Showing papers in "Journal of Ethology in 2011"
TL;DR: The results of this acoustic analysis suggest that a second whistle may be produced by a different caller in response to the first whistle; however, in the case of an absence of a response, the first caller is likely to give further whistles.
Abstract: Bottlenose dolphins (Tursiops truncatus) produce individually distinctive vocalizations—referred to as “signature whistles”—that are thought to function as an individual and conspecific recognition system for maintenance of consistent contact between individuals. Observations and playback experiments were conducted at aquariums to study these whistle–vocal exchanges in bottlenose dolphins. Temporal patterns of vocalization were examined by analyzing the intercall intervals between two consecutive whistles. When a second individual produced a call that was different from the first individual’s vocalization, most of these calls were shorter than 1 s. However, when two consecutive calls were produced by the same individual, the second call rarely occurred within 1 s of the first. These results suggest that a second whistle may be produced by a different caller in response to the first whistle; however, in the case of an absence of a response, the first caller is likely to give further whistles. The results of this acoustic analysis show that the dolphins used in this study mostly used signature whistles during the recorded vocal exchanges.
44 citations
TL;DR: Examination of associations between men’s reproductive success and physical attractiveness from retrospective data obtained from married, divorced, and single samples of Slovakian men found that facially more attractive and taller men were more likely to engage in marriage.
Abstract: Theory suggests that reproductive success is positively associated with an individual’s genetic quality. However, the association between physical attractiveness and reproductive success (i.e., number of offspring) in modern humans remains less clear. Here we examined associations between men’s reproductive success and physical attractiveness from retrospective data obtained from married, divorced, and single samples of Slovakian men. As predicted, facially more attractive and taller men were more likely to engage in marriage. In turn, married men had higher reproductive success than single men. Even when men’s marital status was considered, facially more attractive men had higher reproductive success than their less attractive counterparts. This supports the importance of physical attractiveness in sexual selection in modern humans.
40 citations
TL;DR: This study reports movements of nine individuals photo-identified up to 265 km apart in western Greece, providing further evidence that animals appearing to be “resident” within a given area can temporarily leave and range widely.
Abstract: While bottlenose dolphins in Mediterranean waters often display a high degree of site fidelity, movements across distant areas can occur Such movements have important implications in terms of population viability, particularly in basins with low bottlenose dolphin densities We report movements of nine individuals photo-identified up to 265 km apart in western Greece Four showed a certain degree of site fidelity to one area across several years, but were also found elsewhere, with two individuals moving between two areas This study provides further evidence that animals appearing to be “resident” within a given area can temporarily leave and range widely
39 citations
TL;DR: The number of sperm stored by the female increased with copulation duration only if the male was cannibalised, suggesting that cannibalism increases relative paternity not only through prolongedCopulation duration following a fair raffle model but also through the cannibalism act itself.
Abstract: Female St Andrew’s Cross spiders control copulation duration by timing sexual cannibalism and may thereby control paternity if cannibalism affects sperm transfer. We have investigated the effect of copulation duration on sperm transfer and documented sperm storage patterns when we experimentally reduced the ability of females to attack and cannibalise the male. Virgin males and females were paired and randomly allocated either to a control treatment, where females were allowed to attack and cannibalise the male during copulation, or to an experimental treatment, where females were unable to cannibalise the male. The latter was achieved by placing a paintbrush against her chelicerae during copulation. Our experimental manipulation did not affect copulation duration or sperm storage. However, the number of sperm stored by the female increased with copulation duration only if the male was cannibalised, suggesting that cannibalism increases relative paternity not only through prolonged copulation duration following a fair raffle model but also through the cannibalism act itself. Future studies should explore whether cannibalised males ejaculate more sperm or whether females selectively store the sperm of cannibalised males.
39 citations
TL;DR: The findings show that the contagious effect of yawning is always present throughout the daytime, and both contagious and spontaneous yawning peaked in the early morning and in the late evening, according to the sleepiness time course.
