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1.
Seasonal variation in animal signalling behaviour has been well documented and has contributed much to our understanding of
male signals. In contrast, we know little about seasonal variation in female signals or signals produced jointly by males
and females, such as the vocal duets of birds. Here, we examine how singing behaviour changes in relation to time of year
and breeding stage in rufous-and-white wrens (Thryothorus rufalbus), neotropical songbirds where both males and females sing and where breeding partners coordinate songs to produce vocal duets.
We recorded a colour-marked population of birds over an extended time period encompassing multiple breeding stages. Across
all time frames and breeding stages, males sang at higher rates than females and male solos were more common than duets or
female solos. Males and females showed divergent seasonal patterns of singing. Females sang more often early in the year,
during the pre-breeding season, and female song tapered off as the breeding season progressed. Duetting followed a parallel
pattern, which resulted from females showing less duet responsiveness to their partner’s songs later in the year. Male independent
song rate peaked at the onset of the rainy season – a time when females become fertile – and males showed the highest level
of duet responsiveness during this period. Our results suggest that early in the year, duets appear to be cooperative displays,
functioning in joint territory defence and/or the coordination of breeding activities. When females are fertile, however,
increased duet responsiveness by males is consistent with mate or paternity guarding. 相似文献
2.
Holly L. Hennin Nicole K. S. Barker David W. Bradley Daniel J. Mennill 《Behavioral ecology and sociobiology》2009,64(2):151-159
To attract a breeding partner, males may behave differently when they are bachelors compared to when they are paired. Comparisons
between groups of paired males versus groups of unpaired males in temperate-breeding animals have revealed such differences
in signalling behaviour. Few studies, however, have explored how individual males alter their signalling behaviour with changes
in pairing status, and very few investigations have explored paired versus unpaired male behaviour in tropical animals. During
a 5-year study in Costa Rica, we analysed changes in the singing behaviour of male rufous-and-white wrens (Thryothorus rufalbus) when they were paired and when they were bachelors. We compared three aspects of male vocal behaviour: gross differences
in song output, variation in repertoire use and differences in song structure. Males as bachelors had significantly higher
song output and switched song types less frequently. Contrary to our expectation, bachelors sang significantly fewer song
types from their repertoire compared to when those same males had a breeding partner. Songs sung by bachelor males were higher
in syllabic diversity and had broader-bandwidth terminal syllables than the songs those males sang only when paired. Within
song types, the fine structure of songs remained consistent across pairing status. Our results demonstrate that males change
their singing behaviour with pairing status, delivering songs at a higher rate but with less variety when they are bachelors.
Rufous-and-white wrens are renowned for their vocal duets, and we discuss the pattern of repertoire use in light of their
duetting behaviour. These results enhance our understanding of how male behaviour varies with pairing status and the importance
of vocal signalling behaviour in socially monogamous tropical animals. 相似文献
3.
Valentin Amrhein Lars Erik Johannessen Lena Kristiansen Tore Slagsvold 《Behavioral ecology and sociobiology》2008,62(10):1633-1641
The costs and benefits of bird song are likely to vary among species, and different singing patterns may reflect differences
in reproductive strategies. We compared temporal patterns of singing activity in two songbird species, the blue tit (Cyanistes caeruleus) and the great tit (Parus major). The two species live side by side year round, and they have similar breeding ecology and similar rates of extra-pair paternity.
However, they differ in two aspects of reproductive strategy that may have an influence on song output: blue tits are facultatively
polygynous and have a fairly short breeding season with almost no second broods, whereas great tits are socially monogamous
but more commonly raise second broods. We found that great tit males continued singing at high levels during the egg-laying
and incubation periods, while monogamously paired blue tit males strongly reduced singing activity after the first days of
egg-laying by their female. Since males of both species sang much more intensely shortly before sunrise than after sunrise,
at midday or in the evening, this difference was most conspicuous at dawn. No differences in singing activity were found within
species when testing for male age. We suggest that in contrast to blue tits, great tit males continued singing after egg-laying
to defend the territory and to encourage the female for a possible second brood. 相似文献
4.
