Conditions Affecting Song Acquisition in Nightingales (Luscinia megarhynchos L.)

Hand raised nightingales were alternatively confronted with different series of songs which permitted labeling of particular learning situations and allowed detection of specific consequences of diverse learning conditions. We found that visual contact with a tutor affected both quality and quantity of acquired patterns. Without visual contact the birds acquired only song sections consisting of repeated vocal units', which proved to be relevant for species recognition. With visual contact the birds learnt every presented song type completely (→ song type sharing between tutor and learner). Furthermore, the birds developed additional song types individually: by distinct parameter variation, or by recombination of particular tutor song units (Fig. 1; Table 1). Functional aspects of this type of song acquisition and development are discussed.     

First-Year Common Nightingales (Luscinia megarhynchos) Have Smaller Song-Type Repertoire Sizes Than Older Males

Based on the assumptions that birdsong indicates male quality and that quality is related to age, one might expect older birds to signal their age. That is, in addition to actual body condition, at least some song features should vary with age, presumably towards more complexity. We investigated this issue by comparing repertoire sizes of free‐ranging common nightingale males in their first breeding season with those of older males. Nightingales are a good model species as they are open‐ended learners, where song acquisition is not confined to an early sensitive period of learning. Moreover, nightingales develop an extraordinarily large song‐type repertoire (approx. 180 different song types per male), and differences in repertoire size among males are pronounced. We analysed repertoire characteristics of the nocturnal song of nine nightingales in their first breeding season and compared them with the songs of nine older males. The repertoire size of older males was on average 53% larger than that of yearlings. When analysing two song categories of nightingales, whistle and non‐whistle songs separately, we found similar results. Our findings show marked differences in repertoire size between age categories, suggesting that this song feature may reflect a male's age. We discuss those mechanisms that may constrain the development of larger repertoires in first‐year males. Whether repertoire sizes are crucial for female mate choice or in vocal interactions among conspecific males remains open to further investigations.     

Former Experience Can Modify Social Selectivity during Song Learning in the Nightingale (Luscinia megarhynchos)

Changes in preference for a specific song-learning context, characterized by close proximity of a tutor, were investigated in the nightingale, Luscinia megarhynchos. Two groups of males were tutored with conspecific song for two periods, days 42 to 56, and days 57 to 71. Song types were either presented from tape alone (group A) or were played in the presence of a familiar tutor, i.e. the person who hand-raised the birds (group B). Acquisition success did not differ between the groups for period 2. However, while males of group B acquired songs during both tutoring periods, males of group A learned only during period 2. This indicates that in nightingales the preference for a specific song-learning context decreases during development. A comparison with an earlier study suggests that this shift is not age dependent but primarily due to auditory experience with the song patterns to be learned. Such a mechanism has also been described for the termination of sensitive phases for song learning. Because song acquisition in adult nightingales does not depend any more on close spatial proximity of a familiar tutor, a male in his first spring and later on can learn from a number of singing territorial neighbours, and by this means acquire the large song-type repertoire typical for the species.     

Seasonal changes in the nocturnal singing routines of Common Nightingales Luscinia megarhynchos

Male Common Nightingales Luscinia megarhynchos famously sing at night. There are two distinct types of nocturnal singing routine (the dusk-to-dawn pattern of variation in song rate): (1) dusk and dawn choruses, with little or no song during the middle of the night; (2) a rapid increase in song rate after dusk, reaching a broad peak in the middle of the night, declining towards dawn, and followed by a dawn chorus. Males sing different nocturnal singing routines at different times in the breeding season. Earlier in the breeding season, most males sing Type 2 routines. Later in the breeding season, most males sing Type 1 routines, as do birds on the wintering grounds. At least some individuals may also sing Type 1 routines during the first few days after their arrival on their breeding territories, before the arrival of females. The main function of nocturnal song appears to be mate attraction. The patterns of variation in song rate over the course of the night are qualitatively similar to those predicted by stochastic dynamic programming (SDP) models of daily singing and foraging routines, for birds that do not forage at night, in circumstances when birds can pair at night (Type 2 routines), and when they cannot (Type 1 routines). The observed seasonal changes in the types of routine sung are also consistent with the predictions of these models.     

