bluuebunny/crossref_metadata_2025_split huggingface dataset:
Caching Behaviour in the Gray Jay and the Source-Departure Decision for Rate-Maximizing Scatterhoarders
Authors: Waite Thomas A. , Reeve John D. 
Published: April 2008

AbstractWe developed a model that concerns, in part, how long a scatterhoarder should persist in caching food from an ephemeral, locally abundant source ('bonanza') before moving on in search of other sources. The model assumes that an animal scattering food caches for later use behaves in a manner that maximizes the rate at which it stores recoverable (surviving) food in its habitat. It is shown theoretically that under some conditions it is better not to cache all available food but instead to move on in search of other food sources. This 'source-departure decision' for scatterhoarders is analogous to the patch-departure decision for animals that forage among food patches. It is shown that whether, and at what point, a 'moving-on threshold' is reached should depend on the size of the source, the strength of density-dependent cache theft, and the abundance of sources in the habitat. A field experiment was performed to test the qualitative prediction that gray jays, Perisoreus canadensis, should not persist as long in caching food when a day-long opportunity for caching is restricted to a single source (single-source treatment) as when such an opportunity is divided among a series of disjunct sources (multiple-source treatment). In the single-source treatment, jays tended to cache at lower overall rates, transport food items to more distant cache sites, and spend less time caching. These tendencies became more pronounced later in the day. However, although the rate of caching approached zero in the single-source treatment, the jays did not completely cease caching. This apparent violation of the model is attributed to the behaviour of recaching, a facet of gray jay scatterhoarding behaviour that was not built into the model. This retrieval and redistribution of previous caches resulted in the stabilization of the density of caches near the source. In addition, this switch from single- to multiple-load caching trips arguably would make it economical for gray jays to continue to make caching trips from a source beyond the source-departure point predicted by the model. Our theoretical and empirical results begin to show how scatterhoarders may behave in a manner that maximizes the long-term average rate of storage of recoverable food energy throughout their habitat.
The Effects of a Trade-Off Between Foraging and Brood Defense On Parental Behaviour in the Convict Cichlid Fish, Cichlasoma Nigrofasciatum
Authors: Rangeley Robert W. , Godin JEAN-GUY J. 
Published: April 2008

AbstractParental convict cichlids, Cichlasoma nigrofasciatum, responded to the presence of a potential brood predator by decreasing net energy gains (food intake decreased and energy expenditure increased) while increasing parental effort (large allocation of time to brood defense). These behaviours are important factors in the life-history trade-off between current and future reproductive investments. The allocation of energy into defense behaviours and elevated activity levels, combined with a voluntary reduction of food consumption, represent an investment in the current brood which could (in nature) reduce future reproduction. Contrary to parental investment theory predictions, consistent increases in parental effort with brood age were not evident.
Variable Leadership in Bar-Headed Geese (Anser Indicus) : an Analysis of Pair and Family Departures
Authors: Lamprecht JÜRG 
Published: April 2008

AbstractThis paper reports quantitative leadership differences in semi-captive bar-headed geese (Anser indicus) at different times of the year, and in different types of groups. Leading is defined here as causing the departure or determining the direction of movement of the whole group. No permanent and exclusive leader of a pair or family group was found, rather relative leading frequencies of male, female and young showed a definite shifting pattern. Females led more often than their mates prior to breeding, and on nest pauses during the incubation period, but less often in summer, autumn and early winter. In families there was no difference between the frequencies of male and female leading. Family females led relatively more often than those of pairs without offspring. This difference was related to the presence, not the number, of young. Goslings led the family about as often as the parents during the rearing period in early summer, less often in autumn, winter and next spring. Such differences and changes are to be expected where competence in particular tasks and dependence on partners vary between group members, and where different situations require different abilities. For the geese, the results can be related to the different options of group members and to the different benefits they derive from leaving (or 'staying put') or following (or waiting for the others) in different situations.
Optimal Foraging in Peromyscus Polionotus: the Influence of Item-Size and Predation Risk
Authors: Phelan John P. , Baker Richard H. 
Published: April 2008

AbstractPredictions of optimal foraging theory were tested for Peromyscus polionotus in the laboratory and in two field experiments in which seed item-size was manipulated. In the laboratory, handling times for millet, sunflower seeds, and peanuts were determined. Additionally, energy/handling (E/h) time values were calculated and seed preference experiments were conducted. Mice showed a clear preference for the seeds more profitable in terms of E/h. Seed preference experiments were also conducted in the field to determine the relative influence of optimal foraging and predation risk in diet choice. In the first of the two field experiments, behavioral strategies to reduce predation vulnerability could not influence differential seed selection. As predicted, the mice again showed a preference for the more profitable seed type. In the second experiment, animals were presented with conflicting demands because foraging on a more abundant, but less preferred, seed type afforded the animal an increased ability to avoid predators. Presented with this opportunity to reduce the risk of predation, the animals shifted their preference to the safer, but less profitable food. This shift in seed preference was accompanied by predation-risk-reducing changes in spatial foraging patterns.
Perception of Distress Call Harmonic Structure By the Starling (Sturnus Vulgaris)
Authors: Aubin T. , Bremond J.C. 
Published: April 2008

