bluuebunny/crossref_metadata_2025 huggingface dataset:
The Degree of Mutual Resemblance and its Effect on Predation in Young Birds
Authors: EVANS DAVID L. , CASTORIADES NELLY , BADRUDDINE HANA
Published: May 2010

We presented sets of naive common quails with 6 different sequences of three species of aposematic insects: Cercopis intermedia, Caenocoris nerii, and Eurydema decoratum. All three species had a similar body plan but different marking patterns. Our goal was to determine whether naive predators initially form a sharpely defined image which would stimulate an aversive reaction only in the presence of that signal. In contrast to the discrimination shown by adults of another avian species (SILLÉN‐TULLBERG et al. 1982), these birds usually generalized the warning signals and rejected later, somewhat different, noxious prey after an unpleasant experience. The likelihood of attack declined from 100% with the initial offering of the first species to 37.5% at the first presentation of the second species to 20.8% with the initial offering of the third prey type. We found that overall contact with the aposematic prey decreased significantly (chi‐square test, p < .005) and that eating the test prey ceased completely. Young predators and different predatory species may be less discerning within certain limits or may require a longer time to learn to make fine distinctions than other classes of predators. The processes of generalization may involve stimulus filtration and aides memoires.
Does Nest Defence Deter or Facilitate Cowbird Parasitism? A Test of the Nesting‐cue Hypothesis
Authors: Gill Sharon A. , Grieef Paula M. , Staib Lisa M. , Sealy Spencer G.
Published: May 2010

The nesting‐cue hypothesis poses that avian brood parasites use nest‐defence responses directed toward them by hosts as cues to locate nests to parasitize. Hosts that respond more intensely to brood parasites should provide more cues about nest location than those hosts giving lower intensity responses. Thus, the nesting‐cue hypothesis predicts that within a species parasitized nest owners should respond more intensely than unparasitized nest owners to cowbirds perched near and away from nests. This assumes that hosts respond to cowbirds when they are encountered away from the nest and that host responses gradually increase in intensity as the cowbird nears the nest. The nesting‐cue hypothesis, its assumptions and prediction were tested using six host species of the brown‐headed cowbird (Molothrus ater, Icterinae). We presented a female cowbird model at three distances from host nests and compared the responses elicited. All species responded to the cowbird at all distances, which supports the first assumption. Some of the rarely elicited responses (e.g. contacts) and the proximity of the host to the model varied significantly with distance, which suggests that cowbirds could use nest defence by the host as cues to the location of an active nest. However, parasitized nest owners did not respond more intensely than unparasitized nest owners to the cowbird positioned at any of the distances from the nest, which does not support the nesting‐cue hypothesis itself. Further considerations are discussed that suggest that nest defence is not likely to be used as a nest‐location cue.
Is the Expression of Male Traits in Female Lesser Kestrels Related to Sexual Selection?
Authors: Tella José L. , Forfero Manuela G. , Donázar José A. , Hiraldo Fernando
Published: May 2010

Some lesser kestrel females (Falco naumanni) show male plumage traits, i.e. grey rumps and tails. This phenomenon has seldom been analyzed in birds, and two hypotheses have been suggested to explain it. The first proposes that, when sexual selection acts favouring the expression of a trait in males, females could show the analogous character by genetic correlation (indirect sexual selection). Alternatively, the expression of these traits in females could be favoured by intra‐sexual competition or even by male mate choice selecting ornamented females (direct sexual selection). We have tested if females with male traits are favoured by direct sexual selection, through a 3‐yr observational study of 239 female lesser kestrels. Our results cannot support the predictions, as females with grey plumages do not achieve access to better breeding opportunities or fitness benefits. These traits do not seem to be honest signals of phenotypic quality, since physical condition and survival did not differ between females which showed male traits and those which did not. The expression of male traits in these females increased with their ages, but showing a high individual variability. Finally, since the genetic correlation hypothesis is unlikely in this species because all males have grey rumps and tails, we propose a new age‐related hormonal explanation.
Agonistic Behavior in the Squid Loligo plei (Loliginidae, Teuthoidea): Fighting Tactics and the Effects of Size and Resource Value
Authors: DiMarco F. Paul , Hanlon Roger T.
Published: May 2010

Observations of small schools of squids in captivity suggested that dominance relationships among males were based upon major differences in the frequency or duration of their agonistic behavior, but staged contests showed few differences. During staged contests, squids exhibited up to 21 separate behaviors. Some contests included a complex array of visual signals and side‐by‐side posturing (Lateral Display) followed by physical contact during Fin beating. There was behavioral variability and step‐wise escalation during the contests: squids performed either 1. long sequences of visual signaling followed by Chasing and Fleeing; or 2. short sequences of visual signaling followed by physical Fin beating and ending with Chasing and Fleeing. Size influenced outcome in all contests; larger males were more likely to win the contest. Size had no effect on contest duration, but contest duration was shorter when resource value was high, especially when a male established temporary ownership of a female. We speculate that when the perceived resource value is high, male squids are more likely to engage in a shorter yet riskier fighting tactic.
Individual Recognition Affects Aggression and Dominance Relations in Rainbow Trout,Oncorhynchus mykiss
Authors: Johnsson Jörgen I.
Published: May 2010

