The Journal of the Acoustical Society of America, 2006
Communication is a key aspect of any mating system and is a dramatic feature in the mating behavi... more Communication is a key aspect of any mating system and is a dramatic feature in the mating behavior of North American bison. During their reproductive season, bison bulls defend females from other males by establishing dominance through contests involving multiple signals, the most prominent being the bellow vocalization. While acknowledged that amplitude may be involved in sexual selection, it is rarely measured directly in the field (especially in large mammals) due to difficulties in accurately assessing this parameter. Using strict methodologies accounting for many sources of potential error, the impact that a variety of factors had on bellow amplitude was examined. Amplitude was measured in dB with Lamax and Lcpeak weighting. Parameters increasing amplitude (order of decreasing impact): Number of surrounding bulls bellowing, wind levels, and number of surrounding bulls. Parameters decreasing amplitude (order of decreasing impact): Distance, head orientation, days spent in rut, time of day, number of ...
... Recent studies have documented that in growing calves a single en-gorging female tick produce... more ... Recent studies have documented that in growing calves a single en-gorging female tick produces a growth decrement in the range of 0.6—10.0 g, depending upon the tick species (Norval et al., 1988, 1989; Pegram et ... Drawn from a photograph by Emma Mooring. ...
ABSTRACT Source-filter theory provides a framework to interpret the acoustic structure of vertebr... more ABSTRACT Source-filter theory provides a framework to interpret the acoustic structure of vertebrate vocalizations in relation to biophysical production, and it predicts that specific acoustic parameters can encode information about callers. Because formant frequencies are determined by vocal tract dimensions, with longer vocal tracts producing lower formants, they can be reliable indicators of body size, as well as other important traits. In polygynous species, reliable acoustic cues to fitness-related traits are expected to be under strong sexual selection pressure through male competition and/or female choice. This study investigates whether formant frequencies of male North American bison bellow vocalizations encode information about fitness-related caller attributes. Bison exhibit male-dominance female-defence polygyny, with dominance displays involving bellows. We hypothesized that physical attributes (mass, age) would predict formants and that formants would in turn predict quality indices (dominance, copulations, offspring sired). Our results showed that heavier bulls produced lower formants and that lower formants predicted higher mating success (copulations), even when controlling for mass. Given positive associations between mating success, dominance and reproductive success (offspring sired) in bison, we conclude that bellows with lower formants reflect greater fitness in bulls. We discuss the importance of reliable acoustic cues to size and quality indices in sexual selection contexts. Acoustic signals can be sexually selected if they generate infor-mation about the signaller that enables the signaller or receivers to increase their reproductive success in the context of mate compe-tition or mate choice (Andersson 1994; Espmark et al. 2000). The information contained in these signals can include the caller's competitive ability, quality, condition, motivation or sexual recep-tivity (Bradbury & Vehrencamp 1998). The accuracy or 'honesty' of the information within these signals can be maintained if the signal is costly to produce (Zahavi 1975; Grafen 1990; Zahavi & Zahavi 1997; Vehrencamp 2000) or is controlled by physiological constraints that cannot be faked (Vehrencamp 2000; Fitch & Hauser 2002). The 'source-filter theory' of vocal production examines the causal links between the constraints of vocal anatomy, the physics of sound production and propagation and the specific acoustic properties of the resultant signal (Fant 1960; Titze 1994). Increasingly, this theory has been applied to studies of nonhuman mammal vocalizations, resulting in significant advances for animal communication research (reviewed in Taylor & Reby 2010). The source-filter theory examines vocal production in two independent stages (Fant 1960). In the first stage (the source), air is forced from the lungs through the larynx to create a glottal wave from vocal fold vibrations. This glottal wave (source signal) contains a fundamental frequency with integer multiple harmonics that initially determines the pitch of the voiced signal. In the second stage (the filter), the glottal wave passes through the supralaryngeal vocal tract, which acts as a resonance filter on the wave by selec-tively amplifying or attenuating certain frequencies. This filtering process creates 'formants' or amplified resonant frequency bands within the signal, visible as peaks in the spectral envelope (Titze 1994). The source-filter theory predicts that reliable and indica-tive information about the caller can be generated independently in both the source (typically as fundamental frequency-related parameters) and the filter (typically as formant frequencies). The acoustic properties of these source-filter signals can potentially provide receivers with specific information about the caller, including measures of identity, sex, size, quality, condition,
Page 1. Afr. J. Ecol. 1990, Volume 28, pages 24G249 Differential foraging of oxpeckers on impala ... more Page 1. Afr. J. Ecol. 1990, Volume 28, pages 24G249 Differential foraging of oxpeckers on impala in comparison with sympatric antelope species BENJAMIN L. HART, LYNETTE A. HART and MICHAEL S. MOORING Department ...