Sjouke A. Kingma István Szentirmai Tamás Székely Veronika Bókony Maarten Bleeker András Liker Jan Komdeur 《Behavioral ecology and sociobiology》2008,62(8):1277-1288
Melanin-based ornaments are often involved in signaling aggression and dominance, and their role in sexual selection is increasingly
recognized. We investigated the functions of a melanin-based plumage ornament (facial ‘mask’) in male Eurasian penduline tits
Remiz pendulinus in the contexts of male–male aggression, mating success, and parental care. The penduline tit is a passerine bird with a
unique mating system in which both sexes may mate with several mates in a breeding season, and one (or both) parent deserts
the clutch. Our study revealed that mask size of males is more likely an honest signal used by females in their mate choice
decisions than a trait involved in male–male competition. First, mask size increased with both age and body condition, indicating
that the mask may signal male quality. Second, males with larger masks paired more quickly and had more mates over the breeding
season than males with smaller masks. Third, we found no evidence that male mask size signals male–male aggression or dominance
during competitive encounters. The increased mating success of large-masked males, however, did not translate into higher
reproductive success, as nestling survival decreased with mask size. Therefore, we conclude that there is either no directional
selection on male mask size or males with larger masks receive indirect, long-term benefits. 相似文献
5.
Conny Bartsch Ronja Wenchel Annemarie Kaiser Silke Kipper 《Behavioral ecology and sociobiology》2014,68(7):1163-1171
In bird communication, listening individuals may obtain information on the quality and motivation of a male not only from solo-singing, but also from song interactions and listeners base their future decisions in territorial and mating contexts on such public information. Eavesdropping on male interactions may thus have a strong influence on sexual selection. In singing interactions, temporal coordination (e.g. overlapping vs. alternating) of two singers as well as structural interaction patterns (e.g. song type matching or repertoire matching) have been described, but the latter is far less studied. By conducting dual-speaker playback experiments with common nightingales Luscinia megarhynchos, we simulated an interaction where one singer was repeatedly song–type matching his counterpart. Playbacks were broadcast to male and female nightingales, and their approach behaviour and singing responses (in the case of male focals) were analysed. We found that both, males and females, spent more time with the matched bird, whereas males additionally sang more songs towards the matching bird. This can be taken as strong hint that eavesdropping occurs in nightingale communication and that listening to male vocal contests might be an important strategy for both sexes to adjust their behavioural output. With regard to the function of song matching, we assume that song-matching is not an aggressive signal per se in nightingales. We rather conclude that vocal leaders within an interaction, here the matched bird, may elicit stronger responses in conspecifics than vocal followers, here the matching bird. 相似文献
6.
Maria I. Sandell 《Behavioral ecology and sociobiology》2007,62(2):255-262
In the European starling, Sturnus vulgaris, optimal mating systems differ between males and females. Males gain from polygyny, whereas monogamy increases female fitness.
The cost of polygyny to females lead to intense female–female competition, and it has previously been shown that the intensity
of female aggression during the pre-breeding period can predict the realised mating system. The physiological regulation of
such female aggression in starlings is not yet known. This study examines the role of testosterone in mediating aggressive
behaviours involved in intra-specific reproductive competition in female starlings. Testosterone levels were experimentally
elevated with testosterone implants in females during the pre-laying period. To simulate a situation in which an additional
female tried to mate with the focal female’s mate, a caged female was presented close to a nest-site to which the male could
attract a secondary female. Testosterone was significantly related to several behaviours involved in female–female interactions.
Females with testosterone implants spent significantly more time close to the caged female and produced more song bouts than
control females. In contrast, male behaviour was unrelated to the experimental status of the mate. Females mated to males
that attracted a secondary female were less aggressive towards the caged female than those that remained monogamously mated.
