The Function of the Four Types of Waving Display in Uca lactea: Effects of Audience,Sand Structure,and Body Size

Multiple signals that convey different messages have been reported in many taxa, but relatively few studies have been made on such signals in invertebrates. In the present study, I investigated four types of claw‐waving display used in the fiddler crab Uca lactea to test whether the displays have different functions. Three males with a sand structure beside their burrows (which can attract females) and three males without a sand structure were fenced in an opaque enclosure, and I videotaped their waving displays after releasing two burrowless males or two burrowless females to test the effects of audiences. (a) Lateral‐circular waving tended to occur in enclosures with burrowless females and was performed frequently by males that had sand structures. (b) Lateral‐flick waving was performed frequently by males without sand structures, and its frequency was positively correlated with the signaler’s body size. (c) Rapid‐vertical waving was observed frequently in enclosures with burrowless males, and its frequency was negatively correlated with the signaler’s body size. (d) Circular waving tended to occur in enclosures with burrowless females and was performed frequently by males that had sand structures, and its frequency was positively correlated with the signaler’s body size. In my previous study, lateral‐circular waving was often seen in the breeding season and was mostly performed to female audiences, lateral‐flick waving was frequently performed to neighboring resident males, rapid‐vertical waving was performed mainly to intruding burrowless males, and circular waving did not have apparent audiences in most cases. Finally, I concluded that lateral‐circular waving was used as a courtship display, lateral‐flick waving was related to border disputes, rapid‐vertical waving was used for burrow guarding, and circular waving was used to broadcast the signaler’s general quality.     

Claws and claw waving attract both sexes in the dotillid crab Ilyoplax pusilla

Journal of Ethology - During the breeding season, courting males of many ocypodoids (famously, fiddler crabs) perform claw-waving displays, in which they rhythmically raise, often extend, and lower...     

Size-dependent mating preference of the male fiddler crab Austruca perplexa

In many animals, females prefer large males to small males, which allow large males to be choosier than small males when selecting a mate. We investigated the courtship intensity of small- and large-sized male fiddler crabs (Austruca perplexa) by examining their claw-waving rates (waves/min) towards small- and large-sized females. We found that large males showed a greater preference for large females by producing more waves/min towards them, whereas small males did not show any apparent preference for either large or small females. Moreover, the waving rate of large males was positively correlated with female size, but there was no correlation between waving rate and female size in small males. These results indicate that large males in a population become choosier and show strong mate choice, which is most likely due to their greater preference among females.     

Courtship herding in the fiddler crab <Emphasis Type="Italic">Uca elegans</Emphasis>

Male and female animals are not always complicit during reproduction, giving rise to coercion. One example of a system that is assumed to involve sexual coercion is the mate herding behaviour of fiddler crabs: males push females towards the home burrow with the goal of forcing copulation at the burrow entrance. We recorded and analysed in detail the courtship behaviour of a North Australian species of fiddler crab Uca elegans. Courtship was composed of four main phases: broadcast waving, outward run, herding and at burrow display. During interactions males produced claw-waving displays which were directed posteriorly towards the female and which varied in timing and structure depending on the courtship phase. We suggest that courtship herding in U. elegans is driven primarily by mate choice for the following reasons, (1) females can evade herding, (2) no other reproductive strategies were observed, (3) males broadcast their presence and accompany courtship with conspicuous claw waves, and (4) the behaviour ends with the female leading the male into the home burrow. As an alternative function for herding in U. elegans we suggest that the behaviour represents a form of courtship guiding, in which males direct complicit females to the correct home burrow.     

Causes of a male-biased operational sex ratio in the fiddler crab<Emphasis Type="Italic"> Uca crenulata</Emphasis>

This research investigates the causes of a male-biased operational sex ratio in a population of the California fiddler crab, Uca crenulata. Mensurative studies revealed there were almost twice as many adult males as females, mating occurred across half of the days within the breeding season, and females had much longer individual reproductive cycles than males. Therefore, many more males than females were available for mating on each breeding day. Perhaps as a consequence, males spent a large proportion of their time fighting with neighbors and rapidly waving their large claws when females passed by. Electronic Publication     

Are females of Ilyoplax pusilla (Brachyura: Dotillidae) attracted to groups having more waving males?

Males of the dotillid crab Ilyoplax pusilla wave at approaching females during the breeding season. They also, however, often perform waving that is not directed toward any particular individual. This undirected waving is associated with the presence of male neighbors and may function in male–male competition. It may also, however, act as a long-range female attractant. To test whether undirected waving functions to attract females, we conducted a field experiment that manipulated the abundance of waving males. We found that females preferred to approach groups that had more waving males. This suggests that undirected waving by male I. pusilla functions as a long-range courtship signal.     