AbstractTo examine the ethological role of signal composition in the distress calls of starlings (Sturnus vulgaris), we conducted a series of playback experiments in the field. Earlier researches revealed that frequency modulations are important features of distress calls for triggering the responses of starlings. Another feature, the harmonic structure, was thought to play a role in the coding/decoding process of the call. The aim of this work was to investigate the role of this structure. Four points emerge from these experiments: 1) Ethological message is effectively encoded in the harmonic structure. 2) Wide-band frequency spectra are preferred to narrow-band spectra. 3) Starlings examine the width of the spectrum but not the interval between frequency bands. 4) Spectra with a high intensity upper part produce a stronger response than other types of spectra. Such a coding/decoding process is discussed regarding transmission of information at long range, the ability to appreciate distance, to locate the caller and the possibility of grading the information.
Habitat Shift After Experimental Removal of the Bigger Species in Sympatric Ctenomys Talarum and Ctenomys Australis (Rodentia: Octodontidae)
Authors: Vassallo Aldo I. 
Published: April 2008

AbstractA removal trapping experiment was conducted in the field to investigate if microhabitat choice and population characteristics of Ctenomys talarum are affected by the bigger, dominant Ctenomys australis, in a zone where these subterranean rodent species are geographically sympatric. As reported previously by other authors, the species were distributed in a habitat segregation pattern which characterized the initial state, prior to C. australis removal. I detected a significant habitat shift-that is, changes in microhabitat choice by C. talarum individuals- in response to C. australis removal. However, it is remarkable that this only occurred after one year of continuous removal of C. australis, and was restricted to a very small expansion by C. talarum into the fringe of the area previously occupied by the dominant species. In addition, a slight increase of the C. talarum population density took place which was possibly due to the absence of the other species. It is suggested that the microhabitat typical of C. australis (with deeper, more friable soil and less vegetation) could be suboptimal and thus unpreferred for C. talarum. If the pre-experimental C. talarum population was satiated to its carrying capacity, it is possible that the small number of C. talarum individuals-mostly subadults-had invaded areas previously occupied by C. australis because they had no other choice than a suboptimal habitat. No substantial changes were detected in other population characteristics (sex ratio, age structure, distance between individuals) which were very similar to that in a control area. Interspecific interactions and displacement by the bigger C. australis could be significant but nonetheless marginal in sustaining the pattern of microhabitat segregation between the species. Difference in habitat preference, linked with species differences in body size and colour, are probably of much greater importance.
The Interaction of External and Internal Factors in the Courtship of Parasitic Wasps (Hym., Pteromalidae)
Authors: Jachmann F. , VAN DEN ASSEM J. 
Published: April 2008

AbstractOur topic of interest is the causal organization of courtship and mating behaviour of parasitic wasps (Hymenoptera, Pteromalidae), more especially that of Nasonia vitripennis. Males pursue newly emerged females over a short distance, mount on top, and take up a position at the front, the fore tarsi placed on the female's head. Courtship displays consist of characteristic combinations of motor patterns, which are repeated a variable number of times in so-called courtship cycles. Movements with the wings, head, mouthparts, and antennae are conspicuous components. This applies in particular to head-nodding movements, which occur in series. A female may become sexually receptive while being courted; she signals the onset of this condition with a movement of her antennae. The male will react promptly: he stops courting and backs up into the copulatory position. The signal coincides almost invariably with the first nod of a series; signalling at other times led to a postponement of the backing-up reaction. Because Nasonia males readily court on dummy females, we used a dummy with moveable antennae to investigate the temporal relationship of signal and reaction. We observed two types of postponed backing-up reactions: simple backing up, and backing up after performance of one or more display movements. At the same time, we found a quantitative relationship between durations of the latencies, and the timing of the signal relative to the display. Our investigations produced evidence for endogenous, periodic changes, which take place during the succession of courtship cyles. The postponed backing-up reactions of different types could be explained in terms of interactions between the effects of signalling and the endogenous dynamics of courting males.
Differences in Site Fidelity Among Territorial Males of the Carpenter Bee Xylocopa Varipuncta (Hymenoptera: Anthophoridae)
Authors: Alcock John 
Published: April 2008

