bluuebunny/crossref_metadata_2025_split huggingface dataset:
Endogene Zeitliche Programmierung Der Empfindlichkeitsabnahme Einer Brutpflege-Reaktion Von Pseudocrenilabrus Multicolor (Pisces, Cichlidae)
Authors: Owka Wolfgang 
Published: April 2008

AbstractDas Weibchen des kleinen Maulbrüters Peudocrenilabrus multicolor nimmt während des Ablaichens die Eier in das Maul auf. Nach 10 Tagen (bei 27°C) werden die inzwischen schwimmfähigen Jungen aus dem Maul entlassen. Sie werden weiterhin von der Mutter betreut und bei Gefahr und in der Dämmerung wieder in das Maul aufgenommen. Diese Brutpflegereaktionen erlöschen im Verlauf von 6 bis 7 Tagen. Es wurde untersucht, ob diese Veränderungen von dem synchron verlaufenden Entwicklungsprozess der Jungen oder von einem endogenen Zeitprogramm der Mutter gesteuert werden. 6 Mütter mit Jungen wurden ab dem Entlasstag zu jeweils 3 Tageszeiten einer simulierten Dämmerung (von 300 auf 0,5 Lux) ausgesetzt. Es zeigte sich, daß die Aufnahmeschwelle (Lichtintensität, bei der die Aufnahme der Jungen in das Maul beginnt) von zwei zeitlichen Faktoren bestimmt wird, einer tagesperiodischen Komponente (erhöhte Empfindlichkeit abends) und einer längerfristigen Komponente (Empfindlichkeitsabnahme über mehrere Tage hinweg). Diese Veränderungen erfolgten unabhängig von der Erfahrung mit der Testsituation. Je niedriger die Aufnahmeschwelle war, desto länger wurden die Jungen anschließend im Maul behalten. In der Austauschexperimenten wurden der Mutter ältere oder jüngeren Jungfische untergeschoben als ihrem eigenen Stadium entsprach. Die Dämmerungstests zeigten, daß die Aufnahmeschwellen nicht dem Entwicklungsstadium der Jungen entsprechen, sondern eher dem Stadium der Mutter. Es wird daraus gefolgert, daß die Empfindlichkeitsabnahme über die Brutpflegephase hinweg in der Mutter endogen vorprogrammiert ist.
The Response of Swamp Sparrows To Acoustically Distinct Song Types
Authors: Searcy William A. , Searcy Margaret H. , Marler Peter 
Published: April 2008

Abstract
Male and femal swamp sparrows (Melospiza georgiana) were tested for differential reaction to four acoustically distinct swamp sparrow song types. We tested males by playing bouts of single song types from speakers placed on male territories. Males gave the same kinds of aggressive responses to each of the four song types, and there were no quantitative differences in the strengths of the responses to the different types. In the experiments with females, we played songs to captive female swamp sparrows previously treated with estradiol, and measured response in terms of copulation solicitation display. Females displayed in response to all four song types, and again there were no quantitative differences in the strength of response to the different types. We conclude that different swamp sparrow song types do not convey different messages to either male or female listeners. Although the identity of the particular song type presented was unimportant, the number of types presented was important, at least to females. Females responded more strongly overall to bouts of four song types than to bouts of single song types. This result occurred because females habituated to the repeated presentation of a single song type, and showed a recovery in response when song types were switched. We conclude that the ability to sing multiple song types may aid males in stimulating females to come into reproductive condition and then copulate.
Interspecific Communication Between Ants
Authors: Reznikova Joanna I. 
Published: April 2008

