Territorial contests often occur in the presence of conspecifics not directly involved in the int... more Territorial contests often occur in the presence of conspecifics not directly involved in the interaction. Actors may alter their behavior in the presence of this audience, an "audience effect," and audiences themselves may alter their behavior as a result of observing an interaction, a "bystander effect." Previous work has documented these effects by looking at each in isolation, but to our knowledge, none has investigated their interaction; something that is more likely to represent a realistic scenario for species where individuals aggregate spatially. We therefore have a somewhat limited understanding of the extent and direction of these potentially complex indirect social effects on behavior. Here, we examined how audience and bystander effects work in tandem to modify resident male aggressive behavior towards intruders in European fiddler crabs, Afruca tangeri. We found that male crabs with an audience showed greater aggressive behavior towards an intruder compared with males without an audience, but only if they had acted as a bystander to an aggressive signaling interaction prior to the intrusion. Indeed, bystanding during aggressive interactions elevated aggressive responses to intruders maximally if there was an audience present. Our results suggest that bystanding had a priming effect on territory-holding males, potentially by providing information on the immediate level of competition in the local neighborhood, and that same-sex audiences only matter if males have been primed. This study highlights the fundamental importance of considering broader interaction networks in studying real-world dyadic interactions and of including nonvertebrate taxonomic groups in these studies.
In the hole-nesting pied flycatcher, Ficedula hypoleuca, a male may become polyterritorial after ... more In the hole-nesting pied flycatcher, Ficedula hypoleuca, a male may become polyterritorial after attracting a primary female. However, the female may recognize her mate's song and attack other females that associate with him. Differences in sound degradation amongst different habitats and within nestboxes may, therefore, be important for male and female behaviour since the male may have to move outside female hearing range to avoid harassment, and the female may have to listen for the mate to be able to locate competing females. This may be difficult from inside the nest cavity. We used ten common song elements to test sound degradation with distance in a mixed coniferous and a mixed deciduous forest, measuring broadcast sounds both inside and outside nestboxes. On average, sound degradation increased to a larger extent with distance in the deciduous than the coniferous forest. This is consistent with the shorter polyterritorial distances of flycatchers in the deciduous forest. Furthermore, song degradation was stronger inside the nestboxes. Being inside may, therefore, reduce a female's possibility of detecting and recognizing songs. This may be one reason why female pied flycatchers spend little time within the nest cavity before incubation unlike some other hole nesting species.
Journal of the Acoustical Society of America, Apr 1, 1993
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Journal of the Acoustical Society of America, Aug 1, 2008
The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effec... more The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effect of propagation on individual identity information in vocalizations were quantified in a transmission experiment in prairie habitat. Sounds were propagated ͑0.45 m above the ground͒ at distances up to 400 m. Effects of transmission were measured on three sound types: synthesized sweeps with 1.3 kHz bandwidths spanning in the range of 0.3-8.0 kHz; single elements of swift fox barking sequences ͑frequency range of 0.3-4.0 kHz͒ and complete barking sequences. Synthesized sweeps spanning 0.3-1.6 and 1.2-2.5 kHz propagated the furthest and the latter sweeps exhibited the best transmission properties for long-range propagation. Swift fox barking sequence elements are centered toward the lower end of this frequency range. Nevertheless, measurable individual spectral characteristics of the barking sequence seem to persist to at least 400 m. Individual temporal features were very consistent to at least 400 m. The communication range of the barking sequences is likely to be farther than 400 m and it should be considered a long-ranging vocalization. However, relative to the large home ranges of swift foxes ͑up to 16 km 2 in the experimental area͒ the barking sequence probably functions at intermediate distances.
