Mate choice and cannibalism in a natural population of a stream goby,Rhinogobius sp.

Breeding ecology of the stream goby,Rhinogobius sp. LD (Large Dark), was investigated under natural conditions. Males selectively courted females of similar size to lead them to the nests, whereas females followed courting males preferentially when the relative male size was greater. Male-male competition for a female was relatively infrequent and not severe. Developmental stages of eggs and egg numbers in one nest indicated that males receive 1–3 clutches during one breeding cycle. Males guarding multiple clutches frequently ate some of the eggs, but those guarding single clutches rarely did so. Gravid females in the nest also frequently cannibalized eggs laid by a previous female, probably in order to extend the area available for egg deposition. Mate choice in this species is discussed in relation to paternal ability, limitation of available spawning area and the female-biased sex ratio.     

Mate Choice and Mating Pattern in a Stream Goby of the Genus Rhinogobius

The mate choice and mating pattern of a benthic goby Rhinogobius sp. CB (cross band type) were investigated in the Kamo River, Shikoku, Japan. During the breeding season, gravid females assumed a nuptial color and either males or females initiated a courtship display. Males preferentially courted a female of similar size to lead her to his nest, whereas females courted more frequently when they encountered a large male. Eggs in any one nest were always at the same developmental stage. Sampling data of nesting males and females indicated that, in more than half the nests, males gathered more than one female before spawning. In some nests with eggs, two or three females had spent ovaries, indicating that the eggs were laid by multiple females within a short span of time. However, a comparison between the total number of eggs which females would spawn in one nest and the number of eggs actually deposited suggested that eggs were contributed by one female in most nests. This low level of polygyny in spite of multiple female availability is attributed to a limited available spawning area of the nest.     

The breeding behaviour of Gammarus duebeni

The breeding behaviour of a population of Gammarus duebeni is investigated. The breeding system includes a precopulatory guarding phase by a male of a female and the length of this phase varies markedly over the season. Large size is not of as great advantage in reproductive competition between males as in a stream population of G. pulex. In the spring of 1981 oligochete worms, Nais elinguis, were found in the brood pouches of some females; eggs were seldom present with the worms but rather amorphous debris. The occurrence of the worms and the debris in the females' pouches coincided with the pattern of abundance of the worms previously reported.     

Femme Fatale — the Case of the Threespine Stickleback

In addition to courting females, male threespine sticklebacks must guard their nests from attacks on the eggs by female cannibals. We hypothesized that the presence of females in high densities in tide pools adversely affects a male's health and reproductive success. In the laboratory males housed with conspecific females during the breeding season were in poorer physical condition and died sooner than solitary males and males housed with conspecific males or with heterospecific females.     

Mate Guarding in Male Dall's Porpoises (Phocoenoides dalli)

Mate guarding, whereby a male closely attends and defends a fertile female from extra‐pair matings, is one mating tactic males of many species use to protect their paternity. Although female defense occurs in many species of terrestrial mammal, comparable examples among cetaceans are largely absent, potentially as a result of the wide dispersion and mobility of females and their prey. Here, we investigate whether the close association of individual male Dall's porpoises with individual females during the breeding season is consistent with mate guarding. As mate guarding is predicted to be costly, and in other taxa is often associated with a reduction in foraging efficiency, we also examine whether males trade‐off this activity with time at depth. Males maintained longer associations and closer distances with female partners than with male ones. They also surfaced in greater synchrony with, and more often approached, their female partners than male ones. In contrast to males with male partners, males paired with females engaged in agonistic interactions with other adult males, and infrequently affiliated with extra‐pair individuals. These data suggest males are actively attempting to maintain their associations with females, while also acting to reduce female extra‐pair copulations and increase their own paternity. Guarding males also undertook shorter dives than non‐guarding males, suggesting that they trade‐off time at depth with guarding. Such a trade‐off is likely to involve a reduction in foraging opportunities, due to a decrease in time spent at foraging depth. Mate guarding in this species may be facilitated by the relatively smaller size and decreased mobility of newly calved, estrous females, particularly if females also benefit from guarding.     

Determinants of male mating success in a natural population of a stream goby of the genus Rhinogobius

The mating success of individually identified males of a stream goby, Rhinogobius sp. CB (cross‐band type), was recorded over one breeding season. One to 3 year‐old males were active in mating, but 3 year‐old males, which accounted for 36% of the population, amounted to c . 70% of the total males guarding eggs in the nest. Three quarters of the breeding males had only one brooding cycle, but the others had two or three. All the latter males changed their nest sites between cycles within a riffle. In 1 and 2 year‐old males, the number of brooding cycles contributed more to the mating success than egg mass size in one brooding cycle. For mating success of 3 year‐old males, the egg mass size in one brooding cycle, which can be enhanced by spawning with a large female or multiple females, was as important as the number of brooding cycles. These male reproductive tactics could be attributed to the age‐related ability of nest construction and mate acquisition.     

