Dogs perceive and spontaneously normalise formant-related speaker and vowel differences in human speech sounds

Domesticated animals have been shown to recognise basic phonemic information from human speech sounds and to recognise familiar speakers from their voices. However, whether animals can spontaneously identify words across unfamiliar speakers (speaker normalisation) or spontaneously discriminate between unfamiliar speakers across words remains to be investigated. Here, we assessed these abilities in domestic dogs using the habituation-dishabituation paradigm. We found that while dogs habituated to the presentation of a series of different short words from the same unfamiliar speaker, they significantly dishabituated to the presentation of a novel word from a new speaker of the same gender. This suggests that dogs spontaneously categorised the initial speaker across different words. Conversely, dogs who habituated to the same short word produced by different speakers of the same gender significantly dishabituated to a novel word, suggesting that they had spontaneously categorised the word across different speakers. Our results indicate that the ability to spontaneously recognise both the same phonemes across different speakers, and cues to identity across speech utterances from unfamiliar speakers, is present in domestic dogs and thus not a uniquely human trait

Improving individual identification of wolves (Canis lupus) using the fundamental frequency and amplitude of their howls: a new survey method

Many bioacoustic studies have been able to identify individual mammals from variations in the fundamental frequency (F0) of their vocalizations. Other characteristics of vocalization which encode individuality, such as amplitude, are less frequently used because of problems with background noise and recording fidelity over distance. In this thesis, I investigate whether the inclusion of amplitude variables improves the accuracy of individual howl identification in captive Eastern grey wolves (Canis lupus lycaon). I also explore whether the use of a bespoke code to extract the howl features, combined with histogram-derived principal component analysis (PCA) values, can improve current individual wolf howl identification accuracies. From a total of 89 solo howls from six captive individuals, where distances between wolf and observer were short, I achieved 95.5% (+9.0% improvement) individual identification accuracy of captive wolves using discriminant function analysis (DFA) to classify simple scalar variables of F0 and normalized amplitudes. Moreover, this accuracy was increased to 100% when using histogram-derived PCA values of F0 and amplitudes of the first harmonic

Disentangling canid howls across multiple species and subspecies: Structure in a complex communication channel.

Wolves, coyotes, and other canids are members of a diverse genus of top predators of considerable conservation and management interest. Canid howls are long-range communication signals, used both for territorial defence and group cohesion. Previous studies have shown that howls can encode individual and group identity. However, no comprehensive study has investigated the nature of variation in canid howls across the wide range of species. We analysed a database of over 2000 howls recorded from 13 different canid species and subspecies. We applied a quantitative similarity measure to compare the modulation pattern in howls from different populations, and then applied an unsupervised clustering algorithm to group the howls into natural units of distinct howl types. We found that different species and subspecies showed markedly different use of howl types, indicating that howl modulation is not arbitrary, but can be used to distinguish one population from another. We give an example of the conservation importance of these findings by comparing the howls of the critically endangered red wolves to those of sympatric coyotes Canis latrans, with whom red wolves may hybridise, potentially compromising reintroduced red wolf populations. We believe that quantitative cross-species comparisons such as these can provide important understanding of the nature and use of communication in socially cooperative species, as well as support conservation and management of wolf populations.Recording work was approved by the Institutional Animal Care and Use Committee of the University of Tennessee. AK is supported by a Herchel Smith postdoctoral fellowship at the University of Cambridge. Part of this work was carried out while AK was a Postdoctoral Fellow at the National Institute for Mathematical and Biological Synthesis, an Institute sponsored by the National Science Foundation through NSF Award #DBI-1300426, with additional support from The University of Tennessee, Knoxville. BH is thankful to the State Forest Departments of Himachal Pradesh, J&K, and Maharashtra, and to various zoos in India for permitting us to record howls. HRG is grateful to all who helped with the project: the staff at Colchester Zoo; the Wildwood Trust, the Borror Laboratory of Bioacoustics; the British Library; Lupus Laetus; Polish Mammal Research Institute; Tigress Productions; the BBC Natural History Unit; Longleat Safari Park; Tierstimmen Archiv; Wild Sweden; Wolf Park; the Macaulay Sound Library and the UK Wolf Conservation Trust; and Mike Collins, Teresa Palmer, Monty Sloan, Karl-Heinz Frommolt, Yorgos Iliopoulos, Christine Anhalt, Louise Gentle, Richard Yarnell, Victoria Allison Hughes and Susan Parks. BRM thanks the USDA/APHIS/WS/National Wildlife Research Center for supporting his doctoral research and providing access to captive coyotes; recording work was approved by the NWRC IACUC. SW thanks Mariana Olsen for assistance with data collection, and Yellowstone National Park for permission to record.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.beproc.2016.01.00

