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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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Long Distance Seed Dispersal by Forest Elephants
By dispersing seeds long distances, large, fruit-eating animals influence plant population spread and community dynamics. After fruit consumption, animal gut passage time and movement determine seed dispersal patterns and distances. These, in turn, are influenced by extrinsic, environmental variables and intrinsic, individual-level variables. We simulated seed dispersal by forest elephants ( Loxodonta cyclotis ) by integrating gut passage data from wild elephants with movement data from 96 individuals. On average, elephants dispersed seeds 5.3 km, with 89% of seeds dispersed farther than 1 km. The longest simulated seed dispersal distance was 101 km, with an average maximum dispersal distance of 40.1 km. Seed dispersal distances varied among national parks, perhaps due to unmeasured environmental differences such as habitat heterogeneity and configuration, but not with human disturbance or habitat openness. On average, male elephants dispersed seeds farther than females. Elephant behavioral traits strongly influenced dispersal distances, with bold, exploratory elephants dispersing seeds 1.1 km farther than shy, idler elephants. Protection of forest elephants, particularly males and highly mobile, exploratory individuals, is critical to maintaining long distance seed dispersal services that shape plant communities and tropical forest habitat.
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- Award ID(s):
- 1845649
- PAR ID:
- 10338503
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Date Published:
- Journal Name:
- Frontiers in Ecology and Evolution
- Volume:
- 9
- ISSN:
- 2296-701X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Orangutans are large-bodied frugivores predicted to be effective seed dispersers. We studied Bornean orangutan (Pongo pygmaeus wurmbii) seed dispersal effectiveness, by measuring the quantity of seeds dispersed and the quality of dispersal in Gunung Palung National Park, Borneo, Indonesia (August 2018 to August 2019). For dispersal quality we conducted germination experiments, measured germination rates, and modeled dispersal distances. We systematically collected orangutan fecal samples, feeding behavior, and GPS tracks during focal follows. We sieved 549 fecal samples collected from 36 orangutans and identified the seeds, and of the fecal samples collected 75.2% contained seeds. A total of 24 genera were dispersed via endozoochory. Germination experiments were conducted with orangutan defecated seeds and seeds from fruits. 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. 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, and 60 hours resulted in a mean distances of 592 ± 115m. We conclude orangutans are effective seed dispersers, as orangutans disperse a wide variety of genera over medium to long distances and defecated seeds exhibit high germinability. Orangutans are large-bodied frugivores predicted to be effective seed dispersers. We studied Bornean orangutan (Pongo pygmaeus wurmbii) seed dispersal effectiveness, by measuring the quantity of seeds dispersed and the quality of dispersal in Gunung Palung National Park, Borneo, Indonesia (August 2018 to August 2019). For dispersal quality we conducted germination experiments, measured germination rates, and modeled dispersal distances. We systematically collected orangutan fecal samples, feeding behavior, and GPS tracks during focal follows. We sieved 549 fecal samples collected from 36 orangutans and identified the seeds, and of the fecal samples collected 75.2% contained seeds. A total of 24 genera were dispersed via endozoochory. Germination experiments were conducted with orangutan defecated seeds and seeds from fruits. 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. 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, and 60 hours resulted in a mean distances of 592 ± 115m. We conclude orangutans are effective seed dispersers, as orangutans disperse a wide variety of genera over medium to long distances and defecated seeds exhibit high germinability. Funders: National Science Foundation (BCS-1638823); National Geographic Society; US Fish and Wildlife Services (F19AP00798; F18AP00898); Disney Wildlife Conservation Fundmore » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fevo.2021.789264
