The island canary occurs on the Azores, Madeira and Canary Islands. Based on the field studies conducted in these islands, this chapter investigates the ecology and reproduction of the island canary. The sexes differ in their yellow plumage colouration, and there are subtle differences in morphology between islands that, however, do not coincide with genetic differentiation of populations. The breeding season usually lasts from February to July, with a possible earlier onset at lower latitudes or depending on favourable weather and food availability. Canaries usually form permanent pairs and no extra-pair paternity has been found. There are subtle differences in male song among islands, and seasonal variation in song length and syllable composition, with some syllables preferred by females being more abundant in the breeding season. Recent research shows that these seasonal changes in song are due to the hormone-dependent gene expression in brain areas controlling song.

Acoustic communication is fundamentally constrained by noise. In birds, the masking of mating signals (songs) may reduce fitness and, hence, they have evolved various mechanisms to maintain communication in noise. One of these tactics is the adjustment of song timing to avoid overlap with masking sounds, but previous studies yielded contrasting results regarding the occurrence and magnitude of this behavioural plasticity. Here, we investigated how temporal noise avoidance varies with noise intensity. We exposed singing Canaries ( Serinus canaria ) to playbacks of masking noise of varying amplitude [60–80 dB(A) SPL]. Contrary to our prediction, the birds did not shift song onsets to the silent intervals between noise bursts at high noise amplitudes, nor did they increase singing outside the playback period. Rather, we found that noise generally triggered the onset of song: the Canaries preferentially sang during the noise bursts independent of the noise amplitude. This behaviour is somewhat paradox because it leads to the most unfavourable signal-to-noise ratios. Our results, together with findings from the current literature, indicate marked species differences in the noise-induced song plasticity of birds. Therefore, we suggest a more comprehensive conception of noise that incorporates both supressing and stimulating effects.

Singing in tropical and Southern hemisphere birds often occurs throughout the year in the form of duetting, which is thought to be associated with year-round territoriality. White-browed Sparrow Weavers ( Plocepasser mahali ) are cooperatively breeding songbirds of Eastern and Southern Africa, which live in groups of 2–10 individuals and defend all-purpose territories year-round. Their vocal behaviour is extraordinary as all group members sing duet and chorus song, but the dominant male of the group, additionally, sings a long solo song at dawn that comprises a distinct syllable repertoire. To gain further insight into the functions of the different types of song, the present study aimed at providing detailed quantitative data on diurnal and seasonal variation in singing activity. Therefore, we monitored the song behaviour of five groups of White-browed Sparrow Weavers at several time points during the course of the day and during the course of the year in relation to the groups’ breeding activities and environmental variables such as photoperiod, temperature and rainfall. Diurnally, solo song was heard exclusively during the first hour of vocalization in the morning before the onset of duetting. Seasonally, solo singing was restricted to the summer months. No tight link with breeding activities was found. Solo song duration was related to the density of neighbouring groups but not to group size. Similarly, duet/chorus rate showed large variation between groups and was related to the density of neighbouring groups. Diurnally, duet/chorus rate was significantly higher at the time point wake-up than at other times of the day. Seasonally, there was no difference. The increased singing rate at the time point wake-up, when all birds are present in the territory, suggests that these songs might convey information about territory ownership, group size as well as sex and status of the individuals.

Sex differences in lifespan can vary considerably across species. Variance in lifespan depends on the progression of the mortality rate with age. Males are usually thought to have a shorter lifespan than females, which can be explained by sexual selection acting on secondary sexual traits that affect longevity. Such a bias in mortality between the sexes is also an indicator of the adult sex ratio. While there is evidence for this relationship from species with traditional sex‐roles, little is known about the sex difference in lifespan of species that exhibit a reversal of sex‐roles. Here we investigated sex differences in longevity and hatchling sex ratio in a captive population of barred buttonquails Turnix suscitator, a sex‐role reversed species with a classical polyandrous mating system. We found that males lived on average 1.7 times longer than females. Further, sex ratio at hatching did not divert significantly from parity. Our data suggest that in sex‐role reversed species selective forces act on females leading to a shorter lifespan.

