scholarly journals Occurrence and variability of tactile interactions between wild American crows and dead conspecifics

2018 ◽  
Vol 373 (1754) ◽  
pp. 20170259 ◽  
Author(s):  
Kaeli Swift ◽  
John M. Marzluff
Keyword(s):  
Information Acquisition ◽  
Alarm Call ◽  
Controlled Experiments ◽  
Theme Issue ◽  
Risky Behaviour ◽  
American Crow ◽  
Alarm Calling ◽  
Adaptive Value ◽  
American Crows ◽  
The Dead

Observations of some mammals and birds touching their dead provoke questions about the motivation and adaptive value of this potentially risky behaviour. Here, we use controlled experiments to determine if tactile interactions are characteristic of wild American crow responses to dead crows, and what the prevalence and nature of tactile interactions suggests about their motivations. In Experiment 1, we test if food or information acquisition motivates contact by presenting crows with taxidermy-prepared dead crows, and two species crows are known to scavenge: dead pigeons and dead squirrels. In Experiment 2, we test if territoriality motivates tactile interactions by presenting crows with taxidermy crows prepared to look either dead or upright and life-like. In Experiment 1, we find that crows are significantly less likely to make contact but more likely to alarm call and recruit other birds in response to dead crows than to dead pigeons and squirrels. In addition, we find that aggressive and sexual encounters with dead crows are seasonally biased. These findings are inconsistent with feeding or information acquisition-based motivation. In Experiment 2, we find that crows rarely dive-bomb and more often alarm call and recruit other crows to dead than to life-like crows, behaviours inconsistent with responses given to live intruders. Consistent with a danger response hypothesis, our results show that alarm calling and neighbour recruitment occur more frequently in response to dead crows than other stimuli, and that touching dead crows is atypical. Occasional contacts, which take a variety of aggressive and sexual forms, may result from an inability to mediate conflicting stimuli. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.

scholarly journals Hominin evolutionary thanatology from the mortuary to funerary realm: the palaeoanthropological bridge between chemistry and culture

2018 ◽  
Vol 373 (1754) ◽  
pp. 20180212 ◽  
Author(s):  
Paul Pettitt
Keyword(s):  
Belief Systems ◽  
Upper Palaeolithic ◽  
Theme Issue ◽  
Animal Kingdom ◽  
Core Set ◽  
The Social ◽  
Research Questions ◽  
The Dead ◽  
Animal Community ◽  
Palaeolithic Archaeology

Palaeoanthropology, or more precisely Palaeolithic archaeology, offers the possibility of bridging the gap between mortuary activities that can be observed in the wider animal community and which relate to chemistry and emotion; to the often-elaborate systems of rationalization and symbolic contextualisation that are characteristic of recently observable societies. I draw on ethological studies to provide a core set of mortuary behaviours one might expect hominoids to inherit, and on anthropological observations to explore funerary activity represented in the Middle and Upper Palaeolithic, in order to examine how a distinctly human set of funerary behaviours arose from a more widespread set of mortuary behaviours. I suggest that the most profound innovation of the hominins was the incorporation of places into the commemoration of the dead, and propose a falsifiable mechanism for why this came about; and I suggest that the pattern of the earliest burials fits with modern hunter–gatherer belief systems about death, and how these vary by social complexity. Finally, I propose several research questions pertaining to the social context of funerary practices, suggesting how a hominin evolutionary thanatology may contribute not only to our understanding of human behavioural evolution, but to a wider thanatology of the animal kingdom. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.

scholarly journals West Nile Virus Devastates an American Crow Population

The Condor ◽  
2005 ◽  
Vol 107 (1) ◽  
pp. 128-132 ◽  
Author(s):  
Carolee Caffrey ◽  
Shauna C. R. Smith ◽  
Tiffany J. Weston
Keyword(s):  
West Nile Virus ◽  
North America ◽  
Late Summer ◽  
Total Loss ◽  
West Nile ◽  
American Crow ◽  
Corvus Brachyrhynchos ◽  
American Crows

