Nesting Behavior in Wild and Zoo-Housed Orangutans

Transcription

1 Nesting Behavior in Wild and Zoo-Housed Orangutans M.L. Bastian 1,2, E.S. Herrelko 1,3, M.Brown 1, D.R.Glendinning 1, A.J. Reddy 1, E.Renner 4,1, L.Thompson 1 1 Smithsonian s National Zoo, 2 Duke University, 3 University of Stirling, 4 George Washington University

2 WHAT IS A NEST? Typical Definition of NEST: a structure or place made or chosen by an animal, especially a bird, to shelter its eggs and young; a place where some animals live and usually lay eggs.

3 GREAT APE BEDS/NESTS Unique Nest Function - function as resting platforms, NOT as permanent or semipermanent shelters for young - typically make new (or rebuild old) nest every night He s making his nest now. There! See it? That son-of-a he s got himself a futon!

4 Wild Orangutan Field Sites PhD ( ) post-doc ( )

5 Sungai Lading & Tuanan ( ) Malaysia Indonesian Borneo Sungai Lading Tuanan Distance Sungai Lading - Tuanan: 12.6km adapted from Struebig et al. 2007

6 Artificially High Orangutan Densities SUNGAI LADING SMITHSONIAN S NAT L ZOO WILD ORANGUTANS ZOO-HOUSED ORANGUTANS Indonesian Borneo Washington, D.C.

7 Tuanan Field Site est. Jan 2003 by Carel van Schaik & Maria van Noordwijk

8 Nest-Based Survey for a New Field Site Sungai Tunggul, 2004

9 Drones: Safer Method for Aerial Nest Surveys

10 Sungai Lading Field Site base camp est by Meredith Bastian

11 SUNGAI LADING Similar Habitats Heavily logged peat swamps High botanical overlap - Shannon s Diversity & Evenness Indices - Sorenson s & Ellenberg s Indices TUANAN 1537 tree phenology plot 20 smaller vegetative plots 1612 tree phenology plot 20 smaller vegetative plots

12 Similar Genetics feces --> feces on silica Collecting orangutan feces Orangutan fecal samples Gene flow (historical) Tuanan Sungai Lading Ecological similarity SGL1 SGL2 SGL3 TU1 TU2 Arora et al. 2010; Nietlisbach et al. 2012

13 Orangutan Density Estimates Ground Surveys UNAS Short Course/Follow-up Nest Survey, Sungai Lading 2006 UNAS Short Course, Tuanan 2003 SUNGAI LADING 7.68 indiv./km 2 TUANAN 4.5 indiv./km ha 945 ha extreme habitat compression minimal habitat compression Bastian 2008 (Using Plot vs. Line Transect Method) van Schaik et al (Using Plot vs. Line Transect Method)

14 ORANGUTAN DENSITIES PER MICROHABITAT Tuanan: 4 + ind/km 2 (van Schaik et al. 2005) Sungai Lading: 7 + ind/km 2 (Bastian 2008) 7.68 using Sungai Lading s est. of r (#nests/ou per day) D = d(pxrxt) all plots surveyed (N=23) D 7.74 OU density (indiv/km 2 ) 2 ) d nest density (#nests/km p 0.9 local estim ate proportion of nest builders (avg other OU sites) r 1.15 local estim ate #nests/o U per day (TU/Sebangau estim ate) t 350 local estim ate nest decay rate in days (Sebangau conservative estim ate) D = d(pxrxt) plots in primarily disturbed swamp forest (N=10) D 8.42 OU density (indiv/km 2 ) 2 ) d nest density (#nests/km p 0.9 local estim ate proportion of nest builders (avg other OU sites) r 1.15 local estim ate #nests/o U per day (TU/Sebangau estim ate) t 350 local estim ate nest decay rate in days (Sebangau conservative estim ate) D = d(pxrxt) plots in mix of disturbed swamp & rotan forest (N=8) D 8.28 O U density (indiv/km 2) d nest density (#nests/km 2) p 0.9 local estim ate proportion of nest builders (avg other OU sites) r 1.15 local estim ate #nests/o U per day (TU/Sebangau estim ate) t 350 local estim ate nest decay rate in days (Sebangau conservative estim ate) D = d(pxrxt) plots in primarily rotan forest (N=5) D 5.52 O U density (indiv/km 2) d nest density (#nests/km 2) p 0.9 local estim ate proportion of nest builders (avg other OU sites) r 1.15 local estim ate #nests/o U per day (TU/Sebangau estim ate)