Birdsong is a precisely timed animal behavior. The connectivity of song premotor neural networks has been proposed to underlie the temporal patterns of neuronal activity that control vocal muscle movements during singing. Although the connectivity of premotor nuclei via chemical synapses has been characterized, electrical synapses and their molecular identity remain unexplored. We show with in situ hybridizations that GJD2 mRNA, coding for the major channel-forming electrical synapse protein in mammals, connexin 36, is expressed in the two nuclei that control song production, HVC and RA from canaries and zebra finches. In canaries' HVC, GJD2 mRNA is extensively expressed in GABAergic and only a fraction of glutamatergic cells. By contrast, in RA, GJD2 mRNA expression is widespread in glutamatergic and GABAergic neurons. Remarkably, GJD2 expression is similar in song nuclei and their respective embedding brain regions, revealing the widespread expression of GJD2 in the avian brain. Inspection of a single-cell sequencing database from zebra and Bengalese finches generalizes the distributions of electrical synapses across cell types and song nuclei that we found in HVC and RA from canaries, reveals a differential GJD2 mRNA expression in HVC glutamatergic subtypes and its transient increase along the neurogenic lineage. We propose that songbirds are a suitable model to investigate the contribution of electrical synapses to motor skill learning and production.

Complex motor skills take considerable time and practice to learn. Without continued practice the level of skill performance quickly degrades, posing a problem for the timely utilization of skilled motor behaviors. Here we quantified the recurring development of vocal motor skills and the accompanying changes in synaptic connectivity in the brain of a songbird, while manipulating skill performance by consecutively administrating and withdrawing testosterone. We demonstrate that a songbird with prior singing experience can significantly accelerate the re-acquisition of vocal performance. We further demonstrate that an increase in vocal performance is accompanied by a pronounced synaptic pruning in the forebrain vocal motor area HVC, a reduction that is not reversed when birds stop singing. These results provide evidence that lasting synaptic changes in the motor circuitry are associated with the savings of motor skills, enabling a rapid recovery of motor performance under environmental time constraints.

Many organisms coordinate rhythmic motor actions with those of a partner to generate cooperative social behavior such as duet singing. The neural mechanisms that enable rhythmic interindividual coordination of motor actions are unknown. Here we investigate the neural basis of vocal duetting behavior by using an approach that enables simultaneous recordings of individual vocalizations and multiunit vocal premotor activity in songbird pairs ranging freely in their natural habitat. We find that in the duet-initiating bird, the onset of the partner's contribution to the duet triggers a change in rhythm in the periodic neural discharges that are exclusively locked to the initiating bird's own vocalizations. The resulting interindividually synchronized neural activity pattern elicits vocalizations that perfectly alternate between partners in the ongoing song. We suggest that rhythmic cooperative behavior requires exact interindividual coordination of premotor neural activity, which might be achieved by integration of sensory information originating from the interacting partner.

Aggression is a fundamental part of animal social behaviour. In avian species, little is known about its neural representation. In particular, neural activity following offensive aggression has not been studied in detail. Here, we investigated the patterns of brain activation using immediate-early gene (IEG) expression in male Japanese quail that showed pronounced aggressive behaviours during a 30 min male-male interaction and compared them to those of males that did not interact with a conspecific. In aggressive males, we found a massive induction of the IEG ZENK in pallial brain structures such as the intermediate medial mesopallium, the caudomedial mesopallium and the intermediate medial nidopallium. To a lesser extent, activation was observed in subpallial areas such as the nucleus taeniae of the amygdala and in the medial portion of the bed nucleus of the stria terminalis. Our data suggest that the modulation of aggressive behaviour involves the integration of multisensory information.

