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1. Body temperature estimates for Bornean orangutans (Pongo pygmaeus wurmbii) from internal fecal temperature measurements

   Harwell, Faye S; Scott, Katherine S; Philp, B; Knott, Cheryl D (March 2019, American journal of physical anthropology)

   Monitoring health status is a critical aspect of primate conservation, yet can be difficult to noninvasively investigate in the wild. Because mammals are endothermic, body temperature can be used as a health marker for primates. Using a method previously tested on chimpanzees and humans, we estimated body temperature of wild Bornean orangutans by measuring the internal temperature of fecal samples. Upon quickly collecting a fecal sample after defecation, we recorded internal temperature of the sample at 20-sec intervals for six minutes. Data included a series of temperatures for each sample that we fitted to a sigmoid curve, which was used to estimate body temperature. Estimated body temperature was not affected by sex (F(2,92)= 0.431, P= 0.651), weather (F(2,92)= 1.175, P= 0.313), or collection time (r= -0.074, N= 95, P= 0.468). Estimated body temperature was higher for fecal samples that fell from lower estimated heights (r= -0.23, N= 95, P= 0.0004) and were heavier (r= 0.23, N= 75, P= 0.0475). We compare these results from the field to captive fecal samples, taking place on the ground, to determine the accuracy of this field method. From our field samples (N=95), orangutans appear to have a lower internal body temperature (33.44 ± 1.74 °C) on average than either chimpanzees or humans. Previous studies have demonstrated that orangutans have a lower metabolic rate than other great apes. Lower body temperature may serve as a metabolic adaptation of orangutans to survive extended periods of low food availability when energy needs to be conserved. 

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2. Fecal Temperature of Wild and Captive Bornean Orangutans (Pongo pygmaeus wurmbii) as a Proxy for Body Temperature

   Syainullah, Muhammad; Harwell, Faye S; Gotama, Rinaldi; Junardi, Junardi; Scott, Katherine S; Philp, Brodie; Susanto, Tri Wahyu; Knott, Cheryl D (October 2019, International Conference on Biodiversity for Life: Sustainable Development of Indonesian Biodiversity)

   Primate health status affects individual fitness and survival, yet is difficult to noninvasively investigate in the wild. Using a method tested on chimpanzees and humans, we estimated temperature of fecal samples of Bornean orangutans as a proxy for body temperature. Upon defecation, we recorded peak internal temperature of the samples. Estimated body temperature was influenced by height of defecation (r= -0.23, N= 95, P= 0.0004) and sample weight (r= 0.23, N= 75, P= 0.0475). These estimates were not affected by sex (F(2,92)= 0.431, P= 0.651) or weather (F(2,92)= 1.175, P= 0.313). Our method allowed for fast, consistent sampling, such that time from defecation to collection did not affect the results (r= -0.074, N= 95, P= 0.468), confirming reliable fecal temperatures can be collected from orangutans. We compare our results from the field to captive fecal samples, finding higher body temperatures in captivity. From our samples (N=95), orangutans appear to have a lower internal body temperature (33.44 ± 1.74 °C) on average than either chimpanzees or humans. Previous studies have demonstrated that orangutans have a lower metabolic rate than other great apes. Lower body temperature may serve as a metabolic adaptation of orangutans to survive extended periods of low food availability when energy must be conserved. 

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3. A comparative perspective on orangutans (Pongo pygmaeus wurmbii) as seed dispersers

   Blackburn, Andrea; Rizal, Ahmad; Susanto, Tri Wahyu; Mitra Setia, Tatang; Knott, Cheryl D (October 2019, International Conference on Biodiversity for Life: Sustainable Development of Indonesia Biodiversity 2019)

   Seed dispersal is a process essential for the maintenance and regeneration of tropical forests. Many primates are important seed dispersers, and orangutans are predicted to be important seed dispersers as they are large-bodied and highly frugivorous. However, minimal previous research has been conducted on orangutan seed dispersal behavior. Here, we present our preliminary analyses on orangutan (Pongo pygmaeus wurmbii) seed dispersal behavior. Our data were collected in Gunung Palung National Park in West Kalimantan from August 2018 to August 2019. We collected 549 wild Bornean orangutan fecal samples, of which 75.2% of the fecal samples contained intact seeds. Dispersed seeds ranged in length from 0.1mm to 32.5mm. Next, we used a comparative perspective to understand orangutan seed dispersal effectiveness by placing orangutans in the context of the other apes. Orangutans disperse seeds with similar frequency as some populations of chimpanzees and gorillas. Overall, orangutans appear to be effective seed dispersers based on quantitative seed dispersal measures. Orangutans appear to have a vital ecological role in tropical forests, thus we advocate for the conservation of wild orangutans and the forests they inhabit. Funders: National Science Foundation (BCS-1638823); National Geographic Society; US Fish and Wildlife Services (F19AP00798; F18AP00898); Disney Wildlife Conservation Fund 

