bluuebunny/crossref_metadata_2025 huggingface dataset:
Great Tits and Giving-Up Times: Decision Rules for Leaving Patches
Authors: Ydenberg R.C.
Published: April 2008

In 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

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

1. 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.
The Inactivity of Animals: Influence of Stochasticity and Prey Size
Authors: Sutherland William J. , Moss Dorian
Published: April 2008

As a consequence of prey capture being partly dependent upon chance, each individual may usually spend much of the day inactive even if the population is limited by its food supply. This applies particularly to species that eat large prey and thus experience considerable day-to-day variation in intake which restricts them to relatively rich habitats. Food will be found easily on most days and little time need be spent hunting although, occasionally, they will be unlucky and, despite searching all day, risk starvation. Predators of small prey can survive in environments that provide barely sufficient food as they experience little variation in intake: but they need to search all day to sustain themselves.
The Energetics of Feeding Territoriality in Juvenile Coho Salmon (Oncorhynchus Kisutch)
Authors: Puckett K.J. , Dill L.M.
Published: April 2008

1. A foraging time budget was developed for territorial, nonterritorial, and floater fish. Territorial fish spend 76% of total time at the station, 3% free swimming, 13% feeding, and 5 % in agonistic activity. Floaters spend 18% of their time stationary swimming, 54% free swimming, 10% feeding, and 10% in agonistic activity. Nonterritorial fish spend 50% of their time stationary swimming, 43% free swimming, 2% feeding, and 3% in agonistic activity. 2. Stationary swimming tailbeat frequency for the floater (4.3) is significantly higher than for the territorial fish (3.6). The floater flight tailbeat frequency (8.2) is significantly higher than the territorial chase tailbeat frequency (6.9). Normal feed tailbeat frequencies are similar for all fish groups. Nonterritorial fish tend to move slowly (tailbeat frequency = 3.3) for all activities except normal feed. 3. The total activity budgets for territorial, floater, and nonterritorial fish are 1199, 1318, and 910 cal/kg/hr, respectively. The territorial fish uses 91 % as many calories as the floater fish and the nonterritorial fish utilizes 76% of the territorial budget. 4. Total agonistic costs represent 12 and 14% of the territorial and floater fish activity budgets, respectively. 5. The costs per feeding motion for the territorial, floater, and nonterritorial fish are 4.03, 4.91, 10.1 cal/motion, respectively. 6. The territorial fish has a net energy intake advantage over the floater, and probably over the nonterritorial fish, due to 1) reduced search costs, 2) reduced prey pursuit costs, and 3) reduced agonistic activity costs.
Why Mudskippers Build Walls
Authors: Clayton D.A.
Published: April 2008

The 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

Siamang 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

Inflorescence 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

Three 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

With 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

All 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.
Acoustic Communication in Woodhouse's Toad (Bufo Woodhousei)
Authors: Sullivan Brian K. , Leek Marjorie R.
Published: April 2008

We tested the hypothesis that acoustic stimuli must be similar to the species-typical advertisement call in both dominant frequency and pulse rate to attract female Woodhouse's toads (Bufo woodhousei) in discrimination trials. Using synthetic advertisement calls we determined that females always preferred a synthetic call with the species-specific pulse rate and frequency over synthetic calls in which only pulse rate or frequency was within the range for the species. However, appropriately pulsed, narrow-band filtered noise was a sufficient acoustic stimulus to attract 20% of the females in one-quarter of their discrimination trials. These results are discussed in light of species recognition in bufonids.
Costs and Benefits of Group Foraging in the Teal (Anas Crecca)
Authors: Pöysä Hannu
Published: April 2008

This study examines group foraging in the teal (Anas crecca) in the light of some hypothesized foraging and anti-predator effects of grouping. Results suggest that group foraging in the teal acts as an adaptation to exploit spatially and temporally variable feeding environments. First, in a particular feeding patch, teals responded numerically to the variation in prey abundance. Second, foraging groups attracted teals flying over them. Third, arrivals landed close to the foragers and copied feeding methods used by them. However, the use of marginal feeding sites within the patch increased with group size. This disadvantage and the disturbance and exploitation of prey at and near the water surface may decrease foraging efficiency in large groups. Contrary to the results of several other studies, time-budgeting advantage in terms of increased feeding time and decreased vigilance time seemed not to be an important anti-predator benefit of grouping in the teal.
Male Reproductive Tactics in the Libellulid Dragonfly Paltothemis Lineatipes: Temporal Partitioning of Territories
Authors: Alcock John
Published: April 2008

