Female Domesticated Canaries Research Articles

Characteristics of song, brain-anatomy and blood androgen levels in spontaneously singing female canaries

Females of many northern temperate songbird species sing sporadically. However, detailed descriptions of female song are rare. Here we report a detailed analysis of song in a small number of spontaneously-singing female domesticated canaries (Serinus canaria) under non-breeding, laboratory conditions in a large population of domesticated birds. In-depth analysis showed that these females sang rarely, and the spontaneous songs varied between and within birds over time. Furthermore, spontaneous female songs were distinct from songs of testosterone-induced singing female canaries and from songs of male canaries in both temporal and spectral features. Singing females had significantly elevated plasma androgen levels and a larger size of the major song controlling brain nuclei HVC (used as a proper name) and the robust nucleus of the arcopallium (RA) than non-singing females housed under similar conditions. The sporadically observed production of song and accompanying differences in brain anatomy in female canaries may thus depend on minute intraspecific differences in androgen levels.

Negative impact of urban noise on sexual receptivity and clutch size in female domestic canaries

AbstractIn oscines, male song stimulates female reproduction and females are known to adjust both their sexual preferences and their maternal investment according to song quality. Female domestic canaries are especially responsive to wide frequency bandwidth (4 kHz) male songs emitted with a high‐repetition syllable rate and low minimal frequencies (1 kHz). We previously showed that low‐frequency urban noise decreases female sexual responsiveness for these low‐frequency songs (1–5 kHz) through auditory masking. Based on the differential allocation hypothesis, we predicted that urban noise exposure will equally affect female maternal investment. Using a crossover design, we broadcast low‐frequency songs to females either in an overlapping noise condition or in an alternating noise condition. Females decreased both their sexual responsiveness and their clutch size in the overlapping noise treatment relative to the alternative noise treatment. No differences were found concerning egg size or egg composition (yolk and albumen mass, testosterone concentration). Due to our experimental design, we can exclude a general impact of noisy conditions and thereby provide evidence for a detrimental effect through masking on avian courtship and reproductive output. These results suggest that noisy conditions may also affect avian communication in outdoor conditions, which may partly explain field reports on noise‐dependent breeding success and reduced breeding densities at noisy sites.

Bilateral coordination and the motor basis of female preference for sexual signals in canary song

The preference of female songbirds for particular traits in songs of courting males has received considerable attention, but the relationship of preferred traits to male quality is poorly understood. There is evidence that some aspects of birdsong are limited by physical or physiological constraints on vocal performance. Female domestic canaries (Serinus canaria) preferentially solicit copulation with males that sing special high repetition rate, wide-band, multi-note syllables, called `sexy' or A-syllables. Syllables are separated by minibreaths but each note is produced by pulsatile expiration, allowing high repetition rates and long duration phrases. The wide bandwidth is achieved by including two notes produced sequentially on opposite sides of a syrinx, in which the left and right sides are specialized for low or high frequencies, respectively. The temporal offset between notes prevents cheating by unilaterally singing a note on the left side with a low fundamental frequency and prominent higher harmonics. The syringeal and respiratory motor patterns by which sexy syllables are produced, support the hypothesis that these syllables provide a sensitive vocal-auditory indicator of a male's performance limit for the rapid, precisely coordinated inter-hemispheric switching, which is essential for many sensory and motor processes involving specialized contributions from each cerebral hemisphere.

Bilateral coordination and the motor basis of female preference for sexual signals in canary song

The preference of female songbirds for particular traits in the songs of courting males has received considerable attention, but the relationship of preferred traits to male quality is poorly understood. Female domestic canaries (Serinus canaria, Linnaeus) preferentially solicit copulation with males that sing special high repetition rate, wide-band, multi-note syllables, called 'sexy' or A-syllables. Syllables are separated by minibreaths but each note is produced by pulsatile expiration, allowing high repetition rates and long duration phrases. The wide bandwidth is achieved by including two notes produced sequentially on opposite sides of the syrinx, in which the left and right sides are specialized for low or high frequencies, respectively. The emphasis of low frequencies is facilitated by a positive relationship between syllable repetition rate and the bandwidth of the fundamental frequency of notes sung by the left syrinx, such that bandwidth increases with increasing syllable repetition rate. The temporal offset between notes prevents cheating by unilaterally singing a note on the left side with a low fundamental frequency and prominent higher harmonics. The syringeal and respiratory motor patterns by which sexy syllables are produced support the hypothesis that these syllables provide a sensitive vocal-auditory indicator of a male's performance limit for the rapid, precisely coordinated interhemispheric switching, which is essential for many sensory and motor processes involving specialized contributions from each cerebral hemisphere.