Cooperation and conflict among dunnocks, Prunella modularis, in a variable mating system

The mating system of a population of 90 breeding dunnocks (or hedge sparrow, Prunella modularis) included monogamy, polygyny, polyandry and polygynandry. Monogamous males guarded females during their fertile period to prevent neighbouring males from copulating. The most intense guarding occurred where two (unrelated) males shared a territory. Here, the alpha male tried to prevent the beta male from copulating with the female. Beta males were seen to copulate in only half the cases. They were more likely to succeed when the alpha male found it difficult to guard the female closely because her range was large, the vegetation was dense or there were other females breeding synchronously on the same territory. Close guarding and chasing by males reduced the female's feeding rate and was correlated with unhatched eggs in the nest. Females attempted to escape the alpha male's attentions and actively encouraged the beta male to mate. Beta males only helped to feed the young if they copulated with the female. Nestlings fed by two males and a female got more food and weighed more than those fed by just one male and a female. Indirect evidence suggested that when beta males failed to copulate, they destroyed eggs or young chicks. Females laid larger clutches when two males mated with them as opposed to one, thus adapting their clutch size to the amount of parental care they expected. The results of natural removal experiments and matched comparisons of the same female in different mating systems support these conclusions. For females, selection favours cooperative polyandry, whereas for males if favours polygyny; the variable mating system may reflect the different outcomes of this sexual conflict.     

The Conflict between Nest Guarding and Mate Guarding in Penduline Tits (Remiz pendulinus)

In penduline tits (Remiz pendulinus), polygynous males build several very elaborate nests successively during one breeding season to attract females. The time and effort invested in nest building is positively related to their mating success. Intraspecific competition for nest material resulting in nest material theft, delays males' nest building progress which in turn decreases their mating success. Therefore, a nest guarding strategy was predicted. In many bird species, males develop some kind of paternity strategy during the female fertile phase. However, as nest building and the female fertile phase frequently coincide, one would expect a trade-off between these strategies. In this study we determined in particular how nest guarding in males conflicts with their mate guarding behaviour in penduline tits. Our results show that nest building is costly in terms of a male's time budget. Thieves benefit by increasing their rate of acquiring nest material which reduces the effort invested in nest building. Nest guarding is an efficient strategy to avoid thieves, as indicated by the negative relation between the presence of the male near the nest and the frequency of nest material theft. Nest guarding is required for the whole building period but males, however, increased their mate guarding effort during the peak fertile phase to ensure their paternity. The data suggest that, for the trade-off “mate guarding versus nest guarding”, paternity insurance seems to be more important.     

Pair territoriality in the longnose filefish,oxymonacanthus longirostris

The longnose filefish,Oxymonacanthus longirostris, usually lives in heterosexual pairs, the male and female swimming together and sharing the same territory. Pair territoriality in the species was examined in detail in relation to sexual differences in territorial defense activities. Rigorous pair territoriality was maintained only during the breeding season, although pairs used their home ranges exclusively to a certain extent, during the non-breeding season. The frequency of aggression against other conspecific pairs in the breeding season was higher than in the non-breeding season. Agonistic interactions appear to be over both mates and food resources, the strict pair territoriality in the breeding season possibly being due to mutual mate guarding. In intraspecific aggressive interactions, males usually led their partner females when attacking intruders. The feeding frequency of males was much lower than that of females in the breeding season. Mate removal experiments indicated that females could not defend their original territories solitarily and their feeding frequency decreased. Conversely, males could defend territories solitarily without a decrease in feeding frequency. These results suggest that males contribute most to the defense of the pair territory, with females benefiting from territorial pair-swimming with their partner males.     