Centering Individual Animals to Improve Research and Citation Practices

Modern behavioural scientists have come to acknowledge that individual animals may respond differently to the same stimuli and that the quality of welfare and lived experience can affect behavioural responses. However, much of the foundational research in behavioural science lacked awareness of the effect of both welfare and individuality on data, bringing their results into question. This oversight is rarely addressed when citing seminal works as their findings are considered crucial to our understanding of animal behaviour. Furthermore, more recent research may reflect this lack of awareness by replication of earlier methods – exacerbating the problem. The purpose of this review is threefold. First, we critique seminal papers in animal behaviour as a model for re-examining past experiments, attending to gaps in knowledge or concern about how welfare may have affected results. Second, we propose a means to cite past and future research in a way that is transparent and conscious of the abovementioned problems. Third, we propose a method of transparent reporting for future behaviour research that (i) improves replicability, (ii) accounts for individuality of non-human participants, and (iii) considers the impact of the animals\u27 welfare on the validity of the science. With this combined approach, we aim both to advance the conversation surrounding behaviour scholarship while also serving to drive open engagement in future science

Dogs Produce Distinctive Play Pants: Confirming Simonet

Vocalizations in expressive, nonhuman animals can explain the evolution of human communication. A domain-specific play pant in dogs can signify a comparison to human laughter and can explain the development of interspecies empathy through social contagion. A prescreening survey captured demographic information about the guardian and the dog. Accepted pairs wore wireless microphones, transmitters, and a harness, while a camera captured video. Independent raters analyzed audio and video recordings across training, play and shared rest interactions via an ethogram and RavenLite. There is evidence that dogs produce a play pant. When interacting with their guardians, dogs produced more vocalizations during play than in training or shared rest. A one-way ANOVA resulted in significant differences regarding the presence of vocalizations during the three interactions (F2,39 = 5.897, p = 0.006). While a Tukey post hoc test revealed that fewer play pants were observed during training (0.875 ± 1.30 min, p = 0.018) and shared rest (0.875 ± 1.60 min, p = 0.013) as compared to play interactions (20.63 ± 29.14 min). By validating the canine play pant, our work is among the first to explore the evolution of laughter as a signal between species

Dogs Produce Distinctive Play Pants: Confirming Simonet et al. (2001)

Identifying meaningful vocalizations in nonhuman animals can help explain the evolution of human communications. However, non-speech-like sounds, including laughter equivalents, are not well studied, although they may be meaningful. In this pilot study we investigate whether dogs perform a domain-specific pant during play by capturing vocalizations and behaviors during three interactions: training, play, and rest. Sixteen human and dog dyads participated in a session that included all three interactions in the same order: training, play, rest. During these sessions, each partner wore wireless microphones that transmitted to a receiver and digital recorder, while a standalone digital camera captured video of the interactions. A one-way ANOVA demonstrates that dogs do perform a domain-specific play pant, which was almost completely absent during training and rest. These vocalizations mostly co-occurred with play behaviors (e.g., play bow) or tickling and cuddling. These preliminary findings suggest that a laugh-like play pant is used by dogs during play; future research should explore other interspecific acoustic signals as derived from conspecific signals and having communicative function

Centring individual animals to improve research and citation practices

Modern behavioural scientists have come to acknowledge that individual animals may respond differently to the same stimuli and that the quality of welfare and lived experience can affect behavioural responses. However, much of the foundational research in behavioural science lacked awareness of the effect of both welfare and individuality on data, bringing their results into question. This oversight is rarely addressed when citing seminal works as their findings are considered crucial to our understanding of animal behaviour. Furthermore, more recent research may reflect this lack of awareness by replication of earlier methods – exacerbating the problem. The purpose of this review is threefold. First, we critique seminal papers in animal behaviour as a model for re-examining past experiments, attending to gaps in knowledge or concern about how welfare may have affected results. Second, we propose a means to cite past and future research in a way that is transparent and conscious of the abovementioned problems. Third, we propose a method of transparent reporting for future behaviour research that (i) improves replicability, (ii) accounts for individuality of non-human participants, and (iii) considers the impact of the animals' welfare on the validity of the science. With this combined approach, we aim both to advance the conversation surrounding behaviour scholarship while also serving to drive open engagement in future science

