When lightning strikes, it’s best not to be a giraffe
Scheijen, C.P.J. (2020) Inferred giraffe deaths from lightning strikes. African Journal of Ecology, 58, 860-863. DOI: 10.1111/aje.12785.
No picture of an African savanna would be complete without the presence of at least a couple of giraffe (Giraffa camelopardalis). Standing at over five metres tall, these lumbering giants can exploit a feeding niche unavailable to most hooved animals. However, standing out from the crowd can also result in unexpected dangers.
In southern Africa, terrific storms build over a period of weeks culminating in a violent clash of thunder and lightning. It is well known in these environments that where lightning strikes the ground, fire bursts forth, causing immediate danger to nearby wildlife. However, it has also been recently discovered that certain species are also vulnerable to direct strikes by lightning. Given that lightning bolts tend to hit tall objects, the height of giraffe makes them particularly vulnerable to a sudden death by electrocution.
In a report submitted to the African Journal of Ecology, Ciska Scheijen provides the first detailed description of lightning strikes causing direct death for giraffe individuals. Observations were conducted by monitoring eight individuals daily in a private game reserve located in South Africa during and after a storm.
On 29th February 2020, a short but strong thunderstorm pummelled the reserve, accumulating 65mm of rainfall within two hours. The following day, only six of the eight giraffe could be located. Eventually, the two missing females were located, lying seven metres apart on the red dirt. Upon examination, neither female show signs of predation, save for a couple of jackal marks on the rump. However, a distinctive fracture of the ossicone (the horn-like protuberance on top of a griaffe’s head) indicated that one of the females had been struck directly by lightning. Notably, there were no large trees in the vicinity of either giraffe, considerably raising the likelihood of lightning strike. It was believed that the other female was killed by electrocution via a process called step potential. In this instance, the ground electric current aligns with the lightning strike to transmit current to the giraffe.
The author noted that the site smelt strongly of ammonia, despite finding the carcasses ~1.5 days after death. It is suggested that this smell deters potential scavengers. Indeed, even the eyes of both giraffe, which are commonly the first body parts to be scavenged by corvids were still present.
However, giraffes are not “sitting ducks” when it comes to lightning strikes. There are a number of behavioural adaptions that giraffes commonly undertake during times of inclement weather that mitigate their risk of death. Chief among these is to move to within areas of taller vegetation. By doing so, the giraffes confer the dangers of lightning strikes to trees instead of themselves. It has been noted that giraffe walk ~13% less distance during rainfall events whilst they wait out the storm for this reason.
In 1859, Darwin stated that animals could be particularly well adapted to their environment, but will always be subject to accidental causes of death. In this report, the essentially random strikes of lightning form just that accidental cause. Whilst giraffe populations may have been able to cope with sporadic deaths in the past, today pressure on their populations due to land use change and hunting means that every death is meaningful.