Abstract: Yawning, besides being a spontaneous behavior, can also be evoked by observing others yawn. However, contagious yawning does not always occur, depending possibly on several factors, such as one’s propensity to spontaneously yawn and a heightened level of sleepiness. The aim of this study is to investigate in young adults whether contagious yawning frequency varies throughout the day, and if it is related to the daily time course of spontaneous yawning frequency and level of sleepiness. For the study, 22 subjects were instructed to log hourly, throughout wakefulness, the number of spontaneous yawns and sleepiness level. Subjects were required to continue this procedure for 3 consecutive days, after which they underwent five experimental sessions occurring at regular intervals throughout the same day. During each experimental session, subjects observed others yawn (stimulus condition) and smile (control condition). Our findings show that the contagious effect of yawning is always present throughout the daytime. Both contagious and spontaneous yawning peaked in the early morning and in the late evening, according to the sleepiness time course. However, the frequency of spontaneous yawns was remarkably lower than the frequency of contagious yawns around 19:00. This difference suggests that different mechanisms control spontaneous and contagious yawning.
35 citations
TL;DR: It is shown that poor feeding condition affects pre-copulatory gift construction behaviour and nuptial gift construction may be an honest indicator of male condition and therefore a target of female choice.
Abstract: Pisaura mirabilis males offer a prey wrapped in silk as a nuptial gift that functions as a male mating effort. If nuptial gift construction is costly, males in poor feeding condition would invest less in this behaviour than males in good condition. We investigated frequencies and characteristics of gift construction in males under different sexual stimuli and different feeding conditions. We analysed gift construction behaviours of 17 males exposed sequentially to three treatments: female silk (S), female silk plus female (SF) and no female cues (control; C). The same individuals were first tested when in good feeding condition (young/satiated) and subsequently in poor feeding condition (old/starved). A separate group in good feeding condition controlling for effects of male age was also tested (old/satiated). Presence of female cues (S and SF) elicited much stronger gift construction response in males compared with the control group. Both groups of satiated males constructed nuptial gifts more frequently than starved males, spending more time on gift construction and using more silk. Our findings show that poor feeding condition affects pre-copulatory gift construction behaviour. Nuptial gift construction may be an honest indicator of male condition and therefore a target of female choice.
33 citations
TL;DR: It is suggested that Marmorkrebs have the potential to compete with other species on the same level as P. clarkii, which is itself a highly successful introduced species around the world.
Abstract: The parthenogenetic marbled crayfish, Marmorkrebs, has no known wild population, but has been introduced into natural ecosystems in two continents. Interactions with native crayfish, particularly through fighting, could affect the ecological impact of Marmorkrebs introductions. Marmorkrebs have been characterized anecdotally as having low levels of aggression, which could mitigate their potential to compete with native species. We isolated Marmorkrebs and Louisiana red swamp crayfish (Procambarus clarkii), then conducted size-matched intra and interspecific pairings. Marmorkrebs were as likely to win a fight as P. clarkii, although contests between P. clarkii and Marmorkrebs began significantly faster than contests between two Marmorkrebs. These results suggest that Marmorkrebs have the potential to compete with other species on the same level as P. clarkii, which is itself a highly successful introduced species around the world.
32 citations
TL;DR: Female body colour is an important cue for males in discriminating between sexual maturation stages and Learned mate discrimination depending on copulation experience might help males to detect potential mates effectively and avoid sexually unreceptive immature female.
Abstract: While male mate choice behaviour has been reported in many taxa, little is known about its plasticity and evolutionary consequences. In the damselfly Ischnura senegalensis, females exhibit colour dimorphism (gynomorph and andromorph). The body colour of gynomorphs changed ontogenetically in accordance with sexual maturation, while little change occurred in andromorphs. To test the male mate choice between sexually immature and mature females of both morphs, binary choice experiments were conducted. Virgin males that were reared separately from females after emergence did not show significant preference between sexually immature and mature females for both morphs, indicating that virgin males were unable to discriminate female reproductive status. On the other hand, males that had experienced copulation with gynomorphs preferred sexually mature gynomorphs to sexually immature ones. However, males that had experienced copulation with andromorphs could not discriminate between sexually immature and mature andromorphs, probably due to the absence of significant ontogenetic change in their thoracic colour. Therefore, female body colour is an important cue for males in discriminating between sexual maturation stages. Learned mate discrimination depending on copulation experience might help males to detect potential mates effectively and avoid sexually unreceptive immature female. We finally discuss the adaptive significance of the ontogenetic colour change in females.