Temporal patterns of territory settlement and detectability in mated and unmated Nightingales Luscinia megarhynchos

In many bird species the sex ratio of adults is male-biased, which is likely to have consequences for the ecology as well as for the conservation of a species. For example, when some males remain unpaired in a population, there should be strong selection on behavioural traits that enhance pairing success. A surplus of males is also likely to have important implications for the interpretation of breeding bird survey data. In our study population of Nightingales Luscinia megarhynchos , about half of the males stayed unpaired, suggesting that the number of males encountered singing was greater than the number of breeding pairs. Furthermore, the detectability (the probability of encountering a male singing) of mated males was only two-thirds that of unmated males when censused in the morning or late in the breeding season. The relative detectability was more similar early in the season and during the twilight periods before sunrise and after sunset. Males that arrived earlier on the breeding grounds were more successful in attracting a mate than males arriving later. Some of the unmated males deserted their territories and prospected areas up to 4000 m distant, whereas others settled on the study site only late in the season and may actually have changed territories. We suggest that adult sex ratios and the time of the census should be taken into account when interpreting the results of breeding bird surveys.     

Song Sharing in Neighboring and Non-Neighboring Thrush Nightingales (Luscinia luscinia) and its Implications for Communication

In many passerines, males have repertoires of different songs of which some songs are often shared with other males. Sharing of song repertoires among males can provide insights into the context in which songs were acquired and on the role of song repertoires in inter- and intrasexual communication. Here we studied repertoire sharing in male territorial thrush nightingales ( Luscinia luscinia ). We compared male vocal repertoires of the basic song components, full songs, and the sequencing of songs in a bout. The results show that males differed significantly in the size of their song repertoires but not in the size of the repertoire of basic song components. Moreover, they shared almost all (80%) the repertoire of song components but only 30% of their song types. Neighboring males shared significantly more song types than did non-neighboring males but interestingly they did not share more basic song components than non-neighboring males. These results show that the repertoire of basic song components is under much less sexual selection than the size of song repertoires. Sharing of song repertoires among neighbors presumably results from repertoire conversion over time and from males returning to their territories in the following season. Repertoire sharing then can be an indicator of territory tenure and thus it can be important in repelling rivals and in female choice.     

Foraging Behavior of Nightingales (Luscinia Supergenus): An Experimental Study

Biology Bulletin - Abstract—Foraging techniques influence the morphological peculiarities and ecological specialization of species, also determining their organization in a community. The...     

Nightingales Luscinia megarhynchos in scrub habitats in the southern fens of East Anglia, England: associations with soil type and vegetation structure

The southeast corner of the East Anglian Fens supports a large concentration of Nightingale Luscinia megarhynchos territories. A total of 382 territories were located in extensive surveys in 1999 and 2000, probably representing over 5% of the English population. Transect counts revealed that the Fenland population is restricted in distribution and is associated with localized thickets of scrub. The highest densities are found on humus‐rich soils, suggesting that soil type, in addition to habitat availability, may have a strong influence on the Nightingale's distribution in this region. This paper provides the first assessment of habitat requirements of the Nightingale in scrub, which now forms a principal habitat for the species in England. Detailed studies of the attributes of over 100 Nightingale territories revealed subtle differences in the vegetation structure of these thickets when compared with paired, unoccupied, but apparently similar thickets. The Nightingale territories tended to have a higher proportion of bare ground or short vegetation in the field layer under the canopy, whereas paired sites were more likely to have low field layer vegetation beneath the canopy. The bare ground within the thickets is a feature of shading beneath very dense foliage cover. Within Nightingale territories, low field layer volume and shrub twig volume at the thicket edges was higher than in unoccupied thickets. The differences detected in vegetation structure suggest that a dense and continuous canopy forming a shell over bare ground but with dense low foliage at thicket edges provides the ideal vegetation structure for Nightingales in scrub habitats. Our study suggests that Nightingales occupy scrub of a very specific structure, and specific stage in vegetation succession. This structure probably provides an optimal combination of foraging habitat, microclimate and cover from predators. It is suggested that humus‐rich soils may be preferred because they may support a particularly rich source of invertebrate food, but this remains to be tested empirically.     