The effect of exogenous testosterone in this study indicates that androgens may mediate social behaviours in female starlings
during the breeding season. 相似文献
7.
Trade-off between mate guarding and mate attraction in the polygynous great reed warbler 总被引:5,自引:0,他引:5
Summary In a Swedish population of the polygynous great reed warbler Acrocephalus arundinaceus, about 40% of the males formed pairs with more than one female. Males sang two completely separated types of song: (1) long song when they tried to attract mates and (2) short shong when they guarded a fertile female. As soon as a male had attracted a female he immediately switched from long to short song and apparently guarded her for at least 3 days. Most males left their female and started singing long several days before her fertile period ended. This behavior probably increased the risk of cuckoldry. By assuming that males of polygynous species maximize their fitness over the whole breeding season (i.e., maximize fitness rate), we predicted longer mate guarding periods when the probability of attracting a second female was low and the risk of cuckoldry was high. These predictions were supported by observations. The probability of attracting a second female decreased during the breeding season and, in accordance, the number of days that males sang long song during the primary female's fertile period was negatively correlated with the time of the season. This trend held also for individual males when comparing mating periods of their primary and secondary female. The increasing rate of male intrusions with season may also have contributed to the increasing mate guarding periods.
Offprint requests to: D. Hasselquist 相似文献
8.
P. R. Martin J. R. Fotheringham Laurene Ratcliffe Raleigh J. Robertson 《Behavioral ecology and sociobiology》1996,39(4):227-235
Least flycatchers (Empidonax minimus) and American redstarts (Setophaga ruticilla) overlap in the use of food resources on their breeding grounds, promoting high levels of interspecific aggression by the
socially dominant flycatcher. We examined the role of song in this interspecific aggression by using repeated-measures-designed
playback experiments and observational data on induced aggressive interactions. Flycatchers were more likely to approach the
speaker during presentation of redstart song than during intervals of no song or presentation of control song. Approach was
close enough to enable visual contact with a singing redstart. In contrast, redstarts made significantly fewer flights following
presentation of flycatcher song, when risk of flycatcher attack may be greatest. Reducing the number of flights likely reduces
the risk of flycatcher attack on the redstart, as flycatchers do not attack stationary redstart models and are apparently
dependent on cues from redstart flight for visual heterospecific recognition. Flycatcher-specific responses of redstarts and
marked differences in song morphology rule out misdirected intraspecific aggression as a proximate or ultimate cause of interspecific
response to song. Results indicate that song is an important component in aggressive interactions between these two species,
and reflect the dominant role of the flycatcher in such interactions. Our results also illustrate the capacity for interspecific
interference competition to influence behavior and heterospecific song recognition in two distant avian taxa.
Received: 10 January 1995/Accepted after revision: 8 June 1996 相似文献
9.
In songbirds of the temperate zone, often only males sing and their songs serve to attract females and to deter territorial rivals. In many species, males vary certain aspects of their singing behavior when engaged in territorial interactions. Such variation may be an honest signal of the traits of the signaler, such as fighting strength, condition, or aggressive motivation, and may be used by receivers in decisions on whether to retreat or to escalate a fight. This has been studied intensively in species that sing discontinuously, in which songs are alternating with silent pauses. We studied contextual variation in the song of skylarks (Alauda arvensis), a songbird with a large vocal repertoire and a continuous and versatile singing style. We exposed subjects to simulated territorial intrusions by broadcasting conspecific song and recorded their vocal responses. We found that males sing differently if they are singing spontaneously with no other conspecific around than if they are territorially challenged. In this last case, males produced lower-frequency syllables. Furthermore, they increased the sound density of their song: they increased the proportion of sound within song. They seem to do so by singing different elements of their repertoire when singing reactively. Furthermore, they increased the consistency of mean peak frequency: they repeated syllable types with less variability when singing reactively. Such contextual variation suggests that skylarks might use low frequencies, sound density, and song consistency to indicate their competitive potential, and thus, those song features might be important for mutual assessment of competitive abilities. 相似文献
10.
