Savanna Landscapers? Assessing the seed dispersal ... - SANParks

our questionWhat is the spatialscale at which savannaelephants dispersemegafaunal fruit?gut passage + movement dataSteps:1. identify our megafaunal fruit2. get gut passage rate3. analyses movement data4. dispersal curve estimation

Identifying South Africa’smegafaunal fruitsUsed Operational definition developed byGuimares et al (2008)South African woody flora (n = 1126) was divided into two types.Type 1) fleshy fruits that are 4–10 cm in diameterwith up to 5 large seeds(generally >2.0 cm diameter)Type 2)fleshy/dry fruits that are greater than 10 cmin diameter and have numerous (>) small seeds.

Type 1Megafaunal FruitTypeDescription Family Species Seed Mass Consumed byElephantsType Ifruit fleshyfruit maximum length between 4-10cmnumber of seeds: 1-5(15)Apocynaceae Carissa macrocarpa not known UArecaceaeRapphia australis,Hyphaene petersiana;Hyphaene coriacea;Borassus aethiopumnot known21500156not knownUYYYBalanitaceaeBalanites aegyptiaca;1150YBalanites maughamii;826.84YBoraginaceae Cordia grandicalyx not known UChrysobalanaceae Parinari curatellifolia 3315 UFlacourtiaceae Rawsonia lucida 81.33 UOchnaceae Ochna glauca not known UPapilionoideae Cordyla africana 10000 YSapotaceaeMimusops zeyheri;291.4UVitellariopsis marginatanot knownUStrychnaceae Strychnos cocculoides 476 UType Ibfruit fleshyfruit maximum length between 3-4cmnumber of seeds: 1seed mass > 2000(2)EuphorbiaceaeSchinziophyton12500 YrautaneniiAnacardiaceae Sclerocarya birrea 5405 Y17 species

Identifying South Africa’smegafaunal fruitsUsed Operational definition developed byGuimares et al (2008)South African woody flora (n = 1126) was divided into two types.Type 1) fleshy fruits that are 4–10 cm in diameterwith up to 5 large seeds(generally >2.0 cm diameter)Type 2)fleshy/dry fruits that are greater than 10 cmin diameter and have numerous small seeds.

Type 2Megafaunal FruitTypeDescription Family Species Consumed byElephantsType IIfruit maximumlength > 10cmnumber of seeds:numerousfruit fleshy(6)Rubiaceae Gardenia volkensii YStrychnaceae Strychnos spinosa; StrychnospungensUUBombacaceae Adansonia digitata YBignoniaceae Kigelia africana ICapparaceae Cladostemon kirkii Ufruit dryMimosoideaeFaidherbia albida;Y(8)Albizia brevifolia;UAcacia erioloba;YAcacia nilotica;YAcacia haematoxylonUCaesalpinoideaePiliostigma thonningii;YTamarindus indicaYPapilionoideae Swartzia madagascariensis U14 species


Seed passage experiments withsanctuary elephantsobservationsType 1When foreign theywere initially destroyedType 2•rolled underfoot•taste preferencegradient

Cumulative Number of Mango Seeds RecoveredType 1gut passage +25.020.015.0gut transit = 66 hours10.05.00.00.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0Time Elapsed (h)Gut Transit of Mango Seeds (Mangifera indica) throughthe gut of 4 elephants (2 males, 2 females)

Proportion of Total Melon Presence ScoreType 21.20gut passage +1.000.80gut transit = 96 hours0.600.400.200.000.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0Time Elapsed (h)Gut Transit of Melon (Cucumis melo) throughthe gut of 2 elephants (1 males, 1 females)


+ movement dataThanks to Save theElephants!•Timbavati APNR/KNP•Telemetry data on thirty eightradio-collared wild elephants (27males, 11 females)•8-year collection period

Median Distance Traveled (km)7.006.00R² = 0.9575.004.003.002.001.000.000.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00Time (hours)Median Distance Travelled over Time for 38 elephants (27 males, 11 females)

Distance (km)8070Max =65km6050(14 x)40302090 th %= ~15km10Median = 4.4km012.00 24.00 36.00 48.00 60.00 72.00 84.00 96.00 108.00 120.00 132.00 144.00 156.00 168.00 180.00 192.00Time (hours)1d 2d 3d 4d 5d 6d 7dBox and whisker plot of distance across different time intervals. The lower and upper sides of boxes indicate 10th and90th percentiles. Lines within boxes mark the medians. Whiskers indicate the maximum dispersal distances. Distancetravelled for each interval a result of 50 time series across each of 38 elephants 27 males, 11 females)

Distance (km)807060Max =49km50(14 x)403090 th % =11.6kmMedian =3.6km2010012.00 24.00 36.00 48.00 60.00 72.00 84.00 96.00 108.00 120.00 132.00 144.00 156.00 168.00 180.00 192.00Time (hours)1d 2d 3d 4d 5d 6d 7dBox and whisker plot of distance across different time intervals. The lower and upper sides of boxes indicate 10th and90th percentiles. Lines within boxes mark the medians. Whiskers indicate the maximum dispersal distances. Distancetravelled for each interval a result of 50 time series across each of 38 elephants 27 males, 11 females)


Percentage of Seeds25201510500 4 9 13 17 22 26 30 35 39 43 48 52 56 61 65Dispersal Distance (km)Dispersal curve estimationCurves of dispersal distance were estimated by substituting values of seed gut passagetime by corresponding values of elephant displacement in that time (Westcott et al. 2005,Campos Arceiz et al., 2008).Dispersal Curves for Type 2 megafaunal fruits

How do savanna elephants compare to forest elephants?10 x greater dispersal distance(Campos Arceiz et al.,2008)

some thoughtsseed dispersal distance islinked to home rangewhich in turn is linked towater availabilitylonger dispersal tailMales always show longermax. dispersal distances

How unique is the serviceAfrican savanna elephants provide?highly uniqueservice –65000m50m500m850mMaximum seed dispersal distances for different disperser functional groups.

conclusionselephants bring about extremely long distance dispersal.distances of 30km and over have formerly been treated asextreme LDD events that happen very infrequently – oncein a population in a year (Nathan, 2008).in areas with elephants: this is likely to enable rapidmovements in response to climate change – mobile link betweenvegetation types – enhances genetic diversity.in areas without elephants: dispersal failure is a risk – rangereductions or clumped and aged populations might result.I am hoping to further explore these consequences.

Thank you for listening.Thanks also to:Prof. William Bond my SupervisorMichelle Henley and the Save the Elephants FoundationElephant Whispers Sanctuary in Hazyview

Savanna Landscapers? Assessing the seed dispersal ... - SANParks

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