Males of Paltothemis lineatipes defend stream-edge territories several meters in length. Receptive females fly to the stream to oviposit in very small patches of barely submerged fine gravel; each territory contains at least one but rarely more than two patches. Territorial males intercept incoming gravid females, copulate very briefly with them while hovering over a potential oviposition site, and then release their partners, which usually oviposit for less than 2 min before leaving the stream. Because mated females do not oviposit while in tandem with a male, neighboring territory owners sometimes succeed in stealing females before they have completed oviposition in their first mate's territory. Interrupted females sometimes are receptive, and may copulate with an intruder and oviposit in his territory. Gravid females arrive at the stream primarily in a 3 h mid-morning period during which time the density of territorial males is greatest. Fights for territories are most frequent early in the daily activity cycle, just prior to the time when receptive females are most likely to appear. There are many more males than sites with suitable oviposition substrate. Consequently competition for territories is intense, particularly at locations that attract relatively many females. From 2-4 males may claim favored territories in sequence on a given day, with the same males returning to partition ownership of the location temporally in the same order over several days. Temporal partitioning of certain territories in P. lineatipes appears to be a consequence of the males' ability to identify superior locations and superior times for territoriality, with the result that no one individual can monopolize a productive site for an entire daily flight period.
Recording Behaviour Using a Portable Microcomputer
Authors: Martin Paul , Unwin D.M.
Published: April 2008

This paper describes a microcomputer-based event recorder for recording behavioural observations. The system uses a widely available portable microcomputer (an Epson PX-8) and can be used for recording behaviour in a wide variety of situations. It combines the advantages of a keyboard event recorder with the ease of use and flexibility of paper-and-pencil methods (check sheets), and overcomes many of the problems inherent in specialised event recorders. With the event recorder program, the microcomputer can be used to record the frequencies, durations and latencies of many different categories of behaviour. With the check sheet emulator program, it can be used to obtain a time-sampled record of complex social behaviour, in the same way as with a check sheet. Listings of both programs, which are written in BASIC, are given. No computer programming expertise is required and no specialised hardware need be built in order to use this powerful, flexible and relatively inexpensive system.
Foraging Efficiencies and Techniques of Juvenile and Adult Northern Mockingbirds (Mimus Polyglottos)
Authors: Breitwisch Randall , Lee Ronald , Diaz Marilyn
Published: April 2008

Adult and newly independent juvenile northern mockingbirds foraged on arthropods in the breeding season at similar rates within bouts, but adult efficiency (both as captures/attempt and captures/min) was higher than juvenile efficiency. Adults also captured a greater proportion of large arthropods than juveniles, and adults preferentially fed larger prey to dependent young. Juveniles engaged in more aerial attacks as the season progressed, although their success rate in these bouts did not increase. Both adults and juveniles captured a greater proportion of large arthropods in aerial attacks than in ground attacks. Juvenile success rate in ground attacks increased with season. These observations suggest that juvenile mockingbirds change their foraging behaviour in the first 1-2 months of independence, although the mechanism involved in this change is unknown.
Dominance Relationships in Jackdaws (Corvus Monedula)
Authors: Wechsler Beat
Published: April 2008

Dominance interactions (supplantings) of 26 jackdaws (Corvus monedula) living in a captive flock were recorded for a period of 2 years. The transitivity of the dominance hierarchy did not increase over time. Though there were 238 rank changes in course of the study, a portion of 6 % of all possible triads of the flock was always intransitive. Only 16.5% of the observed supplantings involved aggressive behaviour. There was no significant correlation between the body weight of a jackdaw and its dominance rank. Male-Male dyads had a disproportionally high frequency of dominance interactions and rank changes. Females were more likely to gain in rank in course of a rank change if their mate was already dominant to the opponent and to lose in rank if their mate was subordinate to the opponent. With the males there was no such tendency. Only 5.4% of the observed dominance interactions were temporary reversals with respect to the defined dominance relationship of a dyad. The probability of temporary reversals was increased if the mate of the supplanting jackdaw was present (less than 60 cm away) during the dominance interaction even though it did not interfere. When it was present, it joined the supplanting interaction in 10.0% of the cases. Breeding jackdaws had an increased percentage of reversed dominance interactions in front of their nest box. This site-related dominance was especially marked as soon as the female started to incubate.
Firing Activity of the Weakly-Electric Fish Marcusenius Macrolepidotus (Mormyridae, Teleostei): Logarithmic Repartition of Inter-Pulse Intervals, and Sequential Inequality Testing
Authors: Graff Christian
Published: April 2008