In this study, the hypothesis that individual recognition is used as a cue to reduce the cost of contesting resources in rainbow troutOncorhynchus mykiss, was addressed. The predictions were that the second contest between familiar individuals should be settled with less aggression, and lower probability of status reversal, than a contest between strangers. To test these predictions, similar‐sized juvenile rainbow trout were subjected to two dyadic dominance contests in one of four treatment groups: in half of the pairs, the initially subordinate and dominant individuals were staged against an unfamiliar opponent (of opposite rank to their own) in a second contest, while in the other the initial pair was reunited for the second contest. Further, in half of the pairs, contestants were separated for 3 d between contests, while in the other the second contest was staged immediately after the first. Levels of aggression in contests between familiar individuals were lower than in contests between strangers, which supports the hypothesis that individual recognition reduces aggression. Dominance status was reversed in 31% of the 62 tested pairs. Although the probability of status reversal was not significantly affected by individual recognition, the degree of change in competitive success appeared to be lower in familiar pairs. Separation interacted with familiarity so that the effect of individual recognition generally was less pronounced when pairs were separated between contests, suggesting that the ability to remember opponents is time/limited. In natural streams, salmonids may use individual recognition to reduce the cost of contesting resources within groups, to reduce aggression between territory neighbours and to distinguish ‘cheaters’ from honest signallers.
Courtship and Female Competition in the Majorcan Midwife Toad, Alytes muletensis
Authors: Bush Sarah L. , Bell Diana J.
Published: May 2010

The courtship and mating behaviour of A. muletensis are described based on observations of captive toads. Courtship is prolonged and complex, with both sexes participating actively. Either sex can escape from amplexus and may do so if the partner fails to respond appropriately to courtship manocuvres. Females control the pace and duration of courtship. Females unable to obtain a mate drop their eggs unfertilized. Both sexes produce courtship vocalizations and either sex may initiate courtship, although females were observed to do so only when they were in danger of dropping their eggs. Physical competition in the form of interference and grappling may occur between either males or females, but was observed more frequently between females. The active role played by females during courtship in this species is discussed with regard to sex‐role reversal theory and opportunities for mate choice.
Size‐assortative Schooling in Free‐ranging Sticklebacks
Authors: Peuhkuri Nina , Ranta Esa , Seppä Perttu
Published: May 2010

Schooling behaviour is known to be advantageous for individual fish in many respects, including both foraging and predator avoidance. It has been repeatedly predicted by theory that to benefit most from schooling, individuals should associate together non‐randomly according to their phenotype. Obeying the predictions of theory, several fish species exhibit size‐assortative schooling in the laboratory, but unequivocal evidence for size‐assorted schools in the wild is largely lacking. To ascertain the existence of size‐assorted schools in the wild, we quantified the body‐size distribution of individuals in schools of wild threespine stickleback.Gasterosteus aculeatus, a species that is known to readily form size‐assorted schools under experimental conditions. Data were collected from 24 separate schools of juvenile fish in late summer 1994. The fish in those wild schools were size‐assorted, confirming the previous laboratory findings and, in accordance with current theory, suggesting that the phenotypic characteristics of individuals may be of importance when schools are formed.
Inter‐ and Intraspecific Variation in the Acoustic Habitats of Three Marmot Species
Authors: Blumstein Daniel T. , Daniel Janice C.
Published: May 2010

Closely related species often have remarkably different vocalizations. Some of the variation in acoustic structure may result from species adapting their calls to maximize transmission through their acoustic environments. We document the relative magnitude of inter‐ and intraspecific variation in acoustic transmission properties of the habitats of three closely related marmot species to study the relative importance that the acoustic environment may have played in selecting for species‐specific marmot alarm calls. We used spectrogram correlation to quantify the degree to which pure tones and alarm calls changed as they were broadcast through marmot home ranges to describe the acoustic habitats of golden (M. candata aurea), yellow‐bellied (M. flaviventris), and alpine (M. marmota L.) marmots. Species lived in quantifiably different acoustic habitats. One analysis partitioned variation between species and between marmot social groups (nested within species). We found significant interspecific variation in the acoustic transmission fidelity of the three species' habitats and insignificant intraspecific variation between social groups. Further analysis of a larger sample of alarm calls broadcast through golden marmot social groups found significant intraspecific variation. Interspecific variation greater than intraspecific variation suggests that variable acoustic habitats may be responsible for at least some of the interspecific variation in alarm call structure. This is the first study to use spectrogram correlation to describe habitat acoustics. We discuss aspects of the method that may be useful for others seeking to quantify habitat acoustics.
Eastern Long‐toed Salamander (Ambystoma macrodactylum columbianum) Larvae Recognize Cannibalistic Conspecifics
Authors: Chivers Douglas P. , Wildy Erica L. , Blaustein Andrew R.
Published: May 2010