AbstractLekking males of the carpenter bee Xylocopa (Neoxylocopa) varipuncta compete for landmark territories, where they are occasionally visited by receptive females. In a study conducted over three flight seasons, less than 10% of marked males qualified as long-term residents (i.e. bees that held the same hovering station for 90 min or more on at least two afternoons). However, among the small minority of long-term residents were some bees that returned to the same landmark for up to 3 hr every afternoon for several weeks. These males defeated many intruders in aerial combat during each afternoon. The hypothesis that site-faithful males were individuals of unusual resource-holding power is not supported. Long-term residents were not larger on average than short-term territory holders. Moreover, the frequency of mating by long-term residents was very similar to that of males in the general population, suggesting that long-term residents did not hold territories that were exceptionally attractive to females. Thus, the basis for site fidelity in this species remains elusive. The rarity of site-faithful males in this species may be related to great daily fluctuations in the numbers of potentially receptive females visiting the landmark territories, which may make the timing of male mate-attracting behavior far more important than regularly returning to defend any one site.
Risk-Taking By Juvenile Vervet Monkeys
Authors: Fairbanks Lynn A. 
Published: April 2008

AbstractBecause of their greater vulnerability to mortality, juveniles might be expected to be more conservative than adults in response to novel and potentially threatening situations. Results from research on vervet monkeys (Cercopithecus aethiops sabaeus) in the field and in captivity suggest that the opposite is true. Juveniles in the field were more likely to approach a human observer, and in captivity they had shorter latencies to enter a new area, approach a novel food container, and come within a meter of a strange adult male when compared to younger and older animals. In all four test conditions, risk-taking was an inverted U-shaped function of age. Latency to approach in unfamiliar and potentially dangerous situations declined from birth to two years of age, then increased with age to adulthood.
Polyandry and Incest Avoidance in the Cooperative Stripe-Backed Wren of Venezuela
Authors: Piper Walter H. , Slater Gary 
Published: April 2008

AbstractWe made behavioral observations in 37 social groups of the communal stripe-backed wren during 1990 and 1991 to investigate the recently-discovered shared paternity between dominant and subordinate males (or "SMs"). We found two distinct kinds of social groups that differed in terms of social behavior: "mother" groups, which contained only subordinate males that were sons of the dominant female (termed "DF-sons"), and "stepmother" groups, which contained at least one subordinate male unrelated to the dominant female (termed "DF-stepsons"). In mother groups only dominant males courted dominant females, mate-guarding was infrequent and aggression by dominant males toward other males was absent. On the other hand, stepmother groups were characterized by frequent association with and courtship of dominant females ("DFs") by both dominant males ("DMs") and DF-stepsons and relatively frequent aggression by dominant males toward DF-stepsons. DF-stepsons, moreover, sired 15% of all young in stepmother groups. Thus, incest avoidance dictated the behavior of subordinate males, and the mating system in wren groups was either monogamous or polyandrous, depending upon the relatedness between subordinate males and the dominant female.
Aggressive Performance as a Behavioral Correlate of Plumage Polymorphism in the White-Throated Sparrow (Zonotrichia Albicollis)
Authors: Kopachena Jeffrey G. , Falls J. Bruce 
Published: April 2008

Abstract
Morph and sex-specific differences in aggressive performance were examined in the white-throated sparrow. Among the four morph/sex classes, white-striped males had the strongest response to white-striped models and were the most likely to approach and attend song playbacks independently. The slightly weaker responses of tan-striped males and white-striped females were similar to each other. Tan-striped females were the least aggressive. Aggression by white-striped females enabled tan-striped male x white-striped female pairs to perform as well, or better, than white-striped male x tan-striped female pairs. Tan-striped males paired earlier than white-striped males. An increased prevalence of territorial tan-striped males corresponded to the arrival of females on the breeding grounds. The data are consistent with the hypothesis that negative assortative mating benefits tan-striped males through the supplemental aggression of white-striped females. However, the apparent preference of white-striped females for tan-striped males suggests that there are benefits to negative asortative mating other than those that might arise from differences in aggressive performance.
Sexual Preferences of Female Zebra Finches: Imprinting On Beak Colour
Authors: Weisman R. , Shackleton S. , Ratcliffe L. , Weary D. , Boag P. 
Published: April 2008

Abstract
Sexual preferences of adult zebra finches are influenced by early learning of parental characteristics. We studied how imprinting affects the preference of female zebra finches for male beak colour. The beaks of male and female parents were painted, 2-3 days before hatch and thereafter until the young were fledged, as follows: male red, female orange (R-O group); male orange, female red (O-R group); both male and female red (R-R group); or both male and female orange (O-O group). Females were raised by painted parents until 35 days, then visually isolated from other birds until test at 100 days. In 4-way choice tests using red- and orange-painted stimulus males, females from Groups O-R and R-O chose males with beaks painted the same colour as their father's beak, whereas females from Groups R-R and O-O did not. We conclude that preference for male beak colour was acquired only by females reared by parents with unlike, discriminative, beak colours. The results suggest an associative learning basis for sexual imprinting.
Repertoire Turnover and the Timing of Song Acquisition in European Starlings
Authors: Chaiken Marthaleah , BÖHNER JÖRG , Marler Peter 
Published: April 2008

