Social and ecological correlates of long-distance pant hoot calls in male chimpanzees

Long-distance calls have a variety of functions in different animal species. However, where multiple functions are proposed for a single long-distance call type, little is known about their relative importance. Chimpanzees are one species where several functions have been proposed for their long-distance call, the pant hoot. In this study, we investigated the effect of social factors, including the rank of the caller, party size, fission–fusion rates, and the presence of estrus females as well as ecological factors including the type of food consumed and travel time, on male chimpanzee (Pan troglodytes schweinfurthii) pant hooting, in order to identify the key correlates of this behavior. The wild male chimpanzees of the Kanyawara community, Uganda, produced more pant hoots on days when there were frequent changes in the male, but not female, composition of the focal’s party. This factor accounted for the largest amount of variation in pant hoot production, and we found that males were more likely to repeat a call prior to rather than after fusion with other males, suggesting that the calls facilitate fusion. Pant hoots therefore seem to play a pivotal role in regulating grouping dynamics in chimpanzees. Our study also shows that pant hooting was positively correlated with the rank of the caller, the presence of parous females in estrus, and the consumption of high-quality food, suggesting that pant hoots signal social status or social bonds when between-male competition is high. This study supports the view that pant hoots fulfill a complex social function.     

Do male "long-distance calls" function in mate defense? A comparative study of long-distance calls in primates

Long-distance calls produced by males are common among vertebrate species. Several hypotheses have been proposed to explain features of male long-distance calls and their phylogenetic distribution in primates, but the putative functions of male long-distance calls have yet to be tested comprehensively. We used phylogenetic comparative methods to investigate hypotheses for the function of male long-distance calls. We focused on the mate defense hypothesis, which states that male long-distance calls function in intra-sexual competition for mates, but we also examined factors involving resource defense, mate attraction, and habitat. Phylogenetic reconstruction of male long-distance calls in 158 primate species indicates that the presence of male long-distance calls is the ancestral state. The carrying distance of male long-distance calls is correlated with the size of the home range, which is consistent with the role of male long-distance calls in defending mates, attracting mates, and defending resources. However, measures of male intra-sexual competition were not associated with the evolution of male long-distance calls. Evolutionary transitions were only partly correlated with factors related to mate attraction. Instead, the strongest correlates of male long-distance calls were activity period, body mass, home range, habitat and some measures of resource defense. Our results are consistent with long-distance call production as a costly signal, but detailed study within species is required to assess these costs and the functions of long-distance calls in individual cases. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/.     

Modeling patterns of nonlinearity in ecosystem responses to temperature, CO2, and precipitation changes.

It is commonly acknowledged that ecosystem responses to global climate change are nonlinear. However, patterns of the nonlinearity have not been well characterized on ecosystem carbon and water processes. We used a terrestrial ecosystem (TECO) model to examine nonlinear patterns of ecosystem responses to changes in temperature, CO2, and precipitation individually or in combination. The TECO model was calibrated against experimental data obtained from a grassland ecosystem in the central United States and ran for 100 years with gradual change at 252 different scenarios. We primarily used the 100th-year results to explore nonlinearity of ecosystem responses. Variables examined in this study are net primary production (NPP), heterotrophic respiration (R(h)), net ecosystem carbon exchange (NEE), runoff, and evapotranspiration (ET). Our modeling results show that nonlinear patterns were parabolic, asymptotic, and threshold-like in response to temperature, CO2, and precipitation anomalies, respectively, for NPP, NEE, and R(h). Runoff and ET exhibited threshold-like pattern in response to both temperature and precipitation anomalies but were less sensitive to CO2 changes. Ecosystem responses to combined temperature, CO2, and precipitation anomalies differed considerably from the responses to individual factors in terms of response patterns and/or critical points of nonlinearity. Our results suggest that nonlinear patterns in response to multiple global-change factors were diverse and were considerably affected by combined climate anomalies on ecosystem carbon and water processes. The diverse response patterns in nonlinearity have profound implications for both experimental design and theoretical development.     