Memorization and reproduction of songs in nightingales (Luscinia megarhynchos): evidence for package formation

Summary To examine the properties of avian song memorization, handraised nightingales (Lusdnia megarhynchos) were exposed to three strings composed of 21 or 12 different song types (Fig. 1) which they heard only during the tutoring programs. The analysis of the birds' singing performed several months later revealed a kind of song memorization and production which, hitherto, had not been studied in song birds and is called package formation.Each package was a temporally consistent group of acquired song types which could be traced back to a coherent succession of, usually, three to five (max. seven) model song types. Model song types which a bird failed to acquire were located outside those sequences of model song types that had been acquired and later formed the packages. In contrast to the order of the tutored strings, packages were sung in a variable order. In parallel, neither the frequency of occurrence of the packages nor the performance length was related to the size of the package.We infer from these results that package formation reflects basic properties of the nightingales' song-type memories, which — through segmentation of serially presented learning stimuli — may facilitate the acquisition of large signal repertoires.     

Unattractive Males Guard Their Mates More Closely: an Experiment with Bluethroats (Aves,Turdidae: Luscinia s. svecica)

Mate guarding by close following is assumed to function as a paternity guard in pair-bonding birds. Although this behaviour has been described for many species, little is yet known about the variation in mate-guarding intensity between males in a population and the reason for such variation. In this study, we wanted to examine how mate-guarding intensity relates to the sexual attractiveness of the male. Male bluethroats, Luscinia s. svecica, have a bright throat patch, an ornament extensively displayed during courtship. Two experiments are reported. In the first, we show that males which had their throat patch blackened (with Nyanzol D) before pairing had a lower pairing success than control males. We conclude that the blackening of the throat patch reduced male attractiveness. In the second experiment, a group of males were blackened after pairing. These males guarded their mates more closely than did control males, and spent less effort advertising for secondary mates. Thus, we conclude that a male's mate-guarding intensity is flexible and negatively related to his sexual attractiveness. The mechanisms by which a male can assess the likelihood of becoming cuckolded are discussed.     

Spring arrival patterns of the Cuckoo Cuculus canorus,Nightingale Luscinia megarhynchos and Spotted Flycatcher Musciapa striata in Britain

Data on the arrival dates of Cuckoo, Nightingale and Spotted Flycatcher published in the Royal Meteorological Society phenological reports are presented. From these records, contour maps showing the pattern of progression through Britain were produced for each species. Of the three species, the Cuckoo arrived earliest and progressed the slowest from south to north; it entered Britain by the southeast. The Nightingale arrived later than the Cuckoo and progressed along a southeast to northwest axis. The Spotted Flycatcher was the last to arrive, but progressed with the greatest speed from south to north. Arrival dates of all three species were influenced by the temperature in southern Europe in the month preceding arrival in Britain and by the difference between these temperatures in southern Europe and those a month later in France or Britain. The diminishing population levels of Nightingale may have had a masking effect on its arrival dates. Although mean arrival dates for the three species were strongly influenced by temperature, long-term trend effects should be interpreted with caution as other factors also influence mean arrival dates.     

Ancestral polymorphism in exon 2 of bluethroat (Luscinia svecica) MHC class II B genes

The genes of the major histocompatibility complex (MHC) are important model genes for understanding selective forces in evolution. Here, we document, using a cloning and sequencing approach, high polymorphism at the exon 2 of the MHC class II B (MHCIIB) genes in the bluethroat (Luscinia svecica); a minimum of 61 unique alleles were detected in 20 individuals, and at least 11 functional loci. In addition, several pseudogenes were revealed. The specimens originated from three different bluethroat subspecies (azuricollis, cyanecula and svecica), and we also analysed four specimens of the closely related thrush nightingale (L. luscinia) for comparison. Phylogenetic analyses of the functional alleles revealed 258 equally parsimonious trees with poor statistical support for the majority of nodes. The distribution of the sequences in the trees point to an ancestral origin of the polymorphism in MHC class II B genes, a portion of which predated the phylogenetic split between the bluethroat and the thrush nightingale. Strong signatures of balancing selection were uncovered for the codons coding for the peptide‐binding residues of the functional MHCIIB exon 2 alleles. Our results highlight the importance of duplication and recombination events for shaping passerine MHC and give insights in the evolutionary dynamics of MHC variation among closely related taxa.     