Summary The temporal patterning of vocal interactions between territorial nightingales (Luscinia megarhynchos B). was investigated during nocturnal dyadic singing. We distinguished three forms of temporal performance roles (Table 1; Fig. 3): inserter (preferred song start 0.5–1.0 s after offset of a neighbour's song), overlapper (preferred song start 0.5–1.0 s after onset of a neighbour's song), and Autonomous bird (no evidence for temporal responses adjusted to the timing of a neighbour's singing; Fig. 4). With the beginning of the daily dawn chorus, mutual temporal adjustment of song performances could no longer be ascertained (Fig. 2). To test the flexibility of song onset timing, we presented subjects with three playback programs (I, II, III) simulating a non-flexible conspecific bird. Sequences of songs recorded from a stranger that shared no song types with the subjects were used; intersong pauses were unaltered in I, lengtened in II, and shortened in III. Results confirmed that the timing of song onset can be influenced by the temporal patterning of auditory stimuli (Table 1; Fig. 5): Inserters and overlappers sang at a slower rate during program II than during program I. During program III, which by accelerated stimulus succession caused frequent overlap of songs, inserters and overlappers interrupted their singing behaviour (Fig. 6). This suggests that overlapping, which results in signal interference, is of some functional significance in vocal interactions. 相似文献
11.
Ioana Chiver Bridget J. M. Stutchbury Eugene S. Morton 《Behavioral ecology and sociobiology》2008,62(12):1981-1990
Extra-pair fertilizations are common in many socially monogamous species, and paternity studies have indicated that females
may use male vocal performance and plumage ornaments as cues to assess male quality. Female off-territory forays may represent
a key component of female choice and male extra-pair mating success, and female foray behaviour is expected to be strongly
influenced by indictors of male quality. In this study, we examined how male song and ornamentation affect how often females
left their territories, which males they visited and extra-pair paternity in a socially monogamous passerine, the hooded warbler
(Wilsonia citrina). We radiotracked 17 females during the fertile period and quantified male vocal performance (song output and rate) and plumage
characteristics (size of the black melanin hood and colour of the black hood, yellow cheeks and breast areas). We obtained
blood samples and determined paternity at 35 nests including those of 14 females that we radiotracked. Eleven (65%) of the
17 females forayed off-territory, whilst fertile and female foray rate was positively correlated with the number of extra-pair
young in the nest. Females that left their territories more frequently were paired with males that sang at a low rate. In
addition, extra-pair mates had higher song rates than the social mates they cuckolded (5.3 songs/min vs. 4.4 songs/min). Female
off-territory forays or extra-pair paternity were not significantly related to male plumage characteristics. Our results indicate
that a high song rate influences both the foray behaviour of a male’s social mate and the likelihood that he will sire extra-pair
offspring with neighbouring females. 相似文献
12.