AbstractWith the help of field experiments, the nonantagonistic relations and exchange of information among ants of various species occupying similar ecological niches were studied. Formica pratensis and F. cunicularia glauca, respectively dominant and subdominant in their associations, were chosen as the model pair. The dominant has a defended territory with a clearly defined secondary division. The feeding territory of the subdominant is organized to the type of individual foraging. The use of labyrinths with bait hidden in them showed that the subdominants are more enterprising foragers; when interacting with the dominant they play the role of scouts. The amount of prey of F. pratensis is so dependent on the presence of F. cunicularia that when the nests of this species are isolated, the F. pratensis bring three times less prey. The basis for the interaction of the foragers of different species is interspecific kinopsis and distant training.
A Comparison of Cawing in the European Carrion Crow (Corvus Corone) and the American Common Crow (Corvus Brachyrhynchos)
Authors: Thompson Nicholas S. 
Published: April 2008

AbstractThe American common crow (Corvus brachyrhynchos) has a complex communication system in which the meaning of its sound units ("caws") is determined in part by the temporal format in which they are uttered. Among the subsystems of the crow's communication is "ordinary" or "structured" cawing, in which the caws are uttered in sequences of similar caws, organized in discrete bursts. A comparable cawing format appears to exist in the European carrion crow (Corvus corone). 49 sequences of structured carrion crow cawing were recorded in Somerset, England, during the period from September 1976 to June, 1977. These are similar in organization to 20 sequences of American crow cawing which were re-analyzed for comparison, but the carrion crowbursts are significantly longer in the duration of their caws and in the duration of the pauses between caws within a burst and have significantly fewer caws in an average burst. Carrion crow structured cawing displays the same contextual ambiguities as have been reported for structured cawing in the American crow. Some evidence is developed which suggests that in carrion crow structured cawing as in American crow structured cawing, the variations in caw pattern are related to individuality, although the relationship is not a simple one. The distinction between structured cawing and unstructured cawing seems to be related in a loose way to the more general distinction made with oscine vocalizations between songs and calls. The situation is complicated by the fact that in corvids the term song is traditionally applied to a third class of vocalizations with properties quite distinct from structured and unstructured cawing.
A. the Mechanisms of Stimulus Selection
Authors: Baerends G.P. 
Published: April 2008

AbstractIn this second part of the monograph experiments have been described and discussed which were undertaken to investigate which visual characteristics of the herring gull's egg are effective, and to what extent, in evoking incubaton responses. Inspired by the LORENZian concept 'releasing mechanism', the present study - involving 12 seasons of field work - has grown into an attempt to analyse for a particular case the processing of information received from the environment.
Contests for Space in Breeding Cichlasoma Meeki: the Role of Resource Holding Potential
Authors: Neil Susan J. 
Published: April 2008

Abstract1. The agonistic behaviour of Cichlasoma meeki, the firemouth cichlid, was studied to test five predictions concerning Resource Holding Potential (RHP). Game theoretic models predict that animals should settle contests on the basis of asymmetries in RHP, thereby decreasing contest costs. Breeding pairs of fish were observed to determine how they responded to intruders of different status which encroached into their territory. The defended resource was space, either for spawning or for defence of young. 2. Significant differences were found in the behavioural responses to different species, numbers and sizes of intruder. 3. The majority of contests were short, with extended contests only occurring between conspecific pairs. 4. Escalated (contact) behavioural acts were uncommon, occurring only during extended contests and mainly during contests with conspecific pairs. They were performed primarily at the ends of contests or in bouts within contests. 5. The most costly non-contact behavioural acts were usually performed towards pairs, or towards single fish of size equal to or larger than that of the focal animal. 6. In contests with conspecific pairs there were no differences in the responses towards pairs of different sizes except in the type of behavioural acts performed. In such contests relative size was apparently not a sufficient asymmetry, and factors such as resource asymmetry may have been of greater importance.
Is the Parental-Care Behaviour of Aequidens Paraguayensis (Cichlidae) Optimal?
Authors: Owka Wolfgang 
Published: April 2008