Reproductive ecology of five pipefish species in one eelgrass meadow

Synopsis Synopsis Pipefishes have rarely been watched in the wild and have never before been followed in their common seagrass habitats. This study explores the reproductive ecology of five species of pipefishes living in a Swedish eelgrass meadow during parts of four breeding seasons, tagging four of the species. Pipefish are remarkable for their specialised paternal care: only males aerate, osmoregulate and nourish the developing embryos. Two of the species (Entelurus aequoreus andNerophis ophidion) have simple ventral gluing of eggs on the trunk while three species (Syngnathus acus, S. rostellatus andS. typhle) have fully enclosed brood pouches on their tails. Males of the former species receive eggs from one female while males of the genusSyngnathus receive partial clutches from several females. Sex ratios of adults on the site differed from equal to male-biased to female-biased, according to species.S. typhle were most numerous and were resighted most often. They were present throughout the breeding season whereas there were temporal shifts in the presence of the other species on the meadow and in some sex ratios. Most species occurred in the deeper, denser part of the meadow but there was some habitat separation by species and sex. All species tended to stay low in the eelgrass, primarily coming up above the eelgrass to display and mate. No species showed site fidelity either to a home range or to the meadow, withE. aequoreus adults spending least time on the meadow. Sexual size dimorphism differed: males were larger inS. rostellatus, the same size inS acus and smaller in the other species. Although the species overlap in habitat requirements and breeding season, the only observed interspecific interactions were abortive courtships betweenSyngnathus species.     

Spatial and Temporal Distribution of Song in the Yellowhammer Emberiza citrinella

The temporal and spatial distribution of song was studied in a population of yellowhammers Emberiza citrinella. Song was most frequent during the breeding season, and within the breeding season during the fertile period of both first, second, and replacement clutches. Song activity peaked at sunrise and sunset. During the fertile period most singing took place in the central parts of the territory. Song post heights peaked during the fertile period, and more song posts lacked foliage at that time. Intrusions by male conspecifics peaked in the fertile period and in territories where males sang relatively little. Song activity and mate guarding were strongly positively correlated. Song volume was loud and song was thus apparently used in long-distance communication. These observations are in accordance with a male deterrence hypothesis, suggesting that males sing to deter neighbouring males from trespassing during the fertile period of their mate. A female attraction hypothesis, suggesting that males sing to attract neighbouring females and thereby obtain extra-pair copulations, and a female reproduction hypothesis, suggesting that males sing to start the female reproductive cycle, were partly supported by observations.     

Habitat quality as a predictor of spatial variation in blue tit reproductive performance: a multi-plot analysis in a heterogeneous landscape

Vertebrate studies have rarely investigated the influence of spatial variation in habitat richness on both short-term (breeding) and long-term (offspring recruitment) reproductive performance using simultaneously multi-patch, multi-habitat type and multi-year approaches at landscape level. Here we present results of such an approach using the influence of two oak tree (Quercus ilex, Q. humilis) species on reproductive performance in Corsican blue tits (Parus caeruleus ogliastrae) as a model system. We found that blue tits breeding in rich broad-leaved deciduous patches consistently laid eggs earlier in the season, and produced larger clutches and more fledglings of higher quality, than those breeding in poor evergreen patches. Also, parents, especially males, were in better physical condition in the broad-leaved deciduous than in the evergreen patches. Surprisingly, estimates of long-term effects of reproduction, such as recruitment rates of locally born offspring, did not differ between the two habitat types. Our results suggest that short-term breeding performance and phenotypic quality of both chicks and parents do not necessarily provide reliable information about contributions to following generations at a scale larger than that of the local study plot. Differences in reproductive performance between the two oak habitat types could not be attributed to density-dependent effects, differences in levels of nest predation, or differences in age structure of the birds. We suggest that habitats that are optimal for breeding are not necessarily optimal for survival after the breeding season.     

Chemically-mediated pre-mating behavior in two tetranychid species

We used bioassays to evaluate the arrestment response of male twospotted spider mite, Tetranychus urticae Koch, and Banks grass mite, Oligonychus pratensis (Banks) to whole-body extract from conspecific quiescent deutonymphs. We examined the effect of previous behavior on mite response to extract from female quiescent deutonymphs. We also examined male arrestment and guarding behavior in response to 2 extract concentrations and to extract from male quiescent deutonymphs. Male T. urticae and O. pratensis exhibited similar changes in their behavior in response to the different extracts with which we presented them. Males that were guarding quiescent deutonymphs immediately prior to testing spent more time in an untreated 3.5-mm-diameter circle than did males that were previously engaged in other behaviors. However, when nonguarding males were presented with extract of conspecific female quiescent deutonymphs they remained in the stimulus circle as long as guarding males did in an untreated circle. Arrestment duration of nonguarding males increased at 2 higher extract concentrations. The arrestment response was not exclusive to extracts from female quiescent deutonymphs; nonguarding male mites were also arrested by extracts from male quiescent deutonymphs, although for a shorter time. Duration of arrestment was related roughly to size differences between male and female quiescent deutonymphs. Furthermore, males did not show an exclusive preference for guarding conspecific male or female quiescent deutonymphs. It seems unlikely that the arrestant is a specific sex pheromone. Rather, male mites probably use the arrestant as a necessary cue to focus their attention on an individual that may be a suitable mate. Other tactile, visual, and chemical stimuli may then help males to decide whether to remain and assume mate guarding behaviors.     

