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Elephants and Big Trees - Mitigation Methods

The reporting from the Reserve this month is once again highlighted by the elephant impact within and around the camp area. Conservation and Maintenance Staff spent the entire month, barring three days, attending to elephant damage to camp infrastructure and breakages of the perimeter fence.

A permit was applied for to once again use a helicopter to try and drive the identified damage causing elephant well away from the camp environment and its surrounds.

Elephants Alive requested the following document be distributed to Members and available for reading here. It’s well worth a read and please contact either me or Chris Mayes directly if there are any specific queries around the techniques applied at Ingwelala and how they fit into the broader landscape or the “bigger picture”.

Under the Mitigation Methods listed below, Beehives and Bee pheromones are two options Ingwelala has not yet explored.

I have taken the liberty of extracting the “hands on” techniques applied to deter elephant impact on large trees, and what the findings & results are representing these various methodologies:

Big Tree Mitigation Methods from Elephants Alive:

  • Wire-netting
  • Beehives
  • Rock packing/Pyramids
  • Creosote
  • Bee pheromones
  • Bioneem oil
  • Chilli oil
  • Dung paste

 

Wire-Netting

Purpose: protect tree against ring-barking 
Ring barking: 
- Prevents nutrient flow
- Tree becomes vulnerable to insect invasions and fire damage
- Tree may be hollowed out from the inside 

 Variety of methods/techniques used within the Associated Private Nature Reserves:

Elephant Alive method (as shown by Bateleur Safari Camp):
- Double-wrapping method
- 13 mm Chicken mesh: 1.8 m tall
- Measurement of length of mesh required: (Tree circumference x 2) + 50 cm
- Fold mesh in half and then wrap around tree’s main stem, starting 50 cm above the ground
- End of chicken mesh are stapled to tree using 150-200 mm U-staple nails
- Ensure that tree has a small amount of room to grow, i.e. tree must not be strangled
- Important to monitor wire-netting over time
- Remember: Wire-netting is only effective against bark-stripping


- Our method of wire-netting not an eye-sore for tourists (Edge et al. 2017)

Longevity

Up to 5 years (but ensure that tree is never strangled)

Cost

± R100.00 per tree

Results

Henley (2013): increased tree survival over

3000 days versus unwired trees

Derham et al. (2016): Bark-Stripping: 1.7% wired vs 25% unwired trees after 12 years

Cook et al. (2017): Bark-Stripping: 2% wired

(tusking) vs 26% unwired trees after 2 years

Scale

Can be applied on a large scale across a property


Beehives

- African honeybees have been used to successfully protect crops (King et al. 2017) and trees (Cook et al. 2018) from elephants
- Information on setting up beehives in trees available in a manual on the Elephants Alive website (www.elephantsalive.org)

Two types of hives have been tested:

Longevity

Wooden: > 3 years

Beepak: > 10 years

Cost

Wooden: R620 per tree

Beepak: R5000 per tree

Results (Cook et al. 2018) – 2-year study

(Jejane Private Nature

Reserve)

Impact-type

Bark-stripping

Stem snapping

Uprooting

Branch breakage

Bees

0%

0%

2%

6%

Wire-netting

2%

12%

4%

40%

Control

26%

4%

4%

48%

Scale

Small-scale: Handful of iconic trees around property

  • Feeding may be required during droughts
  • Risks: bee-stings (allergies); Drought; Insecticides
  • Honey production potential for tourists/staff

 Rock packing/Pyramids

- Rings of rocks or pyramids stacked around the main stem of a tree

Problems identified in the Associated Private Nature Reserve:
- not enough distance between tree’s main stem and end of pyramids/rocks. Noticeable trend that elephant impact decreases as pyramid radius around tree increases

- Calculating cost of method: Total cost = Single pyramid cost x Number of pyramids in a square metre x 𝛑(Desired radius)²
- Rocks/pyramids need to be tightly stacked to prevent elephants manoeuvring between gaps
- Rocks/pyramids should try keep elephants 4-5 m away from tree’s main stem
- Caution should be taken for the number of large natural rocks moved around (micro-habitat disturbance)

Longevity

10-20 years (or more) if maintained

Cost

R4.50 per pyramid made (concrete + labour costs) 

= > R2000 per tree

Scale

Small-scale application around particular iconic trees


Creosote

Tins/jars of creosote nailed to the main stem of a tree

article big tree 07

What is creosote? (Choudhary et al. 2002)

  • Coal-creosote is a residue produced during the distillation of coal tar, which is a by-product of the carbonization of coal
  • Creosote is a thick, oily and flammable liquid, and does not easily dissolve in water
  • Creosote has suspected carcinogenic properties and the breakdown of creosote in soil can take months to years to occur
  • In the United States of America, spills of creosote into the environment which exceed 0.454 kg need to be reported to the Environmental Protection Agency

Assessment on 100 trees creosote trees over 9-month period

Category

Result

Number of trees still alive

96

Number of trees dead

4

Number of trees impacted since method went up

23

Number of creosote jars broken

25

- Concern over the spillage of creosote into the environment and breakage of tins/glass
- Comparison to trees without creosote in the same property: No statistically significant difference between the likelihood of a tree being impacted with or without creosote