31 citations
TL;DR: Examination of possible trade-offs between nest crypsis and thermoregulation in Little Grebes revealed that covering clutches is beneficial in terms of deterring predators, because uncovered eggs were more vulnerable to predation.
Abstract: Egg predation is a common feature influencing the reproductive success of open nesting birds. Evolutionary pressure therefore favours building cryptic, inconspicuous nests. However, these antipredatory pressures may be in conflict with thermoregulatory constraints, which select for dry nest material maintaining optimum temperature inside a nest cup during the absence of incubating parents. Here we examined possible trade-offs between nest crypsis and thermoregulation in Little Grebes (Tachybaptus ruficollis), which lay their eggs in floating nests built from wet plant material. As this species regularly covers its eggs with nest material, we experimentally examined (1) the rates of egg predation on covered and uncovered artificial nests and (2) possible thermoregulatory costs from nest covering by comparing temperature and relative humidity changes inside the nest cup. Results revealed that covering clutches is beneficial in terms of deterring predators, because uncovered eggs were more vulnerable to predation. Moreover, covering clutches also had thermoregulatory benefits because the mean temperature and relative humidity inside nest cups covered by dry or wet materials were significantly higher for covered compared to uncovered treatments. Covering clutches in Little Grebes therefore does not pose thermoregulatory costs.
30 citations
TL;DR: These results and those of previous research on the positional behaviour of other squirrels reveal several trends related to body size, arboreal or gliding habits and tropical or temperate forest distribution and contribute to the understanding of evolutionary novelty in multiple levels within the sciurid radiation.
Abstract: The study of the locomotion and postures of arboreal squirrels may provide important contextual information on the evolution of the morphology and ecology of sciurids. In this context, we studied the positional behaviour and habitat use of four adult European red squirrels (Sciurus vulgaris L.) in a mixed coniferous forest in northern Greece. Our results show that, during the study period, S. vulgaris extensively used the forest canopy and the terminal branch zone. The use of small and medium supports of all orientations was also particularly frequent. The positional profile of the species was characterized by the dominance of quadrupedal, clawed and airborne locomotion along with seated and standing postures. Quadrupedalism and sitting appeared to promote terminal branch use for food access and manipulation, while claw climbing favored vertical ranging and retreat to trees after terrestrial foraging. Finally, leaping reduced energetic costs during travelling between food sites within the relatively dispersed forest. These results and those of previous research on the positional behaviour of other squirrels reveal several trends related to body size, arboreal or gliding habits and tropical or temperate forest distribution and contribute to the understanding of evolutionary novelty in multiple levels within the sciurid radiation.
26 citations
TL;DR: Whether lizards in laboratory experiments alter their behaviour in the presence of scats from conspecifics is examined, and results were consistent with a communication system in which lizards use scats to advertise their presence, independent of any direct contact.
Abstract: Many animals use chemical signals for communication between conspecifics and for territory marking. The pygmy bluetongue lizard is normally solitary, focussing activity around the entrance of its burrow, from where it ambushes prey, and rarely contacts other individuals. In this paper we examined whether lizards in laboratory experiments alter their behaviour in the presence of scats from conspecifics. In the first experiment, when lizards were offered a choice of two vacant burrows with or without a scat close to the entrance, they tongue flicked more often at the burrow entrance when the scat was present, and more often chose to occupy the burrow with the scat. An interpretation is that lizards use scat signals to recognise burrows that may be suitable because they have previously been occupied by a conspecific, but that they approach those burrows cautiously in case a resident is still present and likely to resist a takeover. Scats from male lizards were inspected (by both sexes) for longer than scats of female lizards. In the second experiment, when resident lizards were presented with scats outside of their burrows, they inspected and tongue flicked at those scats more often if the scat came from a male than a female lizard, but there was no definitive evidence from our experiments that lizards differentiated in their response to scats from lizards that were found close to or far from the test lizard. The results were consistent with a communication system in which lizards use scats to advertise their presence, independent of any direct contact.