The electric activity of mormyrid fish consists of short electric pulses, all identical, but separated by variable time intervals (inter-pulse interval or IPI). Temporal structures are here extracted from the sequence of IPIs, to show non-randomness in mormyrid electric signal. The electric activity of isolated Marcusenius macrolepidotus is comparable to that of other mormyrids. The pulse waveform is biphasic and symmetrical, it lasts 0.3 to 0.5 ms and its amplitude is about 13 volts. The pulses follow each other with extremely variable IPIs (14-500 ms) with large instantaneous variations. Two new methods of analysis have been developed here. The first is based on the fact that when IPIs are grouped in populations, longer IPI populations have a wider range than shorter ones, a lognormal rather than a normal distribution. The IPIs are therefore classified according not to absolute- but to relative differences: binwidths are in percent, not in milliseconds. The second, non-parametric method (sequential inequality testing), was first used for neurone firing activity. It considers the sign (+ or -) of the difference between successive IPIs, and compares the sequence of these signs with a theoretical random model. When M. macrolepidotus is resting, the sequence of longer and shorter IPIs is not random, as shown by redundancies of patterns of + and - signs. These redundancies and the IPI populations are typical for each individual. When the fish increases its locomotor activity (either spontaneously for a few seconds, or provoked over more than 20 s) the IPIs are shorter. The patterns of + and - are different when the fish is swimming and when resting. Behavioral and electrophysiological data suggest that receiving conspecifics may recognize these rhythm features. The analysis methods developed here may be useful to other stochastic phenomena, such as neural firing activity.
The Significance of Persistent Vocalisation By the Spring Peeper, Pseudacris Crucifer (Anura: Hylidae)
Authors: Forester Don C. , Lykens David V. , Harrison W. Keith
Published: April 2008

1. Male spring peepers exhibit individual variation in calling persistence within as well as between nights. 2. Weather conditions influence nightly variation in calling persistence throughout the reproductive season, but there is a pronounced decrease in calling persistence late in the season which appears to be independent of climate. 3. In four speaker experiments simulating males calling 20, 40, 60, and 80% of the time, there is a positive correlation between time spent calling and mating success. 4. On nights when there is significant variation in calling persistence, females likely respond to those males which are most persistent (i.e. , produce the most conspicuous calls). 5. In four speaker experiments simulating males calling 80, 85, 90 and 95% of the time, mating success is random, suggesting that during periods of peak mating activity the importance of female choice is diminished. 6. Calling persistence is not correlated with body size, therefore males of any age or size class have an opportunity to experience mating success. 7. Anuran vocalization is known to be energetically expensive, and persistent callers (regardless of their size) are likely in good physical condition. 8. We suggest that by responding (either actively or passively) to the most conspicuous calls, females convey to their offspring an advantage above and beyond that accrued by random mating.
Memory for Reward in Probabilistic Choice: Markovian and Non-Markovian Properties
Authors: Davis Derick G.S. , Staddon J.E.R.
Published: April 2008

Pigeons were rewarded with food for pecking keys in various forms of two-armed bandit situation for an extended series of daily sessions in two experiments. The average daily preference (S=R/[R+L]) is very well fit by a markovian linear model in which predicted preference today is an average of predicted preference yesterday and reinforcement conditions today: s(N+1) = as(N) + (1-a)A(N+1), where A(N+1) is set equal to 1 when all rewards are for the Right response, and 0 when all are for the Left, and a is a longterm memory parameter. This linear model explains some apparent paradoxes in earlier reports of memory effects in two-armed bandit experiments. Nevertheless, closer examination of the details of preference changes within each experimental session showed several kinds of non-markovian effects. The most important was a regression at the beginning of each experimental session towards a preference characteristic of earlier sessions (spontaneous recovery). This effect, but not a smaller, less reliable non-markovian reminiscence effect, is consistent with a very simple rule, namely that the effect on preference of each individual reward for a Right or Left response is inversely related to how long ago the reward occurred. Thus, animals learn to prefer the rewarded side each day because these rewards are recent; but they regress to earlier preferences overnight because the most recent rewards become relatively less recent with lapse of time.
Evolution of Nonvisual Communication and Photoperiodic Perception in Speciation and Adaptation of Blind Subterranean Mole Rats
Authors: Nevo Eviatar
Published: April 2008