Territorial contests often occur in the presence of conspecifics not directly involved in the int... more Territorial contests often occur in the presence of conspecifics not directly involved in the interaction. Actors may alter their behaviour in the presence of this audience, an ‘audience effect’, and audiences themselves may alter their behaviour as a result of observing an interaction, a ‘bystander effect’. Previous work has documented these effects by looking at each in isolation, but to our knowledge, none has investigated their interaction; something that is more likely to represent a realistic scenario for species where individuals aggregate spatially. We therefore have a somewhat limited understanding of the extent and direction of these potentially complex indirect social effects on behaviour. Here we examined how audience and bystander effects work in tandem to modify resident male aggressive behaviour towards intruders in European fiddler crabs, Afruca tangeri. We found that male crabs with an audience showed greater aggressive behaviour towards an intruder compared to males without an audience, but only if they had acted as a bystander to an aggressive signalling interaction prior to the intrusion. Indeed, bystanding during aggressive interactions elevated aggressive responses to intruders maximally if there was an audience present. Our results suggest that bystanding had a priming effect on territory-holding males, potentially by providing information on the immediate level of competition in the local neighbourhood, and that same-sex audiences only matter if males have been primed. This study highlights the fundamental importance of considering broader interaction networks in studying real-world dyadic interactions and of including non-vertebrate taxonomic groups in these studies
Background The European population of hedgehogs (Erinaceus europaeus) is declining. It is therefo... more Background The European population of hedgehogs (Erinaceus europaeus) is declining. It is therefore essential to optimise conservation initiatives such as the rehabilitation of sick, injured and orphaned hedgehogs. Wild animals placed in captivity may be prone to chronic stress, potentially causing negative health effects. Therefore, the effects of these rehabilitation efforts should consequently be evaluated. Furthermore, hand-raising orphaned hedgehogs is a laborious and costly task, and it is therefore relevant to document whether they have equal post release survival rates compared to their wild conspecifics. The objectives of this research were therefore to conduct an exploratory study of glucocorticoid levels in hedgehogs from different backgrounds and compare the post release survival of translocated, rehabilitated and wild, juvenile hedgehogs as well as the possible effect on survival of differences in shy or bold behaviour (personality) exhibited by individuals. Results We ...
Low-frequency ambient noise is known to cause shifts in the song frequency of different species o... more Low-frequency ambient noise is known to cause shifts in the song frequency of different species of songbirds, such as the Great Tit (Parus major). The present study was conducted to test the generality of these findings by measuring the distribution of energy across the spectrum of songs of the Great Tit. The studied individuals were either exposed to low-frequency ambient traffic noise in an urban environment (Copenhagen, Denmark) or not exposed to such an environment (the Strødam Reserve north of Copenhagen). A trend throughout all frequency-energy quartiles illustrated that the species sang at an elevated frequency in urban environments compared to rural ones, and that both the upperand lower-frequency-energy quartiles were signifcantly higher in the former.
Songbirds can vary the timing of song production with respect to other singing individuals on a s... more Songbirds can vary the timing of song production with respect to other singing individuals on a song-by-song timescale, for example birds may overlap songs or alternate singing and thereby avoid overlap. Playback was used to study the information contained in such timing of song exchanges in territorial male robins, Erithacus rubecula. The results are consistent with the idea that interacting with a singer either by overlapping or alternating is a way of indicating the intended receiver whereas non-interactive (loop) playback does not give this information. Furthermore, an overlapping pattern of singing generally elicited responses characteristic of highly aroused males. In robins this is shown by a rapid approach and change to an almost continuous, low amplitude pattern of singing referred to as twittering. Thus overlapping could be taken as indicating a high degree of arousal or a willingness to escalate. The response changed during the experimental period, with twittering responses becoming more common regardless of playback treatment. This result is consistent with experimental males having gathered information from interactions between playback and their neighbours in previous trials, that is, they collected information by eavesdropping.
Most territorial songbirds live in communication networks where eavesdropping on vocal interactio... more Most territorial songbirds live in communication networks where eavesdropping on vocal interactions may constitute an important option for gathering information regarding the relative dominance, condition and quality of individuals being eavesdropped upon. The relatively low costs and risks of eavesdropping, together with the obvious advantages of gaining such comparative information about other individuals, predict eavesdropping to be a widespread phenomenon even though it is not necessarily advantageous for the participants to be eavesdropped upon. Special eavesdropper strategies that facilitate eavesdropping (how best to eavesdrop) may therefore have evolved together with strategies for interacting that either co-facilitate (public signaling) or counter eavesdropping directly (private signaling) or indirectly by preventing any subsequent negative consequences of being eavesdropped upon (anonymity). This paper reviews the predictions for the strategies and also gives examples supp...
The ability to imitate complex sounds is rare, and among birds has been found only in parrots, so... more The ability to imitate complex sounds is rare, and among birds has been found only in parrots, songbirds, and hummingbirds. Parrots exhibit the most advanced vocal mimicry among non-human animals. A few studies have noted differences in connectivity, brain position and shape in the vocal learning systems of parrots relative to songbirds and hummingbirds. However, only one parrot species, the budgerigar, has been examined and no differences in the presence of song system structures were found with other avian vocal learners. Motivated by questions of whether there are important differences in the vocal systems of parrots relative to other vocal learners, we used specialized constitutive gene expression, singing-driven gene expression, and neural connectivity tracing experiments to further characterize the song system of budgerigars and/or other parrots. We found that the parrot brain uniquely contains a song system within a song system. The parrot "core" song system is simi...