Abstract In its spread west across North America in 2002, West Nile virus (WNV) reached a population of marked American Crows (Corvus brachyrhynchos) in Stillwater, Oklahoma, in late summer. Within two months, 46 of 120 individuals were missing or known to be dead, 39 of which (33% of the population) are estimated to have died for WNV-related reasons. In 2003, 56 of 78 marked crows disappeared or were found dead between June and November. Five of the 28 juvenile losses were possibly unrelated to WNV, thus we estimate that 65% of our population died because of this pathogen in 2003. The total loss of 72% of population members, including 82% of juveniles, in a single year of WNV exposure raises concern for precipitous declines in American Crow populations in coming years. El Virus del Nilo Occidental Devasta una Población de Corvus brachyrhynchos Resumen. En su diseminación hacia el oeste de América del Norte durante 2002, el Virus del Nilo Occidental alcanzó a fines del verano una población marcada de Corvus brachyrhynchos en Stillwater, Oklahoma. En menos de dos meses, 46 de los 120 individuos registrados desaparecieron o murieron, 39 de los cuales (33% de la población) estimamos que murieron por causas relacionadas con el virus. En 2003, 56 de los 78 cuervos marcados desaparecieron o fueron encontrados muertos entre junio y noviembre. Cinco de las 28 pérdidas de juveniles posiblemente no estuvieron relacionadas con el virus, por lo que estimamos que el 65% de nuestra población murió a causa de este patógeno en 2003. La pérdida total del 72% de los miembros de la población, incluyendo el 82% de los juveniles, en un solo año de exposición al virus plantea preocupaciones en cuanto a la posibilidad de una disminución precipitada de las poblaciones de C. brachyrhynchos en los próximos años.

scholarly journals The Inflected Alarm Caw of the American Crow: Differences in Acoustic Structure Among Individuals and Sexes

The Condor ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 518-529 ◽  
Author(s):  
Jessica L. Yorzinski ◽  
Sandra L. Vehrencamp ◽  
Kevin J. McGowan ◽  
Anne B. Clark
Keyword(s):  
Individual Differences ◽  
Function Analysis ◽  
Acoustic Measurements ◽  
American Crow ◽  
Acoustic Structure ◽  
Corvus Brachyrhynchos ◽  
Call Structure ◽  
American Crows ◽  
The Status ◽  
Family Membership

Abstract Previous research on individual differences in the acoustic structure of vocalizations and vocal recognition has largely focused on the contexts of parent-offspring interactions, territory defense, sexual interactions, and group cohesion. In contrast, few studies have examined individual differences in the acoustic structure of mobbing and alarm calls. The purpose of this study was to explore individual differences in the acoustic structure of the inflected alarm caw of the American Crow (Corvus brachyrhynchos). The alarm caws of 15 wild, marked individuals were recorded and 25 acoustic measurements were made automatically using customized software. A stepwise discriminant function analysis showed that 20 of the 25 variables were important in discriminating among individuals, with 65% classification success. We used factor analysis to reduce the large number of variables to a set of seven meaningful call features. All of these features differed among individuals, suggesting that American Crows have the potential to discriminate among individual birds on the basis of call structure alone. Five of the features differed between the sexes, with call frequency being the most significant. One clearly subordinate male clustered with the females, raising the possibility that social status partially determines the sex-based differences. Encoding of individual identity in alarm contexts may be adaptive if receiver vigilance and approach urgency depend on the status, reliability, or family membership of the alarm signaler.

scholarly journals Social relationships and death-related behaviour in aquatic mammals: a systematic review

2018 ◽  
Vol 373 (1754) ◽  
pp. 20170260 ◽  
Author(s):  
Melissa A. L. V. Reggente ◽  
Elena Papale ◽  
Niall McGinty ◽  
Lavinia Eddy ◽  
Giuseppe Andrea de Lucia ◽  
...  
Keyword(s):  
Social Relationships ◽  
Multiple Correspondence Analysis ◽  
Maternal Investment ◽  
Social Characteristics ◽  
Alloparental Care ◽  
Theme Issue ◽  
Dispersal Patterns ◽  
Death Event ◽  
The Dead ◽  
Aquatic Mammals