Premature loss of winter hair coat can be a serious problem for moose (Alces alces), possibly lea... more Premature loss of winter hair coat can be a serious problem for moose (Alces alces), possibly leading to escalated heat loss and depleted reserves. Studies of captive moose have indicated that premature winter hair loss is associated with infestation by winter ticks (Dermacentor albipictus), and the extent of hair loss is associated with grooming efforts directed at removing the ticks. In this study we observed the grooming behaviour and hair-loss patterns of wild moose throughout the winter to test the prediction that the extent of hair loss would be positively correlated with the rate of grooming actions (oral grooming, scratching, and rubbing). Moose were observed throughout the winter of 1995-1996 at Elk Island National Park, Alberta. Both the proportion of hair loss and the rate of grooming increased from October through April, with hair-loss and grooming rates highest during the period of adult tick engorgement in March and April. Correlation analysis showed that moose which g...
In Experiment 1, five adult female impala were fitted with harnesses that restrained oral self-gr... more In Experiment 1, five adult female impala were fitted with harnesses that restrained oral self-grooming of the anterior part of the body. At the same time, six cohoused female impala were fitted with control harnesses that allowed normal oral grooming. The impala were allowed to habituate to the harnesses for 10 days, and both groups were then exposed to larval ticks (Boophilus decoloratus) by herding them into a tick-seeding corral. During the third week following tick seeding, when female ticks were estimated to have developed into engorging adults, the impala were immobilized, tick numbers on the animals sampled by patch sampling, and the harnesses removed. Observations continued for 5 days following removal of the harnesses. Twenty-minute focal observations were conducted daily on each impala during the habituation, tick-seeded, and postharness phases. Restrained impala had a median of 20 times more adult female ticks (both engorged and unengorged) than control impala. Oral groo...
... Michael S. Mooring a b , Thomas A. Fitzpatrick a , Ian C. Fraser a , Jill E. Benjamin a , Dom... more ... Michael S. Mooring a b , Thomas A. Fitzpatrick a , Ian C. Fraser a , Jill E. Benjamin a , Dominic D. Reisig a , and Tara T. Nishihira a. ... Bighorn sheep generally bedded on upper slopes and rocky outcrops exposed to gusts of wind. ...
... and provided a unique opportunity to collect behavioral data on a wild population ... However... more ... and provided a unique opportunity to collect behavioral data on a wild population ... However, studies of other populations of mountain sheep have reported an interaction between habitat ... Our results indicate that during the summer months of sexual segregation Class 3/4 males at ...
The Journal of the Acoustical Society of America, 2006
Communication is a key aspect of any mating system and is a dramatic feature in the mating behavi... more Communication is a key aspect of any mating system and is a dramatic feature in the mating behavior of North American bison. During their reproductive season, bison bulls defend females from other males by establishing dominance through contests involving multiple signals, the most prominent being the bellow vocalization. While acknowledged that amplitude may be involved in sexual selection, it is rarely measured directly in the field (especially in large mammals) due to difficulties in accurately assessing this parameter. Using strict methodologies accounting for many sources of potential error, the impact that a variety of factors had on bellow amplitude was examined. Amplitude was measured in dB with Lamax and Lcpeak weighting. Parameters increasing amplitude (order of decreasing impact): Number of surrounding bulls bellowing, wind levels, and number of surrounding bulls. Parameters decreasing amplitude (order of decreasing impact): Distance, head orientation, days spent in rut, time of day, number of ...
... Recent studies have documented that in growing calves a single en-gorging female tick produce... more ... Recent studies have documented that in growing calves a single en-gorging female tick produces a growth decrement in the range of 0.6—10.0 g, depending upon the tick species (Norval et al., 1988, 1989; Pegram et ... Drawn from a photograph by Emma Mooring. ...
