Physiological Indicators of Attachment in Domestic Dogs (Canis familiaris) and Their Owners in the Strange Situation Test.

Behaviorally, attachment is demonstrated when one individual maintains close proximity to another individual and shows distress upon separation. For 29 owner-dog dyads, we employed a modified Ainsworth's Strange Situation Test (SST) to investigate whether both members would show a physiological reaction to separation. Dogs experienced a series of separation from and reuniting events with their owners and were introduced to a stranger. Before and after the SST, saliva samples were taken from each dyad to measure stress-related analytes: cortisol (CORT) and chromogranin A (CgA). Dogs exhibited attachment behaviors toward owners as evidenced by more time spent in close proximity, more contact initiated and less time spent near the door, compared to episodes with the stranger. Dogs that initiated more contact with their owners in re-uniting episodes had lower CgA than dogs that initiated less contact, but their owners had higher CgA levels. Also during re-uniting episodes, dogs and owners spent more time near each other when owner CgA levels were low, owner CORT levels were high, and the dog had owner-reported separation anxiety. During the episodes alone with the stranger, dogs with higher CORT spent more time with the stranger. Finally, dogs' initial CgA levels were correlated with their owner's initial CORT levels, and dog final CORT levels were correlated with their owners' final CORT levels, suggesting some hormonal synchrony within the dyad. As all owner-dog dyads were assessed as securely attached, attachment style differences could not explain variation in hormonal or behavioral results. These results suggest that dogs may respond to owner hormonal state and/or behavior and demonstrate that individual differences in responses to a behavioral challenge reflect the stress physiology of both dogs and their owners.

Social behaviour of domestic dogs (Canis familiaris) in a public off-leash dog park.

This study examines the activity budgets and social behaviours initiated and received by 69 focal dogs in an off-leash dog park for 400 s after entry, a time of high activity about which little is known. Using motivationally-neutral labels for social behaviour categories, we describe the frequency of behaviours, and correlations among them. We then examine these relationships in the context of proposed functions for some behaviours in dogs, in terms of information gathering and communication, including visual and tactile signalling. Time spent with other dogs decreased rapidly over the visit, and much of this early interaction involved greeting the park newcomer. Snout-muzzle contact behaviours were ubiquitous, while other behaviours were rarely observed, including aggressive behaviours. Correlations among certain non-contact behaviours initiated and received by focal dogs are consistent with their function as visual signals that may influence the continuation and form of social interactions, and their possible role in social mimicry (i.e., play bow and pull-rear away). Age, sex, and number of dogs present in the park influenced specific aspects of dogs' activity budgets, and a few behaviours. This ethological study provides fundamental data on dog social behaviour in dog parks, about which surprisingly little has been published.

Tonal vocalizations in the red wolf (Canis rufus): potential functions of nonlinear sound production.

The purpose of this study is to further understanding of the function of nonlinear vocalizations in red wolves (Canis rufus) by examining the acoustic, structural, and contextual characteristics of nonlinear sounds as compared to linear sounds. Video recordings of captive wolves from a breeding facility were analyzed. The acoustic nature of sound units was consistent with that of other social canids. The sound units included high-frequency squeaks (2600-9500 Hz) and low-frequency wuhs (160-1600 Hz) occurring either as separate units or in combination as nonlinear units (squeak-wuh frequency jumps, biphonations, squeaks with sidebands) and frequency jumps within squeaks. These low-amplitude sounds occurred in trains of 1-30 units that were classified as squeak vocalizations (49%), wuh vocalizations (19%), and nonlinear vocalizations (any combination including one or more nonlinear units, 32%). Nonlinear vocalizations transitioned directionally from high-frequency units to mixed-frequency units which has implications for the study of sound production and function. Wolves squeaked most often when oriented toward others, implying a solicitation function, while wuh vocalizations were more common during social interactions. Nonlinear vocalizations occurred most often during penmate-play or when oriented toward neighbors, indicating that nonlinear sound production may signal an increase in arousal.