bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of Two Singing Modes By Hooded Warblers as Adaptations for Signalling
Authors: Haven Wiley R. , Godard Renée , Thompson Andrew D. 
Published: April 2008

Abstract
Hooded warblers Wilsonia citrina use two modes of singing, repeat mode (one pattern sung repeatedly) and mixed mode (2-4 other patterns sung in irregular sequence). Intensive focal-individual sampling of 14 males documented the use of these modes of singing throughout the nesting cycle. Males of different ages (first breeding season or later) did not differ in use of the two modes. Time spent singing in repeat mode decreased markedly after acquiring a mate, but time spent singing mixed mode did not change significantly across stages of the nesting cycle. Males sang more when their neighbors sang at a distance of 25 m or more. Repeat mode increased in this situation before a male acquired a mate, while mixed mode increased afterwards. Near a neighbor (within 25 m), males avoided use of repeat mode. Nearby females before the onset of incubation evoked increased use of repeat mode. More distant, calling females elicited little response before incubation, but thereafter calling females tended to suppress all singing. Males used mixed mode proportionately more in locations nearer neighbors. There were no indications that variation in singing influenced the dates on which males acquired mates. Unmated males late in the breeding season sang persistently in repeat mode, even more than eventually mated males had early in the season before they acquired mates. These results provide support, with some reservations, for three hypotheses for the evolution of distinct modes of singing: (1) specializations for male and female listeners; (2) specializations for indicating conditional behavioral tendencies; and (3) specializations for communication in low- and high-noise situations. These hypotheses are not mutually exclusive, and all three in combination might offer the strongest explanation for the evolution of distinct singing modes in this species and other paruline warblers.
Sex-Role Reversal in the Black-Chinned Tilapia, Sarotherodon Melanotheron (RÜPpel) (Cichlidae)
Authors: Balshine-Earn Sigal , Mcandrew Brendan J. 
Published: April 2008

AbstractIn the animal kingdom most species follow standard sex roles: males compete more intensely for mates and females exert greater mate choice. Recent theory suggests that the direction of sexual selection is the outcome of sexual differences in potential reproductive rates (PRRs): the sex with the higher PRR will compete for mates and the sex with the lower PRR will be most selective. This study tests the theory experimentally by examining competition for mates and mate choice in the black-chinned tilapia, Sarotherodon melanotheron, a paternal mouth brooding cichlid. In this species, the PRR of males is lower than that of females. In laboratory competition trials, females were more aggressive: they bit, chased and initiated mouth fights more often than males. Dominant females were also much better at monopolising potential mates compared to dominant males. A second experiment confirmed that males were choosy for size, preferring large partners over small ones, while females did not discriminate for size. Therefore, the prediction of sex role reversal (competitive females and discriminating males) is confirmed.
Parent-Offspring Feeding Relationship of Coots (Fulica Atra) in a Varying Environment
Authors: Amat Juan A. 
Published: April 2008

AbstractPredictions derived from parental investment theory indicate that when the reproductive value of offspring decreases, parental investment should also decrease. If so, it should be expected that in adverse years, parental investment should be lower, given the lower survival prospects of chicks, than in more favourable years. I tested this by recording the frequency with which coots (Fulica atra) fed their chicks during a ten years period in a set of lakes that experienced considerable interannual variations in water levels. Contrary to the prediction, I found that during drier years, chicks were fed more frequently than during wetter years, in which self-feeding by chicks was more frequent. The reason for this could be that for coots the crucial factor for improving reproductive success is the quality rather than the quantity of chicks, and by increasing parental effort during more adverse years, the lower survival prospects of chicks could be attenuated. However, late in the breeding season, when fledging success is lower, chicks were fed by their parents less frequently than in the early breeding season. This could be related to a change in the cost/benefit ratio, itself independent of offspring quality, that parents experience when rearing chicks late in the season due to the start of plumage moult.
More Is Not Always Better: Male Incubation in Two Acrocephalus Warblers
Authors: Kleindorfer Sonia , Fessl Birgit , Hoi Herbert 
Published: April 2008