Baboon loud calls advertise male quality: acoustic features and their relation to rank,age, and exhaustion

Free-ranging adult male baboons give loud two-syllable wahoo calls during dawn choruses, interactions between groups, when chasing females, and in aggressive interactions with other males. Previous research has shown that the rate and duration of these contest wahoos are correlated with a males competitive ability: high-ranking males call more often, call at faster rates, and call for longer bouts than do low-ranking males. Here we report that acoustic features of wahoos also reveal information about male competitive ability. High-ranking males give wahoos with higher fundamental frequencies (F0) and longer hoo syllables. Within-subject analyses revealed that, as males fall in rank, the hoo syllables tend to shorten within a period of months. As males age and continue to fall in rank, F0 declines, hoo syllables shorten, and formant dispersion decreases. Independent of age and rank, within bouts of calling F0 declines and hoo syllables become shorter. Because wahoos are often given while males are running or leaping through trees, variation in these acoustic features may function as an indicator of a males stamina. The acoustic features of contest wahoos thus potentially allow listeners to assess a males competitive ability.Communicated by C. Nunn     

Behavioural trait assortment in a social network: patterns and implications

The social fine structure of a population plays a central role in ecological and evolutionary processes. Whilst many studies have investigated how morphological traits such as size affect social structure of populations, comparatively little is known about the influence of behaviours such as boldness and shyness. Using information on social interactions in a wild population of Trinidadian guppies (Poecilia reticulata), we construct a social network. For each individual in the network, we quantify its behavioural phenotype using two measures of boldness, predator inspection tendency, a repeatable and reliably measured behaviour well studied in the context of co-operation, and shoaling tendency. We observe striking heterogeneity in contact patterns, with strong ties being positively assorted and weak ties negatively assorted by our measured behavioural traits. Moreover, shy fish had more network connections than bold fish and these were on average stronger. In other words, social fine structure is strongly influenced by behavioural trait. We assert that such structure will have implications for the outcome of selection on behavioural traits and we speculate that the observed positive assortment may act as an amplifier of selection contributing to the maintenance of co-operation during predator inspection.     

Behavioural changes in freshwater fish, Cirrhinus mrigala (Hamilton) exposed to cypermethrin

The toxicity of insecticide cypermethrin to the freshwater fish, Cirrhinus mrigala was studied using static bioassay method. The 96 h LC50 was found to be 5.13 microg/l. Increase in opercular movement, loss of equilibrium, increase in surface behaviour, change in body colour, increase secretion of mucus, irregular swimming activity, rapid jerk movement, 'S' jerky, partial jerk, and aggressiveness were observed in fish exposed to lethal concentration of cypermethrin. But in sub lethal concentration changes were observed from that of lethal and with the approach of 14 and 21 day, fish attained to normalcy.     

Seasonal changes of locomotor activity patterns in ruin lizards Podarcis sicula

The daily pattern of locomotor activity of the ruin lizard Podarcis sicula in its natural environment changes from unimodal in spring (with only one activity peak per day) to bimodal in summer (with two well-separated activity peaks per day) and it becomes unimodal again in autumn. In order to establish whether such seasonal changes in pattern might be at least in part controlled by endogenous temporal programs, lizards were collected at different times of the year and immediately after capture their locomotor behavior was tested in the laboratory under constant temperature (29°C) and in darkness. For some individuals tested in the laboratory the locomotor pattern previously expressed in the field was known. Seasonal differences in pattern have been unequivocally found to have an endogenous component, as most lizards in constant conditions retained the locomotor pattern shown in the field during the same season. Besides, in the bimodal lizards the freerunning period of locomotor rhythms () was significantly shorter and circadian activity time (a) longer than in the unimodal ones. Altogether the data are compatible with the idea that both the interdependent changes of and a and the changes in locomotor pattern occurring seasonally in the circadian activity rhythms of P. sicula would depend on changes in the phase relationship between mutually coupled oscillators which drive these rhythms. Correspondence to: A. Foà     