In birds, vocal learning enables the production of sexually selected complex songs, dialects and song copy matching. But stressful conditions during development have been shown to affect song production and complexity, mediated by changes in neural development. However, to date, no studies have tested whether early-life stress affects the neural processes underlying vocal learning, in contrast to song production. Here, we hypothesized that developmental stress alters auditory memory formation and neural processing of song stimuli. We experimentally stressed male nestling zebra finches and, in two separate experiments, tested their neural responses to song playbacks as adults, using either immediate early gene (IEG) expression or electrophysiological response. Once adult, nutritionally stressed males exhibited a reduced response to tutor song playback, as demonstrated by reduced expressions of two IEGs (Arc and ZENK) and reduced neuronal response, in both the caudomedial nidopallium (NCM) and mesopallium (CMM). Furthermore, nutritionally stressed males also showed impaired neuronal memory for novel songs heard in adulthood. These findings demonstrate, for the first time, that developmental conditions affect auditory memories that subserve vocal learning. Although the fitness consequences of such memory impairments remain to be determined, this study highlights the lasting impact early-life experiences can have on cognitive abilities.

Complex motor skills take considerable time and practice to learn. Without continued practice the level of skill performance quickly degrades, posing a problem for the timely utilization of skilled motor responses. Here we quantified the recurring development of vocal motor skills and the accompanying changes in synaptic connectivity in the brain of a songbird, while manipulating skill performance by consecutively administrating and withdrawing testosterone. We demonstrate that a songbird with prior singing experience can significantly accelerate the re-acquisition of vocal performance. We further demonstrate that an increase in vocal performance is accompanied by a pronounced synaptic pruning in the forebrain vocal motor area HVC, a reduction that is not reversed when birds stop singing. These results provide evidence that lasting synaptic changes in the motor circuitry are associated with the savings of motor skills, enabling a rapid recovery of motor performance under environmental time constraints.

Animals that use vocal signals to communicate often compensate for interference and masking from background noise by raising the amplitude of their vocalisations. This response has been termed the Lombard effect. However, despite more than a century of research, little is known how quickly animals can adjust the amplitude of their vocalisations after the onset of noise. The ability to respond quickly to increases in noise levels would allow animals to avoid signal masking and ensure their calls continue to be heard, even if they are interrupted by sudden bursts of high-amplitude noise. We tested how quickly singing male canaries (Serinus canaria) exhibit the Lombard effect by exposing them to short playbacks of white noise and measuring the speed of their responses. We show that canaries exhibit the Lombard effect in as little as 300 ms after the onset of noise and are also able to increase the amplitude of their songs midsong and mid-phrase without pausing. Our results demonstrate high vocal plasticity in this species and suggest that birds are able to adjust the amplitude of their vocalisations very rapidly to ensure they can still be heard even during sudden changes in background noise levels.

The eusocial Damaraland mole-rat Fukomys damarensis represents an extreme example of reproductive skew, in that reproduction is completely blocked in female subordinate group members. Similarly, male subordinates within the colony show no sexual behaviour. In contrast to females, however, non-reproductive males have functional gonads and do not differ in circulating levels of pituitary hormones and testosterone from reproductive males. Nevertheless, they have reduced numbers of follicle-stimulating hormone (FSH) receptors in their testes and they produce fewer spermatozoa with a large proportion of immature spermatozoa and precursors. To understand the mechanism of reproductive suppression operational in subordinate males, we studied the expression of androgen receptor (AR) and progesterone receptor (PGR) genes in forebrain regions involved in the control of reproductive behaviour in male breeders and non-breeders from intact colonies. While it is well documented that testosterone activates male-typical behaviour, the role of progesterone in this process is less clear as previous studies have produced contradictory results. We found the expression of AR and PGR genes in several forebrain regions of male Damaraland mole-rats. The distribution of AR in males matches our previous findings in females. This is the first report showing the distribution of PGR in mole-rats. We found PGR in all areas which were also sensitive to androgens and oestrogens. Analysis of the optical densities of the AR and PGR hybridization signal revealed that breeding males had increased expression of AR and PGR compared to non-breeders in most brain regions examined, which include the medial preoptic area, the bed nucleus of the stria terminalis, the ventromedial nucleus of the hypothalamus, the arcuate nucleus and the medial amygdala. These status-related differences were more pronounced for PGR than for AR. This study shows that breeding position affects the neuroendocrine phenotype of male Damaraland mole-rats. Furthermore, it suggests that androgens and progesterone might act synergistically in activating sexual behaviour in males.