Female preference for large waving claws in the dotillid crab <Emphasis Type="Italic">Ilyoplax pusilla</Emphasis>

Male Ilyoplax pusilla perform a waving display, a simple up-down movement of the claws during the reproductive season. Large males dedicated most of their surface activity to waving displays and gained higher mating success. On the other hand, small males infrequently performed waving displays and devoted their time exclusively to foraging. To examine female preference for the size of waving males, two female-release experiments were conducted. In the experiments, we recorded female choice between small- and large-waving claw models over short (10 cm) and long (25 cm) distances. In both the short- and long-distance choice experiments, significantly more females chose the large-claw model over the small-claw model. The following characteristics may produce obvious age-dependent sexual advertisement in I. pusilla, which grows throughout a life: (1) the strong female preference for large claws; (2) the short, 2-year lifespan that includes only two reproductive seasons; and (3) the lack of alternative mating strategies (e.g., surface mating).     

Age,condition and dominance‐related sexual ornament size before and during the breeding season in the black grouse Lyrurus tetrix

Male ornaments function as honest cues of male quality in many species and are subject to intra‐ and intersexual selection. These ornaments are generally studied during peak expression, however their size outside the breeding season may determine ultimate ornament size and costliness, and as such reproductive success. We investigated whether male black grouse Lyrurus tetrix eye comb size was related to age, condition and measures of male dominance before and during the breeding season. Total combined eye comb size began to increase ~70 d before the start of the breeding season. Adult males (aged ≥ 2 yr old) had consistently larger eye combs than younger males (1 yr old) both before and during the breeding season. Heavier and more dominant adult males (attending the lek more frequently and successfully reproducing) had larger eye combs. For younger males, those that were heavier had larger eye combs. Additionally, males that spent more time on the lek showed increased eye comb size as the breeding season approached. Overall we find that ornament size is positively related to dominance and condition before and during the breeding season. Since dominance is accrued through year‐round interactions in many species, the ability to maintain larger signals over prolonged periods, including outside of the breeding season, is likely to be beneficial for adults. For younger males, it is likely that they cannot sustain or are constrained from producing larger eye combs over long periods of time. They therefore prioritise growth of their ornaments later, and according to the amount of time they spend on the lek.     

Allocleaning in an intertidal ocypodid crab,Macrophthalmus banzai

The ocypodid crabMacrophthalmus banzai often forages on the carapace or walking legs of other conspecific individuals. This behaviour can be classified into 2 types, long cleaning and short cleaning. They are distinguished from each other by the cleaner's approach (slow or quick), duration of cleaning and scoops per bout. Long cleaning was done by a male or a female against a larger crab of either sex. Seasonal and daily frequencies of long cleaning were more or less constant. Immediately before and after a long cleaning, the cleaner was mostly engaged in substratum-feeding. After the cleaning, the recipient tended to return to its own burrow. Short cleaning was done mostly by males against smaller females. Seasonal and daily frequencies of short cleaning exhibited positive correlation with waving display. The cleaner frequently performed waving immediately before cleaning. In addition, short cleaning occurred immediately before surface copulation and before underground pairing of male entry into the female's burrow. These data suggest that the long cleaning is related to feeding and the short cleaning with male courtship.     

A translocation experiment explains regional differences in the waving display of the intertidal brachyuran crab Ilyoplax pusilla

Male waving display by the dotillid crab Ilyoplax pusilla differs among local populations in the frequency of full cheliped extension. In order to clarify whether the local variation is caused by behavioral characteristics specific to a local population or by differing environmental conditions, reciprocal translocation experiments were carried out between two populations in which male waving display clearly differs. The translocated crabs continued to wave in their new environment as they did in their source population, and control crabs exhibited no change in waving. This result suggests that local differences in the claw-waving display of male I. pusilla are caused by intrinsic population differences.     

A community context for aggression? Multi‐species audience effects on territorial aggression in two species of Paridae