Peter Tyack 《Behavioral ecology and sociobiology》1981,8(2):105-116
Summary Interactions of singing humpback whales, Megaptera novaeangliae, with conspecifics nearly were studied during the breeding season off the west coast of Maui, Hawaii. On 35 occasions singing humpbacks were followed by boats (Table 1). The movement patterns of these singing whales and other conspecifics nearby were recorded by observers on land using a theodolite.Thirteen of 35 singers stopped singing and joined with nonsinging whales either simultaneously or within a few minutes after ceasing to sing. Another 15 also stopped singing while under observation and were not seen to join with another whale, but all singing whales that joined with other whales stopped singing. Singing whales often pursue nonsinging whales, while nonsinging whales usually turn away from singers (Figs. 4, 5).When a singer joined with a female and calf unaccompanied by another adult, behavior tentatively associated with courtship and mating was observed (Fig. 7). Such behavior also occurred during several interactions between singers and individuals of unknown sex. Aggressive behavior was observed during three interactions between singers and individuals of unknown sex (Fig. 4) and it predominated whenever more than one adult accompanied a cow and calf. During the other occasions when a singer joined another whale, we could not determine the nature of the interaction. Many times the singers and joiner would surface together only once and would then separate. However, on several occasions the singer and joiner would remain together for as long as we could follow them, up to 1.5 h.The roles of singer and joiner can be interchangeable. For instance, on two occasions a singer joined with a whale that either had been singing or started singing later in the day (Fig. 3). Furthermore, on several occasions, a nonsinging whale appeared to displace the singer. Individual singing humpbacks are not strictly territorial, although singers appear to avoid other singers.As the breeding season progressed, singers sang for longer periods of time (Fig. 2). In addition, the probability of a whale joining with the singer decreased by 42% from the first half of the observation period to the second half. Furthermore, this increase in duration of song bouts occurred during that section of the season when female reproductive activity as measured by rate of ovulation is reported to be decreasing in other areas.Our observations support the hypothesis that humpback song plays a reproductive role similar to that of bird song. Humpbacks sing only during the breeding season. If, as seems likely, most singing humpbacks are male, then singing humpbacks probably communicate their species, sex, location, readiness to mate with females, and readiness to engage in agonistic behavior with other whales. 相似文献
13.
S. L. Vehrencamp J. Yantachka M. L. Hall S. R. de Kort 《Behavioral ecology and sociobiology》2013,67(3):409-419
Acoustic displays with difficult-to-execute sounds are often subject to strong sexual selection because performance levels are related to the sender’s condition or genetic quality. Performance may also vary with age, breeding stage, and motivation related to social context. We focused on within-male variation in four components of trill performance in banded wren (Thryophilus pleurostictus) songs: note consistency, frequency bandwidth, note rate, and vocal deviation. The latter is a composite measure reflecting deviation from the performance limit on simultaneously maximizing both frequency bandwidth and note rate. We compared the changes in these song parameters at three time scales: over the course of years, across the breeding season, and at different times of the day with contrasting agonistic contexts. Vocal deviation decreased and note consistency increased between years, suggesting that experience may improve individual proficiency at singing trills. Consistency also increased across the season, confirming that practice is important for this parameter. Although there was no significant seasonal change in vocal deviation, one of its components, note rate, increased during the season. Neither vocal deviation nor consistency varied with agonistic context. However, note rate increased during playback experiments simulating territorial intrusions compared to dawn chorus singing. The magnitude of a male’s increase in note rate was positively correlated with his aggressive behavior during the playback experiment. Thus consistency, bandwidth, and vocal deviation indicate age, whereas trill rate flexibly indicates the singer’s aggressive motivation. We also found evidence of a within-male trade-off between vocal deviation and consistency. 相似文献
14.
Henrik Pärn Karin M. Lindström Maria Sandell Trond Amundsen 《Behavioral ecology and sociobiology》2008,62(10):1665-1677
The optimal mating system is rarely the same for males and females—whereas males usually benefit from attracting additional
females to the territory, this could incur costs for the resident female. Females should therefore prevent prospecting females
from settling on the territory. We studied the male and female behavioral and hormonal responses to simulated female territorial
intrusions in free-living bluethroats during the pre-laying period. In the study population, polygyny occurs with potential
fitness costs for the resident female. We recorded different aspects of aggressive behavior before and after presentation
of a live female decoy and playback of female song. These behaviors were compared with a set of intrusions using a male decoy.
At the end of a trial, the birds were captured, and blood samples were analyzed for androstenedione, testosterone, estradiol
and corticosterone. During the pre-intrusion period, none of the females were observed. Females generally responded strongly
to the female decoy by increased flight rate, vocalizations, and by conspicuous perching. Nearly half of the males displayed
to the female decoy but never while the resident female was present. We suggest that resident female aggression in bluethroats
prevents courtship by her mate and signals her mating status to the female intruder. Female aggression could therefore prevent
additional females to settle on the territory and shape the mating system. Females that responded with song had higher levels
of estradiol. These findings suggest that estradiol may support aggression in breeding female birds. 相似文献
15.