Larval eastern long‐toed salamanders,Ambystoma macrodactylum columbianum, exhibit trophic polymorphism whereby some individuals (referred to as cannibal morphs) possess a cannibalistic morphology and others (referred to as typical morphs) do not. In a series of laboratory experiments, we documented that typical morphs show an antipredator response when exposed to cannibal morphs but not when exposed to other typical morphs. The antipredator response of the typicals was not dependent on the cannibals being fed conspecifics, as has been shown in other predator‐prey systems. In our experiments, the typicals responded regardless of whether the cannibals had been fed a diet of conspecifics or liveTubifex.Further experiments also showed that in the absence of visual cues, typicals still responded with an antipredator response. However, when only visual cues were available, typicals failed to exhibit a response. This suggests that chemical and/or mechanical cues are of prime importance in cannibal recognition by long‐toed salamander larvae.
Sexual, Seasonal and Group Size Differences in the Allocation of Time between Vigilance and Feeding in the Greater Rhea, Rhea americana
Authors: Reboreda Juan C. , Fernandez Gustavo J.
Published: May 2010

We studied the effect of sex and group size on the proportion of time a greater rhea, Rhea americana, allocates to vigilance and feeding during the breeding and the non‐breeding seasons. We analysed 175 records of focal animals that were feeding alone or in groups of 2 to 26 birds. In both seasons, males spent more time in vigilance and less time in feeding than females. Both sexes spent more time in vigilance and less time in feeding during the breeding season. Sexual and seasonal differences in vigilance were the result of different mechanisms. Males had shorter feeding bouts than females but there were no sexual differences in the length of the vigilance bouts. On the contrary, seasonal differences were the result of males and females having longer vigilance bouts during the breeding season but there were no seasonal differences in the length of the feeding bouts. During the non‐breeding season, individual vigilance was higher in rheas foraging alone than in groups. In this case, solitary birds had longer vigilance and shorter feeding bouts than birds foraging in groups. We discuss the possible effect of intragroup competition and food availability on the allocation of time between feeding and vigilance in this species.
Unusual Pre‐copulatory Behaviour in the Hermaphroditic Planarian Flatworm, Dugesia gonocephala (Tricladida, Paludicola)
Authors: Vreys Carla , Schockaert Ernest R. , Michiels Nicolaas K.
Published: May 2010

Hermaphrodite mating behaviour is poorly understood, particularly in species with internal fertilization and mutual penis insertion. We collected detailed recordings on the frequency, timing and outcome of the mating sequence of the simultaneous hermaphroditic flatworm Dugesia gonocephala (Tricladida, Paludicola). Mating in this species differs from that in other planarians in that receptive partners show a stereotypic pre‐copulatory behaviour which results in copulation in only 17% (n = 342) of all attempts. It includes an unusual phase during which one partner glides on top of the other and first the lower, then both individuals, spread out and flatten. Genital intromission is not possible in this position. All observed copulations (n = 57) were preceded by this behaviour and most mating sequences were interrupted at this stage. Pairs were seen starting new mating sequences up to 11 times. Which animal lay on top varied randomly within a series of attempts. Cocoon production was a good predictor of mating activity, and copulations mainly occurred during the night. Copulations lasted between 24 min and 9.3 h (mean = 4.7 ± 2.3 h) and penises were mutually inserted. In the field, 99% (n = 70) of all matings involved reciprocal spermatophore exchange, compared with only 50% in the laboratory (n = 26). The likelihood of reciprocal spermatophore transfer increased with increasing duration of copulation. Duration was independent of the events that took place during courtship. We discuss the possibility that partners interrupt a copulation when there is no guarantee of reciprocal spermatophore transfer.
The Relative Importance of Habitat Structure and of Prey Characteristics for the Foraging Success of Water Pipits (Anthus spinoletta)*
Authors: Brodmann Paul Alexander , Reyer Heinz‐Ulrich , Baer Boris
Published: May 2010

While many studies on foraging have related energy gain to the density and the size of prey, only few have investigated whether and how habitat structure modifies the gain through affecting foraging success. In this study, the influences of habitat structure and prey characteristics on the foraging success of water pipits, Anthus spinoletta, were investigated experimentally. The birds take longer to find prey in tall than in short vegetation. The effects of vegetation on searching times differ between prey types. These differences are probably caused by variation in prey behaviour and in cryptic colouration, but not by prey size. Searching times increase with decreasing density for mealworms and tipulids, but not for caterpillars. Handling large prey items requires more time than handling smaller prey. Tipulids and caterpillars, which were offered alive, are handled for a longer time than dead mealworms of corresponding size. The success of attacks on flying insects is probably influenced by the prey's flight speed: fast houseflies are missed more often than slow tipulids. Overall, the results show that the time costs of foraging water pipits are influenced to a comparable degree by vegetation structure, by prey density and by other specific prey characteristics such as camouflage, hiding behaviour or agility. The amount of food gathered per unit time is determined primarily by factors that affect searching times, and less by handling and travelling times. Insertion of our data into an optimal diet model leads to the prediction that water pipits should be generalist foragers, which agrees with the observed behaviour.
The Influence of Fat Stores on Magnetic Orientation in Day‐migrating Chaffinch, Fringilla coelebs
Authors: Bäckman Johan , Pettersson Jan , Sandberg Roland
Published: May 2010