15 ALL DAY Follows (Nest-Nest) Sungai Lading: 2.5yrs, 3,260 hrs focal data

16 Morning & Day Nests Nest Checklists Night Nests Time begin building nest Time finish beginning nest Infant in mother s nest? Distance bwn mother/inf nests Tree Species DBH Tree(s) Height Tree(s) Height Nest Nest Position New/Fix Old Roof? (yes, no,?) Mattress? (yes, no,?) Pillow? (yes, no,?) Blanket? (yes, no,?) Nest Smack? (yes/#, no,?) Rain before build nest? Eat first at nest tree? Social play in nest? Time leave nest Twig biting? (yes, no,?) Tree on phenology plot/#? Nest tagging/who/species/date? Leaf carry to nest/time/species?

17 Day & Night Nests Nesting Events (355 total over 297 follows w/ nests): 66 day nests 289 night nests NEST RE-VISITATION DAY NESTS NEW RE-ENTERED REBUILT New > Re-used = 34.14, df= 1, P < Day vs. Night: NS new vs. re-used = 1.78, df= 1, P = NIGHT NESTS NEW RE-ENTERED REBUILT New > Re-used = 29.95, df= 1, P < 0.001

18 Nest Location/Distribution Sungai Lading Transect Map Clustered Nest Distribution 4 Quads: Q1 most frequent = 49.73, df= 1, P < cm Blocks of Study Site A2 A4 B2 B4 B6 C3 C5 D3 D5 E3 E5 E7 F5

19 Nest Tree & Nest Attributes MEAN NEST TREE DBH 59cm (71cm day, 57cm night) MOST FREQUENT NEST TREE HEIGHT 10-20m above ground = , df= 1, P < MOST FREQUENT NEST HEIGHT 10-15m above ground = , df= 3, P < NEST TREE AS A FEEDING SITE PRIOR TO NEST BUILDING DAY NESTS NIGHT NESTS 21% 10% 79% no yes 90% no yes Feeding Sites: Day Nests > Night Nests = 6.41, df= 1, P = 0.001

20 Nest Position - MOST FREQUENT NEST POSITION: 2 (on terminal branch), = 30.86, df= 3, P < Multiple-tree (Position 4) Nests: Tuanan > Sungai Lading, G test: G = 170.1, df= 4, P < despite NS in distribution of Position 4 vs. other nests in Tuanan, = 0.083, df= 1, P = * Population Differences Between Sites * Bastian 2008

21 Nest Embellishments BLANKET 6% day nests; 15% night nests PILLOW MATTRESS ROOF 6% day nests; 13% night nests 31% day nests; 92% night nests 0% day nests; 6% night nests LEAFY PILLOW Most Frequent Embellishment Day & Sg. Lading: Mattress (vs. Tuanan: most frequent = pillow) = , df= 3, P < Day vs. Night Sg. Lading: Mattresses more frequent Night vs. Day = , df= 2, P = 0 LEAFY MATTRESS

22 SUNGAI LADING (SGL) Patchy Innovative Behaviors TUANAN (TU)? = behavior observed = behavior not observed (Poisson > 95%) = insufficient observation time = N/A (based on context of behavior) Analysis indicates a clustering of cultural behaviors by population: = 68.01, df= 1, P < van Schaik et al. 2006, Ramsey et al. 2007, Bastian 2008, Bastian et al. 2012

23 Leaf Carrying for Nest Building Tarantang & Piais branches carried to other sites same & different nest tree species M.Bastian Carried leaves used primarily as mattresses (Sungai Lading) and as pillows (Tuanan) Use of leaves as mosquito repellant Florez 2007; Bastian 2008; Largo et al. 2009; Bastian et al. 2012

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25 Nest Tree Species Preferences Tarantang (Campnosperma coriaceum) Piais (Nephelium maingayi) preferred by orangutans for NIGHT NESTS especially by mothers and infants more so during the mosquito season 5 Top Preferred Nest Tree Species Relative to Species Abundance on Phenology & Smaller Botanical Plots DAY NESTS 5 spp. = 54% all nests Bengaris (K.malacenssis) Sari bangking (C.sarawakanus) Bintan (L.splendens) Piais (N. maingayi) Tutup kabali (D.cf. pseudomalabarica) Tarantang NIGHT NESTS 5 spp. = 34% all nests Bengaris (K.malacenssis) Piais (N. maingayi) Mahawai umb (M.leptopoda/parviflora) Ehang haduk (Diospyros sp.) Tarantang (C.coriaceum)