Mating patterns of woolly spider monkeys,Brachyteles arachnoides: implications for female choice

Summary Woolly spider monkeys show a promiscuous, polygynous mating system in which a receptive female mates with several males, often in rapid succession. Copulation is prolonged with an average duration of 4.1±1.5 (SD) min. Coitus consists of a stationary phase with the male in intromission, followed by stercotypic behaviours of the female which appear to cue and/or accompany male climax and ejaculation. Subadult and adult males show different association patterns with individual females. Subadult males form long-term consortships with particular females while adult males appear strongly attracted to a particular female only when the is receptive. These different behavior patterns of males are viewed as age-specific mating tactics. Males in a mating aggregation show little intermale aggression for sexual access to a receptive female. Large testis size in this species suggests that much intermale competition for reproductive success may be carried out at a postcopulatory level, perhaps by sperm competition. The copulatory pattern of woolly spider monkeys may function primarily as a mechanism of female choice, aiding a female in assessing the quality of males in hei mating aggregation while helping to ensure that maximal high quality spermatozoa will be available at the proper time for fertilization.     

Altered responses to female odors in parasitized male mice: neuromodulatory mechanisms and relations to female choice

There is accumulating evidence that females may preferentially select parasite-free or -resistant males. Minimal attention has, however, been paid to the mate preferences and responses of the parasitized male hosts themselves. Here, we considered the effects of parasitic infection on male host mate responses, the neuromodulatory correlates of these responses, and the relations of these responses to female mate choice. Using an odor “preference” test, we examined the effects of different stages of an acute, sub-clinical infection with the naturally occurring, enteric, single host, protozoan parasite, Eimeria vermiformis, on the responses of male mice, Mus musculus domesticus, to the odors of estrous females along with the responses of uninfected females to the parasitized males. At 4 days post-infection (non-infective, pre-patent stage) E. vermiformis-infected male mice showed a significantly decreased preference for the odors of estrous females, whereas at 10 days post-infection (infective, patent stage) infected males showed a significantly increased preference for the odors of estrous females. Parasitized males displayed no significant changes in their responses to the odors of non-estrous females, supporting effects on the reproductively related responses of the host. In parallel, estrous females displayed a reduced interest in the odors of infected males. Least interest was expressed in the odors of the patent, infective males, consistent with the avoidance of contagion. Using selective opioid peptide receptor agonists and antagonists we found evidence that enhanced kappa opioid peptide (e.g., dynorphin) activity was related to the decreased sexual interest of the pre-infective males, while augmented delta opioid peptide (e.g., enkephalin) activity was associated with the enhanced responses of the infective males to females. We further showed that acute kappa opiate administration reduced the responses of uninfected males to females and that uninfected females displayed modified responses to the odors of uninfected males subject to acute modifications of opioid activity. We suggest that these differential shifts in endogenous opioid activity in the parasitized males are associated with and, or related to alterations in neuro-immune and endocrine functions. These findings show that parasitic infection can have, depending on the stage of infection and associated neuromodulatory changes, either significant facilitatory or inhibitory effects on male host preferences for and responses to females. Received: 22 April 1996 / Accepted after revision: 15 March 1997     

Male-male association patterns and female proximity in the guppy,Poecilia reticulata

If males differ in their ability to attract potential mates, and are able to perceive such differences, theory predicts they should distribute themselves in a manner that increases their probability of obtaining potential matings. The relationship between male-male association patterns and the proximity of females in social groups, however, remains virtually unexplored. Experimental analysis of this relationship in the guppy, Poecilia reticulata, demonstrates that in preference tests males showed a strong tendency to associate with other males that were further away from potential mates than they were themselves. Male guppies pursue a behavioral strategy that involves categorizing other males based on their proximity (and possibly relative attractiveness) to females, remembering the identity of such individuals, and using this information when choosing between other males as associates. Such a strategy may increase a male's chances of being the individual chosen by a female assessing nearby males.     