Earlier experimental studies have demonstrated the ability of day‐migrating birds to perform migration under overcast skies, thereby indicating use of cues other than solar. The orientation behaviour of the chaffinch, a diurnal migrant, was investigated in orientation cage experiments during the autumn migration period. The aim of our experiments was to examine the relationship between different orientation cues and the influence of body condition on directional choices. We obtained the following results: 1. Chaffinches displayed a bimodal distribution of headings along a SW‐NE axis when tested in the local geomagnetic field (controls); 2. When the geomagnetic field was experimentally deflected 90° counterclockwise, the chaffinches responded by changing their preferred axial orientation to SE‐NW; and 3. The predictive power of stored fat reserves became evident when both the control and experimental samples were subdivided into fat and lean individuals. The majority of fat controls orientated towards a seasonally appropriate SW direction, whereas lean controls chose mean directions towards the NE. Experimentals followed the same pattern, but with the expected deflection, i.e. fat birds selected SE headings and lean individuals chose a NW mean direction.
The Role of Vocalization in the Communication between Red Deer Hinds and Calves
Authors: Vaňková Dominika , Bartoš Luděk , Málek Jan
Published: May 2010

Eleven hinds and their calves were observed on a deer farm in order to study their vocal communication. Red deer calves are ‘hiders’, and therefore it was believed that they would need to recognize their mother's voice, but the hinds would not need to recognize the voice of their offspring. The following predictions were tested. First, the calf can recognize its mother by voice. Second, the hind's ability to recognize her calf by voice is less pronounced. The study had two parts. Part I was focused on spontaneous behaviour of the animals. Part II involved experiments with audio recordings. It was observed that the hinds vocalized more frequently than the calves, and it appeared that the vocalization served primarily a contact function. The calves seemed to recognize their mothers' voice better than vice versa. For the hinds, vision was more important than hearing. Thus, the predictions were confirmed.
Behavioural Correlates of Female Social Status and Birth Mass of Male and Female Calves in Reindeer
Authors: Kojola Ilpo
Published: May 2010

In polygyny, male breeding success depends more than female success on body size, and male birth mass may therefore be more strongly correlated with mother's social dominance status. Among female reindeer, Rangifer tarandus, the rate at which a female took over winter feeding craters from conspecifics depended on rank and the mass loss decreased with increasing rank. Birth mass of male calves depended on mother's social rank, but that of female calves did not. Male foetuses appeared to be more effective than females to utilize resources associated with mother's phenotypical superiority.
Conspecific and Heterospecific Attraction: A Mechanism of Web‐site Selection Leading to Aggregation Formation by Web‐building Spiders
Authors: Hodge Margaret A. , Storfer‐Isser Amy
Published: May 2010

This study investigated whether conspecific and/or heterospecific attraction to silk is a mechanism of web‐site selection leading to aggregation formation by two species of web‐building spiders, Hypochilus thorelli Marx (Araneae: Hypochilidae) and Achaearanea tepidariorum (C.L. Koch) (Araneac: Theridiidae). We determined that the spatial distribution of these two spiders was clumped and that H. thorelli had a greater tendency to aggregate than did A. tepidariorum. To determine the mechanism responsible for this spatial pattern, we conducted three field experiments. We examined web‐site selection by H. thorelli in three contexts: no spiders or webs present (cue removed), vacant webs present, and occupied webs present. In the case where no webs were present, there was no tendency for spiders to choose previously occupied sites as web sites. When vacant webs were present, spiders chose to occupy the vacant webs. When occupied webs were present, spiders either invaded webs and evicted the owners, or settled adjacent to and attached their webs to those of residents. Various microhabitat variables (height, angle, temperature, humidity, and substrate character of the rock surface) of randomly selected unoccupied sites and the web sites chosen by spiders were compared. There were no detectable differences between web sites and unoccupied sites with respect to any of the variables measured. This leads us to conclude that web‐site choice by immigrating spiders was based on the presence of silk rather than other features of the site.
Environmental Effects on Agonistic Interactions between Males of the Cockroach Nauphoeta cinerea
Authors: Spohn Bryan G. , Moore Allen J.
Published: May 2010