In signalling interactions, animals can directly address information to a specific individual. Vocal overlapping is such a
signalling strategy used in songbirds, anurans, and insects. In songbirds, numerous studies using high rates of song overlap
to simulate an escalating situation have shown that song overlapping is perceived as a threatening signal by interacting and
by listening (eavesdropping) individuals, indicating a high social relevance of song overlapping. Here we present a playback
experiment on nocturnally singing male territorial nightingales (Luscinia megarhynchos). Using three different rates of song overlap (1, 25, or 50%), we tested whether or not lower levels of song overlapping
act as a signal of aggressive intent and if birds would increase the intensity of their response with increasing level of
song overlapping. Subjects did not vary song duration in response to the different playback treatments but increasingly interrupted
their singing with increasing overlap by the three playback treatments. The effects persisted even after the playback ceased
to overlap and switched to an alternating singing mode. These results expand on previous studies by showing that song overlapping
is interpreted as an aggressive signal even when it is used at low or moderate levels. They suggest that, within the range
tested here, increasing levels of song overlapping are perceived to be increasingly aggressive. 相似文献
16.
Julia Ostner Peter M. Kappeler Michael Heistermann 《Behavioral ecology and sociobiology》2002,52(6):485-495
The aim of this study was to examine effects of seasonal and social factors on male androgen excretion in a seasonally breeding primate living in multimale-multifemale groups. By combining detailed behavioural observations (>2,500 h) on 3 groups of redfronted lemurs living in Kirindy Forest/Madagascar with non-invasive hormone analysis of >800 faecal samples collected concomitantly from the same animals, we tested predictions on: (1) the effect of social status on immunoreactive testosterone (iT) excretion; (2) seasonal variation of iT across reproductive periods; and (3) the relationship between aggression and iT excretion. The study lasted 14 months, covering two mating and one birth season. The results revealed that males fall into two distinct social classes, with one dominant male and several subordinate males in each group. In contrast to our prediction, the behavioural differences between these two classes were not reflected by differences in androgen levels, making physiological suppression of testicular function an unlikely mechanism of male reproductive competition. As expected for a seasonally breeding animal, iT values were elevated during the mating season. Androgen levels tracked the increase in the rate of reproductive aggression during the mating season as predicted by the challenge hypothesis. An increase in aggression due to spontaneous social instability outside the mating season, however, was not linked to a parallel rise of iT. Furthermore, the highest iT levels were obtained during the birth season, which may be part of a male strategy to remain aggressive during this period of high infanticide risk. These findings suggest that redfronted lemurs do not respond with increases in androgens to short-term challenges and that high androgen levels instead correlate with longer-lasting and predictable situations, such as the mating and birth seasons. 相似文献
17.
Bengt -Göran Carlsson 《Behavioral ecology and sociobiology》1991,28(5):321-328
Summary Tengmalm's owl Aegolius funereus is a hole-nesting polygynous species in which female nomadism is a reaction to cyclic lows of staple prey. For 2 years during a peak in vole abundance, I examined recruitment of mates and male singing behavior in a local population. Females and about half of the breeding males seemed to arrive successively throughout the breeding period of the first year. In contrast, a majority of the breeding males and likely also females were already on the breeding grounds at the beginning of the breeding season in the second year. Before breeding in the first peak year, males were singing at up to five different nest holes. All early breeding males (67% of total number) continued to sing at secondary nest holes after attracting and installing primary females. Secondary singing locations were never closer than 300 m from primary females' nest holes, although closer locations were used for singing before mating. All bigynous males with nests within the study area were also singing at tertiary nest holes, but none successfully attracted a third female. Polyterritoriality was confirmed by a late male settling between primary and secondary nest holes of a bigynous male. Polyterritorial behavior and reduced breeding success of secondary females are in line with the deception model. Females apparently could not discriminate between paired and unpaired singing males. Females made short visits to different males before mating. During courtship, the number and quality of nest holes defended by males may have been of particular importance to female choice. 相似文献
18.