Zooplankton responses to hypoxia: behavioral patterns and survival of three species of calanoid copepods

Seasonally recurrent and persistent hypoxic events in semi-enclosed coastal waters are characterized by bottom-water dissolved oxygen (d.o.) concentrations of < 2.0 ml l⁻¹. Shifts in the distribution patterns of zooplankters in association with these events have been documented, but the mechanisms responsible for these shifts have not been investigated. This study assessed interspecific differences in responses to hypoxia by several species of calanoid copepods common off Turkey Point, Florida, USA: Labidocera aestiva (Wheeler) (a summer/fall species), Acartia tonsa (Dana) (a ubiquitous year-round species), and Centropages hamatus (Lilljeborg) (a winter/spring species). Under conditions of moderate to severe hypoxia 24-h survival experiments were conducted for adults and nauplii of these species from August 1994 to October 1995. Experiments on adults used a flow-through system to maintain constant d.o. concentrations. Adults of A. tonsa showed no decline in survival with d.o. as low as 1.0 ml l⁻¹, sharp declines in survival at d.o. = 0.9 to 0.6 ml l⁻¹, and 100% mortality with d.o. = 0.5 ml l⁻¹. Adults of L. aestiva and C. hamatus were more sensitive to oxygen depletion: both species experienced significant decreases in survival for d.o. = 1.0 ml l⁻¹. Nauplii of L. aestiva and A. tonsa showed no significant mortality with d.o. = 1.1 to 1.5 ml␣l⁻¹ and d.o. = 0.24 to 0.5 ml l⁻¹, respectively. In addition, experiments investigating behavioral avoidance of moderate to severe hypoxia were carried out for adults of all three species. None of the three species effectively avoided either severely hypoxic (d.o. < 0.5 ml l⁻¹) or moderately hypoxic (d.o. ≈ 1.0 ml l⁻¹) bottom layers in stratified columns. These results suggest that in␣nearshore areas where development of zones of d.o. < 1.0 ml l⁻¹ may be sudden, widespread, or unpredictable, patterns of reduced copepod abundance in bottom waters may be due primarily to mortality rather than avoidance. Received: 31 August 1996 / Accepted: 24 September 1996     

Behavioural and electrophysiological responses of the olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), to male- and female-borne sex attractants

In the olive fruit fly, Bactrocera oleae, females attract males by producing 1,7-dioxaspiro[5.5]undecane (olean), the main component of the sex pheromone secreted by rectal glands. It has been recently demonstrated that males are able to produce (Z)-9-tricosene (muscalure) in rectal glands, a compound that selectively attracts females. In this study, a male grooming reaction that may transfer the male-borne compounds from rectal to urotergal glands was observed, suggesting that urotergal glands could be involved in B. oleae sexual communication. GC/MS, EAG, GC/EAD analyses and behavioural assays were carried out to compare the role of male rectal and urotergal glands during courtship. In both male glands, olean and muscalure amounts were age dependent. Extracts of rectal glands contained higher amounts of olean and/or muscalure than urotergal ones. Extracts of rectal and urotergal glands of males and females elicited EAG responses in both sexes. GC/EAD showed that female EAG response to male rectal extracts was mainly due to olean and muscalure. Synthetic compounds evoked EAG dose-dependent responses in both sexes, and the EAG response to muscalure was higher as compared to olean. Rectal and urotergal glands from old males were able to attract females, while urotergal glands from young males attracted only males. Overall, our results add knowledge to the mating system of B. oleae, giving first evidences on the electrophysiological activity of muscalure towards both sexes, as well as on the involvement of male urotergal glands in the chemical sexual communication of this pest.     