TL;DR: Spontaneous embraces from the 2008 Summer Olympics Games were analysed, and were found to last for about 3 s, comparable to previously described perceptual and motor units in humans and also in other primate species.
Abstract: Moments of some gestures may stand out from our constantly flowing life-time as memorable experiences. We feel subjective moments as our psychological present. Few behavioral acts can express a shared subjective experience so easily observable than people’s embraces after a significant life-event. Spontaneous embraces from the 2008 Summer Olympics Games were analysed, and were found to last for about 3 s, comparable to previously described perceptual and motor units in humans and also in other primate species. These 3-s segments of time are suggested to be the basic temporal building blocks of our behaviourally expressed subjective experiences.
TL;DR: The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles, and non-lateralized horses may have higher spatial reasoning abilities.
Abstract: The objective of this study was to investigate the ability of horses (Equus caballus) to detour around symmetric and asymmetric obstacles. Ten female Italian saddle horses were each used in three detour tasks. In the first task, the ability to detour around a symmetrical obstacle was evaluated; in the second and third tasks subjects were required to perform a detour around an asymmetrical obstacle with two different degrees of asymmetry. The direction chosen to move around the obstacle and time required to make the detour were recorded. The results suggest that horses have the spatial abilities required to perform detour tasks with both symmetric and asymmetric obstacles. The strategy used to perform the task varied between subjects. For five horses, lateralized behaviour was observed when detouring the obstacle; this was consistently in one direction (three on the left and two on the right). For these horses, no evidence of spatial learning or reasoning was found. The other five horses did not solve this task in a lateralized manner, and a trend towards decreasing lateralization was observed as asymmetry, and hence task difficulty, increased. These non-lateralized horses may have higher spatial reasoning abilities.
TL;DR: It is demonstrated that P. africana is another species that uses a trial and error, or generate and test, algorithm when deriving the aggressive-mimicry signals that will be appropriate in different predator–prey encounters.
Abstract: All species from the jumping spider (Salticidae) genus Portia appear to be predators that specialize at preying on other spiders by invading webs and, through aggressive mimicry, gaining dynamic fine control over the resident spider’s behavior. From previous research, there is evidence that P. fimbriata, P. labiata and P. schultzi derive signals by trial and error. Here, we demonstrate that P. africana is another species that uses a trial and error, or generate and test, algorithm when deriving the aggressive-mimicry signals that will be appropriate in different predator–prey encounters. We discuss the implications of these new findings and the findings from previous work in order to understand the selection factors that drive the evolution of flexibility in aggressive-mimicry strategies.
TL;DR: The results show that hamsters spend little time out of the burrow, thus minimizing risk, but they also show that time spent out ofThe burrow is related to the energy needs of the hamsters; lactating females with high energy needs exposed themselves to much greater risk than did non-lactating females.
Abstract: Foraging theory posits that animals should maximize energy gains while minimizing risks, the largest of which is usually predation. For small burrowing mammals the best measure of risk avoidance may be the time spent in the burrow, although this measure is rarely examined. During the spring of 2005 and 2006 we recorded the foraging behavior of female golden hamsters in their natural habitat in southern Turkey. Data were collected with a data logger and by direct observations. Female golden hamsters averaged 64 min per day above ground in a series of foraging trips with a mean duration of 5.5 min. Two nursing females increased their time out of the burrow by a factor of 6–8 times over the course of 16 days by increasing both the number of trips and the length of each trip. These results show that hamsters spend little time out of the burrow, thus minimizing risk, but they also show that time spent out of the burrow is related to the energy needs of the hamsters; lactating females with high energy needs exposed themselves to much greater risk than did non-lactating females.