Some aquatic mammals appear to care for their dead, whereas others abandon their live offspring when conditions are unfavourable. This incredible variety in behaviours suggests the importance of comparing and contrasting mechanisms driving death-related behaviours among these species. We reviewed 106 cases of aquatic mammals (81 cetaceans and 25 non-cetaceans) reacting to a death event, and extrapolated ‘participant’ ( age class , sex , relationship and decomposition ) and ‘social’ characteristics ( escorting , calf dependence , alloparental care , herding and dispersal patterns ) from published and unpublished literature. A multiple correspondence analysis (MCA) was performed to explore the relationships between these characteristics and death-related behaviours, with species clustered based on MCA scores. Results showed that both cetaceans and non-cetaceans react to death but in different ways. Non-cetaceans, characterized by a short maternal investment, were observed to protect the dead (defending it from external attacks), while cetaceans spent much longer with their offspring and display carrying (hauling, spinning, mouthing with the carcass and diving with it) and breathing-related (lifting and sinking the carcass) activities with the dead generally in association with other conspecifics. Our work emphasizes the need of increased documentation of death-related cases around the world to improve our understanding of aquatic mammals and their responses to death. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.

scholarly journals Water bathing alters threat perception in starlings

2012 ◽  
Vol 8 (3) ◽  
pp. 379-381 ◽  
Author(s):  
Ben O. Brilot ◽  
Melissa Bateson
Keyword(s):  
Alarm Call ◽  
Alarm Calls ◽  
Threat Perception ◽  
Welfare Measure ◽  
Adaptive Value ◽  
Bathing Water ◽  
Vigilance Behaviour ◽  
Ambiguous Cue

The majority of bird taxa perform water bathing, but little is known about the adaptive value of this behaviour. If bathing is important for feather maintenance then birds that have not bathed should have poorer feather condition, compromised escape ability and therefore increased responsiveness to cues of predation. We conducted two experiments examining the behaviour of captive starlings responding to conspecific alarm calls. Birds that had no access to bathing water showed a decreased willingness to feed and increased their vigilance behaviour following an alarm call. We argue that birds denied access to bathing water interpreted an ambiguous cue of threat as requiring more caution than birds that had access, consistent with higher levels of anxiety. Our results support the provision of bathing water for captive birds as an important welfare measure.

The cessation of contact calls does not provoke or modulate alarm behaviour in a social passerine

Behaviour ◽  
2021 ◽  
pp. 1-20
Author(s):  
Estelle Meaux ◽  
Chao He ◽  
Luying Qin ◽  
Eben Goodale
Keyword(s):  
Social Factors ◽  
Group Living ◽  
Alarm Call ◽  
Alarm Calls ◽  
Playback Experiments ◽  
Contact Call ◽  
Alarm Calling ◽  
Alarm Behaviour ◽  
Contact Calls ◽  
Crucial Information

Abstract Vocalizations that signal predation risk such as alarm calls provide crucial information for the survival of group-living individuals. However, alarm calling may attract the predator’s attention and, to avoid this cost, animals can opt for alternative strategies to indicate danger, such as ‘adaptive silence’, which is the cessation of vocalizations. We investigate here whether abrupt contact call cessation would provoke alarm responses, or would reinforce the signal given by an alarm call. In an aviary setting, we conducted playback experiments with a group-living passerine, the Swinhoe’s white-eye, Zosterops simplex. We found that birds did not respond to a sudden call cessation, nor did they have a stronger response to alarm calls followed by silence than to alarm calls followed by contact calls. Confirming previous work investigating contact call rate, it appears that in this species contact calls encode information about social factors but not environmental conditions.

Removing American crows and duck nesting success

1995 ◽  
Vol 73 (3) ◽  
pp. 518-522 ◽  
Author(s):  
Robert G. Clark ◽  
Daryl E. Meger ◽  
Jordan B. Ignatiuk
Keyword(s):  
Breeding Season ◽  
Breeding Success ◽  
Nesting Success ◽  
Relative Importance ◽  
American Crow ◽  
Predator Species ◽  
Game Birds ◽  
American Crows ◽  
Important Predator ◽  
Potential Impact

The American crow (Corvus brachyrhynchs) is reputed to be an important predator of duck eggs, but its potential impact has not been evaluated adequately. We removed breeding crows from their territories prior to and during the duck breeding season to test whether duck nesting success would increase. Nesting success in two removal areas did not differ from that of two control areas. Our results are consistent with several studies indicating that removal of one predator species from a community of predators, including corvids, does not lead to predictable increases in breeding success of game birds. Further work is needed to determine the relative importance of different predators and to learn why removal of one predator species is generally ineffective.