Most songbirds learn their songs from adult tutors, who can be their father or other male conspecifics. However, the variables that control song learning in a natural social context are largely unknown. We investigated whether the time of hatching of male domesticated canaries has an impact on their song development and on the neuroendocrine parameters of the song control system. Average age difference between early- and late-hatched males was 50 days with a maximum of 90 days. Song activity of adult tutor males decreased significantly during the breeding season. While early-hatched males were exposed to tutor songs for on average the first 99 days, late-hatched peers heard adult song only during the first 48 days of life. Remarkably, although hatching late in the season negatively affected body condition, no differences between both groups of males were found in song characteristics either in autumn or in the following spring. Similarly, hatching date had no effect on song nucleus size and circulating testosterone levels. Our data suggest that late-hatched males must have undergone accelerated song development. Furthermore, the limited tutor song exposure did not affect adult song organization and song performance.

The jet grouting process is being applied in a number of ways never attempted before as part of the four-track improvement of the Lower Inn Valley line. In addition to the production of waterproof invert, ground improvement to reduce settlement and for the homogenization of the excavation cross-section in mixed face sections, special mined solutions in particular have been made possible by jet grouting. A horizontal jet grout screen for advance tunnel support was produced for the first time under compressed air conditions; the protection of a complete ring-shaped jet-grouted surround also made a mined compressed air drive possible. The jet grouting process was also used to carry out sealing blocks to enable the mined connection of various mechanically tunneled rescue tunnels to the main tunnel driven by a TBM.The specific conditions on the project combined with the difficult ground conditions typified by Inn gravel sediments, dejection fan deposits and man-made fill demand all the knowledge and ability of the parties involved. The successful application of the jet grouting technique under these conditions assumes a very high quality of construction and a specially adapted quality assurance system. Using the example of the contracts H7-1 Fritzens Tunnel, H4-3 Stans Tunnel and H8 Jenbach Tunnel, the various applications of the jet grouting technique are described, and also the difficulties that arose during construction.

Background: While the song of all songbirds is controlled by the same neural circuit, the hormone dependence of singing behavior varies greatly between species. For this reason, songbirds are ideal organisms to study ultimate and proximate mechanisms of hormone-dependent behavior and neuronal plasticity.Results: We present the high quality assembly and annotation of a female 1.2-Gbp canary genome. Whole genome alignments between the canary and 13 genomes throughout the bird taxa show a much-conserved synteny, whereas at the single-base resolution there are considerable species differences. These differences impact small sequence motifs like transcription factor binding sites such as estrogen response elements and androgen response elements. To relate these species-specific response elements to the hormone-sensitivity of the canary singing behavior, we identify seasonal testosterone-sensitive transcriptomes of major song-related brain regions, HVC and RA, and find the seasonal gene networks related to neuronal differentiation only in the HVC. Testosterone-sensitive up-regulated gene networks of HVC of singing males concerned neuronal differentiation. Among the testosterone-regulated genes of canary HVC, 20% lack estrogen response elements and 4 to 8% lack androgen response elements in orthologous promoters in the zebra finch.Conclusions: The canary genome sequence and complementary expression analysis reveal intra-regional evolutionary changes in a multi-regional neural circuit controlling seasonal singing behavior and identify gene evolution related to the hormone-sensitivity of this seasonal singing behavior. Such genes that are testosterone-and estrogen-sensitive specifically in the canary and that are involved in rewiring of neurons might be crucial for seasonal re-differentiation of HVC underlying seasonal song patterning.

Maintenance strategies, which also contain endurance strength management, will become more and more important in the area of hydraulic machines. To meet these requirements, KELAG started a project with the goal to determine the remaining life time of the substantial generators in use and to develop maintenance arrangements according to the results using state of the art processes.