Savanna Landscapers? assessing the dispersal service provided by elephants

Bunney, Katherine and Bond, William Botany Department, University of Cape Town Pleistocene Extinctions Percentage of genera that have gone extinct over the last 100,000 years.

Giant Kangaroos Enormous Wombats and Rhino-like Marsupials

Mastodons, Mammoths, Ground Sloths, Glyptodonts, Native Horses, Large Camels

Focus has always been on Forest elephants.

Forest elephants been established as forest gardeners, consuming more from more species than any other taxon of large vertebrate disperser

Identified at least 14 woody species relied exclusively on elephants for their dispersal.

No such study has been undertaken for the African Savanna elephants.

Elephant-like proboscidean megaherbivores originated in 60 million years ago

Potential for co-evolution between megafaunal and large vertebrates should be higher in Africa than anywhere else.

Megafaunal Dispersed by the

Lope, – White, 1994 Ndoki, Congo – Blake, 2009

Sacoglottis gabonensis Klainedoxa gabonensis Autranella congolensis Mammea africana Balanites wilsoniana Maranthus sp. Detarium macrocarpum Ornphalocarpum elatum Drypetes gossweileri gabonensis Tridesmostemon ornplalocarpoides Irvingia grandifolia Irvingia robur

rely exclusively on elephants for their effective dispersal Sacoglottis gabonensis Irvingia grandifolia Panda oleosa Mammea africana

Dispersal Distance

?

Long distance dispersal (LDD) - one of the most important contributors to seed dispersal effectiveness.

No data on the spatial scale at which the African savanna elephants disperse seeds.

One might guess at their efficacy:

consume and defecate large quantities of seed - an average of Found in a variety 228 woody seeds of habitats per defecation - Move 11 billion seeds per year

have large home ranges – up to 3000 have long gut km2 in the Kalahari passage times Sands, Southern Africa our question What is the spatial scale at which savanna elephants disperse megafaunal fruit?

gut passage + movement data

Steps:

1. identify our megafaunal fruit 2. get gut passage rate 3. analyses movement data 4. dispersal curve estimation

Identifying ’s megafaunal fruits

Used Operational definition developed by Guimares et al (2008)

South African woody flora (n = 1126) was divided into two types.

Type 1) fleshy fruits that are 4–10 cm in diameter with up to 5 large seeds(generally >2.0 cm diameter)

Type 2)fleshy/dry fruits that are greater than 10 cm in diameter and have numerous (>) small seeds.

Type 1

Megafaunal Fruit Description Family Species Seed Mass Consumed by Type Elephants

Apocynaceae Carissa macrocarpa not known U Type I fruit fleshy fruit maximum length between 4-10cm Arecaceae Rapphia australis, not known U Hyphaene petersiana; 21500 Y number of seeds: 1-5 Hyphaene coriacea; 156 Y (15) Borassus aethiopum not known Y

Balanitaceae Balanites aegyptiaca; 1150 Y Balanites maughamii; 826.84 Y

Boraginaceae Cordia grandicalyx not known U

Chrysobalanaceae Parinari curatellifolia 3315 U

Flacourtiaceae Rawsonia lucida 81.33 U

Ochnaceae Ochna glauca not known U

Papilionoideae Cordyla africana 10000 Y

Sapotaceae Mimusops zeyheri; 291.4 U Vitellariopsis marginata not known U Strychnaceae Strychnos cocculoides 476 U

Type Ib fruit fleshy fruit maximum length between 3-4cm Euphorbiaceae Schinziophyton 12500 Y number of seeds: 1 rautanenii

seed mass > 2000 Anacardiaceae Sclerocarya birrea 5405 Y (2) 17 species Identifying South Africa’s megafaunal fruits

Used Operational definition developed by Guimares et al (2008)

South African woody flora (n = 1126) was divided into two types.

Type 1) fleshy fruits that are 4–10 cm in diameter with up to 5 large seeds(generally >2.0 cm diameter)

Type 2)fleshy/dry fruits that are greater than 10 cm in diameter and have numerous small seeds.

