­CardiOvascular examination in awake Orangutans (Pongo pygmaeus pygmaeus): Low-stress Echocardiography including Speckle Tracking imaging (the COOLEST method)

Introduction: Cardiovascular diseases have been identified as a major cause of mortality and morbidity in Borneo orangutans (Pongo pygmaeus pygmaeus). Transthoracic echocardiography is usually performed under anesthesia in great apes, which may be stressful and risky in cardiac animals. The aim of the present pilot study was hence to develop a quick and non-stressful echocardiographic method (i.e., the COOLEST method) in awake Borneo orangutans (CardiOvascular examination in awake Orangutans: Low-stress Echocardiography including Speckle Tracking imaging) and assess the variability of corresponding variables.Materials and Methods: Four adult Borneo orangutans trained to present their chest to the trainers were involved. A total of 96 TTE examinations were performed on 4 different days by a trained observer examining each orangutans 6 times per day. Each examination included four two-dimensional views, with offline assessment of 28 variables (i.e., two-dimensional (n=12), M-mode and anatomic M-mode (n=6), Doppler (n=7), and speckle tracking imaging (n=3)), representing a total of 2,688 measurements. A general linear model was used to determine the within-day and between-day coefficients of variation.Results: Mean±SD (minimum-maximum) images acquisition duration was 3.8±1.6 minutes (1.3-6.3). All within-day and between-day coefficients of variation but one (n=55/56, 98%) were <15%, and most (51/56, 91%) were <10% including those of speckle tracking systolic strain variables (2.7% to 5.4%).Discussion: Heart morphology as well as global and regional myocardial function can be assessed in awake orangutans with good to excellent repeatability and reproducibility.Conclusions: This non-stressful method may be used for longitudinal cardiac follow-up in awake orangutans.

New estimates of orangutan density in Sungai Palin watershed, Kapuas Hulu, West Kalimantan, Indonesia

Pongo pygmaeus pygmaeus is a subspecies of Bornean orangutan whose distribution is restricted to the northern part of the Kapuas River, West Kalimantan, and is categorized as Critically Endangered. In October 2017 we carried out a survey to estimate orangutan density in the peat-swamp forests of the Sungai Palin watershed, of the upper Kapuas river, Kapuas Hulu, West Kalimantan, Indonesia. Surveys for orangutans in 1991, in nearby Nanga Awen, had indicated the presence of orangutans in the peat-swamp forests of this area. We used distance sampling techniques to estimate orangutan densities from nest observations. We recorded 76 orangutan nests along 4.5 km transects in Sungai Palin in 2017, and 71 orangutan nests were observed along 4.3 km transects in Nanga Awen in 1991, giving densities of 1.29 and 2.62 individuals/km2, respectively. The results of this orangutan survey can be used as a baseline for monitoring of orangutan populations for conservation and management of this watershed landscape.

Orangutans (Pongo pygmaeus pygmaeus) and children (Homo sapiens) use stick tools in a puzzle box task involving semantic prospection

This study compared three captive orangutans and a group of 5-10 year-old children in their ability to use stick tools to solve a series of mazes in a puzzle box, including three puzzles that required semantic prospection. The puzzle box had seven levels and moveable plastic inserts that created three easy, three intermediate, and three difficult maze configurations. Three wood and three plastic stick tools were presented with each maze. All 26 children immediately solved the easy and intermediate mazes. Seventy-nine percent of the children solved the difficult mazes on their first attempt, and nearly all the children solved the difficult mazes on the second attempt, which suggested a majority of children engaged in effective planning. Girls took significantly longer to solve the intermediate mazes while boys took significantly longer to solve the difficult mazes. Two of three orangutans also successfully avoided the dead ends in the difficult mazes and consistently used stick tools to move peanuts to the goal slots, and took longer to solve the intermediate or difficult mazes. Both the children and orangutans preferred to use plastic tools, although both tool types were functional. These results suggest many similarities between orangutans and children’s abilities to use tools in a puzzle box task that requires planning to avoid dead ends.