Fauna and Fire

After reading the article Brandvlei burns  by Anso le Roux in the March edition of Veld & Flora I was a bit perturbed. Nowhere in the article was there any mention of the effect of the burn on the fauna of the region. Was anything done to remove snakes, rodents, porcupines, small buck, tortoises etc. from the area before the burn? If not what evidence was discovered after the burn of fauna that did not escape the burn? I hate to be critical without being constructive and I cannot provide a solution to the apparent necessity for conducting a non-natural burn versus the protection of the wildlife of the area but I have a nagging feeling that a more holistic approach to any problem involving interfering with nature should be made. Friends of mine experienced a horrific fire on their property and afterwards, although the fynbos came back vigorously they now have a problem with moles because any snakes that were on the property and which presumably controlled the mole population are now not present (snake carcases were found after the fire). I appreciate that the Botanical Society has a specialised duty towards Flora but it should not forget Fauna and the need for everything to live in harmony.

Derek McAuley, Somerset West

Anso le Roux replies

With supplementary comments of my professor, Leslie Brown, who has many years of experience in the fire ecology of grassland and savanna, I trust to provide a satisfying report. I completely understand the concern of the reader and agree that mention about the effect of the fire on fauna could have been made in the article. The fact that it was not, does not mean that it was ignored in the planning of the controlled burn as well as in the post-fire monitoring of the area.  Although we are fully aware of the integral role of all living organisms in natural systems, the study of which this controlled burning was part, focuses on vegetation ecology – the main subject at this stage being a floristic analysis of the plant communities around the Brandvlei Dam. Although we recognize the importance thereof, no formal data collection methods pertaining to fauna are applied in this study at the moment. Observations of fauna or faunal activity are noted as observed, but we do not have formal data in this regard. I know the area well and can try and respond to the concerns about the fauna based on my observations and field notes additional to the floristic study.

The ‘natural’ system around the Brandvlei Dam is not natural anymore – it has over decades suffered various impacts, directly and indirectly, through the actions of humans which are still ongoing as we speak.  Managing such an impacted system is not easy. Decisions are taken with the greatest caution not to further impair the natural characteristics thereof, but find practical, functional ways to try and maintain the integrity and resilience of the system.

 The controlled burn had to be done for various valid reasons. I can assure you that it involved a great amount of conscientious planning and that minimal harm to the fauna was one of the priorities.  This taken into account, it was decided to burn only a small area of about 15 hectares. This area involves the northern- and southern facing slopes of one of the hills in the area. No animals needed to be removed from the area before the fire. In the more than six years that we have been traversing the area, we never saw snakes on these specific slopes. I have seen Skaapstekers in a plateau-area more to the east, now and then (not often) encountered Puff Adders on sandy flats close to the river. Our general impression is that snakes tend to avoid the rocky slopes – especially in the dry season. We have seen mass movement of snakes (mostly Skaapstekers) from the riverbed in the direction of the hills in early winter after the rains when the water level of the river increases (we once counted more than a hundred snakes killed in one week on the road between the river and these hills), but do not normally encounter snakes or tortoises on the fairly steep slopes.  The two tortoise species in the area inhabit sandy areas at the bottom of these slopes – we have never observed tortoises on the rocky slopes.

  The burned area was meticulously walked through after the fire. We never found evidence of any animal carcasses after the burn. Extensive termite activity was noted early in the post fire environment, also was rodent activity a common sight at the emergence of the first bulbs. We took care to burn in low-risk conditions. Some pockets within the burned area, where there was not enough fuel to sustain fire, did not burn or only burn partially. Apart from adjacent areas, I believe that these pockets could have provided places of safety to fauna to escape the flames. In a true fire-ecology study it is important that a burned area is large enough with no un-burned strips or pockets within to diminish edge-effects which affects the integrity of the results. We deliberately decided to leave the parts that did not burn (in fire-ecology studies such parts are usually burned clean afterwards) as we felt that they would not have burnt under ‘natural’ conditions – and we appreciated the fact that they may have provided shelter to small animals during the fire.  As I mentioned earlier, although fire in this system is long overdue, fire ecology is not the objective of this present study. The area we burned is small, the allover intensity of the fire was low, fire was not started from two or more sides trapping animals in the middle. Fire on the northern slope was put out when the back-burns were in place before fire was lit on the southern slope. There thus at all times were ample of escape routes for rodents or grysbok and duikers etc.

 As part of an environmental education programme with farm children, we keep record of road-kills. We learnt from experience that the stretch of tar road between the Breede River and the hills bordering the Brandvlei Dam pose a far larger threat to the fauna in the area than conservation management methods such as controlled fire. The ecosystem is adapted to fire and because of the presence of man made structures, natural fires are extinguished.

Fire is a natural phenomenon on earth and has been present before the existence of humans. Thus before humans began using fire it already had an effect on the environment (plants and animals). The vegetation of the fynbos, grassland and savanna areas are typically adapted to fire. This is also the reason why the early Portuguese explorers referred to the western Cape region as “Terra dos fumos” = fire continent.

  Unfortunately humans started seeing fire as a threat to their crops and grazing lands. Due to these destructions fire was increasingly seen as a threat to the natural environment and in many areas forbidden. This in turn has led to woodlands replacing grasslands and forests replacing shrublands and causing a decline in many animal populations which is similar though opposite to the affect of fire on environmental change. After many years scientists have realized and proved that keeping fire out of a fire-prone system is unnatural, interfering with nature and would likely over the long run not maintain the harmony.  Numerous scientific studies have shown that fire does not negatively affect animal populations. Ill planned fires and in areas with a high fuel load can definitely cause unnecessary animal and insect deaths. That is most probably the reason why the friends of Mr McAuley experienced a horrific fire – fire being kept out of the property too long, fire at the wrong time of the year, not properly managed etc. One must remember that the ecosystem is constantly changing and not static. That means that it will not stay the way it is now and support only specific animal and plant species. The changes can be at a micro or macro scale depending what caused it. Thus there will also be a fluctuation in plant and animal populations in any ecosystem. After fire certain insect and bird species would be more prominent in a system and as it changes they will move to other more suitable habitats and be replaced by other species to whom the habitat has become more suitable etc. It must also be stated that most animal species will easily escape the simulated “natural” fire we affected since the intensity was above ground level and it was a fast-moving head fire (with the wind). Therefore all the animals such as rodents, reptiles etc. had (apart from the area burnt being small and having many natural un-burnt areas within which to hide) ample time to creep into holes and under rocks. Due to it being a head fire the fire would swiftly move over animals such as tortoises etc.  

  One must always remember that humans have kept natural fires out of our natural systems and we are trying to simulate nature as best we can. Fire is not a bad thing but rather the implementation of fire by inexperienced humans. Lastly it must be mentioned that we followed accepted normal procedures for implementing fires as is done on all nature reserves and national parks. It is not feasible to catch and remove animals from an area for various reasons (e.g. larger animals can die from stress; there is no guarantee that all will be caught, the question will remain where do we stop – will we collect all animals present and how will we know whether it is all, what about ones just moving through; where will they be kept etc.).  

Although I knew that, due to human interference, fire in this area was long overdue and short term results show to be only positive, I am personally very cautious about controlled burns. It is a matter which needs to be treated with great caution, thorough planning and careful implementation.

I hope that I could answer your question. I will gladly share information about our experience if there are other questions.

Derek McAuley replies: 

 I am completely reassured that Anso and her team did everything within their power to interfere with nature as little as possible. As far as I am concerned that is the end of the story.