The effects of different environments on the agonistic behavior of males of the cockroach, Nauphoeta cinerea were investigated. We compared the social interactions between pairs of males that had been reared during the period of sexual maturation, when social behavior develops, under one of four environmental treatments: (1) control (28°C with ad libitum food and water) (2) heat stress (35°C, ad libitum food and water) (3) water deprivation (28°C), or (4) food and water deprivation (28°C). Different environments affected the structure of the interactions between males and the behavior of both dominant and subordinate individuals. The mean number of agonistic acts per minute was similar for all treatment groups except the water‐deprived group, which was significantly lower. Water‐deprived, food‐ and water‐deprived, and heat‐stress rearing conditions reduced the stability of agonistic interactions relative to the control group. When reared under stressful conditions, dominant‐scored males decreased the number of aggressive acts and increased the number of submissive acts, and subordinate‐scored males decreased the number of submissive acts and increased the number of aggressive acts. Thus, stressful environmental conditions can disrupt agonistic interactions and cause both dominant and subordinate male N. cinerea to adopt different behavioral strategies during male‐male competition.
Recognition by Population and Genetic Similarity in the Mountain Dusky Salamander, Desmognathus ochrophaeus (Amphibia: Plethodontidae)
Authors: Evans A. Lelania , Forester Don C. , Masters Brian S.
Published: May 2010

Adult males and females of Desmognathus ochrophaeus were tested in two‐choice substrate discrimination trials in which salamanders were given a choice of the marked substrates of opposite‐sex individuals from their own population and from a geographically distinct population. Females exhibited a significant preference for the marked substrates of extrapopulation males, whereas there was no evidence that males made any such discrimination of the marked substrates of females. We suggest that females may utilize substrate cues to make initial assessments of potential mates. We compared data from substrate discrimination trials to random amplified polymorphic DNA (RAPD) profiles generated for each individual. There was no evidence that females made any distinction of substrate odours based on our assessment of genetic similarity. The estimated genetic differences between the two populations were minimal.
A Comparison of Spontaneous and Odor‐induced Chin Marking in Male and Female Domestic Rabbits (Oryctolagus cuniculus domestica)
Authors: Martínez‐Gómez Margarita , Guarneros Madai , Zempoalteca René , Hudson Robyn
Published: May 2010

Chin marking by the European rabbit (Oryctolagus cuniculus) is one of the classic but still little understood examples of mammalian chemical communication. To investigate whether the sexes differ in performance of this behavior, we compared the frequency of spontaneous chinning and chinning in response to the chin marks of conspecifics in 20 intact male and 20 intact female chinchilla‐breed rabbits, and in five gonadectomized animals of each sex. Contrary to the expectation of greater chinning activity in males, no significant sex differences were found. Frequencies of spontaneous chinning were similar in the two sexes, large and stable individual differences were observed in both, chinning increased in both when marks from unfamiliar conspecifics were present, and both directed chin marks to objects marked by conspecifics more than to unmarked objects. Individual chinning frequencies correlated positively with urination but not defecation in both sexes, and spontaneous and odor‐induced chinning were significantly reduced both in castrated and ovariectomized animals. The findings suggest that chinning is an equally significant part of the communication system of male and female rabbits and that its expression may be regulated by similar olfactory, hormonal, and social mechanisms.
Costs and Benefits of Maternal Care in a Subsocial Spider, Coelotes terrestris
Authors: Gundermann Jean‐Luc , Horel André , Roland Chantal
Published: May 2010

The maternal social spider Coelotes terrestris demonstrates extended care towards its progeny: the mother guards its egg sac for 3–4 weeks, then stays with its young from the time of their emergence until their dispersal about 1 month later. The present investigation evaluates the adaptiveness of these maternal behaviours by comparing the fitness of females performing them with that of females separated from the egg sac or the spiderlings. By protecting their egg sacs from predation and parasites, and by pursuing this task while supplying the young with food, mothers enhance the survival rate and the development of many of their spiderlings. The costs linked with these activities, estimated by the ability to produce another clutch, appear variable according to the stage in the reproductive cycle. In such terms, the egg sac guarding appears to have a low cost in relation to the care given to the spiderlings.
Learning Influences Courtship Preferences of Male Threespine Sticklebacks (Gasterosteus aculeatus)
Authors: Jenkins Jennifer R. , Rowland William J.
Published: May 2010

Male threespine sticklebacks (Gasterosteus aculeatus) prefer to court the more gravid of a pair of dummy females (Rowland1982, 1989). In this study, males were trained to modify their courtship preferences. Males were given two pre‐punishment preference trials during which two dummy females—one approximating a normally gravid female and the other, a supergravid female, possessing an abnormally large abdomen — were simultaneously presented to males. After pre‐punishment trials, males were subjected to one of two punishment procedures: punishment with weak electric shock (Experiment I) or punishment by the removal of females to simulate female retreat (Experiment II). During punishment trials, males were punished each time they courted the supergravid dummy. Control males were subjected to identical trials, but were not punished for courting the supergravid dummy. Post‐punishment preference trials were given to all males (Experiments I and II). The results of Experiments I and II were similar. Punished and control males did not differ in their courtship preferences in pre‐punishment trials; they preferred to court the supergravid dummy. Punished males, however, spent a significantly lower proportion of time visiting and directed a smaller proportion of zigzags (a courtship display) toward the supergravid dummy than did control males during punishment training (Experiment I) and post‐punishment preference trials (Experiments I and II). These results suggest that courtship preferences of male threespine sticklebacks can be modified through learning. Such a mechanism could be important for adaptive mate choice under natural conditions.
Aimed Object‐throwing by a Wild African Elephant in an Interspecific Encounter
Authors: Wickler Wolfgang , Seibt Uta
Published: May 2010