Abstract
In order to establish unambiguously whether a reputed open-ended learner, the European starling, could memorize new songs in adulthood, we exposed hand-reared male starlings to a series of either live conspecific tutors or tape recordings of conspecific song over a period of 18 months, and isolated them from any other exposure to conspecific song. The song motifs produced by the birds were compared with those of their tutors or training tapes to infer the time of motif memorization. We found that the starlings continued to memorize and produce new song motifs, both within and between breeding seasons, up to the age of at least 18 months. Not all the new motifs in the repertoires had been recently memorized; in some cases there was an apparent lag of a year and a half between memorization and production. There were no significant differences between live-tutored and tape-tutored groups in the timing of learning or in the rate of repertoire turnover (55-92% new motifs in each repertoire sample), although, as we have reported previously, live-tutored birds imitated a greater number of motifs and developed larger repertoires.
Predator Inspection Behaviour Covaries With Schooling Tendency Amongst Wild Guppy, Poecilia Reticulata, Populations in Trinidad
Authors: Magurran Anne E. , Seghers Benoni H. 
Published: April 2008

Abstract
When fish inspect a predator they incur risk. One way of reducing the cost of inspection is to approach predators in groups large enough to benefit from the safety in numbers advantages of schooling. In a survey of nine populations of guppies, Poecilia reticulata, in their native streams in Trinidad, we observed marked variation in schooling behaviour. Guppies from sites also inhabited by a major predator, the pike cichlid, Crenicichla alta, devoted more time to schooling than those from less dangerous locations where the cyprinodont Rivulus hartii was present. We found a strong correlation between schooling tendency and the group sizes adopted by guppies inspecting a realistic model predator. Since guppies in dangerous localities approached a potential predator in large groups it seems unlikely that many of these fish were caught in a Prisoner's Dilemma. Inspections by singleton fish were rare in high-risk locations but predominated in those populations where risk from fish predators was reduced.
Age, Sex and Prior Site Experience Have Independent Effects On the Foraging Success of Wintering Snow Buntings
Authors: Smith Richard D. , Metcalfe Neil B. 
Published: April 2008

AbstractIntraspecific variation in foraging success amongst birds is often associated with differences between individuals in competitive ability or experience. However, it is usually difficult to separate the importance of experience per se from that of age. Here we examined the feeding rates of wintering snow buntings (Plectrophenax nivalis) at Cairn Gorm, North-east Scotland in both competitive and non-competitive situations. Although flock-size/density and stage of the feeding bout accounted for most of the explainable variation in peck-rates, there remained significant and additive residual effects of both age and prior experience of the site (older/more experienced birds achieving higher feeding rates) and these effects were very similar for birds feeding alone or in flocks. Sex differences in feeding rates were only apparent in large flocks, where males (the dominant sex) had faster peck-rates than females. Birds without previous experience (whether age or site-related) showed increases in relative feeding rate during the course of the winter, whereas experienced birds did not. This suggests that the differences between experienced and inexperienced birds were due to learning rather than the disproportionate loss of poor foragers.
Affiliation Patterns Among Male Costa Rican Squirrel Monkeys
Authors: Boinski Sue 
Published: April 2008

AbstractRemarkably close male bonding exists among Costa Rican squirrel monkeys, Saimiri oerstedi. In this population males were philopatric, exhibited no male-male within-troop aggression, and only very slight evidence for a dominance hierarchy. Juvenile, young and full adult males were spatially clumped in same-age male cohorts. A less intense, secondary association was also shown between the young and full adult male cohorts. These associations were most dense over a spatial scale of 5 m or less, but can also be detected in a 5-10 m distance from a focal male. Males also cooperated in 1) sexual investigation of females during the mating season, 2) aggressive interactions with males of neighboring troops, and 3) valiant defense of infants and subadults from potential predators. In contrast, the spatial association among adult females never exceeded random expectations and only a transitory period of cooperation was observed among mothers during the birth season. Furthermore, there was little evidence of bonds between the sexes. Seasonal variation in affiliation patterns was best explained by fluctuations in food availability and, secondarily, reproductive activity. These results are surprising both from the perspective of the general pattern of male affiliation among primates and the often marked aggression and dominance relationships among males documented in captive and wild populations of South American squirrel monkeys. The ultimate explanation is suggested to be the disparate distribution of fruit resources exploited by South and Central American squirrel monkeys, mediated by effects on female affiliation and dispersal patterns.