Tracking of food quantity by coyotes (Canis latrans)

Previous studies have demonstrated that Weber's Law mediates quantitative discrimination abilities across various species. Here, we tested coyotes’ (Canis latrans) ability to discriminate between various quantities of food and investigated whether this ability conforms to predictions of Weber's Law. We demonstrate herein that coyotes are capable of reliably discriminating large versus small quantities of discrete food items. As predicted by Weber's Law, coyotes’ quantitative discrimination abilities are mediated by the ratio between the large and small quantities of food and exhibit scalar variability. Furthermore, in this task coyotes were not discriminating large versus small quantities based on olfactory cues alone.     

Experimental Babesia gibsoni infection in coyotes (Canis latrans)

Four 5 mo old captive raised coyotes (Canis latrans) were experimentally inoculated with approximately 1 x 10(6) Babesia gibsoni organisms. Parasites were detected 1 wk post-inoculation in all coyotes with maximum parasitemia of 8-11% occurring at 34 wk. Parasitemias remained at or above 1% for at least 12 wk and were still detectable 20 wk post-inoculation. All experimentally infected coyotes developed pale mucous membranes, splenomegaly, and a positive heme reaction in urine while one coyote exhibited mild depression and inappetence. Infected coyotes also developed a regenerative anemia, thrombocytopenia, and neutropenia. The mild clinical signs coupled with the high level and long duration of parasitemia indicate that coyotes could serve as reservoirs for B. gibsoni. Entrance of this foreign parasite into the United States suggests the need for strict quarantines and thorough health and blood film examinations for imported animals.     

Transmission of Ancylostoma caninum and Alaria marcianae in coyotes (Canis latrans)

One of seven female coyotes (Canis latrans) captured in Webb County, Texas during September 1986 and confined and mated in holding facilities at Millville, Utah whelped the following spring. The maternal female (greater than 5-yr-old) and her five neonates were killed at 22 days postparturition. All were infected with adult Ancylostoma caninum and were passing eggs in their feces. Also, the neonates and maternal female were infected with immature and adult Alaria marcianae, respectively. These findings suggested that the transmammary route is an important transmission mechanism for acquisition of these species of helminths in coyotes. The lack of overdispersion in the frequency distribution of these parasites and infection of the entire litter indicated that transmission from the infected female was nonselective among the pups.     

Cross modal perception of body size in domestic dogs (Canis familiaris)

While the perception of size-related acoustic variation in animal vocalisations is well documented, little attention has been given to how this information might be integrated with corresponding visual information. Using a cross-modal design, we tested the ability of domestic dogs to match growls resynthesized to be typical of either a large or a small dog to size-matched models. Subjects looked at the size-matched model significantly more often and for a significantly longer duration than at the incorrect model, showing that they have the ability to relate information about body size from the acoustic domain to the appropriate visual category. Our study suggests that the perceptual and cognitive mechanisms at the basis of size assessment in mammals have a multisensory nature, and calls for further investigations of the multimodal processing of size information across animal species.     

When dogs look back: inhibition of independent problem-solving behaviour in domestic dogs (Canis lupus familiaris) compared with wolves (Canis lupus)

Domestic dogs have been recognized for their social sensitivity and aptitude in human-guided tasks. For example, prior studies have demonstrated that dogs look to humans when confronted with an unsolvable task; an action often interpreted as soliciting necessary help. Conversely, wolves persist on such tasks. While dogs'' ‘looking back’ behaviour has been used as an example of socio-cognitive advancement, an alternative explanation is that pet dogs show less persistence on independent tasks more generally. In this study, pet dogs, shelter dogs and wolves were given up to three opportunities to open a solvable puzzle box: when subjects were with a neutral human caretaker, alone and when encouraged by the human. Wolves were more persistent and more successful on this task than dogs, with 80% average success rate for wolves versus a 5% average success rate for dogs in both the human-in and alone conditions. Dogs showed increased contact with the puzzle box during the encouragement condition, but only a moderate increase in problem-solving success. Social sensitivity appears to play an important role in pet and shelter dogs'' willingness to engage in problem-solving behaviour, which could suggest generalized dependence on, or deference to, human action.     