TL;DR: Domesticated female zebrafish discriminated the sexes using both visual (body colour) and olfactory cues; however, wild-derivedZebrafish were too distressed for behavioural experiments under these laboratory conditions, which explains their lack of attraction to males.
Abstract: We investigated sex recognition in female zebrafish (Danio rerio) to better understand the underlying sensory mechanisms and identify male secondary sexual traits. Females were simultaneously presented with two fish, a male and a female, in a flow-chamber apparatus, and females’ relative attraction towards males was observed under different conditions. With domesticated fish, females were more attracted to males when presented with both visual and chemosensory cues from stimulus fish. They still discriminated the sexes when only visual cues were provided, but not when white ambient light was changed to yellow, indicating that colour plays a role. Sex discrimination under yellow light was improved when chemosensory cues were also provided. Surprisingly, females’ attraction to males was not more pronounced in the morning when mating occurs. Domesticated females discriminated the sexes when presented with wild-derived, as well as domesticated fish, whereas wild-derived females did not show any biases for domesticated or wild-derived males. Behavioural observations indicated that the wild-derived females were distressed, which explains their lack of attraction to males. In summary, domesticated female zebrafish discriminated the sexes using both visual (body colour) and olfactory cues; however, wild-derived zebrafish were too distressed for behavioural experiments under these laboratory conditions.
TL;DR: It is hypothesized that male horns have evolved due to intra-sexual selection, in which males use these horns as weapons in aggressive interactions, and logistic regression analysis revealed that neither horn length nor horn use were significant factors for contest outcome.
Abstract: Sexual dimorphism, the difference between the sexes in secondary sexual characters, is in general driven by processes of sexual selection. The horn-headed cricket, Loxoblemmus doenitzi, exhibits sexual dimorphism in head shape. Males have flat heads and triangular horns on both sides of their heads, whereas females have rounded heads and no horns. We hypothesized that male horns have evolved due to intra-sexual selection, in which males use these horns as weapons in aggressive interactions. We tested two predictions of this hypothesis by conducting agonistic trials with field-caught males of L. doenitzi: (1) the horns should be used in agonistic interactions between males, and (2) the asymmetry in horn size or horn use may determine contest outcome. Horn length was significantly correlated with thorax length and hind femur length. During agonistic interactions, males aggressively used their horns by beating the opponent’s horns with their own or by poking the opponent’s body. However, logistic regression analysis revealed that neither horn length nor horn use were significant factors for contest outcome. Instead, body size was significant for determining contest outcome. We discuss possible scenarios for evolution of male horns in L. doenitzi.
TL;DR: Questions regarding empathy in non-humans should focus on more intricate levels as suggested by DeWaal (Annu Rev Psych 59: 279–300, 2008), rather than adhering to the assertion that empathy is uniquely human.
Abstract: In a unique case where a chimpanzee infant captured by human poachers was returned by researchers to her natal group, an adolescent male helped the injured mother carry her infant on each of 2 days following the return. I explore various hypotheses to explain this behavior and suggest that the apparent recognition of both the infant’s and mother’s needs by the male supports the consideration of empathy in this case. As data accumulate, questions regarding empathy in non-humans should focus on more intricate levels as suggested by DeWaal (Annu Rev Psych 59: 279–300, 2008), rather than adhering to the assertion that empathy is uniquely human.
TL;DR: Variation in counterattack success may exist between these two forms of Stigmaeopsis miscanthi, and there is some correspondence between male-to-male belligerence and counterattack effectiveness against predators.
Abstract: In Japan, Stigmaeopsis miscanthi (Saito) occurs in two forms that are differentiated by the intensity of male-to-male aggression, i.e. there is a low aggression and a high aggression group (known as the LW and HG forms, respectively). The effects of counterattack behavior against predators were experimentally compared between the two forms. Parental males and females of both forms could achieve significant counterattack success against Typhlodromus bambusae, a specific predator, and counterattack efficiency increased significantly with parental density. Furthermore, the HG form showed a stronger tendency than the LW form to kill predator larvae. Thus, variation in counterattack success may exist between these two forms, and there is some correspondence between male-to-male belligerence and counterattack effectiveness against predators.