Type 2

Megafaunal Fruit Description Family Species Consumed by Type Elephants Type II fruit maximum fruit fleshy Rubiaceae Gardenia volkensii Y length > 10cm (6) Strychnos spinosa; Strychnos number of seeds: Strychnaceae U pungens U numerous Bombacaceae Adansonia digitata Y

Bignoniaceae africana I

Capparaceae Cladostemon kirkii U

fruit dry Mimosoideae Faidherbia albida; Y (8) Albizia brevifolia; U Acacia erioloba; Y Acacia nilotica; Y Acacia haematoxylon U

Caesalpinoideae Piliostigma thonningii; Y Tamarindus indica Y Papilionoideae Swartzia madagascariensis U

14 species our question What is the spatial scale at which savanna elephants disperse megafaunal fruit?

gut passage + movement data

Steps:

1. identify our megafaunal fruit 2. get gut passage rate 3. analyses movement data 4. dispersal curve estimation

Seed passage experiments with sanctuary elephants

observations

When foreign they were initially destroyed Type 1

•rolled underfoot •taste preference gradient Type 2

Type 1 gut passage +

25.0

20.0

15.0 gut transit = 66 hours

10.0 CumulativeNumber ofMango Seeds Recovered 5.0

0.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 Time Elapsed (h)

Gut Transit of Seeds ( indica) through the gut of 4 elephants (2 males, 2 females) Type 2 gut passage + 1.20

1.00

0.80 gut transit = 96 hours

0.60

0.40 ProportionofTotal PresenceMelon Score

0.20

0.00 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 Time Elapsed (h)

Gut Transit of Melon (Cucumis melo) through the gut of 2 elephants (1 males, 1 females) our question What is the spatial scale at which savanna elephants disperse megafaunal fruit?

gut passage + movement data

Steps:

1. identify our megafaunal fruit 2. get gut passage rate 3. analyses movement data 4. dispersal curve estimation

+ movement data

Thanks to Save the Elephants!

•Timbavati APNR/KNP

•Telemetry data on thirty eight radio-collared wild elephants (27 males, 11 females)

•8-year collection period

7.00

R² = 0.957 6.00

5.00

4.00

3.00

MedianDistance Traveled (km) 2.00

1.00

0.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 180.00 200.00 Time (hours)

Median Distance Travelled over Time for 38 elephants (27 males, 11 females) 80

70

Max =65km

60

50

(14 x)

40 Distance (km) Distance 30

20

90th %= ~15km 10 Median = 4.4km

0 12.00 24.00 36.00 48.00 60.00 72.00 84.00 96.00 108.00 120.00 132.00 144.00 156.00 168.00 180.00 192.00 Time (hours) 1d 2d 3d 4d 5d 6d 7d

Box and whisker plot of distance across different time intervals. The lower and upper sides of boxes indicate 10th and 90th percentiles. Lines within boxes mark the medians. Whiskers indicate the maximum dispersal distances. Distance travelled for each interval a result of 50 time series across each of 38 elephants 27 males, 11 females) 80

70

60

(14 x) 50

Max =49km

40 Distance (km) Distance 30

90th % =11.6km 20

Median =3.6km 10

0 12.00 24.00 36.00 48.00 60.00 72.00 84.00 96.00 108.00 120.00 132.00 144.00 156.00 168.00 180.00 192.00 Time (hours) 1d 2d 3d 4d 5d 6d 7d

Box and whisker plot of distance across different time intervals. The lower and upper sides of boxes indicate 10th and 90th percentiles. Lines within boxes mark the medians. Whiskers indicate the maximum dispersal distances. Distance travelled for each interval a result of 50 time series across each of 38 elephants 27 males, 11 females) our question What is the spatial scale at which savanna elephants disperse megafaunal fruit?

gut passage + movement data

Steps:

1. identify our megafaunal fruit 2. get gut passage rate 3. analyses movement data 4. dispersal curve estimation

25

20

15

10 Percentage ofSeeds

5

0 0 4 9 13 17 22 26 30 35 39 43 48 52 56 61 65 Dispersal Distance (km) Dispersal curve estimation Curves of dispersal distance were estimated by substituting values of seed gut passage time 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 thoughts

seed dispersal distance is linked to home range which in turn is linked to water availability

longer dispersal tail

Males always show longer max. dispersal distances How unique is the service African savanna elephants provide?

highly unique service – 65000m

50m

500m

850m

Maximum seed dispersal distances for different disperser functional groups. conclusions elephants bring about extremely long distance dispersal. distances of 30km and over have formerly been treated as extreme LDD events that happen very infrequently – once in a population in a year (Nathan, 2008). in areas with elephants: this is likely to enable rapid movements in response to climate change – mobile link between vegetation types – enhances genetic diversity. in areas without elephants: dispersal failure is a risk – range reductions 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 Supervisor Michelle Henley and the Save the Elephants Foundation Elephant Whispers Sanctuary in Hazyview