... Exam-ples have been reported in which birds were heard singing with different volumes dependi... more ... Exam-ples have been reported in which birds were heard singing with different volumes depending on the motivational state of the bird. ... 145 The result of the sp1. measurements is supported by measurements achieved with similar equipment by SVANE (pers. ...
Parrots are renowned for their vocal learning abilities. Yet only few parrot species have been in... more Parrots are renowned for their vocal learning abilities. Yet only few parrot species have been investigated and empirically proven to possess vocal learning abilities. The aim of this study was to investigate if short-term vocal learning may be a widespread phenomenon among Psittaciformes. Through an interactive experiment we compare the ability of four parrot species, the peach-fronted conure (Aratinga aurea), the cockatiel (Nymphicus hollandicus), the peach-faced lovebird (Agapornis roseicollis) and the budgerigar (Melopsittacus undulatus), to vocally match playback of contact calls. All four species made an overall change to their contact call in response to the playback, and they also varied the degree of similarity with the playback call throughout the playback experiment. The peach-fronted conure showed the biggest overall changes to their contact calls by vocally matching the playback call and the budgerigar showed the least change. The cockatiel and the peach-faced lovebird ...
Animal personality research is receiving increasing interest from related fields, such as evoluti... more Animal personality research is receiving increasing interest from related fields, such as evolutionary personality psychology. By merging the conceptual understanding of personality, the contributions to both fields of research may be enhanced. In this study, we investigate animal personality based on the definition of personality traits as underlying dispositional factors, which are not directly measurable, but which predispose individuals to react through different behavioural patterns. We investigated the shyness-boldness continuum reflected in the consistency of inter-individual variation in behavioural responses towards novelty in 47 farmed American mink (Neovison vison), which were raised in identical housing conditions. Different stages of approach behaviour towards novelty, and how these related within and across contexts, were explored. Our experimental design contained four tests: two novel object tests (non-social contexts) and two novel animated stimuli tests (social con...
ABSTRACT In several avian and mammal social species, contact calls are hypothesized to function i... more ABSTRACT In several avian and mammal social species, contact calls are hypothesized to function in maintaining group cohesion, coordinating activities between group members and negotiating fissions and fusions of multiple groups during foraging and roosting. They are therefore expected to exhibit acoustic features that make them suitable for communication of identity information. We investigated this in the monomorphic Peach-fronted Conure, a tropical parakeet living in open forest and scrubland habitats. The species is highly social outside the breeding season where it is assumed to live in a fission–fusion social system. In this study, contact calls from 10 visually isolated male and female Peach-fronted Conures were recorded outside the breeding season. Results from the multivariate analysis of variance and spectrographic cross-correlation with principal coordinates analysis procedure showed that contact calls varied highly between individuals and indicated that caller identity could be encoded in the duration, peak frequency, max frequency and 25%, 50% and 75% frequency energy quartiles of contact calls. The 50% frequency and 75% energy quartile was also significantly higher for females than for males. Furthermore, the results showed an inverse relationship between two morphometric measures and two spectral parameters, suggesting that variation in call parameters could also allow receivers to obtain information about the body size of the caller. Discriminant function analysis showed that contact calls could be correctly classified to individuals in 100% and to sexes in 91% of the cases, suggesting that there is sufficient variation in contact call parameters to enable vocal recognition of individuals and sex.
Strong social bonds can make an important contribution to individual fitness, but we still have o... more Strong social bonds can make an important contribution to individual fitness, but we still have only a limited understanding of the temporal period relevant to the adjustment of social relationships. While there is growing recognition of the importance of strong bonds that persist for years, social relationships can also vary over weeks and months, suggesting that social strategies may be optimized over shorter timescales. Using biological market theory as a framework, we explore whether temporal variation in the benefits of social relationships might be sufficient to generate daily adjustments of social strategies in wild baboons. Data on grooming, one measure of social relationships, were collected from 60 chacma baboons (Papio ursinus) across two troops over a six month period. Our analyses suggest that social strategies can show diurnal variation, with subordinates preferentially grooming more dominant individuals earlier in the day compared with later in the day. These findings...
