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1. Quantifying free simple sugars in orangutan foods using spectrophotometry: Implications for orangutan feeding ecology

   Robinson, Natalie ; Lang, Lexi ; Kane, Erin ; Knott, Cheryl ( April 2018 , 87th Annual Meeting of the American Association of Physical Anthropologists)

   Orangutans (Pongo pygmaeus wurmbii) in Gunung Palung National Park, West Kalimantan, Indonesia experience significant seasonal and annual fluctuations in the availability of their preferred food, ripe fruit. When ripe fruit is limited, orangutans increase their consumption of bark, pith, and leaves, which are continuously available and may act as fallback foods. While these foods are presumed to be less nutritious, it is not clear whether this is the case. Free simple sugars (FSS) provide orangutans with readily-metabolizable energy, and are thus an important nutritional compound for food choice. Here, we examine FSS concentrations in a variety of orangutan foods (n=54) to better understand orangutan foraging and nutritional ecology. We predicted that preferred foods would have higher concentrations of FSS than fallback foods. We analyzed FSS concentrations using a modified phenol-sulfuric acid method, and tested sample absorbency using a spectrophotometer at 490 nm. We analyzed 54 samples from 48 species, examining six plant parts: bark, flowers, leaves, pulp, seeds, and skin/pulp. Although preliminary results indicated no statistically significant differences in sugar content across the six food categories (F(5,47)=1.78, p=0.14), we did find that preferred foods (fruit pulp and seeds) had an average sugar concentration that was significantly higher (4.7%) than fallback foods (leaves and bark) (t=2.355, p=0.04). Therefore, as predicted, we find that orangutans prefer food types with higher concentrations of FSS. Obtaining adequate caloric and nutritional intake is crucial for orangutan reproduction and development, and thus this study provides new insight into what drives orangutan dietary choices. National Science Foundation (BCS-1638823, BCS-0936199, 9414388), National Geographic Society, US Fish and Wildlife (F15AP00812, F12AP00369, 98210-8-G661), Leakey Foundation, Disney Wildlife Conservation Fund, Wenner-Gren Foundation, Nacey- Maggioncalda Foundation. 

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2. What’s for dinner? Diurnal variation in wild Bornean orangutan food and nutrient choices

   DiGiorgio, Andrea ; Blackburn, Andrea ; Knott, Cheryl ( April 2018 , 87th Annual Meeting of the American Association of Physical Anthropologists)

   Previous observational research on primate feeding ecology has demonstrated that some primates consume fruit in the morning and leaves in the afternoon. However, diurnal patterning of feeding bouts has not been demonstrated for many of the apes, nor for relatively solitary primates. Furthermore, whether this has nutritional consequences is unclear. Orangutans are largely frugivorous omnivores that also incorporate leaves, bark, pith, and insects in their diet. As primarily solitary animals, their foraging and food choices are not restricted by group size and group decisions – thus they provide an excellent species with which to examine individual ape foraging choices. In accord with previous research, we hypothesized that orangutans would select energy rich and easy to digest foods (i.e., fruit) in the morning, then move to leaves and more fibrous food sources later in the day in order to allow more digestion time, and possibly to gain necessary macronutrients at the optimal time. We examined whether orangutans exhibited diurnal patterning of feeding bouts using 51 full day follows of wild Bornean orangutans (Pongo pygmaeus wurmbii) occurring May 2015 – January 2016 at Gunung Palung National Park, West Kalimantan, Indonesia. While there is a statistically significant difference in food types eaten at different times of day (χ2 = 76.3, p = 0.03), this difference is driven by increased consumption of leaves and pith in the afternoon hours, while fruit is consistently consumed throughout the day. We discuss this in the contexts of optimal nutrient selection and the Geometric Framework of Nutrition. Funding: National Science Foundation (BCS-1638823; BCS-1613393), NSF GRFP (DGE-1247312); Boston University; National Geographic Society, US Fish and Wildlife (F15AP00812), Leakey Foundation, Disney Wildlife Conservation Fund; Wenner-Gren Foundation; Nacey-Maggioncalda Foundation 

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3. Potential influence of climate and anthropogenic variables on water security using blue and green water scarcity, Falkenmark index, and freshwater provision indicator

   https://doi.org/https://doi.org/10.1016/j.jenvman.2018.09.012  

   Veettil, A.V ; Mishra, A.K. ( December 2018 , Journal of environmental management)