Song Learning in the Anna Hummingbird (Calypte anna)

Songs of wild male Anna hummingbirds (Calypte anna) consist of syllables grouped into phrases. Nearest neighbors tend to share similar syllable types, rhythms and syntax. Songs from different localities contain different syllable types, syntax and repetition indices. A male raised by hand in isolation produced a song consisting of highly variable syllable types of a wide frequency range. The song was simple in structure, and syllables were not grouped into phrases. Three males raised by hand as a group sang songs containing two stereotyped syllable types sung in alternating sequence and without phrase structure. These three males shared syllable types and syntax. The data from our study indicate that despite its relatively simple syrinx the Anna hummingbird learns syllable types, frequency, rhythm and syntax (as do oscines with their more complex syringes) during the song development process.     

斑胸草雀的鸣声学习

鸣声是鸟类重要的生物学特征和分类特征。由于生理结构和神经控制方面的差异,不同种群和同一种群的不同个体都有自己特有的鸣声特征,正是利用这些特征,鸟类才能在集群、取食、迁徙、喂雏、御敌和求偶等行为中进行通讯。作为一种能够利用语音信息进行交流的高等脊椎动物,斑胸草雀的鸣声特别是鸣啭能力获得,需要有一个适宜的学习对象,并在一段特定的时间内,经历复杂的学习过程才能实现。     

Molecular and phenotypic divergence in the bluethroat (Luscinia svecica) subspecies complex

Subspecies complexes may provide valuable insights into the early stages of the speciation process. The bluethroat (Luscinia svecica) consists of many morphologically distinct subspecies that differ most strikingly in the ornamental colour pattern of the male throat. We investigated the genetic and phenotypic differentiation in this subspecies complex, using (i) microsatellite genotyping (11 loci) of a sample of 364 individuals from bluethroat populations in Europe and Asia, and (ii) spectrometric and morphological measurements of a sample of 131 museum skin specimens. Population genetic analyses, based on microsatellite allele frequency variation, revealed a slight but significant overall population differentiation (F(ST) = 0.042). There was a well-differentiated southern group of subspecies with white or no throat spots and a less-differentiated northern group of chestnut-spotted populations. Phylogenetic analyses indicated that the southern all-blue and white-spotted forms are ancestral to the chestnut-spotted subspecies. In addition to the qualitative variation in throat plumage pattern already described in the literature, we found significant quantitative variation among subspecies in hue, chroma and brightness of the ultraviolet (UV)/blue throat coloration, and this variation seemed to be unrelated to the phylogenetic distance between subspecies.     

Age-Related Variation in Mate-Guarding Intensity in the Bluethroat (Luscinia s. svecica)

Female extra‐pair copulations (EPCs) have selected for male paternity guarding strategies in many bird species. In the bluethroat, Luscinia s. svecica, males guard their mates closely during the last 2 d before the start of egg laying, but there is great individual variation in the intensity of mate guarding. Here we show that some of this variation is related to male age. Old males guarded their mates with much lower intensity and sang more than young males, although the latter difference was not statistically significant. Controlling for male age, male and female coloration and size were not significantly related to the intensity of mate guarding. We have previously shown that young and old males had a similar paternity loss in their own broods. On the other hand, old males were far more successful than young males in achieving extra‐pair fertilizations. These patterns suggest that young and old males have different trade‐offs between preventing paternity loss in own nest and gaining paternity in others, because male skills in obtaining EPCs improve with experience and/or because of female preferences for old males as copulation partners. There were no significant relationships between paternity and male mate‐guarding behaviour during the fertile period, indicating that mate guarding is not a very effective paternity‐assurance strategy in the bluethroat.     

The generic and species relationships of the reputed endemic Malagasy genus Pseudocossyphus (family Turdidae)

The generic and specific relationships of the Malagasy rock-thrushes, variously placed in the genus Monticola or as an endemic genus Pseudocossyphus, are examined using morphological and molecular characters. On the basis of mitochondrial DNA cytochrome b sequence data it was concluded that all Malagasy rock-thrushes fall between Asian Monticola and a species group of Monticola occurring in numerous Old World areas. It is recommended that all Malagasy species be placed in the genus Monticola. Relationships between various named forms of Malagasy rock-thrushes indicate: M. imerinus is a distinct species, M. bensoni is a synonym of M. sharpei, the subspecies M. sharpei erythronotus should be elevated to a full species, and that no geographic forms of M. sharpei (including interioris and salomonseni) should be recognized on the basis of current evidence. These taxonomic conclusions have important implications for conservation projects currently underway on Madagascar.