Abstract
This study investigates male and female incubation ability in two monogamous Acrocephalus warblers with overlapping, equally sized territories and similar prey abundance. Given the longer breeding time window of the moustached warbler (A. melanopogon) compared with the reed warbler (A. scirpaceus), the trade-off between the need for biparental care and the cost of inefficient incubation is discussed. Hourly protocols and egg temperature measurements were analyzed with regard to four primary questions: male and female incubation ability, the role of environmental parameters, hatching success and the influence of male incubation on female time allocation. In both species, males increase egg temperature per minute at a slower rate than do females. There is no species difference in the percentage of incubation per hour for males (20%) or females (50%). Ambient temperature influences male incubation only in the moustached warbler during the early season (April) when male incubation correlates with hatching success. The male reed warbler shows daily temporal selectivity throughout the breeding season, increased incubation during rainfall, and no correlation with hatching success. In both species, females receive direct benefits of increased foraging time through male incubation. However, only the female reed warbler adjusts her incubation duration to previous male incubation. Thus, female reed warblers maximise the male component and thereby reduce the total incubation phase with high male effort whereas the incubation phase is increased with above average male effort in the moustached warbler.
The Effect of Hunger On the Learning of New Food Preferences in the Mongolian Gerbil
Authors: Forkman Björn 
Published: April 2008

AbstractA new and more profitable food type was introduced to three groups of Mongolian gerbils (Meriones unguiculatus). When first presented with the new food one group was sated, another was hungry and the third group was hungry and expected a food shortage. In addition to the new food all groups had access to familiar food during the experimental sessions. The group that expected a food shortage had a lower intake of new food than either of the other groups, both in absolute and relative numbers. Both the sated and the hungry group ate the same absolute amount of new food during the first presentation, but since the sated animals had a lower total intake, the new food represented a higher proportion of the intake for these animals. The animals were then tested during the subsequent days (all groups now hungry). Thc group that had been sated showed a stronger preference for the new and profitable food than the hungry group, which in turn showed a stronger preference than the expected food shortage group. This means that in a semi-natural situation a strong need may actually decrease the rate of learning. The results can be explained in terms of risk prone/risk aversive behaviour along the lines of previous studies of risk sensitivity in optimal foraging. In an additional experiment it was shown that sated individuals will decrease their total intake of food when presented with both new and familiar food, in comparison with when only familiar food is present. This may have the effect of enhancing learning about the new food.
Avoidance Response By Adult Newts (Cynops Pyrrhogaster and Notophthalmus Viridescens) To Chemical Alarm Cues
Authors: Marvin Glenn A. , Hutchison Victor H. 
Published: April 2008

AbstractMany fishes and aquatic invertebrates use chemical alarm cues to avoid predation, however relatively little is known about the occurrence of chemical alarm cues in amphibians. We tested the response of adult fire-bellied newts (Cynops pyrrhogaster) and red-spotted newts (Notophthalmus viridescens) to chemical cues from damaged tissues of newts and other salamanders. Both species avoided chemical cues from a conspecific skin extract. Notophthalmus viridescens also avoided chemical cues from C. pyrrhogaster skin extract, but the converse was not true. Neither species avoided chemical cues from a conspecific viscera extract, plethodontid salamander (Desmognathus and Plethodon) skin extracts, or a conspecific skin extract which had been heated. These results indicate that the avoidance behaviour is an alarm response to chemical cues released from damaged newt skin and is not a general response to chemical cues from damaged salamander tissue. This study provides the best evidence to date for an avoidance response by caudate amphibians to chemical alarm cues.
Intertidal Breeding and Aerial Development of Embryos of a Stickleback Fish (Gasterosteus)
Authors: Macdonald J.F. , Bekkers J. , Macisaac S.M. , Blouw D.M. 
Published: April 2008

Abstract
Males of the newly discovered 'white' stickleback disperse their embryos over the filamentous algae in which they nest and, unlike any other stickleback, they provide no subsequent parental care. Previously known populations of white sticklebacks nest only in shallow subtidal waters where filamentous algae are abundant. Our purpose in this paper is to describe highly divergent populations at Spry Bay, Nova Scotia, Canada, in which males build nests on bare rock in the subtidal and intertidal zones, and disperse their embryos over bare rock. Intertidal embryos are exposed to air and are vulnerable to desiccation at low tide. Field studies reveal that nests are built from locally available materials directly on the rock substrate. They are constructed very quickly and tend to be less substantial than subtidal nests. Internest distances are shorter in the intertidal zone than in adjacent subtidal areas. Dispersed intertidal embryos tend to settle into crevices between stones where the microenvironment remains moist and temperate between tides due to the presence of organic detritus and shade. Such embryos survive, develop, and hatch. Similar behaviours occur at other sites in Nova Scotia, and we know that it has persisted for at least four years at Spry Bay. We conclude that breeding and dispersing embryos over bare rock substrate, and intertidal breeding, are novel but stable breeding repertoires. We hypothesize that they have evolved secondarily to the evolution of emancipation from parental care in the white stickleback.
Temporal Structure in Stickleback Behaviour
Authors: Sevenster P. , FEUTH-DE BRUIJN E. , Huisman J.J. 
Published: April 2008