The evolution of vocal and vibrational communications and photoperiod perception in the blind subterranean mole rat of the Spalax ehrenbergi superspecies, are reviewed in the context of adaptation and active speciation in the subterranean ecotype. Progressive evolution of the acoustic system and regressive evolution of the atrophied eye coupled with progressive evolution in photoperiodic perception and biorhythmicity systems, are discussed. Prospects are suggested for future research at the molecular, anatomical and organismal levels, in the twin evolutionary processes of adaptation and speciation. Spalax appears to be a uniquely productive evolutionary model for the study of evolutionary structural reductions and hypertrophies as well as functional shifts in evolution. It provides particularly a rich observational and experimental material to critically evaluate the challenges recently levelled against the synthetic theory of evolution concerning gradualism in speciation, the "adaptationist programme", and the role of natural selection as a creative force in evolution.
Experimental Polygyny and Colony Closure in the Ant Messor Barbarus (L.) (Hym. Formicidae)
Authors: Provost Eric , Cerdan Philippe
Published: April 2008

Colonies of Messor barbarus are monogynous. At the laboratory, it is possible to form polygynous colonies. This experimental model was used to study the influence of the number of queens on the degree of colony closure: are polygynous colonies more frequently open than monogynous ones? Experiments in which alien workers were transferred between monogynous and polygynous colonies showed that the latter had a lower degree of closure. The queen might play a major role in the recognition processes between individuals belonging to either the same or different colonies.
Plumage Quality and Mate Choice in Mallards (Anas Platyrhynchos)
Authors: Weidmann Uli
Published: April 2008

The suspected relevance of plumage quality of drakes for the choice of mates by ducks has been confirmed in a series of experiments. Drakes were ranked according to the extent of naturally occurring blemishes (deviations from the plumage of an ideal drake) and introduced, two at a time, to a resident group of female "adjudicators", who would choose drakes by following one of them and/or by performing aggressive acts against one or both. We could predict the outcome in almost every case. In other experiments we could influence female choice by making attractive drakes ugly or unattractive ones more beautiful by means of staining and bleaching. The success in these experiments of isolating the effects of plumage quality from the many other factors which usually influence mate choice in females was a consequence of the drakes' apparent lack of interest in the females to whose pen they were introduced for a short time only. When several females chose the same good looking male, intense rivalry and aggressive behaviour occurred among the females. The possible effect of such rivalry on female mate choice was briefly examined; it appeared to be unimportant in our experiments.
Male Song as a Cue for Mate Choice in the European Starling
Authors: Eens Marcel , Pinxten Rianne , Verheyen Rudolf Frans
Published: April 2008

This study had two aims. First, we looked at individual differences in song characteristics between males of the European starling, and we related song behaviour to factors such as male age, pairing date, polygyny and male breeding success. Second, we experimentally tested whether song has an effect on female mating decisions. 1. During the breeding season, male starlings sing a very long and complex song consisting of a rapid succession of large number of different song types. We observed marked differences between males in average song bout length (a song bout was defined as a period of at least five seconds of song containing no pauses larger than 1.5 seconds) and in song repertoire size. Average song bout lengths ranged from 16 to 35 seconds. The individual repertoire size ranged from 23 to 67 song types. Repertoire size and average song bout length were positively correlated. 2. Both in the field and in captivity, yearling males sang shorter average song bout lengths and had smaller repertoire sizes than older males. 3. Males singing longer average song bouts and having larger repertoire sizes attracted females for pairing before their rivals with shorter average song bouts and smaller repertoire sizes.
Onset and Maintenance of Maternal Prey-Supply Activity in the Spider Coelotes Terrestris (Araneae, Agelenidae)
Authors: Bessekon Denis Assi , Horel Andre , Gundermann Jean-Luc
Published: April 2008