ABSTRACT Source-filter theory provides a framework to interpret the acoustic structure of vertebr... more ABSTRACT Source-filter theory provides a framework to interpret the acoustic structure of vertebrate vocalizations in relation to biophysical production, and it predicts that specific acoustic parameters can encode information about callers. Because formant frequencies are determined by vocal tract dimensions, with longer vocal tracts producing lower formants, they can be reliable indicators of body size, as well as other important traits. In polygynous species, reliable acoustic cues to fitness-related traits are expected to be under strong sexual selection pressure through male competition and/or female choice. This study investigates whether formant frequencies of male North American bison bellow vocalizations encode information about fitness-related caller attributes. Bison exhibit male-dominance female-defence polygyny, with dominance displays involving bellows. We hypothesized that physical attributes (mass, age) would predict formants and that formants would in turn predict quality indices (dominance, copulations, offspring sired). Our results showed that heavier bulls produced lower formants and that lower formants predicted higher mating success (copulations), even when controlling for mass. Given positive associations between mating success, dominance and reproductive success (offspring sired) in bison, we conclude that bellows with lower formants reflect greater fitness in bulls. We discuss the importance of reliable acoustic cues to size and quality indices in sexual selection contexts. Acoustic signals can be sexually selected if they generate infor-mation about the signaller that enables the signaller or receivers to increase their reproductive success in the context of mate compe-tition or mate choice (Andersson 1994; Espmark et al. 2000). The information contained in these signals can include the caller's competitive ability, quality, condition, motivation or sexual recep-tivity (Bradbury & Vehrencamp 1998). The accuracy or 'honesty' of the information within these signals can be maintained if the signal is costly to produce (Zahavi 1975; Grafen 1990; Zahavi & Zahavi 1997; Vehrencamp 2000) or is controlled by physiological constraints that cannot be faked (Vehrencamp 2000; Fitch & Hauser 2002). The 'source-filter theory' of vocal production examines the causal links between the constraints of vocal anatomy, the physics of sound production and propagation and the specific acoustic properties of the resultant signal (Fant 1960; Titze 1994). Increasingly, this theory has been applied to studies of nonhuman mammal vocalizations, resulting in significant advances for animal communication research (reviewed in Taylor & Reby 2010). The source-filter theory examines vocal production in two independent stages (Fant 1960). In the first stage (the source), air is forced from the lungs through the larynx to create a glottal wave from vocal fold vibrations. This glottal wave (source signal) contains a fundamental frequency with integer multiple harmonics that initially determines the pitch of the voiced signal. In the second stage (the filter), the glottal wave passes through the supralaryngeal vocal tract, which acts as a resonance filter on the wave by selec-tively amplifying or attenuating certain frequencies. This filtering process creates 'formants' or amplified resonant frequency bands within the signal, visible as peaks in the spectral envelope (Titze 1994). The source-filter theory predicts that reliable and indica-tive information about the caller can be generated independently in both the source (typically as fundamental frequency-related parameters) and the filter (typically as formant frequencies). The acoustic properties of these source-filter signals can potentially provide receivers with specific information about the caller, including measures of identity, sex, size, quality, condition,
Page 1. Afr. J. Ecol. 1990, Volume 28, pages 24G249 Differential foraging of oxpeckers on impala ... more Page 1. Afr. J. Ecol. 1990, Volume 28, pages 24G249 Differential foraging of oxpeckers on impala in comparison with sympatric antelope species BENJAMIN L. HART, LYNETTE A. HART and MICHAEL S. MOORING Department ...
Premature loss of winter hair coat can be a serious problem for moose (Alces alces), possibly lea... more Premature loss of winter hair coat can be a serious problem for moose (Alces alces), possibly leading to escalated heat loss and depleted reserves. Studies of captive moose have indicated that premature winter hair loss is associated with infestation by winter ticks (Dermacentor albipictus), and the extent of hair loss is associated with grooming efforts directed at removing the ticks. In this study we observed the grooming behaviour and hair-loss patterns of wild moose throughout the winter to test the prediction that the extent of hair loss would be positively correlated with the rate of grooming actions (oral grooming, scratching, and rubbing). Moose were observed throughout the winter of 1995-1996 at Elk Island National Park, Alberta. Both the proportion of hair loss and the rate of grooming increased from October through April, with hair-loss and grooming rates highest during the period of adult tick engorgement in March and April. Correlation analysis showed that moose which g...
In Experiment 1, five adult female impala were fitted with harnesses that restrained oral self-gr... more In Experiment 1, five adult female impala were fitted with harnesses that restrained oral self-grooming of the anterior part of the body. At the same time, six cohoused female impala were fitted with control harnesses that allowed normal oral grooming. The impala were allowed to habituate to the harnesses for 10 days, and both groups were then exposed to larval ticks (Boophilus decoloratus) by herding them into a tick-seeding corral. During the third week following tick seeding, when female ticks were estimated to have developed into engorging adults, the impala were immobilized, tick numbers on the animals sampled by patch sampling, and the harnesses removed. Observations continued for 5 days following removal of the harnesses. Twenty-minute focal observations were conducted daily on each impala during the habituation, tick-seeded, and postharness phases. Restrained impala had a median of 20 times more adult female ticks (both engorged and unengorged) than control impala. Oral groo...
... Michael S. Mooring a b , Thomas A. Fitzpatrick a , Ian C. Fraser a , Jill E. Benjamin a , Dom... more ... Michael S. Mooring a b , Thomas A. Fitzpatrick a , Ian C. Fraser a , Jill E. Benjamin a , Dominic D. Reisig a , and Tara T. Nishihira a. ... Bighorn sheep generally bedded on upper slopes and rocky outcrops exposed to gusts of wind. ...
... and provided a unique opportunity to collect behavioral data on a wild population ... However... more ... and provided a unique opportunity to collect behavioral data on a wild population ... However, studies of other populations of mountain sheep have reported an interaction between habitat ... Our results indicate that during the summer months of sexual segregation Class 3/4 males at ...
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