Abstract
Research was started into a possible circadian periodicity in the behaviour of the threespined stickleback. The behaviour of solitary males in the sexual phase of their breeding cycle was studied under constant conditions, including illumination of constant brightness (LL). No, 'free-running', circadian rhythm was found. Both the frequency of nest-visits and the rate of creeping-through (which shows an ultradian periodicity) were remarkably constant over long periods. Also, operant conditioning experiments, in which the male could switch the lights on or off, did not reveal any circadian fluctuation in the preference for light or dark. In the course of the long-term recordings 'rest-periods' were found, lasting some 10 to 50 minutes, in which the fish was surprisingly inactive, and did not visit the nest. Although some characteristics of these 'rest-periods' seem to point to a 'sleep-like' nature, others seem to argue against this.
Attachment and Social Withdrawal in Autism: Hypotheses and Findings
Authors: Buitelaar J.K. 
Published: April 2008

AbstractAutism is characterized by an impaired development in social interaction and communication and a markedly restricted repertoire of activities and interests. This paper summarizes the research into the social abnormalities in autism, and reviews the empirical support for two behavioural hypotheses on autism, i.e. that autism results from impaired attachment, or from intense and prolonged approach-avoidance conflicts. The core social impairment of autistic subjects seems to be a deficit in attunement and timing of actions and reactions rather than a difference in frequencies of behaviours. Attachment behaviour of most, if not all autistic children tends to be disorganized; nevertheless, they do form attachment relationships in terms of preferential proximity seeking or reunion behaviour in the Strange Situation Test. Attachment studies performed sofar however have methodological limitations ; particularly the study of maternal-infant attunement and reciprocity has been neglected. Empirical evidence fails to support the presence of approach-avoidance conflicts in autistic subjects, and is further at variance with the predicted consequences of such conflicts. Insufficient attention has hitherto been paid to the clinical heterogeneity of autism in behavioural studies. A promising approach to deepen our understanding of the development of the autistic symptomatology is the early detection and subsequent behavioural study of 1-2 year old children at high-risk for autism. Finally, behaviour observation studies in autistic subjects are likely to benefit from the concurrent assessment of physiological indices of arousal, and from the integrated measurement of social-cognitive processes.
Absence of 'Youngest Ascendancy' in the Dominance Relations of Sisters in Wild Japanese Macaques (Macaca Fuscata Yakui)
Authors: Hill David A. , Okayasu Naobi 
Published: April 2008

AbstractDominance relations among females were studied in a small, well-habituated troop of Yakushima macaques (Macaca fuscata yakuz) in southernjapan. Data were collected using focal animal sampling over a 20-month period. Although the frequency of aggression was much lower than that reported for provisioned groups, and support in agonistic interactions was rare, a clear linear dominance hierarchy was apparent. In each of the four pairs of sisters in the troop the older was dominant to the younger. This is contrary to the pattern commonly reported for provisioned groups of Japanese and rhesus macaques, in which dominance among sexually mature sisters tends to be inversely correlated with age. For each pair of sisters in the study troop the mother was alive and healthy when the younger daughter became sexually active, but no cases were seen of a mother aiding one daughter against another. We therefore conclude a) that the absence of youngest ascendancy was due to a lack of support, rather than a lack of potential allies, and b) that both frequent agonistic support and youngest ascendancy are most likely to occur under conditions where concentrated food resources result in frequent and intense aggression.
Induction and Development of a Filial Predisposition in the Chick
Authors: Hampton Neil G. , Bolhuis Johan J. , Horn Gabriel 
Published: April 2008

Abstract
Filial preferences in young domestic chicks, Gallus gallus domesticus, are influenced by at least two systems: one involved in learning about stimuli to which the animals are exposed, and the other a predisposition to approach stimuli resembling conspecifics. The predisposition is manifest in dark-reared chicks as an emerging preference for a rotating, stuffed jungle fowl over a rotating red box. In previous studies, 24 h-old visually naive chicks were placed in running wheels for 2 h. Throughout this time the chicks were in darkness. A significant preference for the stuffed fowl was found 24 h, but not 2 h later. In the present study it was shown that the predisposition becomes manifest at 10 h (Experiment la) and 5 h (Experiment 1 b) after either placement in running wheels, or after the chicks had been trained by exposure to a rotating red box. In Experiment 2 it was shown that placement in running wheels was not necessary for the predisposition to emerge. However, handling the birds was sufficient for the induction of a significant preference, expressed 5 h later. Exposure to a maternal call for 2 h (Experiment 3) was also sufficient to induce the development of the visual predisposition 24 h later. These results show that a visual predisposition to approach certain stimuli becomes manifest in dark-reared chicks between 2 and 5 h after the experience of handling, and that exposure to a maternal call is also sufficient to induce this predisposition.
Escape Behaviour of Juvenile Psammodromus Algirus Lizards: Constraint of or Compensation for Limitations in Body Size?
Authors: Martín José , López Pilar 
Published: April 2008