CANARIES CAN'T CHEAT ON SEXY A SYLLABLES

Male birds have many features in their arsenal to attract healthy female mates, including ostentatious plumage, complex dances and elaborate vocal performances. However, Roderick Suthers, from Indiana University, USA, and Eric Vallet and Michel Kreutzer, both from the Université Paris Ouest Nanterre La Defense, France, explain that it is unclear exactly how a male bird's vocal performance communicates his fitness. According to the team, female domestic canaries are particularly willing to mate with males that incorporate a specific wide bandwidth two-note syllable – the so-called ‘sexy’ A syllable, executed at a high 15 syllables s–1 repetition rate – into their repertoire. So, Suthers and his colleagues decided to analyse the males' vocal tract gymnastics to find out how difficult the syllable's trills are to coordinate and how they convey information about male fitness (p. 2950).Explaining that the two sides of the bird's syrinx are capable of producing sound independently – with the left side producing low frequency notes while the right side produces high frequency sounds – Suthers and his colleagues surgically implanted two thermistors, one in each side of the male canary's syrinx, to measure airflow through the organ and to determine which side of the syrinx produced the pair of characteristic sexy syllable notes. The team also inserted a cannula into one of the bird's airsacs to determine the airflow direction. Repeating the surgery on two other birds, the team then recorded the birds' songs and determined which side of the syrinx produced each note.Having identified seven sexy syllables in the birds' recitals and analysed the airflow producing them, the team found that each sexy syllable was produced as the birds pulsed their breath while exhaling. Also, each syllable was separated by minibreaths – when the birds inhale swiftly after a syllable to replace the exhaled air – allowing the bird to sustain a lengthy recital. The team says, ‘The combination of these two respiratory strategies permits high note repetition rates’, allowing the males to hit the 15 syllables s–1 repetition rate required for a syllable to be deemed ‘sexy’ by the female. In addition, Suthers and his colleagues found that despite repeating the syllables at an extremely high rate, each syllable still had a wide frequency bandwidth, which is a key feature of sexy syllables, achieved by sequentially alternating two notes, one from either side of the syrinx.The team explains that as each half of the syrinx is controlled by one brain hemisphere, it is the ability of the males to coordinate the two brain hemispheres (bilateral coordination) to alternate the pair of sexy syllable high and low frequency notes – resulting in a wide bandwidth spectrum – that allows the female to assess her suitor's coordination and quality. They also suggest that listening for two-note sexy syllables allows females to rule out cheats with poor bilateral coordination that could produce similar effects by only using one half of the syrinx.So, it appears that females have evolved a preference for sexy syllables because they reveal how well coordinated males are. The team says, ‘Females who prefer these traits should have a higher probability of choosing a male with excellent bilateral coordination than females that choose based on only one or a few of these traits’.

Female canary mate preferences: differential use of information from two types of male–male interaction

During mate choice, females can assess male quality by sampling one male after the other or by paying attention to the outcomes of male–male interactions. The latter strategy, called eavesdropping, allows females access to information about males' relative quality and therefore reduces the time, energy and other costs associated with searching for a mate. For oscine females, information can be gathered both by listening to male–male singing interactions and by visually observing male–male interactions. To date, however, there has been no comparison of the subsequent behaviour of females according to the specific type of information (acoustic or visual) gathered from male–male interactions. In two successive experiments, we explored how female domestic canaries, Serinus canaria, use visual and acoustic information obtained from a male–male interaction to direct their sexual behaviour. We found that, whereas females preferred the overlapping song of a singing interaction, they avoided the winner of a physical contest over food. The function and range of signals used in these two types of male–male competition may account for this discrepancy. Timing of song during countersinging is the expression of ritualized dominance relationships using a long-range secondary sexual trait, whereas threat displays used in food competition are not secondary sexual traits and are potentially harmful at close proximity. The timing of song during countersinging seems to be a more important cue for females than dominance over food in determining their sexual behaviour.

Does maternal social hierarchy affect yolk testosterone deposition in domesticated canaries?