Results suggest that creosote is not an effective method for protecting trees against elephant impact and should be replaced with a more suitable method


Bee Attack Pheromone

article big tree 08

- Bee attack pheromone helps bees recruit more bees from their colony to handle large predators (Nouvian et al. 2016)
- Bee attack pheromone is comprised of iso-amyl acetate and 2-heptatone compounds which have been synthetically turned into a synthetically produced Specialised Pheromone and Lure Application Technology. (SPLAT) paste : Developed by Prof. Mark Wright (University of Hawaii at Manoa) and Dr Agenor Mafra-Neto (ISCA Technologies)
- Research carried out in Balule with Transfrontier Africa and Elephants Alive (Wright et al. 2018)

  • 86% of elephants encountering smell in Jejane Private Nature Reserve displayed avoidance behaviours (Jejane is the beehive project study site)
  • Results suggest that this method may be effective if elephants have prior knowledge of bee attacks (learnt association)

- Early research phase - not yet available to public
- Can last up to 2 months when applied (weather dependant)


Bioneem Oil 

 article big tree 09

What is Bioneem? (Benmhend et al. 2012)
- Bioneem is pressed directly from seeds of the Neem tree (Azadirachta indica), which is a tropical evergreen tree native to India
- Bioneem is an insecticide that controls insects which are harmful in agriculture, forestry and horticulture, and can be used in place of chemical insecticides
- Bioneem is effective against more than 400 pests of economic importance
- Half-life of bioneem: 3-22 days (45 minutes in water exposure)

Method:
- Bioneem is sprayed over the branches and stem of a tree as an elephant deterrent
- Hypothesis: Elephants do not like the smell/taste of bioneem and will not impact the tree

Bioneem effects (Benmhend et al. 2012):
- Anti-feedant and repellent: deters insects from feeding on treated plant
- Insect growth regulation: disrupts insect development. Insects do not reach adulthood
- Oviposition deterrent: insects are prevented from laying eggs on bioneem plants
- Honeybees and other pollinators avoid plants with bioneem

Risks:
- What else in the environment is affected if an insecticide is used solely as an elephant repellent?
- Short half-life means that trees will need to be continuously sprayed

Far more research is required on this product before being used in a protected area


Chilli Oil

article big tree 10

- Chillies have been used as elephant detergents in sprays (Osborn and Rasmussen 1995), chilli-grease covered fences (Osborn and Parker 2002) and dung balls
- Hessian ropes soaked in chilli oil (capsicum mixed with oil) is now being tested on trees in Olifants North (Balule)
- Thornybush are directly paste chilli oil onto tree stem
- Reapplication every 2-4 weeks (weather dependent)
- Oil-based chilli lasts longer than water-based chilli
- Study sites require evaluation to test the effectiveness of the hessian ropes (Olifants North) and direct pasting (Thornybush) methods

More data is required at a manageable scale
Elephants Alive have a product in small quantity measuring 2 million Scoville Heat Units (SHU)


Dung Paste

Tree healing properties: 

- Alteration of the old cow dung and clay tree healing method
- Anti-bacterial properties and adhesion constituents
- Seals tree wounds and prevents pathogens to otherwise exposed surfaces

Suggested method:
- Clay + buffalo/cattle dung mixed with fermented elephant dung (amounts can be reduced for small quantities of trees) 
- Fresh buffalo/cattle manure gathered in 100kg or ¾ 200Ltr drum (no oil or chemicals inside) 
- Elephant manure 100kg in 200ltr (CLEAN NB) drum filled water ¾. Add 2kg sugar press through to dissolve and keep doing for 3 days or so until fermentation stops. Press plug forming at top down as much as needed 
- 200kg clay – from destroyed anthills or ones not in use 

On day of use, mix the fresh buffalo/cattle manure with the clay and add the fermented elephant ‘tea’ to the mixture. Ensure the final mix is not too fluid-like
Use a brush to paint the tree’s main stem, covering as much as you can

article big tree 11


Conclusions

Summary table of methods:

article big tree 11

Identifying method of use:

  • What is my purpose for protecting the trees? Vulture nest? Aesthetic/Ecological purposes/Tree propagation purposes?
  • How many trees am I wanting to protect and what am I prepared to spend on a mitigation method?
  • What species or size classes of trees am I wanting to protect?
  • What type of elephant impact am I trying to protect against?
  • Is my property exposed to intense fires?
  • How close are the trees to my property or lodge?
  • Tourist perceptions – what am I willing to let my tourists see in/on/around the trees?

Summary:

  • Tree populations are affected at various demographic stages
  • Landscape management approaches can manipulate elephant encounter rates with big trees
  • Methods are available to protect individual trees against impact
  • Method of choice is dependent on your management requirements and available resources
  • Certain methods are still undergoing testing and caution is required before largescale usage
  • No method is fool proof, but survival rates of big trees can be increased if methods are applied correctly

 

by John Llewellyn.