Isotope recycling in lactating dogs (Canis familiaris)

Isotope-based techniques for the measurement of water turnover, energy expenditure, and milk intake often assume that there is no recycling of isotopes once they have left the labeled animal. In experiments involving lactating females or their suckling offspring, there are several possible routes of isotope recycling. These include the consumption of labeled milk by offspring, the ingestion of labeled excreta, and the rebreathing of exhaled labeled CO(2) or water vapor by both mother and offspring. Isotope recycling might be especially important during lactation because the offspring are in close contact with each other and their mother for prolonged periods. We show here in 24- to 30-day-old domestic dog Canis familiaris puppies that there was no detectable transfer of (18)O or (2)H from labeled to unlabeled pups in two litters (16 pups, 8 labeled, 8 unlabeled) that were weaned early and independent of their mother. However, there was a significant transfer of both isotopes from labeled to unlabeled pups and from labeled pups to their mothers in nine equivalent nursing litters of the same age (27 labeled, 26 unlabeled pups). The increases in enrichment of isotopes in unlabeled offspring were greater than the increases in enrichment of the mothers. This indicates that maternal ingestion of offspring excreta and subsequent transfer of isotope in milk is not the sole pathway of recycling. Additional routes must also be important, such as exchange of isotope between pups on saliva-coated nipples and perhaps direct ingestion of excreta by unweaned young. Recycling is unlikely to be an important factor when determining maternal metabolic rate during peak lactation in domestic dogs. However, experiments that are designed to assess the energy demands of pups and isotope-based estimates of water turnover in offspring may need to take into account any effects of isotope recycling. In a theoretical example, removing the effects of recycling increased the measured energy expenditure in pups by up to 7% and increased the calculated elimination rates of both isotopes by up to 11.1% in (18)oxygen and 10.9% in (2)hydrogen.     

Using faecal DNA sampling and GIS to monitor hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

The US Fish and Wildlife Service's (USFWS) Red Wolf Recovery Program recognizes hybridization with coyotes as the primary threat to red wolf recovery. Efforts to curb or stop hybridization are hampered in two ways. First, hybrid individuals are difficult to identify based solely on morphology. Second, managers need to effectively search 6000 km(2) for the presence of coyotes and hybrids. We develop a noninvasive method to screen large geographical areas for coyotes and hybrids with maternal coyote ancestry by combining mitochondrial DNA sequence analysis of faeces (scat) and geographic information system (GIS) technology. This method was implemented on the Alligator River National Wildlife Refuge (1000 km(2)) in northeastern North Carolina. A total of 956 scats were collected in the spring of 2000 and 2001 and global positioning system (GPS) coordinates were recorded. Seventy-five percent of the scats were assigned to species and five coyote/hybrid scats were detected. Placement of scat location coordinates on a map of the experimental population area revealed that four of the coyote/hybrid scats were detected within the home ranges of sterilized hybrids. The other coyote/hybrid scat indicated the presence of a previously unknown individual. We suggest this method be expanded to include more of the experimental population area and be optimized for use with nuclear markers to improve detection of hybrid and back-crossed individuals.     