Interdemic variation in mixed-species association patterns: common diurnal primates of Kibale National Park, Uganda

We used interdemic variation in the tendency to form mixed-species groups to examine the costs and benefits of association among the primates of Kibale National Park, Uganda. A year-long survey of six sites revealed that the amount of time that the five common diurnal primates [red colobus (Procolobus tephrosceles), black-and-white colobus (Colobus guereza), redtail monkeys (Cercopithecus ascanius), blue monkeys (Cercopithecus mitis), and grey-cheeked mangabeys (Lophocebus albigena)] spent in mixed-species groups varied dramatically among sites. In many cases, the proportion of time that species associated was positively related to their densities. By using detailed behavioral observations of redtail monkeys and red colobus made over 4 years (2660 h) at four sites, we were able to reject the null hypothesis that associations occur by chance for only one of four sites. However, a correlative approach exploring the costs and benefits of association suggests that ecological variables do influence association patterns. We found that redtail monkeys and red colobus overlapped in diet (19.2% of their foraging effort) and traveled further when in mixed-species groups than when alone. Having demonstrated this, we examined the applicability of the ecological constraints model for predicting the proportion of the time spent in mixed-species groups based on food availability. For this analysis we concentrated on red colobus from the site with 35 months of observation and demonstrated that their tendency to be in mixed- species groups was related to food availability. We used two methods to examine if mixed-species associations function to decrease predation risk. First, chimpanzees are known to prey heavily on red colobus, but rarely kill other primates. The time red colobus spent in mixed-species groups was correlated to chimpanzee density, but it was not for the other monkey species, suggesting that mixed-species groups serve to decrease predation risk. Second, when red colobus groups contain more infants and are presumably at the greatest risk of predation, they form mixed-species groups most often. These results demonstrate that the costs and benefits of mixed-species associations vary dramatically over small spatial and temporal scales. If such variation is generally the case, then studies conducted at different locations or different times could easily highlight the importance of difference selective agents in favoring mixed-species associations. Received: 10 February 1999 / Received in revised form: 16 September 1999 / Accepted: 2 October 1999     

Production and perception of situationally variable alarm calls in wild tufted capuchin monkeys (Cebus apella nigritus)

Many mammalian and avian species produce conspicuous vocalizations upon encountering a predator, but vary their calling based on risk urgency and/or predator type. Calls falling into the latter category are termed “functionally referential” if they also elicit predator-appropriate reactions in listeners. Functionally referential alarm calling has been well documented in a number of Old World monkeys and lemurs, but evidence among Neotropical primates is limited. This study investigates the alarm call system of tufted capuchin monkeys (Cebus apella nigritus) by examining responses to predator and snake decoys encountered at various distances (reflecting differences in risk urgency). Observations in natural situations were conducted to determine if predator-associated calls were given in additional contexts. Results indicate the use of three call types. “Barks” are elicited exclusively by aerial threats, but the call most commonly given to terrestrial threats (the “hiccup”) is given in nonpredatory contexts. The rate in which this latter call is produced reflects risk urgency. Playbacks of these two call types indicate that each elicits appropriate antipredator behaviors. The third call type, the “peep,” seems to be specific to terrestrial threats, but it is unknown if the call elicits predator-specific responses. “Barks” are thus functionally referential aerial predator calls, while “hiccups” are better seen as generalized disturbance calls which reflect risk urgency. Further evidence is needed to draw conclusions regarding the “peep.” These results add to the evidence that functionally referential aerial predator alarm calls are ubiquitous in primates, but that noncatarrhine primates use generalized disturbance calls in response to terrestrial threats.     

Population differences in male responses to chemical mating cues in the white-spotted longicorn beetle, Anoplophora malasiaca

Adult Anoplophora malasiaca beetles were collected from field populations inhabiting three different host plants: Citrus, Salix and Vaccinium. Male orientation responses towards odours of wounded branches of each host plant were examined. Males of all three populations were attracted most frequently to odours of their original hosts, indicating that male orientation behaviour was induced by the odours of the plants from which they were originally collected. We also observed the mating responses of the males to elytra extracts from young and mature females of the three populations and chemically analysed those extracts. Citrus males were highly responsive to female extracts, regardless of origin. Salix males were less reactive than Citrus males, but responded moderately to female extracts of all populations. Vaccinium males were never attracted to Citrus female extracts and responded more to extracts from mature Vaccinium and Salix females, indicating that males might distinguish female origin and maturity. All eight hydrocarbons, four ketones, and three lactones that were previously identified as female contact sex pheromones were found in the extracts of three populations and both ages. Higher amounts of lactones on mature females likely caused greater male responses. These results suggested that males would be more likely to approach a female feeding on the same host plant and subsequently recognise her sexual maturity based on the profile of contact sex pheromones on her elytra.     