Dominance is a relative measure that allows asymmetrical relationships between individuals to be quantified. These kinds of relationships often depend on aggressive behaviour and the steroid hormone most frequently associated with aggressiveness is testosterone. Testosterone is present in both sexes and implanting it can provoke a rise of individual aggressiveness leading consequently to an increase of social status. Many researchers have studied the relationship between plasma testosterone and dominance but few have focused on yolk testosterone and social hierarchy. Thus we aimed to study the possible influence of the mother's social status on egg yolk testosterone deposition. Our hypothesis is that dominant females lay eggs containing more testosterone than subordinate females. We recorded the social hierarchy of 24 female domesticated canaries, Serinus canaria , and studied the influence of their social status on the concentration of testosterone in their egg yolks and on other egg characteristics. Our results show a significant relationship between a mother's social status and the amount of testosterone deposited in its yolks: the more dominant the females are, the more concentrated in testosterone their eggs are. Our results also show that yolk testosterone increases with laying order, whereas no relationship between mothers' rank number and their clutch size or egg mass was found. We conclude that there is a clear effect of maternal social status on yolk testosterone and discuss dominance inheritance.

Social competition and plasma testosterone profile in domesticated canaries: An experimental test of the challenge hypothesis

The challenge hypothesis predicts that plasma testosterone (T) concentration is high when male–male competitions are high and decreases when males are engaged in paternal care. In monogamous species, T concentration increases at the beginning of the breeding period and decreases after egg laying. According to the challenge hypothesis, increasing competition should also lead to T increase. The aim of our study was to test this hypothesis. In a first experiment, we measured the T profile of domesticated canaries housed with their mate in separated cages without competition. In a second one, we created a competition by housing male and female domestic canaries together (in an aviary) and emphasized this competition by limiting food access. We also studied social status effect. Our results showed no effect of social status in both sexes and no differences in female's T concentration. Concerning males, we obtained a clear monogamous T profile from the ones housed in a low competition situation and a polygamous profile from the others housed in high competition situation. Thus, our results support the hypothesis of the plasticity of the mechanisms controlling T concentration according to environmental conditions.

Is he all he says he is? Intersexual eavesdropping in the domestic canary, Serinus canaria

Recent studies have pointed out that passerine females pay great attention to male territorial interactions and that they extract information on the quality of males from their territorial songs. We investigated whether female domestic canaries use information gained through eavesdropping when they choose mates. We evaluated the females' sexual preferences for tape-recorded male songs previously heard during an ‘interaction-like’ situation during which the song of one male overlapped the song of the other. Females were tested during two consecutive experiments. In the first experiment, we measured the preference for male songs containing sexually attractive phrases; in the second, the attractive phrases were removed. When a sexually attractive phrase was included in the song, the females failed to show a significant preference but in the second experiment, the females preferred the songs of males that appeared to be able to overlap the songs of their opponents. In the first experiment, the information might have been contradictory: on the one hand, some males seemed to be of poorer quality than others, as they were losing the song contest, but, on the other hand, these same males were producing songs with a sexually attractive phrase, regarded as a signal of quality; the females might have been confused by this apparently inconsistent information. Overall, this study agrees with previous work on eavesdropping, and extends the evidence for such eavesdropping as a choosy female sexual strategy across species.

Dominance-related foraging in female domesticated canaries under laboratory conditions

Many experiments have tested the foraging behaviours of birds relative to their social status. However, results are still not completely clear about the relationship between foraging behaviour and social status in birds. Some studies have shown that dominants use subordinates as food finders, while others show the opposite. Whether dominants search by themselves or wait to exploit the findings of a subordinate is still an unanswered question. For testing these alternative hypotheses, we carried out a laboratory experiment that used female common domesticated canaries, Serinus canaria (L., 1758). We used strict female flocks to avoid any bias based on pair bonds. We looked at the foraging behaviours of females relative to their social status using a foraging board. Our results showed that dominant females behaved as their own food finder. They began searching in the first position and had greater re-search behaviours, which allowed them to find seeds more rapidly than subordinates. Our study showed that foraging behaviour of dominants may be independent of the activities of subordinates. Our results also showed that there was no difference between the number of attacks received by dominants and subordinates when they were on the foraging board, which suggests that subordinates accessed the foraging board less frequently to avoid competition with dominants. We also suggest that environmental conditions may be one explanation for the differences observed among the different studies.

Sexual preferences for songs in female domestic canaries ( Serinus canaria ): can late song exposure, without social reinforcement, influence the effects of early tutoring?