TL;DR: Evidence is provided of the effect of the crabs’ shelter on surface activity and social interactions in the natural habitat of C. granulatus and supplies valuable tools for field and laboratory studies using this crab as an animal model.
Abstract: The use of shelters has had a predominant adaptive value in many species throughout evolution. Shelters provide protection and reduce the risk of predation during the search for food and mates. However, they imply the additional danger of having the refuge appropriated by an intruder because of intraspecific competition, especially in densely populated communities. In this work we studied the burrow-centred strategies of exploration and the burrow-oriented escape responses of the crab Chasmagnathus granulatus during surface activity outside their burrows. Exploratory excursions were described through diverse characteristics that enabled their functional analysis and categorization. Results showed that surface exploration is mainly accomplished by slow and near-the-burrow excursions that could be composed of two or three stages. Exploratory behaviour is drastically replaced by a conspicuous burrow-oriented escape response when crabs are faced with an aerial stimulus or the approach of a conspecific neighbour. We describe and compare this escape run with regard to whether individual survival or burrow resource is at risk. This study provides evidence of the effect of the crabs’ shelter on surface activity and social interactions in the natural habitat of C. granulatus and supplies valuable tools for field and laboratory studies using this crab as an animal model.
TL;DR: Behavioral trials were performed to determine if aggressive interactions occur between invasive H. cyanoguttatus and native bluegill, indicating that this invasive species may have fundamentally different strategies of aggression compared with native L. macrochirus.
Abstract: The Rio Grande cichlid (Herichthys cyanoguttatus) has been established in the Greater New Orleans Metropolitan area for at least 20 years, and its effect on native fishes is unknown. Behavioral trials were performed to determine if aggressive interactions occur between invasive H. cyanoguttatus and native bluegill (Lepomis macrochirus). When defending a territory as the resident, L. macrochirus were markedly aggressive, averaging 11.6 aggressive actions per 10-min behavioral trial. In contrast, L. macrochirus were extremely passive as invaders, with 0.5 aggressive actions per trial. Herichthyscyanoguttatus were equally aggressive as residents and as invaders, averaging 4.9 and 6.0 aggressive actions per trial, respectively. Herichthys cyanoguttatus interacted aggressively with native species whether they held territory or not, indicating that this invasive species may have fundamentally different strategies of aggression compared with native L. macrochirus. These differences may explain the continued success of H. cyanoguttatus as an invasive fish in southeastern Louisiana.
TL;DR: It is found that reconciliation occurs only in the non-feeding context and that it works in reducing the risk of renewed aggression in a wild group of wild brown lemurs.
Abstract: Post-conflict behaviour has been widely investigated in anthropoid primates but not extensively in prosimians. Here, we report the reconciliation pattern of a 14-individual group of wild brown lemurs (Eulemur fulvus) in the Berenty gallery forest (South Madagascar). We found that reconciliation occurs only in the non-feeding context and that it works in reducing the risk of renewed aggression. Thus, reconciliation would provide an immediate positive feedback that is probably independent of the quality of the relationship between opponents. Reconciliation may also be a hic-et-nunc mechanism, needed to avoid conflict spreading across group members, possibly leading to social disruption.
TL;DR: Data is presented on male red deer movements between sub-populations in southern Sweden during the rut to investigate whether these movements could be breeding dispersal driven by mate competition.
Abstract: Breeding dispersal can be of significant ecological and evolutionary importance. Yet, it is seldom considered in mammals. I present data on male red deer (Cervus elaphus) movements between sub-populations in southern Sweden during the rut. I investigated whether these movements could be breeding dispersal driven by mate competition. During the ruts of 1998–2009, I recorded 91 movements of males. The longest movement distance was 18.5 km. Dispersal was not restricted to yearlings or sub-adults, but also observed among adult stags. Of 91 movements observed, 7 were made by yearlings, 46 by sub-adults and 38 by adults. There was a significant move among yearlings and sub-adults towards areas with a higher ratio of females/adult males and towards areas with more females. The movements between rutting areas thereby seemed driven by sexual competition.