1. Territorial aggression in birds is widely observed and is commonly linked to sex, age, body size, physiology, seasonal cues, food resource, urbanization, and a variety of social contexts including conspecific audience effects. However, little is known about the heterospecific audience effects on territorial aggression.
2. Here, we address an emerging idea that heterospecific audience effects may be pervasive influences in the social lives of free‐living birds. We tested the hypothesis that the composition, number, and relative body size of heterospecific audiences observing an aggressive contest will influence the response probability and intensity of aggression displayed.
3. We subjected two Paridae species, tufted titmouse (TUTI, Baeolophus bicolor) and Carolina chickadee (CACH, Poecile carolinensis), to playbacks of aggressive calls during a breeding season in north‐central Florida. At widely spaced playback sites (N = 134) in woodland habitats, we characterized the makeup of heterospecific audiences, aggression type (intra vs. interspecific territoriality), local population density, and various environmental factors (tree density, wind speed, and noise level) that are likely to influence territorial aggression.
4. We found that the presence of heterospecific audiences increased TUTI aggression levels and that both parids were more likely to respond to playback stimuli when their audiences had higher heterospecific diversity (more heterospecific individuals and species). We also found TUTI were more likely to respond when CACH were present but not vice versa.
5. In conclusion, we found evidence that heterospecific audiences significantly influenced the metrics of territorial aggression of free‐living animals and we suggest that the definition of audience effects on the behavior of free‐living animals be expanded to incorporate heterospecific audiences.

     

Females without infants: mating strategies in two species of captive macaques

Bonnet (Macaca radiata) and rhesus (Macaca mulatta) macaque females were observed during the breeding season to evaluate differences in mating strategies between females without infants and females with dependent offspring. Rhesus nonmothers participated in consortships earlier in the breeding season and initiated and received more approaches with adult males than rhesus mothers did. Bonnet nonmothers entered estrus earlier, began copulating earlier, and approached and presented to adult males more often than bonnet mothers did. Interacting with males frequently and early in in the breeding season may improve nonmothers' chances of conceiving and bringing offspring to term, with little competition from mother peers.     

Waving Display in Females of Uca polita and of other Australian Fiddler Crabs

Since 1979 it is known that, in Australian species of Uca, female waving exists in addition to usual male display. The present paper deals mainly with female waving in U. polita studied in Darwin (North Australia). A few remarks on U. dampieri, U. vomeris, U. seismella and U. hirsutimanus are added. The species mentioned are members of two species groups or subgenera, which characterizes female waving as an ancestral (plesiomorph) trait. Frame by frame analysis of film sequences (open air shots) indicate homology of movements in the two sexes of U. polita. As in males, waving of females can be combined with locomotion on radial paths starting from the burrow entrance and the display is performed in series with a corresponding number of gestures. Unlike males, waving females mostly use both their chelipeds and tend to show shorter durations with regard to many of the waving parameters chosen. However, significant differences refer only to a limited number of parameters. The biological context of female waving was gathered from films and field observations. High intensity waving is released by conspecifics approaching from far (wanderers without burrows) and from the neighbourhood. Typically, only females and small males elicit high intensity display in a resident female. Waving normally stops in presence of larger males, especially of the male living in a resident breeding unit with the female in question. In spite of this, a pure agonistic (defensive) character of female waving is unlikely. Advertising of breeding condition seems to play a role similar to that in males. The few displaying females that exist in a given colony (about 2.5% in U. polita) show signs of special sexual excitement: brightening of carapace colours and sometimes spontaneous performance of waving, i.e. display immediately after emergence from the burrow in absence of any conspecific.     

Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens)

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and male—male competition.     

Costs and benefits of variable breeding plumage in the red-backed fairy-wren

The red-backed fairy-wren is a socially monogamous passerine bird which exhibits two distinct types of breeding male, bright males that breed in bright red and black plumage and dull males that breed in dull brown plumage. Most males spend their first potential breeding season in dull plumage and subsequent breeding seasons in bright plumage, but a relatively small proportion of males develop bright plumage in their first breeding season. This study quantifies morphology, behavior, and reproductive success of dull and bright males to assess the adaptive costs and benefits of bright plumage while controlling for age. Older bright males (two years of age or older) attempted to increase their reproductive success via copulations with extrapair females, whereas younger (one-year old) bright males and dull males did not. Thus, older bright males spent less time on their own territories, intruded on neighboring groups with fertile females more frequently, gave more courtship displays, and had larger sperm storage organs than did younger bright males and dull males. Microsatellite analyses of paternity indicate that the red-backed fairy-wren has extremely high levels of sexual promiscuity, and that older bright males had higher within-brood paternity than dull males or younger bright males. Regardless of age, bright males were more attractive to females in controlled mate choice trials than were dull males, and both age classes of bright males obtained higher quality mates earlier in the breeding season than did dull males, when nesting success was higher. In conclusion, although it appears that bright plumage increases access to higher quality mates, age also plays a central role in determining a male's overall reproductive success because of the high levels of sexual promiscuity exhibited by the red-backed fairy-wren.     