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4. Orangutan Seed Dispersal in Gunung Palung National Park, Borneo, Indonesia: Dispersal Quantity, Germination Rates, Gut Transit Times, and Dispersal Distances

   Blackburn, Andrea; Susanto, Tri Wahyu; Knott, Cheryl D (March 2020, 7th Frugivores And Seed Dispersal Symposium 2020)

   Orangutans are large-bodied frugivores predicted to be important seed dispersers, however little is known about their seed dispersal effectiveness. To understand wild Bornean orangutan (Pongo pygmaeus wurmbii) seed dispersal effectiveness, we measured the quantity of seeds dispersed, and we considered the quality of dispersal by measuring germination rates of gut-passed and control seeds, gut transit times, and dispersal distances. Research was conducted in Gunung Palung National Park, Borneo, Indonesia (August 2018 to August 2019). We systematically collected orangutan fecal samples, feeding behavior, and GPS tracks during consecutive full-day focal follows. We sieved 549 fecal samples collected from 36 orangutans to count and identify seeds (>2mm). Out of the fecal samples collected, 413 (75.2%) contained seeds. A total of 24 genera were dispersed via endozoochory. Orangutan fecal samples contained a mean of 1.17 genera (range 0-7). Germination experiments were conducted with orangutan defecated seeds and seeds from fruit. A significantly higher percent of orangutan defecated seeds germinated for 5 out of 6 genera than control seeds with pulp (p<0.01). A significantly higher percent of orangutan defecated seeds germinated for 3 out of 6 genera compared to control seeds without pulp (p<0.01). Gut transit times in wild orangutans ranged from 39.5 to 87 hours (n=6). Finally, we modeled seed dispersal distances using orangutan movement tracks (n= 30) with gut passage durations of 45 and 60 hours. Gut retention times of 45 hours resulted in a mean dispersal distance of 507 ± 123m (range 69 - 1341), and 60 hours resulted in a mean distance of 592 ± 115m (range 83 - 1260). We conclude orangutans are effective seed dispersers with similar efficacy to other great apes. Orangutans disperse a wide variety of genera over medium to long distances and gut passed seeds germinate at higher rates compared with controls. Keywords: Ecology, Seed dispersal effectiveness, Movement, Tropical, Asia Funders: National Science Foundation (BCS-1638823); National Geographic Society; US Fish and Wildlife Services (F19AP00798; F18AP00898); Disney Wildlife Conservation Fund 

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5. A comparison of great ape life histories in captivity

   Harwell, Faye; Knott, Cheryl D. (November 2020, 6th Annual Meeting of the Northeastern Evolutionary Primatologists)

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   Primates, especially great apes, have slow life histories and long lifespans compared to other mammalian groups. Data pertaining to life history variables can be difficult to collect in the wild considering that species can have longer lifespans than the duration of a field site’s existence. Here, we examine life history variables for captive-born great apes housed in the United States. Using studbook data, we investigate stillbirth rates, age at first birth (AFB), interbirth intervals, number of offspring, twinning rates, mean lifespan and maximum lifespans. Analyses presented here exclude individuals with estimated birthdates. The oldest maximum lifespan was recorded for gorillas (60.07yrs (female); n= 656) followed by chimpanzees (57.40yrs (female); n= 559), orangutans (54.88yrs (female); n= 660), and bonobos (52.15yrs (female); n= 144). Excluding individuals living ≤10 years of age, mean lifespan is similar for all great apes in captivity (F(3,417)= 0.849, p= 0.467; bonobos: 23.5 ± 9.8yrs; chimpanzees: 25.2 ± 10.6yrs; gorillas: 26.2 ± 10.2yrs; orangutans: 24.2 ± 10.0yrs). The stillbirth rate is highest in chimpanzees (0.147; n=559) then gorillas (0.144; n=658), bonobos (0.125; n=144), and orangutans (0.010; n=681). Gorillas (11.4 ± 3.7yrs) have a younger AFB, on average, than chimpanzees (15.9 ± 6.9yrs), bonobos (14.3 ± 6.9yrs), or orangutans (14.4 ± 5.1yrs) (F(3,377)= 13.97, p< 0.0001). We discuss how our findings are influenced by changes in husbandry practices as well as the captive environment. By examining the life histories of captive populations, we highlight the plasticity these species exhibit in relation to the timing of developmental and reproductive events. 

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