The relationship between age, relative numerousness judgment, and summation was investigated in 11 Western lowland gorillas (Gorilla gorilla gorilla). Experiments 1 and 2 evaluated the gorillas' ability to select the larger of 2 food quantities before and with training. The majority of gorillas did not reliably select the larger quantity in Experiment 1 until receiving training to do so in Experiment 2. Experiment 3 evaluated their ability to select the larger of 2 pairs of quantities. All gorillas selected the larger pair more often than chance, and the old were less accurate and slower than were the young. For most gorillas, performance in relative numerousness judgment with training and summation was comparable with previous reports in chimpanzees and orangutans.

This study investigated the effects of performing animal-training sessions with Asian small-clawed otters ( Aonyx cinerea) while zoo visitors watched. The effects of having an interpreter present to describe the otters and their training on zoo visitors were also assessed. The data from 389 visitors to Zoo Atlanta’s otter exhibit were analyzed, and exhibit stay times and animal activity levels were recorded during four conditions (passive exhibit viewing, interpretation-only sessions, public animal- training sessions, and public animal training with interpretation sessions). The findings suggest that public animal training and public animal training with interpretation produce more positive zoo experiences, training perceptions, exhibit size and staff assessments, and longer visitor exhibit stay times when compared to passive exhibit viewing and interpretation-only sessions. This study quantifies an outcome of positive reinforcement training beyond its effects on animals and extends the benefits to zoo visitors by providing information on how to increase positive perceptions and experiences for zoological park visitors.

This study focused on the relationship between nonhuman animal behavior and envi-ronment- specifically, between the undesirable behavior exhibited by domestic pet-ting zoo animals in the presence of humans and the spatial design of the petting zoo environment. A spatial feature of a petting zoo referred to as a retreat space was ma-nipulated so that it affected the animals' opportunity for individual control over inter-action with humans. Three conditions were tested: no retreat space, semi-retreat space, and a full-retreat space. The subjects of this study were 5 African pygmy goats (Capra hircus) and 2 Romanov sheep (Ovis aries). Investigators used a focal sam-pling technique to analyze approximately 27 hr of behavioral data collected. The data were analyzed using multiple linear regression methods. The findings suggest that the full-retreat design beneficially moderated both sheep and goat behavior: Undesirable behaviors were lowest in the full-retreat condition. This study provides information that may improve human-animal interactions in a petting zoo setting and may in-crease animal well-being through exhibit design and management techniques.