Seasonal and diurnal use of eight different call types by Indian peafowl (<Emphasis Type="Italic">Pavo cristatus</Emphasis>)

The vocal displays of male Indian peafowl (Pavo cristatus) are thought to be sexually selected traits. To clarify the specific call types involved in breeding, as well as to provide basic information on the vocalisations of Indian peafowl, we conducted monthly daytime recordings in a large feral population in Japan. Based on 13,420 records, we identified seven different call types made only by males and six alarm calls uttered by both sexes. Furthermore, we found seasonal and diurnal changes in the calling activity of peafowl. Three of the male call types (keow, ka and hoot-call) were particularly important for breeding, as sexually mature males produced them only during the breeding season, in a similar diurnal pattern to other breeding behaviours. A digital video image relating to the article is available at .     

Audience Design through Social Interaction during Group Discussion

This paper contrasts two accounts of audience design during multiparty communication: audience design as a strategic individual-level message adjustment or as a non-strategic interaction-level message adjustment. Using a non-interactive communication task, Experiment 1 showed that people distinguish between messages designed for oneself and messages designed for another person; consistent with strategic message design, messages designed for another person/s were longer (number of words) than those designed for oneself. However, audience size did not affect message length (messages designed for different sized audiences were similar in length). Using an interactive communication task Experiment 2 showed that as group size increased so too did communicative effort (number of words exchanged between interlocutors). Consistent with a non-strategic account, as group members were added more social interaction was necessary to coordinate the group''s collective situation model. Experiment 3 validates and extends the production measures used in Experiment 1 and 2 using a comprehension task. Taken together, our results indicate that audience design arises as a non-strategic outcome of social interaction during group discussion.     

Seasonal sex role changes in the blenniid Petroscirtes breviceps, a nest brooder with paternal care

The plasticity of the sex roles in the blenniid fish Petroscirtes breviceps , a nest brooder with exclusive paternal care, was studied throughout an 8 month breeding season. Males performed most courtships early and late in the breeding season, whereas females performed most in the middle of the season. These results indicated that the sex of individuals initiating courtship changed seasonally, with courtship role reversal in the middle of the season. Intrasexual aggression in both sexes occurred much more frequently in mid-season than in the early and late seasons. Males frequently fought when available nest sites were limited, regardless of the presence of females, suggesting that males competed for nests in order to qualify to mate (resource competition). In contrast, courting females fought only in mid-season, when females' relative success in entering nests decreased, indicating that females competed for limited mating opportunities (mating competition). The reversed courtship roles and female mating competition in mid-season suggested that the sex roles in P. breviceps changed seasonally from the conventional roles to reversed roles and back again during one breeding season. This study provides the first empirical evidence of multiple changes in the sex roles of animals within a breeding season.     

Polygyny in Willow Warblers <Emphasis Type="Italic">Phylloscopus trochilus</Emphasis> (Sylviidae,Passeriformes) in Middle European Russia: Differences in songs of polygynous and monogynous males

The study was performed in May to July of 1995 in Middle Russia (Skadovskii Zvenigorod Biostation, MSU, Moscow oblast: 55°44′ N, 36°51′ E). Monoterritorial polygyny was observed in one of seven studied Willow Warbler males Phylloscopus trochilus. The distance between the nests of the first and second females was 90 m. In the nest of the first female, five nestlings hatched on June 10 and the flight of the fledglings occurred on June 23. In the nest of the second female, a 5-to 6-day-old nestling of the cuckoo Cuculus canorus was found on June 18. The male actively participated in feeding the young in the first nest and did not participate in the feeding of the young in the second nest. The songs of the bigamous male differ significantly from the songs of monogamous males in the middle and final parts of the breeding cycle. The song of the bigamous male in the idle and end of the breeding season is similar to that in the beginning of the breeding season. Unmated males in the middle of the breeding season also retain a more permanent structure of their songs in comparison with breeding males. This case of polygyny seems to be related to special characteristics of the males such as their singing activity and the structure of their songs.     

Reproductive activity of ruffed lemurs (Varecia variegata variegata) in a Madagascar rain forest

Mating activity was observed during four breeding seasons in two groups of black and white ruffed lemurs (Varecia variegata variegata) living in lowland rain forest on Nosy Mangabe island, Madagascar. The onset of the May-July breeding season was signalled by behavioral changes in adult males. Males made forays outside their usual home ranges, were more aggressive to other males, and performed appetitive and other sex-specific behaviors more frequently. Females showed receptive and proceptive behaviors during a 1-2 day behavioral estrus. Ruffed lemurs mated monogamously, polyandrously, and polygynously. These observations do not support previous assertions that they live only in monogamous families. Limited evidence suggests females exercised mate choice and may have preferred familiar males. © 1993 Wiley-Liss, Inc.