Territorial contests often occur in the presence of conspecifics not directly involved in the int... more Territorial contests often occur in the presence of conspecifics not directly involved in the interaction. Actors may alter their behavior in the presence of this audience, an "audience effect," and audiences themselves may alter their behavior as a result of observing an interaction, a "bystander effect." Previous work has documented these effects by looking at each in isolation, but to our knowledge, none has investigated their interaction; something that is more likely to represent a realistic scenario for species where individuals aggregate spatially. We therefore have a somewhat limited understanding of the extent and direction of these potentially complex indirect social effects on behavior. Here, we examined how audience and bystander effects work in tandem to modify resident male aggressive behavior towards intruders in European fiddler crabs, Afruca tangeri. We found that male crabs with an audience showed greater aggressive behavior towards an intruder compared with males without an audience, but only if they had acted as a bystander to an aggressive signaling interaction prior to the intrusion. Indeed, bystanding during aggressive interactions elevated aggressive responses to intruders maximally if there was an audience present. Our results suggest that bystanding had a priming effect on territory-holding males, potentially by providing information on the immediate level of competition in the local neighborhood, and that same-sex audiences only matter if males have been primed. This study highlights the fundamental importance of considering broader interaction networks in studying real-world dyadic interactions and of including nonvertebrate taxonomic groups in these studies.
In the hole-nesting pied flycatcher, Ficedula hypoleuca, a male may become polyterritorial after ... more In the hole-nesting pied flycatcher, Ficedula hypoleuca, a male may become polyterritorial after attracting a primary female. However, the female may recognize her mate's song and attack other females that associate with him. Differences in sound degradation amongst different habitats and within nestboxes may, therefore, be important for male and female behaviour since the male may have to move outside female hearing range to avoid harassment, and the female may have to listen for the mate to be able to locate competing females. This may be difficult from inside the nest cavity. We used ten common song elements to test sound degradation with distance in a mixed coniferous and a mixed deciduous forest, measuring broadcast sounds both inside and outside nestboxes. On average, sound degradation increased to a larger extent with distance in the deciduous than the coniferous forest. This is consistent with the shorter polyterritorial distances of flycatchers in the deciduous forest. Furthermore, song degradation was stronger inside the nestboxes. Being inside may, therefore, reduce a female's possibility of detecting and recognizing songs. This may be one reason why female pied flycatchers spend little time within the nest cavity before incubation unlike some other hole nesting species.
Journal of the Acoustical Society of America, Apr 1, 1993
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Journal of the Acoustical Society of America, Aug 1, 2008
The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effec... more The acoustic environment of swift foxes Vulpes velox vocalizing close to the ground and the effect of propagation on individual identity information in vocalizations were quantified in a transmission experiment in prairie habitat. Sounds were propagated ͑0.45 m above the ground͒ at distances up to 400 m. Effects of transmission were measured on three sound types: synthesized sweeps with 1.3 kHz bandwidths spanning in the range of 0.3-8.0 kHz; single elements of swift fox barking sequences ͑frequency range of 0.3-4.0 kHz͒ and complete barking sequences. Synthesized sweeps spanning 0.3-1.6 and 1.2-2.5 kHz propagated the furthest and the latter sweeps exhibited the best transmission properties for long-range propagation. Swift fox barking sequence elements are centered toward the lower end of this frequency range. Nevertheless, measurable individual spectral characteristics of the barking sequence seem to persist to at least 400 m. Individual temporal features were very consistent to at least 400 m. The communication range of the barking sequences is likely to be farther than 400 m and it should be considered a long-ranging vocalization. However, relative to the large home ranges of swift foxes ͑up to 16 km 2 in the experimental area͒ the barking sequence probably functions at intermediate distances.