AbstractAequidens paraguayensis from South America is a biparental larvophilic mouthbrooder. Adhesive eggs are laid on a substrate and fanned until hatching (substratebrooding). The hatching larvae are taken into the mouth by the female. Subsequently the parents relieve each other in mouthbrooding their offspring (larvophilic mouthbrooding). In comparison with pure substratebrooders-which are thought to represent the ancestral state-the time lag between spawning and hatching is shortened. This is interpreted as due to a general selective advantage of the mouthbrooding technique over the substratebrooding technique. Why then didn't evolution favour the transition from mouthbrooding of larvae to mouthbrooding of eggs (ovophilic mouthbrooding) thus allowing the extension of mouthbrooding up to spawning like in other cichlid species? An hypothetical answer is that this is not due to the lack of the adequate selection pressure but may relate to the nonavailability of appropriate ovophilic variants. This would imply that the parental care behaviour in this species is not optimal. To support this hypothesis experimental evidence on how broodcaring is regulated is given: 1. The uptake of larvae at hatching is induced by stimuli from the hatching wrigglers. Mouthbrooding can be induced at any time of the substratebrooding phase by presenting larvae to the adults. 2. The readiness to take up larvae into the mouth is maintained by the simultaneous presence of larvae within the mouth and of egg-like structures outside of it. 3. Females with induced uptaking readiness are not able to retrieve adhesive eggs from the substrate. 4. Females without uptaking readiness fan adhesive eggs, but eat loose eggs. 5. Females with induced uptaking readiness take up loose eggs in their mouths and mouthbrood them successfully at least until hatching. They behave like ovophilic mouthbrooders. Experimentally created ovophilic variants can be used to test the non-optimality hypothesis in nature or under semi-natural conditions. It is concluded that at least two independent traits must change simultaneously within the same generation to produce an ovophilic variant out of a larvophilic ancestor: on the one hand induction of an egg eating inhibition together with mouthbrooding readiness, on the other hand loss of adhesiveness of eggs. In the neodarwinian view of evolutionary change this is only possible if there is pleiotropy of the traits under consideration. The unlikeliness of pleiotropy may explain why A. paraguayensis has not become an ovophilic mouthbrooder, i.e. is not optimally designed.
Great Tits and Giving-Up Times: Decision Rules for Leaving Patches
Authors: Ydenberg R.C. 
Published: April 2008

AbstractIn this paper I examine the hypothesis that animals employ simple decision rules in exploiting patchily distributed food. This idea arises from the supposition that animals probably cannot compute the optimal patch residence time in the same manner that is calculated in optimal foraging models. Instead they may only approximate the optimal solution using a simple, robust rule-of-thumb. I considered three rules-of-thumb that great tits foraging in a simple experimental habitat may use: a number expectation, a time expectation, and a giving-up time. The experimental habitat consisted of an operant patch in which great tits had to search for food by hopping on a perch. The probability of reward declined for successive patch hops according to a predetermined stochastic schedule. In order to maximize food intake, the great tits had to occasionally leave the patch and fly across the experimental room to reset the reward schedule by hopping on a second perch. Three different lines of investigation were followed to test which of the three departure rules were employed: (a) a statistical analysis showed that there was a strong tendency for great tits to leave the patch only after several successive hops had gone unrewarded; (b) a computer simulation showed that a simple giving-up rule could produce a distribution of patch residence times similar to that observed; (c) an experiment in which the reward schedule was manipulated, successfully altered the patch residence times in accord with predictions made on the basis of a giving-up time rule. Thus, all three tests produced evidence in favour of the giving-up time rule. Although the great tits used a giving-up time rule, a residence time would have resulted in a higher rate of intake. One potential explanation of this apparent error is that the natural food of great tits has a clumped distribution, to which a giving-up time is better suited than a residence time rule. Finally, I point out that the observed giving-up time was much more variable than might be expected if it were adjusted solely in response to the habitat rate of intake. I suggest some hypotheses to explain this large variation.
Geographic Variation in the Sexual Behaviour of the Guppy, Poecilia Reticulata (Peters)
Authors: Luyten P.H. , Liley N.R. 
Published: April 2008