TL;DR: Kin recognition between first instar caterpillars and eggs may have been important in the evolution of some of the butterfly’s adaptations, and possibly as an opportunity for kin selection.
Abstract: Females of the neotropical butterfly Heliconius erato phyllis lay eggs individually, which, after hatching into caterpillars, can be cannibalistic towards neighboring eggs. Laboratory experiments were conducted to test for kin recognition between first instar caterpillars and eggs. Two experiments were performed, putting three eggs in the vertices of an equilateral triangle made of green paper with side length of 0.5 cm. In the first experiment, two of the three eggs were full siblings; in the second experiment, one group consisted of three eggs from three independent nonrelated females, and in the other group all three eggs were full siblings. The frequency of cannibalism in experiment 1 (SSN, sibling–sibling–nonsibling) was 66% for nonrelated eggs and 34% for sibling eggs (P = 0.0018). In experiment 2, in group NNN (three nonsibling eggs) it was 83%, and for group SSS (three sibling eggs), the frequency of cannibalism was 53% (P < 0.0001). These results indicate kin recognition (caterpillar–egg). This recognition may have been important in the evolution of some of the butterfly’s adaptations, and possibly as an opportunity for kin selection.
TL;DR: The results suggest that males modify their strategy according to their individual abilities: mate-guarding intensity was positively correlated with the black breast badge size.
Abstract: Several factors can influence the risk of cuckoldry through extra-pair paternity for male birds. The number of neighbouring males is thought to affect the chance of females engaging in extra-pair copulations, and species which breed both socially (colonially) and solitarily provide an ideal opportunity to test the effect of close proximity on extra-pair behaviour and paternity guards. In this study, the extent to which male house sparrows, Passer domesticus, used two alternative strategies, namely frequent copulation and mate-guarding, to ensure paternity was investigated. We also examined how males vary the two paternity guards according to their breeding sociality. Pairs at the dense colony started to copulate at a higher rate at the beginning of the fertile period than those of the medium-sized colony and solitary breeding pairs. Male house sparrows appear to fine-tune their strategies according to the breeding density. Both strategies are alternatively used in the weak fertile period but are simultaneously used in the peak fertile period. Our results suggest that males modify their strategy according to their individual abilities: mate-guarding intensity was positively correlated with the black breast badge size.
TL;DR: Relative tail-tip badge size, relative belly patch size and relative tail length could significantly predict an individual’s body mass, and body condition was positively correlated with relative taillength, suggesting that resident males may establish their social dominance by communicating their body mass and condition through frequent tail curling.
Abstract: This study addresses several basic questions relating to the roles of badges and displays in establishing social structure in male Phrynocephalus vlangalii. Significant differences in body mass and condition were found between resident and floater males of P. vlangalii, and resident males engaged in tail curling and agonistic interactions more frequently than floater males. Frequency of tail curling was correlated negatively with body mass in floater males, but was not correlated with body mass and condition in resident males. Relative tail-tip badge size, relative belly patch size and relative tail length could significantly predict an individual’s body mass, and body condition was positively correlated with relative tail length, suggesting that resident males may establish their social dominance by communicating their body mass and condition through frequent tail curling.
TL;DR: Findings suggest that, in Sintra, C. algerina is locally adapted to a locally abundant oecobiid species.
Abstract: Geographic variation in a predator’s reliance on kairomones from prey was investigated. The predator studied, Cyrbaalgerina, is an araneophagic (spider-eating) jumping spider (Salticidae) and the prey were oecobiid spiders (Oecobiidae). There were two study sites (Sintra and Tavira), both in Portugal. Oecobiusmachadoi was a common oecobiid in Sintra, but no oecobiids were found in Tavira. Staged encounters showed that oecobiid-specific prey-capture behaviour was adopted by the C. algerina in Sintra but not in Tavira. In experiments using a Y-shaped olfactometer, significantly more Sintra C. algerina individuals chose the side with oecobiid odour instead of the blank side when the odour came from females of a sympatric species (O. machadoi), but not when the odour came from O. machadoi males or from females of an allopatric species (O. amboseli). Regardless of whether the odour came from O. machadoi or O. amboseli, the Tavira C. algerina did not choose the odour side significantly more often than the blank side. These findings suggest that, in Sintra, C. algerina is locally adapted to a locally abundant oecobiid species. Whether this example of geographic variation in kairomone use is a behavioural ecotype or instead an instance of phenotypic plasticity is currently unknown.