Serologic survey for diseases in free-ranging coyotes (Canis latrans) from two ecologically distinct areas of Utah

The influence of habitat and associated prey assemblages on the prevalence of canine diseases in coyotes (Canis latrans) has received scant attention. From December 1997 through December 1999, we captured 67 coyotes in two ecologically distinct areas of Utah (USA): Deseret Land and Livestock Ranch and US Army Dugway Proving Ground. These areas differ in habitat and prey base. We collected blood samples and tested for evidence of various canine diseases. Prevalence of antibodies against canine parvovirus (CPV) was 100% in the Deseret population and 93% in the Dugway population. All juveniles in both populations had been exposed. We found no difference in the prevalence of antibodies against canine distemper virus (CDV) between the two populations (7% versus 12%; P = 0.50). However, we did find an increase in antibodies with age in the Deseret population (P = 0.03). Evidence of exposure to canine adenovirus (CAV) was found in both populations (52% and 72%; P = 0.08). Prevalence of CAV antibodies was influenced by age on both areas (Deseret: P = 0.003; Dugway: P = 0.004). Antibodies to Francisella tularensis were low on both areas (2% and 4%). We found a significant difference (P = 0.001) in the prevalence of exposure to Yersinia pestis between the two populations: 73% in Deseret compared to 11% in Dugway. This difference is most likely due to the prey species available in the two ecologically distinct study areas.     

Hemispheric specialization in domestic dogs (Canis familiaris) for processing different types of acoustic stimuli

Lateralization is considered to be a fundamental feature of vertebrate brains. The aim of the present study was to examine the impact of functional cerebral asymmetry on processing of auditory stimuli in the domestic dog (Canis familiaris) during the orientation reaction. The experiment was conducted on 46 dogs (25 females and 21 males). Four types of auditory stimuli were used in the experiment (three meaningful stimuli: cat meowing, dog barking, the "sit" command ("siad" in Polish), and a neutral word ("wir", meaning "whirl" in Polish). It was predicted that the orientation reaction (turning the head towards the stimuli) would take place only in the case of meaningful sounds. It was also expected that dogs would show consistent lateralization. As predicted, all three meaningful stimuli elicited the orientation reaction. The response of the examined dogs to cat meowing showed significant lateralization with dominant leftwards movement, which hints towards activation of the right cerebral hemisphere and may be related to strong emotions evoked by this stimulus. Contrary to results of previous studies, dogs reacting to dog barking turned their heads leftwards more often, which suggests activation of the right cerebral hemisphere, probably related to the emotional meaning of the stimulus. The "sit" command consistently evoked the orientation reaction but there was no significant lateralization of this movement.     

Fine‐scale movements and behaviors of coyotes (Canis latrans) during their reproductive period

In canids, resident breeders hold territories but require different resources than transient individuals (i.e., dispersers), which may result in differential use of space, land cover, and food by residents and transients. In the southeastern United States, coyote (Canis latrans) reproduction occurs during spring and is energetically demanding for residents, but transients do not reproduce and therefore can exhibit feeding behaviors with lower energetic rewards. Hence, how coyotes behave in their environment likely differs between resident and transient coyotes. We captured and monitored 36 coyotes in Georgia during 2018–2019 and used data from 11 resident breeders, 12 predispersing residents (i.e., offspring of resident breeders), and 11 transients to determine space use, movements, and relationships between these behaviors and landcover characteristics. Average home range size for resident breeders and predispersing offspring was 20.7 ± 2.5 km² and 50.7 ± 10.0 km², respectively. Average size of transient ranges was 241.4 ± 114.5 km². Daily distance moved was 6.3 ± 3.0 km for resident males, 5.5 ± 2.7 km for resident females, and 6.9 ± 4.2 km for transients. We estimated first‐passage time values to assess the scale at which coyotes respond to their environment, and used behavioral change‐point analysis to determine that coyotes exhibited three behavioral states. We found notable differences between resident and transient coyotes in regard to how landcover characteristics influenced their behavioral states. Resident coyotes tended to select for areas with denser vegetation while resting and foraging, but for areas with less dense vegetation and canopy cover when walking. Transient coyotes selected areas closer to roads and with lower canopy cover while resting, but for areas farther from roads when foraging and walking. Our findings suggest that behaviors of both resident and transient coyotes are influenced by varying landcover characteristics, which could have implications for prey.     