A wild and presumably female African elephant (Loxodonta africana) was observed when she threw with her trunk various materials ‐ mud, soil, vegetation ‐ to an interfering white rhino (Ceratotherium simum). Objectthrowing, a special type of animal tool‐behaviour, seems to be used by elephants not only in aggression but also for exploration
The Response to Novel Foods in Common Marmoset (Callithrix jacchus): The Effects of Different Social Contexts
Authors: Vitale Augusto , Queyras Armelle
Published: May 2010

The main aim of this study was to verify if the response to novel foods in common marmoset (Callithrix jacchus) is influenced by different social settings. This question was tested in three tests involving four social groups. The data regarding the response to novel foods were collected from a total of eight food‐naive young. In particular, we explored if direct contacts between food‐naive and experienced individuals would have a different effect on the response to novel food by the first, in comparison with a situation in which only visual contacts were allowed. These two different social settings were then compared to a situation in which the response to novel food was not mediated by the experience of group‐mates. The results showed a significantly higher number of intervals in which naive young, in social settings, were observed feeding compared with a control test. However, this result was confirmed only in the case of novel foods, not in the case of familiar foods. Furthermore, in the tests in which direct social contacts were allowed, naive young obtained food from group‐mates significantly more often in the case of novel than familiar foods. This study suggests that although naive young, when left in pairs, responded quickly to novel foods without the need to observe or interact with experienced group‐mates, a process of social facilitation was evident. Such a process was not observed in the case of familiar foods, confirming the hypothesis that social facilitation operates in order to acquire novel foods in the diet of the group in the long term.
Electrocommunication and Social Behaviour in Marcusenius senegalensis (Mormyridae, Teleostei)
Authors: Scheffel Andreas , Kramer Bernd
Published: May 2010

The electric organ discharges (EODs) of Marcusenius senegalensis, a West African freshwater fish, are bipolar pulses of short duration (220 ± SE 13 μs). In males (n = 10; 10.1–13.1 cm standard length — which is around the size of getting mature), the duration of EOD pulses was of significantly greater variance than in females (n = 9; 9.8–12.8 cm standard length). Male EODs also showed a tendency for a longer duration than female EODs.

Groups of three as well as of 14 M. senegalensis formed temporary schools in a ‘naturally’ equipped 720‐1 tank. While swimming slowly in a loose school during their nocturnal active phase, fish discharged in irregular long‐short‐long inter‐EOD interval patterns. Near neighbours displayed a tendency to discharge in intervals of similar duration (nearest neighbour distance < 1/2 fish length).

On removal of a plastic partition that had separated a pair of fish for at least 3 days, mutual threat displays followed by fighting were observed. During threatening, the fish alternated regularly between bursts of a high discharge rate and short discharge breaks; the rate of change was 4/s.

The subdominant animal in a group of two was attacked frequently and often ceased discharging when the dominant fish approached. Courtship behaviour involving gonadally mature fish was accompanied by high‐discharge‐rate displays with intervals of constant duration in both fish, and the reciprocal display of ‘preferred’ EOD latencies in the 12 ms range.

The results demonstrate electric communication by distinct inter‐discharge interval patterns in the social behaviour of this mormyrid fish.
Scent Counter‐marking by Male Meadow Voles: Females Prefer the Top‐scent Male
Authors: Johnston Robert E. , Sorokin Evan S. , Ferkin Michael H.
Published: May 2010

Scent counter‐marking, in which one individual deposits scent in close proximity to the scent of another individual, is a widespread but poorly understood aspect of olfactory communication. Recent work with golden hamsters suggests that animals may have specially evolved mechanisms for determining which individual has marked most recently, and this work emphasizes the need for studies with other species. In Experiment 1 it was shown for the first time that male meadow voles, Microtus pennsylvanicus, scent mark with urine and anogenital scents and probably also counter‐mark with these scents. Female meadow voles, after investigation of an area marked by two males, preferred the whole‐body odours of the male that had marked the arena most recently (Experiment 2). After females investigated a male's home cage that had just been marked by another male, they again preferred the whole‐body odours of the male that had marked in the cage most recently (Experiment 3). These results demonstrate that female voles, like male hamsters, can distinguish the top or most recent individual's scent from the bottom or older scent in places marked by two males, and further indicate that female voles may prefer the individual that deposited the top scent. Taken together, the results suggest that counter‐marking by male voles may be a type of competitive advertising and that females may base mate‐choice decisions on information from the pattern of such counter‐marks.
Fighting in Males of the Autumn Spider, Metellina segmentata: Effects of Relative Body Size, Prior Residency and Female Value on Contest Outcome and Duration
Authors: Hack Mace A. , Thompson David J. , Fernandes Donna M.
Published: May 2010