TL;DR: The Siberian chipmunk, Tamias sibiricus, was introduced into the suburban forest of Sénart in the late 1970s where it naturalised and juveniles are involved in the spread of this ground squirrel, bearing in mind that movements estimated may have been underestimated due to the use of capture–mark–recapture methods on a limited trapping area.
Abstract: The Siberian chipmunk, Tamias sibiricus, was introduced into the suburban forest of Senart in the late 1970s where it naturalised. Juvenile dispersal of this solitary ground-dwelling squirrel is not known, while it is an important component of the invasion process. From 2003 to 2007, mark–recapture techniques were used to determine how dispersal movements differed between year, cohort, sex and body mass. Distances moved were calculated between the location of first capture during the year of birth and the arithmetic centre of the trapping locations obtained the next year. Excluding heaviest individuals, e.g. 80 g, that must have already dispersed and thus lowered the estimation of averaged distance moved, our results shows that the dispersal distance in juvenile males (168 ± 24 m, n = 39) was greater than in females (83 ± 11 m, n = 66), with no effect detected for either year or cohort. Juveniles are thus involved in the spread of this ground squirrel, bearing in mind that movements estimated may have been underestimated due to the use of capture–mark–recapture methods on a limited trapping area.
TL;DR: This work uses high-speed videography to demonstrate that the suctorial organs of Eremochelis bilobatus are its primary means of capturing insect prey and presents calculations of the adhesive pressure exerted by these suctorIAL organs during real prey capture events.
Abstract: Solifugids (Arachnida, Solifugae) have unique evertable adhesive organs on the tips of their pedipalps, named ‘suctorial’ or ‘palpal’ organs. Previous studies have shown that these organs enable solifugids to climb smooth glass-like surfaces and have hypothesized that these structures facilitate prey capture. Here, we use high-speed videography to demonstrate that the suctorial organs of Eremochelis bilobatus are its primary means of capturing insect prey. We also present calculations of the adhesive pressure exerted by these suctorial organs during real prey capture events.
TL;DR: The results suggest that Derby elands that range over a large enclosure with dense vegetation cover adjust their maternal behavior in compliance with potential predator risk, facing a trade-off between nursing and vigilant behavior in the wild.
Abstract: Mother–offspring interactions soon after parturition play a key role in the survival of mammals. We investigated the suckling behavior of semi-captive Western Derby eland (Taurotragus derbianus derbianus) in a 60-ha enclosure covered by dense savanna vegetation in Senegal and farmed Common eland (T. oryx) on an open 2-ha pasture in the Czech Republic. We hypothesized that the basic pattern of suckling bout duration and mother–offspring interactions would be similar between species, but would vary in response to the environmental conditions and breeding system. During three calving periods, we observed the suckling of 27 and 23 calves of Derby and Common elands, respectively, between the ages of 1–5 months, and the interactions between mother and calf before and during suckling. Suckling bout duration increased with the age of the calves for both elands. However, in Derby elands we recorded longer suckling bouts in male than female calves and shorter suckling bouts in primiparous mothers than multiparous ones; no differences were found in farmed Common elands. The animals’ active approach to mother–offspring contact, for example naso–anal contact, and initiation and termination of suckling, resulted in longer suckling bouts in Derby elands. The results suggest that Derby elands that range over a large enclosure with dense vegetation cover adjust their maternal behavior in compliance with potential predator risk, facing a trade-off between nursing and vigilant behavior in the wild. The suckling behavior of farmed elands, on the other hand, reflects the conditions of captivity without predators and with the small available area enabling permanent visual contact of animals.