The activity patterns of nonworking and working sled dogs.

There are limited studies investigating the combined effects of biological, environmental, and human factors on the activity of the domestic dog. Sled dogs offer a unique opportunity to examine these factors due to their close relationship with handlers and exposure to the outdoors. Here, we used accelerometers to measure the activity of 52 sled dogs over 30 days from two locations in Canada. The two locations differ in the working demands of dogs, therefore we used linear mixed effects models to assess how different factors impact daytime and nighttime activity of working versus nonworking dogs. During the daytime, we found that males were more active than females among nonworking dogs and younger dogs were more active than older dogs among working dogs. Alaskan huskies had higher activity levels than non-Alaskan husky breeds in working sled dogs during the day. Nonworking dogs were slightly more active during colder weather, but temperature had no effect on working dogs' activity. The strongest predictor of daytime activity in working dogs was work schedule. These results indicate that the influence of biological factors on activity varied depending on dogs' physical demands and human activity was the most powerful driver of activity in working dogs.

The hybrid skull of the eastern coyote (Canis latrans var.): Nonmetric traits and craniomandibular shape.

The increasing awareness that hybridization, and resultant gene flow, plays a major role in animal diversification has led to a growing number of studies that have focused on assessing the morphological consequences of this process. Analyses of mammalian hybrids have identified skeletal effects of hybridization, including a suite of anomalous dental and sutural traits on the skull that are present at high frequencies in hybrid populations. These studies have also detected consistent patterns of morphological shape and size differences between hybrids and parental taxa across a wide variety of organisms. However, more research is required to understand the universality of these traits and shape/size differences. Building on these previous studies, a sample of genetically determined canid hybrids was examined, specifically the eastern coyote (Canis latrans var.), a hybrid between coyotes, wolves, and dogs, to test whether this group exhibits a comparable pattern of anomalous nonmetric characters, and to assess differences in craniomandibular shape and size. First, specimens of C. latrans var., C. latrans, and C. lupus were scored for anomalous traits, including supernumerary and rotated teeth, dental crowding, and sutural anomalies. Geometric morphometric analyses were then conducted on a subset of these individuals to explore craniomandibular size and shape variation, as well as allometry. The results are largely consistent with other studies, indicating that the incidence of dental anomalies, dental crowding, and sutural anomalies is significantly higher in hybrids. However, differences are not significant for supernumerary teeth. The exploration of morphometric variation identifies intermediate morphology in the hybrids, and some indication of greater morphological variability in the mandible. When these results are combined with previous studies, they suggest that skeletal signatures of hybridization are common to different mammalian taxa across multiple generations; however, some traits such as supernumerary teeth may be lost after a few generations.