In the funnel-web spider Coelotes terrestris (Agelenidae) the young are provided with prey by their mother for several weeks following emergence from the egg sac. Such a maternal activity has previously been shown to be influenced by stimuli emitted by the young (i.e. during mother-offspring interactions), which ensures the tuning of the prey supply to the offspring. The present paper aims to shed light on the conditions of onset and maintenance of prey-supply tendency. The experimental procedure consisted in confronting females, either sub-adult or at various stages of their reproductive life cycle, with a group of spiderlings constant in number and age, and in recording the behavioural interactions following the capture of a prey item. Females which did not yet have post-emergence offspring did not supply prey to the spiderlings and exhibited aggressive reactions towards them. In contrast, females which had had post-emergence offspring, even though their dispersal could have taken place many weeks before, provided prey to the experimental spiderlings, and behaved towards them as their real mothers would have done. When exposure to the experimental situation was prolonged for one week, the tendency to supply the young clearly appeared in previously unresponsive adult females (inseminated or incubating), but no change was observed in sub-adults. The results show that, in Coelotes terrestris, the maternal tendency to supply prey requires a particular internal state, which seems to develop at the time of the offspring's emergence but which does not become extinct after their dispersal. The results also suggest that the development of this internal state can somehow be influenced by stimuli from the young.
Variation in Time and Energy Budgets of Breeding Wheatears
Authors: Moreno Juan , HILLSTRÖM Lars
Published: April 2008

We examined the sources of variation in time allocation of males and females of the wheatear (Oenanthe oenanthe) on the island of Öland, South Sweden, throughout the breeding season. We quantified rates of prey capture attempts and specified foraging methods used. From respirometric measurements of basal metabolic rate and temperature-dependent metabolism on captive wheatears, and after having made certain assumptions abour the costs of different activities, we estimated the energy budgets of both sexes during the different reproductive phases. Males and females differed in their time allocation and foraging rates during prelaying, laying, and incubation, but not while feeding grown nestlings. During prelaying and laying, females foraged at higher rates than males; they also perched less often, gleaned more on the ground, and flew less. Although incubation was the least costly phase for females because of their low activity, high foraging rates yet indicated that this phase may represent an energetic bottleneck as a result of restrictions on foraging time. After incubation, females switched from foraging mostly on the ground during early breeding phases to hunting from elevated perches during later breeding phases. The shift in foraging behavior corresponds to the drastic changes in time allocation. Relatively high daily energy expenditures (DEE) by brooding females coupled with low foraging rates may explain the observed posthatching body mass losses. In both sexes, high required energy acquisition rates when feeding large nestlings indicate that parent wheatears then may encounter another energetic bottleneck. Postfledging was the least costly phase because, compared with the period of feeding nestlings, there were reduced thermostatic costs and a marked drop in flight time. Males and females had similar DEEs during prelaying, laying and nestling feeding, but females had lower needs during incubation. The elective components of energy budgets during nestling feeding, as well as the estimated sum of the elective components throughout the season, were 12% higher for males than for females. The elective components of the energy budgets varied more than the obligatory components (basal + thermoregulation), especially in females, and were more important in determining the variation of DEE throughout the breeding season. A validation study with doubly labeled water indicated that the energy budget model used was accurate enough for comparisons between sexes or breeding phases, but not for measuring individual variation.
Pseudomale Behaviour and Spontaneous Masculinization in the All-Female Teleost Poecilia Formosa (Teleostei: Poeciliidae)
Authors: Schlupp Ingo , Parzefall Jakob , Epplen JÖRG T. , Nanda Indrajit , Schmid Michael , Schartl Manfred
Published: April 2008

Pseudosexual behaviour is a rare phenomenon associated with unisexuality in vertebrates. In the gynogenetic, all-female teleost Poecilia formosa, rare individuals occur that resemble males of closely related gonochoristic species both in behaviour and external morphology. These masculinized gynogens and normal gynogens are members of the same clone, as demonstrated by DNA-fingerprinting. The behaviour of these masculinized gynogens is described and compared to the behaviour of the gonochoristic species Poecilia mexicana, P. latipinna and their hybrid as well as androgen-treated individuals of P. formosa. No statistically significant differences were found between masculinized gynogens and hormone-treated individuals nor between the gonochoristic P. mexicana and P. latipinna males. Differences exist between gonochoristic and unisexual species. Possible causes and effects of masculinized gynogens are discussed.
Singing in Relation To Social Dominance and Testosterone in White-Throated Sparrows
Authors: HAVEN WILEY R. , Piper W.H. , Archawaranon Manee , Thompson Elizabeth Wyrick
Published: April 2008