Sex roles, parental experience and reproductive success of eastern kingbirds, Tyrannus tyrannus

We quantified parental behaviour of eastern kingbirds during the incubation and nestling periods to determine parental roles, and to examine the impact of previous breeding experience (defined as having bred on the territory in the past) on behaviour and reproductive success. Females performed all incubation, while males spent more than 60% of their time in vigilant or nest guarding behaviour during incubation. Parental roles were not defined as sharply during the nestling period. Females spent more time vigilant, but males provisioned young at only 54% of the rate of females. Vigilance and nest watching were still primarily male duties. Male and female behaviour did not vary with the pair's combination of experience (e.g. experienced-experienced versus inexperienced-inexperienced in previous-current breeding season, respectively) during either phase of reproduction, but experienced males were more vigilant during incubation and fed young relatively more than inexperienced males. Experienced females were also more efficient foragers. Although behaviour did not differ among the four combinations of pair experience, inexperienced pairs none the less lost the most young to starvation and predation. Consequently, inexperienced pairs fledged one less nestling per nesting attempt than did pairs with at least one experienced breeder. Our results suggest that having at least one experienced breeder substantially improved a pair's reproductive success. We propose that female site fidelity is a safeguard to avoid the lower breeding success a female would incur if she were to move to a new territory and breed with an inexperienced male. Copyright 1999 The Association for the Study of Animal Behaviour.     

Habitat selection by dispersing yellow-headed blackbirds: evidence of prospecting and the use of public information

In migratory birds individuals may prospect for potential breeding sites months before they attempt to breed and should use the cues most predictive of future reproductive success when selecting a breeding site. However, what cues individuals use when prospecting and which cues are used in selecting a breeding site are unknown for most species. I investigated whether yellow-headed blackbirds (Xanthocephalus xanthocephalus) prospect for future breeding sites and whether they select breeding habitats based on food availability, male or female density, or the average number of young produced per female in the previous year. Although it is often assumed that migratory birds prospect for potential breeding sites at the end of the breeding season, I investigated this by recording all visits to sites early and late in the breeding season. I found that males and females who visited sites other than the site at which they bred were more likely to disperse than individuals only observed at the site where they bred, and that males and females were more likely to prospect late in the breeding season. Both food availability and density in year ^x were not predictive of the number of young per female in year ^x+1; however, the number of young produced per female at a site in year ^x was predictive of the number of young per female in year ^x+1. As expected, dispersers used the most informative cue, the number of young per female and moved to sites with a relatively high number of young per female. This study suggests that individuals prospect for potential breeding sites late in the breeding season when they can use information gathered from the reproductive success of other individuals (i.e., public information) to select a breeding site.     

Breeding site fidelity in penduline tit Remiz pendulinus in Southern Hungary

Birds move between breeding locations to gain a better territory, avoid competition or reduce the deleterious effect of inbreeding. We investigated breeding site fidelity in a small European passerine, the penduline tit (Remiz pendulinus). This species has an exceptionally diverse breeding system, in which both males and females may have up to 5–7 mates in a single breeding season, and the eggs are incubated by a single parent: either the male or the female. We investigated the movements of males and females within three breeding seasons in Southern Hungary (2002–2004). Males moved for shorter distances between breeding sites (116 m, 63–333 m; median, lower quartile–upper quartile) than females (942 m, 415–2,382 m). Movements of males and females were consistent between years, and they were repeatable between subsequent nests of males, but not of females. Taken together, our results suggest that adult male penduline tits are more site-faithful than adult females. We suggest that this difference has an implication on their breeding ecology since male parental behaviour (desert/care) is expected to be influenced by local mating opportunities, whilst female parental behaviour is likely to depend on the mating opportunities in a large area around their breeding site.     

