The effect of visitors on the behavior of zoo-housed western lowland gorillas (Gorilla gorilla gorilla).

Primates, especially apes, are popular with the public, often attracting large crowds. These crowds could cause behavioral change in captive primates, whether positive, neutral, or negative. We examined the impact of visitors on the behavior of six western lowland gorillas (Gorilla gorilla gorilla), observing the troop over 6 weeks during high season (4.5 hr/day, 35 days, May-July 2016). We used focal scan sampling to determine activity budget and enclosure usage, and focal continuous sampling to identify bouts of anxiety-related behavior (visitor-directed vigilance, self-scratching, and aggression). Both daily zoo-entry numbers (VGATE ) and instantaneous crowds at the exhibit (VDENSITY ) were measured. Overall, VGATE had little effect across behaviors. However, consistent with the more acute time frame of measurement, VDENSITY was a better predictor of behavior; at high crowd volumes, we observed significant group-level changes in activity budget (increased inactivity, increased locomotion, and decreased environment-related behaviors), increase in some anxiety-related behaviors, and decreased enclosure usage. Although contributing similar effects, it could not be determined if crowd numbers, composition, or noise most affected the troop, nor any chronic effects of exposure to large crowds. Nevertheless, our findings suggest that measures to minimize the impacts of large crowds at the exhibit would be beneficial. Furthermore, we highlight potential discrepancies between common methods for measuring visitor numbers: VGATE is less sensitive to detecting visitor effects on behavioral indices than VDENSITY . Future studies should appropriately match the biological time frame of welfare indicators and visitor measures used to ensure the reliability of findings.

Preliminary investigation into the housing of dwarf hamsters.

BACKGROUND: Although pet hamsters are widely available, the literature on their husbandry and health is limited, and guidelines for the care of hamsters are variable. This study investigated housing in different dwarf hamster species, focusing on factors affecting co-housing failure. METHODS: An online cross-sectional survey shared on social media investigated potential factors influencing co-housing failure of dwarf hamsters in captivity, such as sex, species and resources provided. RESULTS: The majority of hamsters had not received veterinary care and were provided with fewer food and water sources than animal numbers, while 12% were kept in enclosures less than 75 cm in length. Co-housing failure was more likely in dwarf hamsters older than 6 months (odds ratio 4.75, p = 0.005, 95% confidence interval = 1.607-14.13). There was no association found between sex or species and co-housing failure. LIMITATIONS: There was likely a degree of selection bias as the owners who completed the questionnaire may have had more knowledge of dwarf hamster husbandry than the general population of owners. CONCLUSION: Key welfare concerns regarding dwarf hamster care in captivity were identified as inadequate enclosure sizes, a high prevalence of co-housing failure arising from aggression, especially in hamsters more than 6 months old, and inadequate resource provision for many pair- or group-housed animals. Further investigation of the welfare impacts of resource provision deficits is required.

Estimation of the number and demographics of companion dogs in the UK.

BACKGROUND: Current estimates of the UK dog population vary, contain potential sources of bias and are based on expensive, large scale, public surveys. Here, we evaluate the potential of a variety of sources for estimation and monitoring of the companion dog population in the UK and associated demographic information. The sources considered were: a public survey; veterinary practices; pet insurance companies; micro-chip records; Kennel Club registrations; and the Pet Travel Scheme. The public survey and subpopulation estimates from veterinary practices, pet insurance companies and Kennel Club registrations, were combined to generate distinct estimates of the UK owned dog population using a Bayesian approach. RESULTS: We estimated there are 9.4 (95% CI: 8.1-11.5) million companion dogs in the UK according to the public survey alone, which is similar to other recent estimates. The population was judged to be over-estimated by combining the public and veterinary surveys (16.4, 95% CI: 12.5-21.5 million) and under-estimated by combining the public survey and insured dog numbers (4.8, 95% CI: 3.6-6.9 million). An estimate based on combining the public survey and Kennel Club registered dogs was 7.1 (95% CI: 4.5-12.9) million. Based on Bayesian estimations, 77 (95% CI: 62-92)% of the UK dog population were registered at a veterinary practice; 42 (95% CI: 29-55)% of dogs were insured; and 29 (95% CI: 17-43)% of dogs were Kennel Club registered. Breed demographics suggested the Labrador was consistently the most popular breed registered in micro-chip records, with the Kennel Club and with J. Sainsbury's PLC pet insurance. A comparison of the demographics between these sources suggested that popular working breeds were under-represented and certain toy, utility and miniature breeds were over- represented in the Kennel Club registrations. Density maps were produced from micro-chip records based on the geographical distribution of dogs. CONCLUSIONS: A list containing the breed of each insured dog was provided by J. Sainsbury's PLC pet insurance without any accompanying information about the dog or owner.