Singing by white-throated sparrows Zonotrichia albicollis during the winter
in natural situations occurred most frequently among birds with high rank in
a dominance hierarchy. Genetic morph, age and sex had no significant
influence on singing during winter. Among testosterone-implanted birds in
small groups in large aviaries, dominance rank strongly influenced singing.
Testosterone-treated birds with top rank sang most frequently, those with
second rank less, and those with lower rank never. As a testosterone-treated
bird's rank changed in the course of regroupings with new opponents, its
frequency of singing also changed. Dominance in a group thus interacted with
testosterone to promote singing. In addition, grouped birds in May before
treatment with testosterone did not sing. As a consequence, it seems likely
that the normal seasonal development of territorial behavior and singing
involves cascading interactions of endocrine states and social
circumstances.
A Formal Notation To Aid Analysis of Complex Behaviour: Understanding the Tactical Deception of Primates
Authors: Byrne R.W.
Published: April 2008

A formal notation is argued to be useful in representing theories of complex animal behaviour. This "production system" approach, originally derived from artificial intelligence, is explained with a series of examples of tactical deception in primates. These examples are controversial, since they might suggest intentionality and thinking in non-humans, and their interpretation is not straightforward. The ease of representing competing explanations of sophisticated behaviour (for instance those used in behaviourist psychology, animal ethology, and cognitive science) in the single formalism of production systems, may eventually aid a rapprochement between disciplines with interests in the evolution of intelligence.
Startle and Habituation Responses of Blue Jays (Cyanocitta Cristata) in a Laboratory Simulation of Anti-Predator Defenses of Catocala Moths (Lepidoptera: Noctuidae)
Authors: Ingalls Victoria
Published: April 2008

Blue jays were used in laboratory experiments to determine what visual characteristics of Catocala hindwings are important in eliciting and maintaining startle reactions in avian predators. Hand-reared blue jays, inexperienced with warningly coloured, inedible prey, took significantly longer to touch novel colours that possessed bold, black bands than to touch novel, unbanded colours when these discs covered a food reward. Thus, being conspicuous (as opposed to simply being novel) appears to enhance startle reactions. Bold patterns are commonly found on aposematic prey and Catocala hindwings. These same hand-reared birds also tended to take longer to touch novel coloured discs of yellow and red hues as opposed to discs of blue, green, or purple hues. The colours that produced the greatest hesitation are similar to the colours found on Catocala hindwings. Red-yellow colours are also characteristic of aposematic prey. Wild-caught birds took longer to habituate to startling stimuli when presented with several different startling disc types during the habituation process. Thus, predator pressure may explain why several different Catocala species with different hindwing colours occur sympatrically.
The Role of Dispersal in Structuring the Chitwan Tiger Population
Authors: Smith JAMES L. DAVID
Published: April 2008

Dispersal in tigers was studied in Royal Chitwan National Park, Nepal. Thirty six adult and young were studied to monitor movements and social interactions relative to dispersal. Fourteen subadults were followed from before their dispersal until they died or established post-dispersal territories. Subadult tigers became semi-independent of their mother when her next litter was born. They usually remained within her natal area until the subsequent litter began to move with her at about 2 mos of age. Animals dispersed between 19 and 28 mos. Males dispersed farther than females and settled in poorer habitat. Three of 4 females settled adjacent to their mothers; in two cases the mother shifted her territory allowing the daughter to take over a large portion of the mother's former territory. Wounds on young prior to dispersal indicated that aggression prompted dispersal. Fjghts were observed between dispersers and residents. After fights, dispersers always left the resident's area. All 4 dispersing females established breeding territories. Females settled next to their mothers tending to reduce the genetic variance of a male's offspring. Eight of 10 males became localized in temporary, post-dispersal territories; 4 of the 8 survived. Two males died of poisoning and 2 from intrasexual aggression. Surviving males either expanded temporary territories or shifted to new areas to establish breeding territories. The Chitwan tigers are an isolated remnant of a population once continuous across the lowlands of Nepal. Effective population size was estimated to be <30 animals. Tigers did not disperse across cultivated areas but did travel through degraded forest habitat. No animal dispersed outside the Chitwan region and there appear to be effective barriers separating Chitwan from the two nearest populations 150 and 250 kms distant. The Chitwan population is probably one of the largest tiger populations remaining in the world. Isolation and small size threaten these populations with stochastic events that may lead to further reduction in population size.
Sound Transmission: a Basis for Dialects in Birdsong?
Authors: Date E.M. , Lemon R.E.
Published: April 2008