Abstract
The guppy, Poecilia reticulata, exhibits marked intraspecific variation in behaviour and morphology and occurs over a wide range of natural environments in Trinidad, West In-dies. In this paper we examine the hypotheses that: 1) in clear mountain headstream waters in Trinidad, where Rivulus hartii is the only major aquatic predator, sexual selection has favoured the evolution of visual components of courtship behaviour in the guppy, and 2) in turbid lowland rivers with numerous aquatic predators selection has resulted in greater dependence upon non-visual components of courtship. Guppies were observed in four rivers in Trinidad. In two mountain headstreams guppies were evenly distributed across and along the river. Guppies in a lowland river and a 'midstream' river occurred in small schools close to the water's edge. Males guppies in the headstreams performed more frequent sigmoid displays and displays of longer duration than males in the turbid lowland river and the midstream river. Males in the turbid lowland river were found to exhibit higher frequencies of gonopodial thrusts than males in the other three rivers. Offspring of guppies from the four rivers were raised under identical conditions in the laboratory, free from predation and other selective agents. The results of observations of courtship behaviour in laboratory-raised fish are consistent with those obtained in the field. The overall similarity of results in the field and the laboratory provides evidence that there is a genetic basis to the observed behavioral differences between populations.
Predation and the Evolution of Precopula in the Isopod Asellus Aquaticus
Authors: Verrell Paul A. 
Published: April 2008

Abstract1. The predatory behaviour of the smooth newt (Triturus vulgaris) on the isopod Asellus aquaticus was studied and the typical predatory sequence described. 2. Male Asellus in precopula experience a reduced risk of predation relative to single males. They seem to show an antipredator behaviour which 'confuses' the newt. 3. Precopula was probably influenced by both natural and sexual selection during the course of its evolution in this isopod.
Why Mudskippers Build Walls
Authors: Clayton D.A. 
Published: April 2008

AbstractThe proximate mechanisms of territorial behaviour in Boleophthalmus boddarti, an amphibious gobiid mudskipper that builds and maintains polygonal mud-walled territories provides a good example of the elastic disc concept of territories. The occurrence of wall building is density dependent and a contiguous mosaic of territories is only produced at high fish densities. Wall removal and replacement experiments show that the mud-wall acts as a visual barrier and reduces aggression between neighbouring territorial fish.
Mate Change Enhances Duetting Activity in the Siamang Gibbon (Hylobates Syndactulus)
Authors: Geissmann Thomas 
Published: April 2008

AbstractSiamang gibbons produce long and complex duet songs. The hypothesis that duetting may act as advertisement of the presence and the status of a mated pair has repeatedly been suggested for duetting birds. If a pair bonding effect of the duet is actually attained through a partner-directed learning effort resulting in a pair-specific duet, the learning investment should be concentrated into a time period as short as possible in order to avoid competitors. Therefore, after the formation of a new pair, an increase of singing activity should be expected. In order to test this prediction, the singing activity of a pair of captive siamang before and after a partner exchange was compared. In the newly formed pair, an increase in singing activity was observed. Additional observations on a second new pair show a similar trend. In this case, both new mates remained in their familiar place so that their singing activity was unlikely to be affected by the process of establishing a new territory.
Foraging Path Selection in Bumblebees: Hindsight or Foresight?
Authors: Soltz Roberta Lynn 
Published: April 2008

AbstractInflorescence richness and density did not effect the magnitude or variation in magnitude of the turning angles between inflorescences in the paths of foraging bumblebees. The pooled data indicated that bumblebees tended to move straight through the Vicia patch regardless of raceme density. The angular distributions from the field data were similar to those derived from a computer model in which consumers just visited the nearest inflorescences provided that they revisited few flowers. These results imply that the foraging paths of bumblebees may be determined, in part, by a tendency to visit nearest inflorescences. The distribution of turning angles from individual rather than pooled data, however, suggest that active selection of inflorescences with between two and six flowers may also play a role in determining the foraging path. I found no evidence for area-restricted foraging. This may be due to the heterogeneity of the natural resource patches.
Perception of Distress Calls in Mallard Ducklings (Anas Platyrhynchos)
Authors: Evans Christopher S. , Gaioni Stephen J. 
Published: April 2008

