bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractSome 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

AbstractObservations 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

AbstractIn 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

AbstractThe 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

AbstractSchooling 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

AbstractClosely 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

AbstractLarval 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

AbstractWe 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

AbstractHermaphrodite 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

AbstractWhile 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

AbstractEarlier 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

AbstractEleven 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

AbstractIn 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

AbstractThis 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

AbstractThe 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

AbstractAdult 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.