The environmental adaptation hypothesis (EAH) regarding birdsong dialects or ncighbourhoods states that song similarities between neighbouring individuals arise because of common influences on their songs exerted by the acoustic environment of their habitat. An assumption of the hypothesis is that sounds are distorted differently by different types of habitat. A prediction of the hypothesis is that some songs or parts of songs transmit better than others, depending on the habitat of their origin. We tested the assumption and prediction by comparing the attenuation and differential attenuation of pure tones, decreases in modal frequencies of computer simulated songs of American redstarts (Setophaga ruticilla), and the decay of redstart songs and white noise at deciduous, coniferous and open forest sites. The songs were representative of those used by redstarts living in thc three habitats. Results supported the assumption of acoustic differences between habitats but did not support the prediction that some songtypes transmit with less distortion in specific habitats than in others. The EAH also predicts that individuals which inhabit similar vegetation should share more song features than individuals which inhabitat dissimilar vegetation. To test this prediciton samples of songs were taken from the three habitats in different years. There were significant associations by habitat in both samples, but only one of several variables measured was significant and the discriminating variable was not the same for the two periods. Considering together the tests of the assumption and the two predictions, we conclude that for American redstarts evidence of the influence of the acoustic features of habitat on the formation of song dialects is mixed and not convincing.
Timing and Use of Paternity Guards By Male Chaffinches
Authors: Sheldon B.C.
Published: April 2008

I studied the relative timing and extent to which male chaffinches used two alternative paternity guards, frequent copulation and mate guarding by close following. Males guarded their mates strongly, and guarding peaked in intensity on day -2 relative to laying. Male mate guarding intensity varied predictably with the value of the female to the male in three ways: (a) guarding intensity increased from day to day as laying approached, as does the risk of a single EPC fertilizing an egg. (b) Males reduced their level of guarding when their females laid the penultimate egg of the clutch and were therefore no longer fertile. (c) The diurnal pattern of guarding varied with respect to whether laying had begun, which might represent a male response to an 'insemination window', when sperm would be less likely to fertilize an egg. Males also copulated frequently with their mates, with a peak rate of 4.4 copulation attempts per hour on day -3 relative to laying, with an estimated total of 207 copulation attempts (83 successful) per clutch. The peak in copulation frequency occurred earlier than the peak in mate guarding intensity. Males did not show any behavioural response to an increased risk of extra-pair copulations, assessed by the proportion of neighbouring males that were free to seek extra-pair copulations. I propose that in chaffinches frequent copulation is a relatively 'low-cost, high-risk' paternity assurance mechanism compared to mate guarding, and that the mechanism males employ depends upon the amount of information that males have about whether the female is going to lay, which represents the value of the female to the male. Fine-tuning of male behavioural mechanisms with the female value as a resource provides good evidence that the mechanisms are adaptations to sperm competition.
Variation in Male Relationships in Bonobos and Chimpanzees
Authors: Furuichi Takeshi , Ihobe Hiroshi
Published: April 2008

1. Inter-male relationships were compared between two groups of bonobos at Wamba, Zaire, and a group of chimpanzees at the Mahale Mountains, Tanzania. 2. Although distribution of females is much different between the two species, frequencies of affinitive interactions between males (inter-individual proximity and grooming) were similar between the species. 3. By contrast, marked inter-species differences were found in agonistic aspects of male relationships. Such differences could be related to the different estrus patterns of females. 4. Male relationships of both species may have been reflecting the male-bonded strategy which was taken by a common ancestor. Within this framework, males of each species seem to have developed differentiated social tactics for the access to females showing different patterns of distribution and estrus.