Kevin J. Delaney J. Andrew Roberts George W. Uetz 《Behavioral ecology and sociobiology》2007,62(1):67-75
Male signaling behaviors are often studied in a single context but may serve multiple functions (e.g., in male–male competition
and female mate choice). We examined the issue of dual function male signals in a wolf spider species Schizocosa ocreata (Hentz) that displays the same species-specific signaling behaviors in both male–male and male–female contexts. These signaling
behaviors have been described as either aggression or courtship according to the context observed. We tested the possibility
of dual functions by comparing the relationship between behaviors and outcome of male–male contests (winner/loser) and male–female
mating encounters (mating success). Frequency, rate, and mean duration of signaling behaviors did not vary with outcome of
male–male contests, which appears instead to be based upon relative size and body mass. Winners of contests had significantly
greater body mass than losers, and greater mass relative to opponents was significantly associated with probability of winning.
Overall, signaling rates were much higher in male–female interactions than in male–male contests and were higher for males
that successfully mated than for those that did not mate. Mean duration of some male displays was also greater for males that
successfully mated. However, male size was not associated with probability of mating. Taken together, results suggest an intersexual
selection context for the current function of male signals in these wolf spiders and that increased display vigor is associated
with male mating success. 相似文献
19.
Palestina Guevara-Fiore Jessica Stapley Penelope J. Watt 《Behavioral ecology and sociobiology》2010,64(10):1665-1672
Males vary in the degree to which they invest in mating. Several factors can explain this variation, including differences
in males’ individual condition and the fact that males allocate their energy depending on the context they face in each mating
attempt. Particularly, female quality affects male reproductive success. Here, we studied whether male guppies (Poecilia reticulata) strategically allocated more mating effort, in terms of mating behaviour and male–male competition, when they were matched
with a receptive (R) female than a non-receptive one. In accordance with our prediction, we found that males increased their
mating behaviour when they were with a receptive female. Even though male guppies can inseminate non-receptive females, we
only found high levels of courtship between males that were with a receptive female rather than a non-receptive one. Although
there was little affect of female receptivity on male–male competition, we found that males chased and interrupted courtships
more with receptive females than with non-receptive females regardless of odour. Finally, we also studied whether the sexual
pheromone produced by receptive female guppies is a cue that males use in order to increase their mating effort. We found
that males were more attracted to a female when they perceived the sexual pheromone, but only increased their mating and aggressive
behaviours when females showed receptive behaviour. This strategic increase in mating effort could result in higher male reproductive
success because mating attempts towards receptive females are likely to be less costly and males could have a greater probability
of fertilisation. 相似文献
20.
A wide variety of hypotheses has been proposed to explain the structural diversity in bird song repertoires. Song diversity
is frequently described in terms of song “types” or within-type “variants.” Male Puget Sound white-crowned sparrows, Zonotrichia leucophrys pugetensis, produce variants of their single adult song type by altering the number of repetitions of syllables in the terminal trill.
We tested whether variation in trill length correlated with distance to the receiver and with signaling context as predicted
by the eavesdropping avoidance hypothesis and the strategic signaling hypothesis. In accordance with the eavesdropping avoidance
hypothesis, males sang variants with shorter trills, and sang quieter and less frequently when near their mate during the
incubation phase than during spontaneous singing while unpaired. Males also sang variants with short trills, but at a high
rate and variable amplitude when within 10 m of an opponent during close male–male territorial interactions. In agreement
with the strategic signaling hypothesis, males decreased trill length immediately before chasing an opponent, but did not
change length consistently prior to flight. We conclude that the occurrence of short quiet songs sung near the mate agrees
with predictions of the eavesdropping avoidance hypothesis, while short songs sung near other males are best explained by
the strategic signaling hypothesis. Trill length variation may be a conventional signal of aggressive intentions in male–male
contests stabilized by receiver-imposed retaliation costs. 相似文献