Size‐assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

Anthropogenic hybridization of historically isolated taxa has become a primary conservation challenge for many imperiled species. Indeed, hybridization between red wolves (Canis rufus) and coyotes (Canis latrans) poses a significant challenge to red wolf recovery. We considered seven hypotheses to assess factors influencing hybridization between red wolves and coyotes via pair‐bonding between the two species. Because long‐term monogamy and defense of all‐purpose territories are core characteristics of both species, mate choice has long‐term consequences. Therefore, red wolves may choose similar‐sized mates to acquire partners that behave similarly to themselves in the use of space and diet. We observed multiple factors influencing breeding pair formation by red wolves and found that most wolves paired with similar‐sized conspecifics and wolves that formed congeneric pairs with nonwolves (coyotes and hybrids) were mostly female wolves, the smaller of the two sexes. Additionally, we observed that lower red wolf abundance relative to nonwolves and the absence of helpers increased the probability that wolves consorted with nonwolves. However, successful pairings between red wolves and nonwolves were associated with wolves that maintained small home ranges. Behaviors associated with territoriality are energetically demanding and behaviors (e.g., aggressive interactions, foraging, and space use) involved in maintaining territories are influenced by body size. Consequently, we propose the hypothesis that size disparities between consorting red wolves and coyotes influence positive assortative mating and may represent a reproductive barrier between the two species. We offer that it may be possible to maintain wild populations of red wolves in the presence of coyotes if management strategies increase red wolf abundance on the landscape by mitigating key threats, such as human‐caused mortality and hybridization with coyotes. Increasing red wolf abundance would likely restore selection pressures that increase mean body and home‐range sizes of red wolves and decrease hybridization rates via reduced occurrence of congeneric pairs.     

CWD prions remain infectious after passage through the digestive system of coyotes (Canis latrans)

ABSTRACT

Chronic wasting disease (CWD) is a geographically expanding prion disease of wild and captive cervids in North America. Disease can be transmitted directly, animal to animal, or indirectly via the environment. CWD contamination can occur residually in the environment via soil, water, and forage following deposition of bodily fluids such as urine, saliva, and feces, or by the decomposition of carcasses. Recent work has indicated that plants may even take up prions into the stems and leaves. When a carcass or gut pile is present in the environment, a large number of avian and mammalian species visit and consume the carrion. Additionally, predators like coyotes, likely select for disease-compromised cervids. Natural cross-species CWD transmission has not been documented, however, passage of infectious prion material has been observed in the feces of crows. In this study we evaluated the ability of CWD-infected brain material to pass through the gastrointestinal tract of coyotes (Canis latrans) following oral ingestion, and be infectious in a cervidized transgenic mouse model. Results from this study indicate that coyotes can pass infectious prions via their feces for at least 3 days post ingestion, demonstrating that mammalian scavengers could contribute to the translocation and contamination of CWD in the environment.     

Sensitivity of double centrifugation sugar fecal flotation for detecting intestinal helminths in coyotes (Canis latrans)

Fecal analysis is commonly used to estimate prevalence and intensity of intestinal helminths in wild carnivores, but few studies have assessed the reliability of fecal flotation compared to analysis of intestinal tracts. We investigated sensitivity of the double centrifugation sugar fecal flotation and kappa agreement between fecal flotation and postmortem examination of intestines for helminths of coyotes (Canis latrans). We analyzed 57 coyote carcasses that were collected between October 2010 and March 2011 in the metropolitan area of Calgary and Edmonton, Alberta, Canada. Before analyses, intestines and feces were frozen at -80 C for 72 hr to inactivate Echinococcus eggs, protecting operators from potential exposure. Five species of helminths were found by postmortem examination, including Toxascaris leonina, Uncinaria stenocephala, Ancylostoma caninum, Taenia sp., and Echinococcus multilocularis. Sensitivity of fecal flotation was high (0.84) for detection of T. leonina but low for Taenia sp. (0.27), E. multilocularis (0.46), and U. stenocephala (0.00). Good kappa agreement between techniques was observed only for T. leonina (0.64), for which we detected also a significant correlation between adult female parasite intensity and fecal egg counts (R(s)=0.53, P=0.01). Differences in sensitivity may be related to parasite characteristics that affect recovery of eggs on flotation. Fecal parasitologic analyses are highly applicable to study the disease ecology of urban carnivores, and they often provide important information on environmental contamination and potential of zoonotic risks. However, fecal-based parasitologic surveys should first assess the sensitivity of the techniques to understand their biases and limitations.     

