of adjacent neighbours’ songs. Acoustic analyses revealed that males could potentially use the syntactical arrangement of syllables in sequences to identify the songs of their neighbours. Neighbour interactions in skylarks are thus subtle relationships that can be modulated according to the spatial position of each neighbour.     

Territorial meadow pipit males (<Emphasis Type="Italic">Anthus pratensis</Emphasis>; Passeriformes) become more aggressive in female presence

Although mate guarding as prevention of extra-pair copulation is common among birds, evidence for aggressive behaviour involving physical contact related to mate guarding in passerines is scarce and cases of the presence of one partner directly influencing the aggressiveness of the other are lacking. We investigated the intra-specific territorial behaviour of male meadow pipits (Anthus pratensis; Passeriformes: Motacillidae) at the beginning of the breeding season by placing a pipit model accompanied by an intra-specific song playback in the territory of socially paired males and compared the responses of males whose mates were physically present during trials with those whose females were out of sight. The level of aggression of males was significantly higher in the presence of the female; half of the males in this group physically attacked the model (the most intense and risky aggressive behaviour). Physical attacks did not occur among males whose female was absent during the trial; response to the playback by most of these males was only weak. This pattern may be related to the prevention of extra-pair copulation; if the risks involved in the conflict are outweighed by potential loss of paternity, such aggressive mate guarding may pay off. The apparently overlooked effect on the territorial behaviour of a partner’s passive physical presence during conflict should be further evaluated because it may be important for the design and interpretation of results of behavioural experiments.     

Postnatal nutrition influences male attractiveness and promotes plasticity in male mating preferences

Poor early-life nutrition could reduce adult reproductive success by negatively affecting traits linked to sexual attractiveness such as song complexity. If so, this might favor strategic mate choice, allowing males with less complex songs to tailor their mating tactics to maximize the reproductive benefits. However, this possibility has been ignored in theoretical and empirical studies. By manipulating the micronutrient content of the diet (e.g., low or high) during the postnatal period of male zebra finches, we show for the first time (1) that males reared on a poor (low) micronutrient diet had less complex songs as adults; (2) that these males, in contrast to the high micronutrient diet group, were more selective in their mating strategies, discriminating against those females most likely to reduce their clutch size when paired with males having less complex songs; and (3) that by following different mating strategies, males reared on the contrasting diets obtained similar reproductive benefits. These results suggest that early-life dietary conditions can induce multiple and long-lasting effects on male and female reproductive traits. Moreover, the results seem to reflect a previously unreported case of adaptive plasticity in mate choice in response to a nutritionally mediated reduction in sexual attractiveness.     

Phonotaxis during walking and flight: are differences in selectivity due to predation pressure?

Female selectivity was tested in Tettigonia viridissima during two different phonotaxis situations; compensated walking and tethered flight. For two of the three temporal parameters that are important for call recognition in T. viridissima, selectivity was similar in the two situations. Selectivity for the third parameter (minimum interval duration between the double pulses) was much higher during walking than during flight: walking females responded only to stimuli with intervals of 28 ms or longer, while call models with intervals of 18 ms were attractive during flight. One interneuron (TN-1) is probably involved in filtering the minimum interval duration. As this neuron is also the most likely candidate for transmitting bat calls during flight, it is suggested that the selectivity differences between walking and flying might be due to the need for detecting predator signals during flight, when TN-1 would be occupied listening for bats. With TN-1 unavailable for song processing during flight, temporal selectivity for the minimum interval duration should be reduced, as was found here.