Males of the autumn spider, Metellina segmentata (***Araneac: Metidae), compete for access to mates by guarding the orb webs of mature females. We investigated the influences of relative male righting ability and resource value on fighting behaviour by staging interactions in the field on webs occupied by females. In these contests, the larger male nearly always defeated its opponent when it was at least 10% greater in size. For smaller size asymmetries between opponents, the male previously resident on the female's web usually won the contest. Contest duration decreased exponentially with increasing size asymmetry between opponents, as predicted if each male assessed its relative size and adjusted its fighting strategy according to its likelihood of winning. Contest duration was also greater when the prior resident was the lighter opponent, or when size and residency asymmetries favoured different opponents as winners. Prior residents fought longer over larger, more fecund females, indicating an adjustment of fighting effort according to assessments of resource value. In contrast, intruders did not increase their fighting effort over larger females, suggesting an inability to assess female size quickly and accurately. Assessment appears to reduce the costs of settling conflicts, but imperfect information can result in inaccurate assessments and unexpected outcomes. Assessment strategies are used by other types of spiders to resolve contests, but this appears to be the first evidence for such strategies among orb‐web‐building spiders.
Dimorphic Males Display Alternative Reproductive Strategies in the Marine Amphipod Jassa marmorata Holmes (Corophioidea: Ischyroceridae)
Authors: Clark Rachel Ann
Published: May 2010

Discrete dimorphism of males within a species is often the result of selection for alternative reproductive strategies, and these strategies may be evolutionarily stable (ESS). An ESS may be either mixed (genetically fixed differences) or conditional (flexible differences related to varying environmental conditions) (PARKER 1984). Mature males of the marine amphipod Jassa marmorata are dimorphic. Large ‘major’ males have a greatly enlarged thumb (propodus) on their 2nd gnathopods, while small ‘minor’ males exhibit thumbs that are reduced, and CONIAN (1989) suggested that minors may exhibit a different mating strategy from majors. Ratios of males and females fluctuate seasonally (FRANZ 1989) and female body size is inversely correlated with temperature (FRANZ 1989) so male dimorphism could be a flexible response to varying environmental conditions. I sampled a natural population of J. marmorata over a 1‐yr period, quantified major and minor morphology, and measured male behaviour and mating success in experimental arenas that contained varying proportions of male morphs and females. Morphology of the two morphs is discrete; female body size varies with season with significantly smaller individuals in summer and fall; body size predicts morph type; and ratios of majors, minors and females fluctuate seasonally. Finally I showed that majors and minors use different mating tactics to gain access to receptive females, and that these behaviours depend on the male's own morphology and on the environmental setting that it finds itself in. Major males fight, display and attempt to evict other males to mate with receptive females. Minors never fight with, display to or attempt to evict majors, but they infrequently display to and attempt to evict other minor males. Furthermore, mating success of the two morphs was not significantly different and may depend on whether males are with a majority or minority of their own type. These data support the conclusion that major and minor male J. marmorata display evolutionarily stable alternative reproductive strategics, but more work should address the nature of this ESS.
Territorial Behaviour and Social Organization as a Function of the Level of Aggressiveness in Male Mice
Authors: Sandnabba N. Kenneth
Published: May 2010

Territoriality and social organization were examined in relation to different genetic dispositions for aggressive behaviour. The animals used in the study were male mice of the 51st and 52nd generation of selection for high (Turku Aggressive, TA) and low (Turku Non‐Aggressive, TNA) levels of aggressiveness. The level of aggressiveness of the animals was assessed by means of individual tests with non‐aggressive standard opponents, after which they were allowed to form individual territories in a 102 times 204 times 90 cm enclosure. TA and TNA males were placed in different enclosures. After 2 wk, when the partitions between individual pens were removed, the behaviour of the animals was observed for a 7‐d period. Excessive fighting between the highly aggressive TA males occurred, resulting in the formation of dominant‐subordinate relationships. A great number of attacks inflicted were found to be associated with dominance in the colony, and correlated with a high level of aggressiveness when the animals were individually tested for aggression after having been in colony environments. The level of aggressiveness of the TA males that had become subordinates had significantly decreased. The TNA males fought less and were more often found to stay in their original territory for the entire period of observation. The results suggest that different genotypes for aggression arc related to differences in territoriality and social organization in mice.
Nest Predation Avoidance: an Alternative Explanation for Male Incubation in Acrocephalus melanopogon
Authors: Kleindorfer S. , Hoi H.
Published: May 2010