Seasonal variation in male alternative reproductive tactics

Genetic parentage analyses reveal considerable diversity in alternative reproductive behaviours (e.g. sneaking) in many taxa. However, little is known about whether these behaviours vary seasonally and between populations. Here, we investigate seasonal variation in male reproductive behaviours in a population of two‐spotted gobies (Gobiusculus flavescens) in Norway. Male two‐spotted gobies guard nests, attract females and care for fertilized eggs. We collected clutches and nest‐guarding males early and late in the breeding season in artificial nests and used microsatellite markers to reconstruct parentage from a subset of offspring from each nest. We hypothesized that mating, reproductive success and sneaking should be more prevalent early in the breeding season when competition for mates among males is predicted to be higher. However, parentage analyses revealed similar values of mating, reproductive success and high frequencies of successful sneaking early (30% of nests) and late (27% of nests) in the season. We also found that multiple females with eggs in the same nest were fertilized by one or more sneaker males, indicating that some males in this population engage in a satellite strategy. We contrast our results to previous work that demonstrates low levels of cuckoldry in a population in Sweden. Our results demonstrate marked stability in both the genetic mating system and male alternative reproductive tactics over the breeding season. However, sneaking rates may vary geographically within a species, likely due to local selection influencing ecological factors encountered at different locations.     

Body Size and Multiple Copulations in a Neotropical Grasshopper with an Extraordinary Mate-Guarding Duration

After copulation, male grasshoppers of Sphenarium purpurascens (Orthoptera: Pyrgomorphidae) remain in a postinsemination association with their mate. A male can spend as many as 17 days mounted on a female. Guarding duration is related to both male and female body size and the female's mating history. Longest guarding durations were recorded at the middle of the reproductive season, when the probability of encounter between the sexes (sex ratio and population density) was decreasing, at the beginning of the associated dry season. These guardings were associated with large individuals of both sexes and with females that had more previous partners. Moreover, a positive association was found among guarding duration, female and male body size and age, and number of copulations performed by the males. Maybe males invest time and sperm in females as a function of the probability of sperm competition. Nevertheless, guarding may provide benefits to both sexes. Males may reduce the possibility of sperm competition, and females may obtain nutritional benefit for themselves or their offspring as a result of multiple copulations. Changes in male investment in guarding duration and number of copulations may be the result of physiological constraints related to seminal and/or sperm production. Moreover, guarding duration could be constrained by ecological factors such as a reduction of food availability associated with the beginning of the dry season.     

Reproductive biology and ecology of white‐winged trumpeters (Psophia leucoptera) and recommendations for the breeding of captive trumpeters

The reproductive biology and ecology of a wild population of white‐winged trumpeters (Psophia leucoptera) were studied in southeastern Peru from 1983 to 1987. Because little information is available about any of the trumpeter species and because trumpeters have proven difficult to breed in captivity, information relevant to breeding and management of captive trumpeters is reported in this paper. White‐winged trumpeters lived in territorial social groups that ranged in size from four to 13 individuals. A typical territorial group contained three adult males, two adult females, and several sexually immature offspring, but smaller temporary groups sometimes formed for the duration of the breeding season. Only the dominant female contributed eggs to the clutch, and all adult males in the group competed to obtain copulations with her. Eggs were laid in elevated nesting cavities and no nest was constructed. The average clutch size was three eggs and incubation was not begun until the final egg was laid. The dominant male and female shared most of the incubation duties, but subordinate males covered approximately 15% of the incubation shifts. Eggs hatched approximately 27 days after incubation was begun and chicks left the nesting cavity the day after they hatched. Chicks were completely dependent on older birds to feed them for their first 3 weeks and then gradually began to feed themselves more and more food. The subordinate adult males fed chicks the most food, the dominant male and female and older offspring fed chicks an intermediate amount, and the subordinate adult female fed chicks the least. Young chicks behaved aggressively toward each other but were separated by adults before they injured each other. If at least one chick from the clutch survived, trumpeters did not breed again until the beginning of the next breeding season the following year. Zoo Biol 19:65–84, 2000. © 2000 Wiley‐Liss, Inc.     

Female brown-headed cowbirds', Molothrus ater, organization and behaviour reflects male social dynamics

In four large aviaries, we studied social assortment and reproductive behaviour of female brown-headed cowbirds housed with males differing in age class and in corresponding levels of intrasexual interaction. Juvenile and adult females resided with either (1) adult males, (2) juvenile males, (3) adult and juvenile males, or (4) no males. We observed social behaviour of males and females from September 1999 through to the 2000 breeding season. Throughout the year, males in the different conditions showed different levels of social interaction, with adult males being most engaged in male-male interactions and juvenile males being least engaged in male-male interactions. Females in the four conditions differed in their associations with males and with other females. In conditions with adult males, females spent more time near males, approached males more often, and associated with females less. During the breeding season, females in conditions with more adult males copulated more and produced more fertile and viable eggs. In the condition where females were housed with juvenile males, they copulated less, laid fewer eggs and destroyed more of their eggs. Results indicate that throughout the year, females are sensitive to male age and behaviour in their social group, and that this sensitivity can have reproductive consequences. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.