Integrity of mating behaviors and seasonal reproduction in coyotes (Canis latrans) following treatment with estradiol benzoate

Coyotes (Canis latrans) are seasonally monestrous and form perennial pair-bonds. Breeding is dominated by each pack's alpha male and female, and both sexes share responsibility for territory defense and pup-rearing. They are also opportunistic predators on domestic livestock and pets. But while dominant adults have been implicated as primary killers, depredation is reduced when coyotes are without pups. Contraception, therefore, may represent a non-lethal solution for conflicts between coyotes and humans. Steroid hormones successfully control fertility in some species, but have been considered contraindicated in wildlife and canids in particular; specific concerns include possible induction of aberrant behavior, or uterine and hematopoietic pathologies. Herein we describe a study examining the physiological effectiveness, health safety, and behavioral consequences following treatment of estrous coyotes with exogenous estrogen. We treated captive adult female coyotes in estrus with 0.01 mg/kg estradiol benzoate (EB), either before (n = 5) or immediately after ovulation (n = 6), then documented reproductive outcome, physiological variables and behavioral responses, during and after treatment. Pregnancy was averted in six females treated after ovulation, suggesting that appropriate timing of treatment proved crucial. A transient suppression of sexual behavior was observed, and in some cases, estrus appeared slightly lengthened. However, neither ovulation nor mating behavior was fully suppressed. Importantly, non-pregnant females (and their mates) displayed diestrous socio-sexual behavior similar to pregnant coyotes (behavioral pseudopregnancy). Furthermore, non-pregnant coyotes did not mate again until the next native breeding season, and we observed no deleterious physiological effects during diestrus or subsequent ovarian cycles.     

Urinary behavior of female domestic dogs (Canis familiaris): influence of reproductive status,location, and age

The urinary behavior of adult domestic dogs (Canis familiaris) is sexually dimorphic with respect to the posture (males lift a leg and females squat), frequency of urination (males urinate more frequently than females), and tendency to direct urine at specific objects in the environment (males are more likely than females to direct their urine). Such behavioral differences have led to the belief that urination functions largely, or exclusively, in elimination in female dogs, while having the additional function of scent marking in male dogs. In this study, we observed urinary behavior of six spayed and six non-estrous intact female Jack Russell Terriers during walks on and off their home area. The females ranged in age from 0.4 to 11.2 years. Frequency of urination was positively correlated with age, and females four or more years old directed the majority of their urinations at objects in the environment. Overall, females urinated more frequently and directed more of their urinations when walked off their home area than when walked within their home area. Spayed females were more likely than non-estrous intact females to ground-scratch following defecation; we detected a similar trend for ground-scratching after urination. There was, however, considerable variation among spayed females in the tendency to display ground-scratching behavior. Overall, the most common posture displayed by females while urinating was the squat-raise. Other postures, in order of their frequency of occurrence included squat, arch-raise, combination, and handstand. Females used the squat-raise and arch-raise postures more when off their home area than when on their home area. Overall, there was substantial individual variation among females in the postures used while urinating. Our data indicate that female urinary behavior varies with location and reproductive status, and that substantial individual differences exist among females for some patterns of behavior. Additionally, the large percentages of directed urinations by spayed (60.8%) and non-estrous intact females (56.7%) in our study suggest that urination in female dogs does not function solely in elimination, but that it also has a significant role in scent marking, even when females are not in estrus.