ALARM CALLING IN THREE SPECIES OF MARMOTS

Behaviour ◽  
1999 ◽  
Vol 136 (6) ◽  
pp. 731-757 ◽  
Author(s):  
Daniel Blumstein
Keyword(s):  
Alarm Call ◽  
Vancouver Island ◽  
Alarm Calls ◽  
Playback Experiments ◽  
Micro Structure ◽  
Stimulus Class ◽  
Call Structure ◽  
Alarm Calling ◽  
Degree Of Risk ◽  
Lines Of Evidence

AbstractMany species produce alarm calls that vary according to situation. Theoretically, alarm call structure could covary with predator type and could communicate potentially ''referential information, or calls could covary with the degree of risk a caller experienced when it emitted a call. Using similar methods, I studied the ways in which Olympic (Marmota olympus), hoary (M. caligata), and Vancouver Island marmots (M. vancouverensis) communicated situational variation. I observed both natural alarm calling, and I artificially elicited alarm calls with simulated terrestrial and aerial predators. I used playback experiments to study marmots' responses to different alarm call variants. All three species produced four roughly similar but distinctive loud alarm vocalizations that could be categorized by their relative shape, duration, and whether calls were quickly repeated to create multi-note vocalizations. In addition, the Vancouver Island marmot produced a fifth loud alarm call-the kee-aw. Call micro-structure varied as a function of the distance the caller was from an alarming stimulus and the type of alarming stimulus. Two lines of evidence suggest that all three species had alarm calls associated with the caller's risk (i.e. they were not referential). First, marmots often changed call types within a calling bout: there were no unique stimulus-class specific vocalizations. Second, marmot responses to alarm calls were graded: marmots did not have unique responses to different call types. These three close taxonomic relatives with superficially similar calls, communicated risk differently.

scholarly journals The moral standing of the dead

2018 ◽  
Vol 373 (1754) ◽  
pp. 20170270 ◽  
Author(s):  
Steven Luper
Keyword(s):  
Moral Standing ◽  
Theme Issue ◽  
The Dead ◽  
Do So

In choosing to do certain things, we appear to presuppose that we can act in the interests the dead, and that we have a duty to do so. For example, some of us go to great lengths to carry out their final wishes. Given that the dead no longer exist, however, it seems that nothing can be good or bad for them: they lack prudential interests. In that case, it is hard to see how we could owe them anything. They seem to lack moral standing altogether. In this essay, I will rebut this line of thought. I will claim that in some cases things that happen after people die are indeed good or bad for them. Their interests can still be advanced or hindered, so the dead have moral standing. This article is part of the theme issue ‘Evolutionary thanatology: impacts of the dead on the living in humans and other animals’.

scholarly journals Female putty-nosed monkeys ( Cercopithecus nictitans ) vocally recruit males for predator defence

2021 ◽  
Vol 8 (3) ◽  
Author(s):  
Frederic Gnepa Mehon ◽  
Claudia Stephan
Keyword(s):  
Alarm Call ◽  
Cost Benefit ◽  
Alarm Calls ◽  
Context Specificity ◽  
Sexual Dimorphisms ◽  
Alarm Calling ◽  
Cost Benefit Ratio ◽  
Female Behaviour ◽  
Context Specific ◽  
Predator Defence

Alarm calls can trigger very different behavioural changes in receivers and signallers might apply different alarm call strategies based on their individual cost-benefit ratio. These cost-benefit ratios can also vary as a function of sex. For instance, male but not female forest guenons possess loud alarms that serve warning and predator deterrence functions, but also intergroup spacing and male–male competition. In some forest guenons, the context specificity and alarm call repertoire size additionally differs between females and males but it remains unclear if this corresponds to similar sexual dimorphisms in alarm calling strategies. We here experimentally investigated whether general female and more context-specific male alarm calls in putty-nosed monkeys ( Cercopithecus nictitans ) had different effects on the opposite sex's behaviour and whether they might serve different female and male alarm calling strategies. We presented a leopard model separately to the females or to the male of several groups while ensuring that the opposite sex only heard alarm calls of target individuals. While female alarms led to the recruitment of males in the majority of cases, male alarms did not have a similar effect on female behaviour. Males further seem to vocally advertise their engagement in group defence with more unspecific alarms while approaching their group. Males switched alarm call types once they spotted the leopard model and started mobbing behaviour. Females only ceased to alarm call when males produced calls typically associated with anti-predator defence, but not when males produced unspecific alarm calls. Our results suggest that sexual dimorphisms in the context specificity of alarms most likely correspond to different alarm calling strategies in female and male putty-nosed monkeys.

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