We studied the relative effects of early and late song exposure without social reinforcement on female sexual preferences in the domestic canary (Serinus canaria). Young female canaries were tape-tutored during their first 4 months of life with songs of either domestic or wild male canaries (DT and WT conditions). When they reached sexual maturity, these females were placed in breeding conditions and some of them were re-exposed to songs. During this “late exposure” the females, according to their experimental group, were either presented with new domestic or wild songs (DL and WL conditions) over 40 days, or were kept without song stimulation (− condition). Afterwards, we assessed the sexual preferences of all the females for domestic or wild songs using the copulation solicitation display assay. The results showed that both DT/– and DT/DL females showed a clear preference for domestic songs. However, whereas WT/WL females preferred wild songs; WT/– females did not show any preference. Finally, DT/WL and WT/DL females failed to show any preference. It appeared that a second song experience at the beginning of their first breeding season, without any social reinforcement, allowed the emergence or stabilisation of early preferences, or interfered with these early preferences depending on whether the song category used during the late exposure phase matched or not the song category used during the early tutoring phase, and also depending on which category was used during the first tutoring phase. This behavioural plasticity could help young adult females to adjust the ‘standard’ they built during infancy to new environmental conditions.

Adult Female Canaries Respond to Male Song by Calling

We describe a new assay for measuring the response to song playback by adult female domesticated canaries,Serinus canaria. We tested song perception and discrimination by measuring the frequency of particular female calls (`single calls') given in response to male song playbacks. We observed that females responded differently to songs of different species (canaries vs. pine siskin,Carduelis spinus) and to songs of different canary strains (domesticated vs. wild canaries). In addition, females were especially responsive to songs containing a particular type of song phrase (`A' phrases).This new assay provides equivalent results to the standard method (copulation solicitation displays) traditionally used to assess female song preferences. Our new assay has the advantage that it allows one to measure female song responsiveness without having to use estradiol implants and during both long and short day photoperiods. However, females responded differently in long and short days. We suggest that, by calling, females could both provide information about their sexual interest and attract the attention of particular males.

Early tutoring and adult reproductive behaviour in female domestic canary ( Serinus canaria )

We studied the effect of early tutoring on the subsequent sexual preferences and reproductive activity of female domestic canaries (Serinus canaria). Young female canaries were exposed during the first 4 months of life to songs of either domestic or wild canaries. When adult, these females were again exposed to domestic or wild songs. In the first experiment, the sexual responses of the females to unfamiliar domestic and wild songs were quantified with the copulation solicitation display (CSD) assay. In the second experiment, the same females were tested again with modified tutoring songs. In the third experiment, song stimulation of nest-building and egg-laying was studied. Domestic-strain-tutored females gave more CSDs to domestic than to wild songs. In contrast, wild-strain-tutored females showed no sexual preference. We propose that the sexual preference of adult domestic-strain-tutored female canaries for domestic songs is the consequence of learning and categorisation processes. The discrepancy between the results of the domestic-strain-tutored females and those of the wild-strain-tutored females suggests that female canaries have a predisposition to learn songs of their own strain rather than songs of an alien strain. In the third experiment nest-building and egg-laying activities appeared to be unaffected by early tutoring conditions: there was no significant differential effect of the different tutoring and exposure conditions on nest-building and egg-laying scores. Mate attraction and stimulation of females’ reproductive activity appear to be two separate functions of male song, which may have been shaped by different evolutionary constraints.

Adult female domesticated canaries can modify their song preferences

Previous research has shown that acoustic experiences in early life influence song preferences in female domesticated canaries, Serinus canaria. We do not know, however, if they can modify song preferences in adulthood. In the experiments reported here, one group of young female domesticated canaries was reared in acoustic isolation in early life without song tutoring, while two groups were tutored with a playback song (one with wild canary song and one with domesticated canary song). We tested these three groups of females once they had reached adulthood, prior to breeding, using copulation-solicitation displays as an index of their song preferences. The females were then placed in an aviary with males during the breeding period, after which they were retested. We observed that the song preferences of females reared in acoustic isolation and those tutored with wild canary song had changed. These females were able to develop new song preferences in adult life. These results are discussed in relation to current views on song preferences and sexual imprinting.