Bioacoustic Detection of Wolves:Identifying Subspecies and Individuals by Howls

SIMPLE SUMMARY: This study evaluates the use of acoustic devices as a method to monitor wolves by analyzing different variables extracted from wolf howls. By analyzing the wolf howls, we focused on identifying individual wolves, subspecies. We analyzed 170 howls from 16 individuals from the three subspecies: Arctic wolves (Canis lupus arctos), Eurasian wolves (C.l. lupus), and Northwestern wolves (C.l. occidentalis). We assessed the potential for individual recognition and recognition of three subspecies: Arctic, Eurasian, and Northwestern wolves. ABSTRACT: Wolves (Canis lupus) are generally monitored by visual observations, camera traps, and DNA traces. In this study, we evaluated acoustic monitoring of wolf howls as a method for monitoring wolves, which may permit detection of wolves across longer distances than that permitted by camera traps. We analyzed acoustic data of wolves’ howls collected from both wild and captive ones. The analysis focused on individual and subspecies recognition. Furthermore, we aimed to determine the usefulness of acoustic monitoring in the field given the limited data for Eurasian wolves. We analyzed 170 howls from 16 individual wolves from 3 subspecies: Arctic (Canis lupus arctos), Eurasian (C. l. lupus), and Northwestern wolves (C. l. occidentalis). Variables from the fundamental frequency (f0) (lowest frequency band of a sound signal) were extracted and used in discriminant analysis, classification matrix, and pairwise post-hoc Hotelling test. The results indicated that Arctic and Eurasian wolves had subspecies identifiable calls, while Northwestern wolves did not, though this sample size was small. Identification on an individual level was successful for all subspecies. Individuals were correctly classified with 80%–100% accuracy, using discriminant function analysis. Our findings suggest acoustic monitoring could be a valuable and cost-effective tool that complements camera traps, by improving long-distance detection of wolves

High-pitch sounds small for domestic dogs: abstract crossmodal correspondences between auditory pitch and visual size

Humans possess intuitive associations linking certain non-redundant features of stimuli - e.g. high-pitched sounds with small object size (or similarly, low-pitched sounds with large object size). This phenomenon, known as crossmodal correspondence, has been identified in humans across multiple different senses. There is some evidence that non-human animals also form crossmodal correspondences, but the known examples are mostly limited to the associations between the pitch of vocalizations and the size of callers. To investigate whether domestic dogs, like humans, show abstract pitch-size association, we first trained dogs to approach and touch an object after hearing a sound emanating from it. Subsequently, we repeated the task but presented dogs with two objects differing in size, only one of which was playing a sound. The sound was either high or low pitched, thereby creating trials that were either congruent (high pitch from small object; low pitch from large objects) or incongruent (the reverse). We found that dogs reacted faster on congruent versus incongruent trials. Moreover, their accuracy was at chance on incongruent trials, but significantly above chance for congruent trials. Our results suggest that non-human animals show abstract pitch sound correspondences, indicating these correspondences may not be uniquely human but rather a sensory processing feature shared by other species

Not afraid of the big bad wolf: calls from large predators do not silence mesopredators

Large predators are known to shape the behavior and ecology of sympatric predators via conflict and competition, with mesopredators thought to avoid large predators, while dogs suppress predator activity and act as guardians of human property. However, interspecific communication between predators has not been well‐explored and this assumption of avoidance may oversimplify the responses of the species involved. We explored the acoustic activity of three closely related sympatric canids: wolves Canis lupus, coyotes Canis latrans, and dogs Canis familiaris. These species have an unbalanced triangle of risk: coyotes, as mesopredators, are at risk from both apex‐predator wolves and human‐associated dogs, while wolves fear dogs, and dogs may fear wolves as apex predators or challenge them as intruders into human‐allied spaces. We predicted that risk perception would dictate vocal response with wolves and dogs silencing coyotes as well as dogs silencing wolves. Dogs, in their protective role of guarding human property, would respond to both. Eleven passive acoustic monitoring devices were deployed across 13 nights in central Wisconsin, and we measured the responses of each species to naturally occurring heterospecific vocalizations. Against our expectation, silencing did not occur. Instead, coyotes were not silenced by either species: when hearing wolves, coyotes responded at greater than chance rates and when hearing dogs, coyotes did not produce fewer calls than chance rates. Similarly, wolves responded at above chance rates to coyotes and at chance rates when hearing dogs. Only the dogs followed our prediction and responded at above chance rates in response to both coyotes and wolves. Thus, instead of silencing their competitors, canid vocalizations elicit responses from them suggesting the existence of a complex heterospecific communication network