Abstract
We compared the escape behaviour of juvenile and adult Psammodromus algirus lizards, by using data of escape performance in the laboratory and field observations of escape behaviour. We specifically examined whether a differential escape response is a constraint of body size, or whether juveniles behave differently in order to maximize their escape possibilities taking into account their size-related speed limitations. In the laboratory, juvenile lizards were slower than adult lizards, and escaped during less time and to shorter distances, even when removing the effect of body size. In the field, juveniles allowed closer approaches and after a short flight usually did not hide immediately, but did so after successive short runs if the attack persists. Approach distance of juveniles was not affected by habitat, but initial and total flight distances were shorter in covered microhabitats. There was no significant effect of environmental temperature on approach and initial flight distances of juveniles. However, the total flight distances were significantly correlated with air temperatures.
Ranging of Conspecific Songs By Kentucky Warblers and Its Implications for Interactions of Territorial Males
Authors: Haven Wiley R. , Godard Renée 
Published: April 2008

AbstractKentucky warblers (Oporornis formosus) each sing a single song pattern. To determine whether males could range (estimate the distance to) conspecific songs, we presented clean and reverberated versions of strangers' songs to 12 males in a factorial design. To assess differences between the playbacks and the subjects' own songs or neighbors' songs, we measured differences in minimal repetition periods between repeated acoustic elements in songs, features that could contribute to assessment of reverberation. Results indicated that Kentucky warblers can range conspecific songs and that similarity between playback songs and established neighbors' songs or a subject's own songs did not enhance this ability. Direct evidence that males misjudged the distance to reverberated playbacks excluded other interpretations of the results based on differences in the detectability or habituation of clean and reverberated songs. These results suggest further that assessment of reverberation is sufficient for ranging and that perceptual analysis of song is not necessarily linked to overt production. As a consequence, repertoires of songs do not necessarily promote interference between territorial neighbors.
Responses To Songs With Altered Tonal Quality By Adult Song Sparrows (Melospiza Melodia)
Authors: Strote Jared , Nowicki Stephen 
Published: April 2008

Abstract
Pure-tone sounds are a common and distinctive feature of many birdsongs. We used field playback experiments to test whether this tonal quality is perceptually salient to adult male song sparrows in the context of song recognition, by comparing responses to playback of normal songs with responses elicited by songs that had harmonics added. This species was chosen for study based on the recent finding that young song sparrows do not show a preference for songs with pure tones over songs with harmonics when choosing model songs to copy during their sensitive phase for learning. We found adult song sparrows to be significantly more responsive to normal song than to harmonic song, consistent with results from adult birds of other species. We conclude that the perceptual salience of the tonal quality of song changes during ontogeny or is context-dependent.
Silk Investment in Gifts By Males of the Nuptial Feeding Spider Pisaura Mirabilis (Araneae: Pisauridae)
Authors: Lang Andreas 
Published: April 2008

AbstractAdult males of the hunting spider Pisaura mirabilis wrap up prey with silk and pass these nuptial gifts to females prior to copulation. The females digest the nuptial gifts, including the silk, during mating. Laboratory experiments were carried out to determine the amount of silk males of P. mirabilis invest in nuptial gifts, and its possible role in sexual reproduction. The amount of silk was always small, indicating that the silk of the nuptial gift has little nutritional value for females. Males that had more time to wrap up the prey produced a larger amount of silk. Starved males required more time than satiated males to produce a given amount of silk. A larger male body size had a positive effect on the amount of silk. In general, the size of the prey used for nuptial gifts had no influence on the amount of silk. However, due to handling problem, smaller males produced no silk for very large flies. Females took more time to digest a nuptial gift with a larger amount of silk than a nuptial gift with a smaller amount of silk. A possible interpretation of the adaptive significance of wrapping is that males use silk to prolong the copulation time during mating.