A chorus song style influences sexual responses in female canaries

We examined whether the playback of a chorus song style (i.e., two songs presented simultaneously from a single speaker) influences sexual song preferences of female domesticated canaries, Serinus canaria. Six females were treated with estradiol and their responses to the different types of song were measured as the frequency of copulation solicitation displays. Females responded preferentially to a chorus song style and reacted less to presentation of single songs (conspecific and heterospecific). These observations suggest that females sexual responses are elicited by two songs heard simultaneously. Our results are discussed in relation to current views on the song preferences of females and the phenomenon of chorus singing in songbirds.

Song Tutoring Influences Female Song Preferences in Domesticated Canaries

Abstract Laboratory experiments were designed to examine the influence of previous acoustic experience on later song preferences in female domesticated canaries (Serinus canaria). Young females were reared in acoustic isolation (five groups). In these five groups, one was reared without tutoring and four were exposed to taped tutoring songs (playbacks of three different songs, two conspecific and one heterospecific). One of the four tutored groups was exposed to all three songs, while each of the remaining groups was exposed to one of the three songs. When adult, all females were tested using copulation solicitation displays as an index of their song preferences. We demonstrated that females reared without tutoring were especially responsive to a particular domesticated canary song. This song contained a special song phrase type (Vallet & Kreutzer, 1995) that elicits high levels of sexual response. In general, a similar preference was also observed in the groups reared with tutoring. In addition, the females' preferences in tutored groups were also positively and strongly affected by conspecific songs, when these songs had been heard during the previous tutoring. In fact, females seemed to be able to selectively respond to a song containing a special song phrase, but were also able to learn conspecific songs.

Obtaining copulation solicitation displays in female canaries without estradiol implants

Female domesticated canaries (Serinus canaria) respond to conspecific song with copulation solicitation display (CSD) between 22 and 27 days after their first offspring has hatched. This period could be used to investigate the acoustical preferences of female canaries. This non-invasive method respects the natural reproductive cycle and could be an alternative to the invasive method of estradiol implants.

Peahens lay more eggs for peacocks with larger trains

Reproduction is costly and individual decisions about when and how much to invest in reproduction will relate to potential benefits in terms of offspring survivorship or mating success. For those organisms that can reproduce more than once, individuals should invest relatively more in reproduction when the potential benefits are high. If females gain directly or indirectly from choosing attractive, highly ornamented males, then it could be predicted that females mated to these males should invest more in reproduction. Here we report the first test of this prediction for a lekking species, peafowl (Pavo cristatus), in which males do not provide resources for offspring, and females prefer to mate with those males that possess the most elaborate trains. We find that peahens randomly mated to males that vary in the degree of ornament produce more eggs for those peacocks with more elaborate trains. We could find no evidence to support the possibility that this difference arises as a result of difference between males in their ability to fertilize eggs.

Syllable Phonology and Song Segmentation: Testing Their Salience in Female Canaries

By stimulating female common domesticated canaries with computer edited song stimuli, we investigated the salience of own breed phonology or song segmentation. These own breed acoustic parameters versus alien breed's and heterospecific ones were tested using copulation solicitation displays as an index of female responses. We found that females gain information about their own breed identity from both phonology and song segmentation. Border strain syllables or segmentation ensure high levels of responses, similar to those elicited by own breed ones. By contrast, harzer strain, wild canary and greenfinch phonology or segmentation elicited low levels of displays. The weaker reactions were recorded to harzer phonology. Processes involved in female recognition of multipartite songs are discussed and compared to those used by male oscines.

Effect of exogenous serum gonadotrophin (PMS) on aspects of reproductive development in female domesticated canaries

PMS was injected thrice weekly for four weeks into first winter and second winter canaries during the following periods: September‐October, November‐December, January‐February and February‐March. Measures were made of ovary and oviduct weight, brood‐patch development (defeathering, vascularity and sensitivity changes), nest‐building and egg‐laying. PMS caused overy growth in all months: this was greatest in the second year birds in February. Both control and treated ovaries increased in size towards the breeding season. Oviduct growth depends mainly on the size of the treated ovary. Defeathering was produced by PMS in all months: its rate and extent increased towards the breeding season. Vascularity was also produced by PMS. It was least in November‐December but after that the rate at which it appeared increased towards the breeding season. By contrast, the effect of PMS on brood‐patch skin sensitivity was greater in the autumn group than subsequently. Nest‐building occurred in September‐October, but was then very slight until February‐March, which is the beginning of the breeding season. Eggs were laid in most months; fewer injections were needed to produce egg‐laying as the breeding season approached.