AbstractThree experiments examined mallard ducklings' perception of conspecific distress calls, as measured by their tendency to alternate their own vocalizations with tape-recorded test calls. This alternation response involved a duckling inhibiting its own calls during the tape-recorded stimuli, and then calling during the interstimulus intervals. 1. In Experiments 1 and 2, when ducklings were tested with calls having note periods that were substantially shorter or longer than the normal note period for distress calls, they showed a significant decrement in their call alternation response. The effects of shortening and lengthening note period, however, were not symmetrical: shortening note period by a given amount had a greater effect on responding than lengthening note period by that same amount. This response asymmetry may be due to a selection pressure operating to enable ducklings to discriminate between distress calls and another conspecific vocalization, contentment calls, which have shorter note periods than distress calls. 2. Experiment 3 examined the effect on ducklings of simultaneously manipulating two acoustic features known to be important for duckling recognition of distress calls: the temporal patterning of the notes within the call, and the frequency sweep found at the end of each distress note. Ducklings tested with a call having both a shortened note period, and the terminal frequency sweep removed from each note, displayed a significantly worse alternation response than ducklings tested with calls having either shortened note periods, or deleted frequency sweeps, but not both. The ducklings in the latter two treatments, in turn, had a significantly worse alternation response than ducklings tested with a normal call. Thus, the effects of manipulating these two acoustic features summated. 3. These results are consistent with a model of auditory perception in mallard ducklings in which recognition of a species-typical call depends on the summation of outputs from a set of perceptual filters each tuned to a specific acoustic feature of the call. Experiments are currently in progress to examine whether this model can be applied to mallard duckling perception of a second species-typical vocalization, the duckling contentment call.
Changes in Behavior With Increasing Experience With a Novel Prey in Fry of the Central American Cichlid, Cichlasoma Managuense (Teleostei: Cichlidae)
Authors: Meyer Axel 
Published: April 2008

AbstractWith increasing experience with the novel prey, Daphnia, the fish became less hesitant to attack Daphnia. The fish took fewer nonprey items per prey item with increased experience. They also became more efficient in handling the novel prey. There was no indication of the formation of a search image. The multiple regression model revealed that, although the fish grew during the experimental period, their increased size did not contribute significantly to the increase in capture success. Contrary to previous studies size did not influence capture success within the size range used in these experiments. The individual variation in capture success was large in all groups of Cichlasoma managuense. The most successful predators were the fish who persistantly attempted to catch prey and had the highest number of previous experiences with the novel prey. The morphological variable weight was negatively correlated with capture success, which may suggest that a hungrier fish is more motivated to prey and a more successful predator. An increase in eye diameter brought about an increase in capture success, due probably to an increased visual acuity, hence it may suggest a possible ecological effect of this morphological variable.
Temporal Rules Regulating Affiliative Vocal Exchanges of Squirrel Monkeys
Authors: Biben Maxeen , Masataka Nobuo 
Published: April 2008

AbstractAll contact calls (chuck vocalizations) occurring in a group of ten captive squirrel monkeys were recorded over 200 minutes. The temporal distribution of inter-chuck intervals was bimodal, with one peak at short intervals (0.1-0.2 sec) and another peak at relatively longer intervals (1.4-1.5 sec). Sequalae analysis revealed that in two consecutive chucks separated by intervals longer than 0.5 sec, the following call took place independently of the preceding chuck. If two chucks occurred at intervals of 0.5 sec or less, on the other hand, the following caller vocalized in response to the preceding vocalization. The results indicate that if squirrel monkeys intend to respond to chucks given by others, they should do so within the next 0.5 sec. Otherwise, they should not vocalize during that period. This temporal rule allows the animals to determine whether a caller of the following chuck really responds to the preceding call or not, when two chucks are heard consecutively.