26 Social Nesting MEAN PARTY SIZE (MPS) - Overall MPS: (vs for Tuanan) Female-Only MPS: (vs ) Male-Only MPS: (vs. 1.28) MEAN NIGHT NEST PARTY SIZE (NNPS) - Overall NNPS: (<4% of all night nests) NEST SHARING (>1 independently ranging orangutans in a single nest) - Night Nest Sharing: 2/289 (<1% of all night nests)

27 Zoo-Housed Orangutan Nest Study

28 Orangutans at NZP Batang Bonnie Iris Lucy Kyle Kiko GREAT APE HOUSE O-LINE THINK TANK

29 NZP s O-Line (Orangutan Transit System) Connects Great Ape House & Think Tank via eight 50ft tall towers/490ft cable system Think Tank can house one group of orangutans overnight

30 Nest Location Maps Data Collection Period: 1 year (July 2014 July 2015) Total Recorded Night Nests: 1043 nesting events, 850 night nests

31 SHEET & BLANKET Nest Materials & Embellishments SHEET & MATTRESS SHEET, BLANKET & PILLOW SHEET & SHEET BAG ROOF MATERIALS: e.g. Hay, Cotton, Fleece, Burlap, Paper, Cardboard

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33 Nest Forts

34 NEST HEIGHT GROUND vs. ELEVATED Great Ape House (GAH): Ground > Elevated, Nest Location = , df= 1, P < Think Tank (TT): Ground > Elevated, = 92.04, df= 1, P < on a shelf in a hammock Building Difference in Nest Heights? Elevated Nests > Frequent at GAH vs. TT, = 6.45, df= 1, P = ROOM PREFERENCES (GAH) Rm 4 preferred over 5 other rooms, = , df= 1, P < Rank of Room Preference: 4 > 3 > 5 > 1 > 2 > 6 NIGHT NEST LOCATION PREFERENCES Great Ape House: 62 total nest locations identified Top 5 preferred locations (8% nest sites) = 55% all night nests Think Tank: 18 total nest locations identified Top 5 preferred locations (28% nest sites) = 66% all night nests

35 Nest Fidelity NZP Orangutans: How often in a nest next 6:30AM check? NO > YES, = 30.25, df= 1, P < When in a nest at EOD & next AM, in same ROOM? YES > NO, = 4.83, df= 1, P = (high room fidelity) When in a nest at EOD & next AM, in same NEST? NO > YES, = 41.51, df= 1, P < (low PM-AM nest fidelity) In (same) nest next AM? YES > NO = 175, df= 1, P < WILD orangutans at Sungai Lading: Habituated > Unhabituated OUs in nest next AM = 21.31, df= 1, P < 0.01 Time nest builder left nest in AM to start day: Exit nest before > after 6:30AM, = 32.77, df= 1, P < 0.001, BUT Wide range time exit nest/indiv., NS diff. exit before/after 6:30AM, Unhabituated Follows: 3:52AM 11:34AM (7:42 hrs) Habituated Follows: 4:02AM 12:48PM (8:46 hrs) = 0.29, df= 1, P = 0.593

36 Orangutan Social Networks Outside yard only Inside/Outside

37 Nearest Nest Neighbors Nest Nearest Neighbor data - reliable proxy for Actual Nearest Neighbor data? Overall YES, = 5.26, df= 1, P = Nest Nearest Neighbor vs. Actual Nearest Neighbor - may be better measure for less social individuals (e.g. Lucy) - may more accurately reflect mutual social dynamics between certain pairs, e.g. Iris & Batang

38 Nest Sharing Night Nest NZP: 22/855 (nearly 3% of all night nests) vs. Nest Sg. Lading: 2/289 (<1% of all night nests) Sharing ABSENT at Tuanan & most other wild sites = 3.65, df= 1, P = (trend)

39 Next Steps Building Preferences - For each of 5 individuals who travel between GAH / TT when given choice - For Batang when in each social grouping Male Nest Location Nearest Neighbor / Nest Location Fidelity - Differences in nest NN or nest location fidelity for females according to how many/which male(s) in building nights nesting at GAH? - Differences for each male based on nesting location of other male? Nest Embellishments - Systematically document night nest materials available/used & function Innovations in Nesting Context - Document across SSP institutions - Determine if nest NN data predict shared innovative behaviors - Use future webcams to document nighttime/early am nesting behavior Nesting under orangutan-made waterfall

40 Questions? NZP Primate keeper team and field assistants & researchers of Sungai Lading and Tuanan for data collection Thank You!