Territorial contests often occur in the presence of conspecifics not directly involved in the int... more Territorial contests often occur in the presence of conspecifics not directly involved in the interaction. Actors may alter their behaviour in the presence of this audience, an ‘audience effect’, and audiences themselves may alter their behaviour as a result of observing an interaction, a ‘bystander effect’. Previous work has documented these effects by looking at each in isolation, but to our knowledge, none has investigated their interaction; something that is more likely to represent a realistic scenario for species where individuals aggregate spatially. We therefore have a somewhat limited understanding of the extent and direction of these potentially complex indirect social effects on behaviour. Here we examined how audience and bystander effects work in tandem to modify resident male aggressive behaviour towards intruders in European fiddler crabs, Afruca tangeri. We found that male crabs with an audience showed greater aggressive behaviour towards an intruder compared to males without an audience, but only if they had acted as a bystander to an aggressive signalling interaction prior to the intrusion. Indeed, bystanding during aggressive interactions elevated aggressive responses to intruders maximally if there was an audience present. Our results suggest that bystanding had a priming effect on territory-holding males, potentially by providing information on the immediate level of competition in the local neighbourhood, and that same-sex audiences only matter if males have been primed. This study highlights the fundamental importance of considering broader interaction networks in studying real-world dyadic interactions and of including non-vertebrate taxonomic groups in these studies
Background The European population of hedgehogs (Erinaceus europaeus) is declining. It is therefo... more Background The European population of hedgehogs (Erinaceus europaeus) is declining. It is therefore essential to optimise conservation initiatives such as the rehabilitation of sick, injured and orphaned hedgehogs. Wild animals placed in captivity may be prone to chronic stress, potentially causing negative health effects. Therefore, the effects of these rehabilitation efforts should consequently be evaluated. Furthermore, hand-raising orphaned hedgehogs is a laborious and costly task, and it is therefore relevant to document whether they have equal post release survival rates compared to their wild conspecifics. The objectives of this research were therefore to conduct an exploratory study of glucocorticoid levels in hedgehogs from different backgrounds and compare the post release survival of translocated, rehabilitated and wild, juvenile hedgehogs as well as the possible effect on survival of differences in shy or bold behaviour (personality) exhibited by individuals. Results We ...
Low-frequency ambient noise is known to cause shifts in the song frequency of different species o... more Low-frequency ambient noise is known to cause shifts in the song frequency of different species of songbirds, such as the Great Tit (Parus major). The present study was conducted to test the generality of these findings by measuring the distribution of energy across the spectrum of songs of the Great Tit. The studied individuals were either exposed to low-frequency ambient traffic noise in an urban environment (Copenhagen, Denmark) or not exposed to such an environment (the Strødam Reserve north of Copenhagen). A trend throughout all frequency-energy quartiles illustrated that the species sang at an elevated frequency in urban environments compared to rural ones, and that both the upperand lower-frequency-energy quartiles were signifcantly higher in the former.
Songbirds can vary the timing of song production with respect to other singing individuals on a s... more Songbirds can vary the timing of song production with respect to other singing individuals on a song-by-song timescale, for example birds may overlap songs or alternate singing and thereby avoid overlap. Playback was used to study the information contained in such timing of song exchanges in territorial male robins, Erithacus rubecula. The results are consistent with the idea that interacting with a singer either by overlapping or alternating is a way of indicating the intended receiver whereas non-interactive (loop) playback does not give this information. Furthermore, an overlapping pattern of singing generally elicited responses characteristic of highly aroused males. In robins this is shown by a rapid approach and change to an almost continuous, low amplitude pattern of singing referred to as twittering. Thus overlapping could be taken as indicating a high degree of arousal or a willingness to escalate. The response changed during the experimental period, with twittering responses becoming more common regardless of playback treatment. This result is consistent with experimental males having gathered information from interactions between playback and their neighbours in previous trials, that is, they collected information by eavesdropping.
Most territorial songbirds live in communication networks where eavesdropping on vocal interactio... more Most territorial songbirds live in communication networks where eavesdropping on vocal interactions may constitute an important option for gathering information regarding the relative dominance, condition and quality of individuals being eavesdropped upon. The relatively low costs and risks of eavesdropping, together with the obvious advantages of gaining such comparative information about other individuals, predict eavesdropping to be a widespread phenomenon even though it is not necessarily advantageous for the participants to be eavesdropped upon. Special eavesdropper strategies that facilitate eavesdropping (how best to eavesdrop) may therefore have evolved together with strategies for interacting that either co-facilitate (public signaling) or counter eavesdropping directly (private signaling) or indirectly by preventing any subsequent negative consequences of being eavesdropped upon (anonymity). This paper reviews the predictions for the strategies and also gives examples supp...
The ability to imitate complex sounds is rare, and among birds has been found only in parrots, so... more The ability to imitate complex sounds is rare, and among birds has been found only in parrots, songbirds, and hummingbirds. Parrots exhibit the most advanced vocal mimicry among non-human animals. A few studies have noted differences in connectivity, brain position and shape in the vocal learning systems of parrots relative to songbirds and hummingbirds. However, only one parrot species, the budgerigar, has been examined and no differences in the presence of song system structures were found with other avian vocal learners. Motivated by questions of whether there are important differences in the vocal systems of parrots relative to other vocal learners, we used specialized constitutive gene expression, singing-driven gene expression, and neural connectivity tracing experiments to further characterize the song system of budgerigars and/or other parrots. We found that the parrot brain uniquely contains a song system within a song system. The parrot "core" song system is simi...