Association patterns of spider monkeys: the influence of ecology and sex on social organization

Summary In this paper I consider how the costs and benefits of group living in spider monkeys (Ateles geoffroyi) vary between troop members. The results suggest that ecological factors set an upper limit to the number of spider monkeys that can associate and still efficiently exploit the available resources. In addition, the needs of the individual appears to influence the type and size of the subgroup it chooses. Adult males band together, travel over a large area, and are frequently sighted near the community's boundary. In contrast, adult females spend more time solitary than males and have association patterns that are strongly influenced by the presence of a dependent infant. Females with dependent infants tend to travel in small subgroups or alone, avoid the boundaries of the community's home range, and exhibit a restricted pattern of use of their range. The results suggest that males may be attempting to locate females with which they can breed, while mothers attempt to protect their infants by avoiding conspecifics and potentially dangerous situations near territorial boundaries.     

Variability in the spatial association patterns of sponge assemblages in response to environmental heterogeneity

Previous work on tropical sponge assemblages has provided strong evidence that sponges coexist on coral reefs through a diversity of positive and negative associations; however, the majority of this work has focused on Caribbean coral reefs. Here, we investigate the intra-phyletic spatial associations between the 20 most abundant sponge species at two sites experiencing different environmental regimes in the Wakatobi National Marine Park, Indonesia. We used a Monte Carlo simulation approach to compare the number of spatial associations between each species pair to that expected if species distribution patterns were non-associative (i.e. random). We found that sponges were predominately randomly distributed at the high coral cover site, whereas most sponges were negatively associated with other sponges at the sedimented, low coral cover site. We also found differences between distribution patterns for specific species at the two sites; a number of species that showed a random distribution pattern at the high coral cover site had negative association patterns at the low coral cover site. Our research supports recent ecological studies suggesting that interactions between species are unlikely to be homogenously distributed, as we found that some sponge species interactions differed depending on the environmental regimes in which they were found; this suggests that species interactions may be spatially variable. Finally, our results contrast with studies from elsewhere, as the sponge assemblages at these two sites in the Wakatobi appear to be dominated by negative associations and random distribution patterns rather than widespread competition.     

Behavioural switching in a central place forager: patterns of diving behaviour in the macaroni penguin (Eudyptes chrysolophus)

Recording the activity of animals as they migrate or forage has proven hugely advantageous to understanding how animals use their environment. Where animals cannot be directly observed, the problem remains of how to identify distinct behaviours that represent an animal’s decision-making process. An excellent example of this problem is that of foraging penguins, which travel to sea to find prey to provision their young. Without direct sampling of the prey field, we cannot calibrate patterns of movement with prey capture, and therefore we cannot determine how different activities link to decision-making. To overcome this, we use a hidden markov model (HMM), which is a machine-learning technique that seeks to identify the underlying states of a system from observable outputs. We apply HMM to determine classes of behaviour from repetitive dives. We take dive data from 103 breeding macaroni penguins at Bird Island, South Georgia, for which we have measures of weight gain over a trip. We identify two classes of behaviour; those of short-shallow and long-deep dives. Using these two behaviours, we calculate the transition probabilities between these states and analyse these data to determine what predicts variation in the transition probabilities. We found that the stage of reproduction during a season, the sex and year of an individual influenced the probability of transition between long-deep and short-shallow sequential dives. We also found differences in the hourly transition rates between the four reproductive stages (incubation, broodguard, crèche and premoult) over a daily cycle. We conclude that this application of HMMs for behavioural switching is potentially useful for other species and other types of recorded behaviour.