In the monogamous moustached warbler, male incubation changes from predictably variable (it is dependent on ambient temperature and time of day in April) to high average levels across the day (with no predictor variables in May) as the season progresses. In contrast, females contribute the constant incubation component from April to May. This paper investigates possible explanations for the change in male incubation effort involving changing risks to either (1) embryonic survival within the egg, and/or (2) egg predation. Using egg temperature readouts, the probability of reaching the 25 °C thermal threshold (below which embryonic development ceases) across the season against the probability of predator sightings 0–15 m from the nest was calculated. The results show an inverse relationship between these two risks. During April, male incubation correlates with egg cold stress and changeovers between males and females occur prior to egg cooling below the thermal stress line. During May, the risk of predation increases. The results show increased predator encounter rates from April to May and active nest defense by the incubating parent. Furthermore, high male incubation reduces brood predation. Selection for reduction of the costs of laying replacement clutches (after predation) is suggested given high male incubation and infrequent male‐female changeovers during midday, when egg temperatures are highest, with direct benefits to females of increased foraging. Thus, the shift in male incubation across the season may be explained by minimization of changing risk to offspring survival.
Increased Response of the Short‐Toed Treecreeper Certhia brachydactyla in Sympatry to the Playback of the Song of the Common Treecreeper C. familiaris
Authors: Gil Diego
Published: May 2010

The two European species of treecreepers, the short‐toed treecreeper Certhia brachydactyla and the common treecreeper C. familiaris, occupy different habitats, but are sympatric to a certain extent. The response to specific and heterospecific song was studied both in a sympatric and in an allopatric population of short‐toed treecreeper in the Iberian Mountains (Burgos, Castilla‐León, Spain). Short‐toed treecreepers in sympatry showed a more aggressive response towards the song of the common treecreeper than those in allopatry. Although strict interspecific territoriality was not found, the experimental data suggest that the altitudinal distribution pattern of the two species may be a consequence of the increased aggression. This interspecific aggression may be advantageous for the short‐toed treecreeper, as it may achieve a loose interspecific territoriality resulting in some spacing. However, a non‐adaptive hypothesis for this behaviour cannot be rejected.
The Effect of Hunger on Shoal Choice in Golden Shiners (Pisces: Cyprinidae, Notemigonus crysoleucas)
Authors: Reebs Stephan G. , Saulnier Nancy
Published: May 2010

When an animal has a choice of joining one group over another, its decision may depend on its relative vulnerabilities to predation and starvation. For example, a well‐fed animal may choose a large group of individuals with body size matching its own because this gives good protection against predators, but a hungry animal may prefer smaller groups made up of smaller individuals because this decreases food competition. To test this idea, a choice between various shoals was given to golden shiners, Notemigonus crysoleucas, that were either well fed or deprived of food for 48 h. In a choice of 10 vs. 3 shoalmates, both well‐fed and hungry shiners spent more time near the shoal of 10. In a choice of 20 vs. 3 shoalmates, both well‐fed and hungry shiners again preferred the larger shoal, but in one replicate this preference was significantly weaker in the hungry fish. This reduced preference did not appear to be an artefact of increased mobility by hungry fish searching for food. In a choice between shoals of small vs. large conspecifics, small well‐fed shiners, small hungry shiners, and large well‐fed shiners preferred shoalmates with body size matching their own, but large hungry shiners preferred smaller individuals. These results are consistent with the hypothesis that hungry fish sacrifice safety from predation in their shoaling behaviour (by avoiding larger groups to a certain extent and by risking the oddity effect) so as to decrease food competition.
Reciprocal Allogrooming in Wild Impala Lambs
Authors: Mooring Michael S. , Hart Benjamin L.
Published: May 2010

Adult impala engage in a form of reciprocal allogrooming distinguished by a high degree of reciprocity and ***lack of influence of dominance or relatedness on partner preference or distribution of grooming between partners. A previous study on reciprocal allogrooming of captive newborn impala lambs in a zoological park found that the allogrooming emerged as early as the first week after birth and was identical in structure and reciprocity to allogrooming in adults. Because these findings of apparently unique allogrooming behavior of newborn impala could have been a reflection of the effects of being born and raised in a small, stable captive herd, it was necessary to investigate reciprocal allogrooming in newborn impala in the wild. The emergence, reciprocity, rate, and partner distribution of reciprocal allogrooming in wild newborn impala were observed at two study sites: a national park in Zimbabwe and a game farm in South Africa. Maternal one‐way grooming between mother and newborn emerged as distinct from reciprocal allogrooming and rapidly declined after week 1 postpartum. Reciprocal allogrooming by lambs was first seen between 5 and 8 d postpartum, and as soon as the behavior occurred it was the same basic pattern as seen in adult impala. The reciprocity index for lambs was near 0.5, indicating that lambs delivered as much grooming during an encounter as the partner. Lambs were grooming frequently with non‐mother adults and other lambs by week 1 or 2; by week 3 and onward the allogrooming rate of lambs was more than twice that of their mothers, as predicted by the body size principle of the programmed grooming model. The strong predisposition of neonatal impala lambs to deliver reciprocal allogrooming as early as the first or second week postpartum would appear to reflect a genetically acquired adaptation to the threat of tick infestation in their natural habitat.