... Exam-ples have been reported in which birds were heard singing with different volumes dependi... more ... Exam-ples have been reported in which birds were heard singing with different volumes depending on the motivational state of the bird. ... 145 The result of the sp1. measurements is supported by measurements achieved with similar equipment by SVANE (pers. ...
Parrots are renowned for their vocal learning abilities. Yet only few parrot species have been in... more Parrots are renowned for their vocal learning abilities. Yet only few parrot species have been investigated and empirically proven to possess vocal learning abilities. The aim of this study was to investigate if short-term vocal learning may be a widespread phenomenon among Psittaciformes. Through an interactive experiment we compare the ability of four parrot species, the peach-fronted conure (Aratinga aurea), the cockatiel (Nymphicus hollandicus), the peach-faced lovebird (Agapornis roseicollis) and the budgerigar (Melopsittacus undulatus), to vocally match playback of contact calls. All four species made an overall change to their contact call in response to the playback, and they also varied the degree of similarity with the playback call throughout the playback experiment. The peach-fronted conure showed the biggest overall changes to their contact calls by vocally matching the playback call and the budgerigar showed the least change. The cockatiel and the peach-faced lovebird ...
Animal personality research is receiving increasing interest from related fields, such as evoluti... more Animal personality research is receiving increasing interest from related fields, such as evolutionary personality psychology. By merging the conceptual understanding of personality, the contributions to both fields of research may be enhanced. In this study, we investigate animal personality based on the definition of personality traits as underlying dispositional factors, which are not directly measurable, but which predispose individuals to react through different behavioural patterns. We investigated the shyness-boldness continuum reflected in the consistency of inter-individual variation in behavioural responses towards novelty in 47 farmed American mink (Neovison vison), which were raised in identical housing conditions. Different stages of approach behaviour towards novelty, and how these related within and across contexts, were explored. Our experimental design contained four tests: two novel object tests (non-social contexts) and two novel animated stimuli tests (social con...
ABSTRACT In several avian and mammal social species, contact calls are hypothesized to function i... more ABSTRACT In several avian and mammal social species, contact calls are hypothesized to function in maintaining group cohesion, coordinating activities between group members and negotiating fissions and fusions of multiple groups during foraging and roosting. They are therefore expected to exhibit acoustic features that make them suitable for communication of identity information. We investigated this in the monomorphic Peach-fronted Conure, a tropical parakeet living in open forest and scrubland habitats. The species is highly social outside the breeding season where it is assumed to live in a fission–fusion social system. In this study, contact calls from 10 visually isolated male and female Peach-fronted Conures were recorded outside the breeding season. Results from the multivariate analysis of variance and spectrographic cross-correlation with principal coordinates analysis procedure showed that contact calls varied highly between individuals and indicated that caller identity could be encoded in the duration, peak frequency, max frequency and 25%, 50% and 75% frequency energy quartiles of contact calls. The 50% frequency and 75% energy quartile was also significantly higher for females than for males. Furthermore, the results showed an inverse relationship between two morphometric measures and two spectral parameters, suggesting that variation in call parameters could also allow receivers to obtain information about the body size of the caller. Discriminant function analysis showed that contact calls could be correctly classified to individuals in 100% and to sexes in 91% of the cases, suggesting that there is sufficient variation in contact call parameters to enable vocal recognition of individuals and sex.
Strong social bonds can make an important contribution to individual fitness, but we still have o... more Strong social bonds can make an important contribution to individual fitness, but we still have only a limited understanding of the temporal period relevant to the adjustment of social relationships. While there is growing recognition of the importance of strong bonds that persist for years, social relationships can also vary over weeks and months, suggesting that social strategies may be optimized over shorter timescales. Using biological market theory as a framework, we explore whether temporal variation in the benefits of social relationships might be sufficient to generate daily adjustments of social strategies in wild baboons. Data on grooming, one measure of social relationships, were collected from 60 chacma baboons (Papio ursinus) across two troops over a six month period. Our analyses suggest that social strategies can show diurnal variation, with subordinates preferentially grooming more dominant individuals earlier in the day compared with later in the day. These findings...
Uploads
Papers by T. Dabelsteen