Stimulus luminance and the spatial acuity of domestic fowl (Gallus g. domesticus).

The luminance dependence of spatial acuity in domestic fowl was measured directly over stimulus luminances ranging from 0.06 to 57.35 cd m(-2). At the highest luminance, acuity was around 6.5 c deg(-1), in agreement with previous studies in this species. As stimulus luminance decreased, acuity fell with increasing rate to 3.2 c deg(-1) at 0.06 cd m(-2), following the same shape as acuity functions for other mammalian and avian species. These findings suggest that the rod-cone transition for domestic fowl is between 0.45 and 1.79 cd m(-2). Over the photopic range from 1.79 to 57.35 cd m(-2) the change of acuity for fowl was 1%, compared with 32% for humans. For domestic fowl, the Rovamo-Barten MTF model of contrast sensitivity accounted for the behaviour of acuity as a function of luminance down to mesopic levels.

Measuring and modelling the spatial contrast sensitivity of the chicken (Gallus g. domesticus).

The spatial contrast sensitivity (CSF) of the chicken has been measured using a behavioural technique. The results obtained show that spatial vision in this species is relatively poor compared with the human observer. For a visual stimulus luminance of 16 c dm(-2), the upper frequency limit of spatial vision in the chicken (acuity) was found to be about 7.0 c deg(-1), with peak spatial vision occurring at around 1.0 c deg(-1). Under equivalent stimulus conditions, the acuity of the human is around 50 c deg(-1) with a peak in spatial vision at about 3.0 c deg(-1). Peak spatial contrast sensitivity in the chicken was also found to be only about 2% that for the human. At a lower stimulus luminance of 0.1 c dm(-2), the chicken CSF reduced in overall magnitude and indicated an acuity level of about 5.0 c deg(-1). These experimental results were successfully modelled using modulation transfer (MTF) theory. This theoretical treatment enabled important neural mechanisms underlying spatial vision in the chicken to be revealed. The role played by spatial vision in the chicken's ability to recognise detailed shapes in its visual environment was also examined by deploying the CSF as a visual weighting function with the Fourier series of a chicken comb.

Investigating social discrimination of group members by laying hens.

Social relationships in domestic fowl are commonly assumed to rely on social recognition and its pre-requisite, discrimination of group-mates. If this is true, then the unnatural physical and social environments in which commercial laying hens are typically housed, when compared with those in which their progenitor species evolved, may compromise social function with consequent implications for welfare. Our aims were to determine whether adult hens can discriminate between unique pairs of familiar conspecifics, and to establish the most appropriate method for assessing this social discrimination. We investigated group-mate discrimination using two learning tasks in which there was bi-directional exchange of visual, auditory and olfactory information. Learning occurred in a Y-maze task (p<0.003; n=7/8) but not in an operant key-pecking task (p=0.001; n=1/10). A further experiment with the operant-trained hens examined whether failure was specific to the group-mate social discrimination or to the response task. Learning also failed to occur in this familiar/unfamiliar social discrimination task (p=0.001; n=1/10). Our findings demonstrate unequivocally that adult laying hens kept in small groups, under environmental conditions more consistent with those in which sensory capacities evolved, can discriminate group members: however, appropriate methods to demonstrate discrimination are crucial.

Development of a raceway method to assess aversion of domestic fowl to concurrent stressors.

The requirement for assessing the effects of stressor combinations in improving the welfare of animals has not been widely recognised. Knowledge of the effects of concurrent stressors is needed to improve environments such as transport, where animals are presented with many simultaneous challenges. However, no method for measuring the effects of different stressors with a common unit is currently available. A locomotor passive avoidance method was developed as a common currency measure of the aversion of domestic fowl to concurrent stressors, using vibrational and thermal stressors as an exemplar. Juvenile fowl, fasted overnight, were trained to run a raceway into a goal-box for small food rewards (FR1). When running consistently, the reinforcement schedule was superimposed with a FR5 treatment schedule (60 min confinement in the goal-box with either a control of no other stressors [N] or concurrent vibration and thermal stressors [VT]). Subsequent latency to return to the goal-box was recorded as a measure of aversion. The factors affecting bird response were addressed in a series of experiments to optimise the method and clarify interpretation of results. Pre-feeding (20% ration 2 h prior to testing) did not affect response, but increasing the number of treatment presentations facilitated learning and increased method sensitivity. Treatment responses were consistent across experiments; overall VT was avoided (P<0.001), but N was not. However, there was large individual variation in response to VT. A final experiment indicated that, given a visual discriminatory cue, birds were capable of learning the required association between entering the goal-box and receiving the treatment, suggesting that the delay responses were due to aversion rather than the immediate impact of treatment on ability to respond. Further work is required to test the singular stressors, but the method retains common currency potential for assessing aversion to multiple stressors.