Euthanizing Elderly Elephants: An Impact Analysis

Summary

When elephants reach their sixties, they lose their last set of molars and starve to death. Euthanizing elderly elephants might seem like a good way to prevent their suffering from starvation. Unfortunately, while there’s little good evidence about how many elephants die of molar loss, the research on causes of death suggests that it’s relatively rare, and the research on elephant longevity suggests that few elephants live to be old enough for molar loss to be an issue. Thus, euthanasia of elderly elephants is unlikely to be a high-impact intervention for people interested in wild-animal suffering.

Why Elephant Euthanasia Might Seem Like A Good Idea

Elephants are among the most intelligent of animal species. They are capable of recognizing themselves in the mirror (Plotnik, De Waal, and Reiss, 2006), which is typically considered to be a sign of consciousness. They are capable of understanding that certain behaviors can be ‘means’ to a desired ‘end’ (Irie-Sugimoto et al, 2008). They are capable of tool use and even a slight amount of tool construction (for instance, they break in half sticks which are too long) (Hart and Hart, 1994). Their numerical ability is believed to be superior to that of nonhuman primates (Irie-Sugimoto et al, 2009).

Elephants exhibit behavior consistent with experiencing empathy (Byrne et al, 2008): they protect other elephants which are too small or too sick to defend themselves, comfort each other when distressed, and babysit calves. If elephants are too weak to walk, other elephants may attempt to assist them through pushing or pulling; if an elephant has a spear protruding from their body, other elephants will try to remove the spear.

Elephants have six sets of molars (Moss, 1996). Over the course of their lives, each set of molars will wear out and be replaced by another. When they lose the last set of molars in their sixties, they are no longer capable of eating and may starve to death (Moss, 1996). Humans have come up with multiple ways of assessing animal welfare, all of which involve slightly different concepts of what animals need (Fraser, 2008; Botreau et al, 2007; OIE, 2008). However, it is widely agreed that starving to death is highly painful and a violation of the animal’s welfare. For this reason, it may be useful to encourage people to euthanize elephants before they starve.

Elephant euthanasia appeared surprisingly tractable when I began this paper. Unlike usual wild-animal-suffering poster children such as insects, elephants are charismatic megafauna. Historically, humans have been far more willing to care about large, cute flagship species than about ecosystems or species diversity as a whole. Experiments have shown that people are more willing to give money to charismatic species than they are to non-charismatic species (White, Gregory, Lindley, and Richards, 1997). Indeed, elephants themselves have been used as flagships for conservation and for African wildlife sanctuaries (Leader-Williams and Dublin, 2000).

A lot of people have a non-interventionist bias with regards to the environment. Animal cruelty laws for pets are uncontroversial; while ending factory farming is more controversial, it still has greater buy-in than wild animal suffering, which is very much a fringe position. There are a couple reasons for this bias, such as sentimental ideas about ‘nature’ and the idea that humans hurting animals is worse than humans failing to intervene to prevent animals being hurt. However, anecdotally, a lot of people seem to reject wild-animal suffering as a cause area because the scale is too big for people to do anything about. Offering a practical thing that people can do may increase acceptance that wild-animal suffering is bad. This logic has previously been used to justify an elephant ‘welfare state’ (Pearce, 2015); my proposal, however, is more limited.

Furthermore, killing elephants is already considered an acceptable means of elephant management. Parks already regularly cull elephants when they fear that the presence of too many elephants will harm biodiversity, although this has been phased out in recent years and animal welfare advocates tend to object to it (Whyte, 2004).

Why Elephant Euthanasia Doesn’t Work

Unfortunately, euthanasia of elephants is unlikely to be a useful intervention, because most elephants do not live long enough to die of molar loss.

Cause of Death

A status report on Kenyan elephants collected information about all the causes of death in elephants from 1992 to 2002 (Thouless et al, 2008). It is rare for wildlife authorities to record more than a small percentage of elephant deaths, because most elephant populations live in remote locations. This may systematically distort our knowledge of common causes of elephant death: for instance, statistics typically show a higher percentage of deaths resulting from problem animal control than is actually the case, because every instance of shooting a problem elephant should be recorded. The rate of death by natural causes varies according to which park they are in: for instance, in Tsavo, 15% of elephants whose deaths were recorded died of natural causes, while in Laikipia-Samburu 18% died of natural causes and in Meru 8% died of natural causes. While deaths by accident or sickness are not counted as deaths by natural causes, it does include other common ways that elephants die, such as starvation during droughts; therefore, only a fraction of deaths by natural causes are cases of starvation due to molar loss.

