In The Origin of Species, Charles Darwin (1859) wrote that: ‘there must be much fortuitous destruction, which can have little or no influence on the course of natural selection’. His reasoning was that some organisms could be ‘the best adapted to their conditions…
[but]…destroyed by accidental causes,’ such that ‘natural selection will be powerless’ in these instances. Stochastic factors, such as extreme weather events, can cause fatalities to individuals otherwise well-adapted to their environment.
Specific atmospheric conditions create weather patterns associated with a high probability of lightning, but the predicted location of lightning strikes is essentially random (although modern technology can pinpoint, with limited accuracy, a probable radius). Direct lightning strikes kill approximately 27 people per year in the United States (NOAA, 2020). Wildlife mortalities resulting from lightning
strikes have been recorded but the number of records are scarce and do not provide much detail (Anonymous, 2015; Blumenthal, 2014;
Gomes, 2012; Oliver, 2003). Diagnosis of lightning strikes is often based on circumstantial evidence (Janzen, 2020). Lightning can kill
animals in four ways: (a) direct strikes (hitting the animal directly), (b) side flashes (animal is near an object that is hit by lightning), (c) step potential (a discharge of lightning into the surface of the ground that happens if two parts of the body are in contact with the ground align in the direction of the electric ground current) and (d) touch potential (when the upper body makes contact with higher elevation of the stricken object while another part of the body is still in contact with the ground) (Gomes, 2012).
Given that lightning bolts tend to hit tall objects, especially in open areas, the height of giraffes may make them particularly vulnerable to fatal electrocution. However, they may have behavioural adaptations to reducing chances of mortality from lightning, for example seeking shelter during a thunderstorm or moving to thickly vegetated areas. This report is the first to provide detailed circumstances about lightning directly striking giraffes: fatalities that are ‘fortuitous destruction’.