   Land use change and climate variability have significantly altered the regional water cycle over the last century thereby affecting water security at a local to regional scale. Therefore, it is important to investigate how the climate, land use change, and water demand potentially influence the water security by applying the concept of water footprint. An integrated hydrological modeling framework using SWAT (Soil and Water Assessment Tool) model was developed by considering both anthropogenic (e.g. land use change, water demand) and climatic factors to quantify the spatio-temporal variability of water security indicators such as blue water scarcity, green water scarcity, Falkenmark index, and freshwater provision indicators in Savannah River Basin (SRB). The SRB witnesses a significant change in land use land cover (e.g. forest cover, urban area) as well as water demand (e.g. irrigation, livestock production). Overall our results reveal that, SRB witnessed a significant decrease in blue water due to the climate variability indicating that the precipitation has more control over the blue water resources. Whereas, green water was more sensitive to changes in land use pattern. In addition, the magnitude of various water security indicators are different within each county suggesting that water scarcity are controlled by various factors within a region. An integrated assessment of water footprint, environmental flow, anthropogenic factors, and climatic variables can provide useful information on the rising (how and where) of water related risk to human and ecological health. 

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4. Behavioral Evidence of Wild Bornean Orangutans Navigating to Non-Fruit Foods – Implications for Fallback Foods

   DiGiorgio, AL ; Susanto, TW ; Knott, CD ( January 2021 , American journal of physical anthropology)

   null (Ed.)

   In 2015, Lambert and Rothman urged primate nutritional ecologists to revise the view of fallback and optimal foods from stable traits inherent in the food to variable qualities determined by the state of the consumer. Here we provide behavioral evidence to support this revision. In primates, fruit is often the preferred food category because it is typically high-energy, high-carbohydrate, and low in fiber. Orangutans in particular, are said to consume fruit preferentially and when it is available, whereas leaves, bark, and pith are often considered fallback foods. Using movement ecology, we ask if wild Bornean orangutans (Pongo pygmaeus wurmbii) navigate only to fruit, or whether navigation to non-fruit foods is supported by our data. We find that orangutans do deviate from a direct fruit-to-fruit path to consume non-fruit foods (n = 54, range 8% - 84%; p = 6.819e-07.) Next, we ask if orangutans consume non-fruit foods when in the proximity of fruit resources. We find that 25.5% of the time that orangutans eat a non-fruit food, there is an available fruit within 50m (n=308). Building on previous research finding that orangutans maintain a 10.1:1 NPE:P balance, we use this geospatial data showing that orangutans navigate to and choose non-fruit foods, even when fruit is available, to suggest that orangutans are seeking foods based on their current nutritional state and not only to maximize energy. This supports the claim that 'fallback' is not an inherent characteristic of a food, but rather is in the state-dependent eye of the consumer. Funders: National Science Foundation (BCS-1638823; BCS-1613393), NSF GRFP (DGE-1247312); Boston University; National Geographic Society, US Fish and Wildlife (F15AP00812), Leakey Foundation, Disney Wildlife Conservation Fund; Wenner-Gren Foundation; Nacey-Maggioncalda Foundation, Princeton University 

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5. Behavioral Evidence of Wild Bornean Orangutans Navigating to Non-Fruit Foods – Implications for Fallback Foods

   DiGiorgio, AL ; Susanto, TW ; Knott, CD ( January 2020 , 6th Annual Meeting of the North Eastern Evolutionary Primatologists)

   null (Ed.)

   In 2015, Lambert and Rothman urged primate nutritional ecologists to revise the view of fallback and optimal foods from stable traits inherent in the food to variable qualities determined by the state of the consumer. Here we provide behavioral evidence to support this revision. In primates, fruit is often the preferred food category because it is typically high-energy, high-carbohydrate, and low in fiber. Orangutans in particular, are said to consume fruit preferentially and when it is available, whereas leaves, bark, and pith are often considered fallback foods. Using movement ecology, we ask if wild Bornean orangutans (Pongo pygmaeus wurmbii) navigate only to fruit, or whether navigation to non-fruit foods is supported by our data. We find that orangutans do deviate from a direct fruit-to-fruit path to consume non-fruit foods (n = 54, range 8% - 84%; p = 6.819e-07.) Next, we ask if orangutans consume non-fruit foods when in the proximity of fruit resources. We find that 25.5% of the time that orangutans eat a non-fruit food, there is an available fruit within 50m (n=308). Building on previous research finding that orangutans maintain a 10.1:1 NPE:P balance, we use this geospatial data showing that orangutans navigate to and choose non-fruit foods, even when fruit is available, to suggest that orangutans are seeking foods based on their current nutritional state and not only to maximize energy. This supports the claim that 'fallback' is not an inherent characteristic of a food, but rather is in the state-dependent eye of the consumer. Funders: National Science Foundation (BCS-1638823; BCS-1613393), NSF GRFP (DGE-1247312); Boston University; National Geographic Society, US Fish and Wildlife (F15AP00812), Leakey Foundation, Disney Wildlife Conservation Fund; Wenner-Gren Foundation; Nacey-Maggioncalda Foundation, Princeton University 

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