ParkPercent Deaths By Natural Causes
Tsavo15%
Laikipia-Samburu18%
Meru8%
Amboseli11% / 12%1The first number includes reports of carcasses only, while the second number includes all elephants which have not been observed for a period of time.
Mara8%
Mt. Kenya4%
Mt. Elgon12%
Marsabit14%
Nasalot-South Turkana-Rimoi-Kamnarock9%
Shimba Hills20%
Eastern (Lamu, Garissa, Tana River)3%
Aberdares18%

There are other sources of information about the causes of death for elephants. The Amboseli Elephant Research Project maintains the only continuous, long-term data set for an individually known, free-ranging elephant population (Moss, 2001). Two-thirds of the deaths of adult elephants with a known cause were the product of human activity. However, this may be selection bias, because the cause of death of most elephants was unknown. In the Kenyan Samburu and Buffalo Springs reserves, the cause of death of various elephants was recorded (Wittemyer et al, 2005). Not a single death due to molar loss (or for starvation in general) was recorded. However, only about three-fifths of the carcasses could be recovered; it is possible (although perhaps unlikely) that the elephants who died of molar loss could not be recovered. However, males were the most likely to die, and the author notes that very few males were over the age of 45 — implying that they did not die of molar loss.

Life Expectancy

So from cause-of-death research we can figure that a relatively small percentage of elephants die of molar loss. To figure out how small, we’ll have to turn to circumstantial evidence. Elephants die of starvation from molar loss if they don’t die of anything else; therefore, if elephants typically die too young for molar loss to be an issue, it probably isn’t. Irritatingly, while many studies offer a life expectancy for elephants, few offer an indication of how high the variance is.

Among the Amboseli elephants, life expectancy at birth was 41 for females and 24 for males (Moss, 2001); eyeballing the survivorship curve, less than five percent of the males, and less than twenty percent of the females, lived long enough for molar loss to even be an issue. Another study of the Amboseli elephants found that the mean longevity of females was 34 and 95% died by age 65 (Lee et al, 2016). Although the Amboseli elephants are killed because they compete with livestock and as part of the manhood ritual of the Maasai tribe, Amboseli elephants were not poached heavily for ivory and the Amboseli park does not kill elephants to keep the population density down. For this reason, we can expect typical elephant populations to have shorter expected lifespans.

In another study of the Samburu reserves, the life expectancy at birth was found to be 22 for females and 19 for males — again, far too young for molar loss to be an issue (Wittemyer, Daballen, and Douglas-Hamilton, 2013). The oldest male lived to be 54; however, the oldest female did live to 64, old enough that she could conceivably have died of molar loss, although her cause of death was not recorded and she is very much an outlier.

A study of elephants in Eritrea stated that the median age at death was 15, although it also pointed out that this was much younger than most elephant life expectancies (Yacob et al, 2004). A study using pictures of elephants taken since 1976 in Addo Elephant National Park found only five female elephants that lived to be older than fifty, despite the park containing several hundred elephants (Whitehouse and Hall-Martin, 2000). (The study did not provide information about male elephants, but since male elephants have a higher mortality rate than female elephants, the situation is unlikely to be better for them.) Furthermore, one study of elephant teeth estimated that the median age at death for male elephants was 30 and for female elephants, 45 (Lee et al, 2012); this estimate excluded deaths of calves under two years, which are about a fifth of all deaths. Few elephant skeletons are lacking teeth or only have part of the last molar in place, suggesting that most elephants die before they reach that age (Nancy Todd, personal communication, April 9 2016).

In addition to the higher-quality evidence about when elephants die, some low-quality evidence suggests that elephants do not live long enough for molar loss to be an issue. In captivity, the life expectancy of Asian elephants is 45 years in North America and 48 years in Europe (there was not sufficient data to determine the lifespan of captive African elephants) (Wiese and Willis, 2004). However, this is likely to be a poor reflection of lifespans of wild elephants, because (on one hand) zoos may not provide an optimal environment for elephant health and (on the other hand) zoos may protect elephants from dangers like ivory poaching and culling.

Some studies have sampled elephants’ ages while they’re alive, instead of waiting for them to die. These studies also confirm that most elephants are fairly young. In Kidepo Valley National Park, less than ten percent of elephants were over the age of thirty, mostly due to drought and poaching disproportionately affecting older elephants (Aleper and Moe, 2006). One cull found that, adjusting for the underrepresentation of adult males among culled animals, less than five percent were over age 55 and none were over 60 (Haynes, 1985); while this provides some information about the age distribution of elephants, it will tend to underestimate the number of elephants that would live to age 60 if they weren’t culled.

Conclusion

There are currently 470,000 African elephants in the world and perhaps fifty thousand Asian elephants (WWF), and the annual mortality rate for elephants is about three percent (Wittemyer et al, 2005); of these, perhaps fifteen percent are of natural causes, and death by molar loss represents, say, ten percent of deaths by natural causes. Therefore (with a pretty significant error bar) one might guess that about 200 elephants die of old-age molar loss each year, spread across many parks.

One might propose a broader euthanizing of elephants: for instance, euthanasia during droughts or of sick elephants. I expect this to be intractable given how poorly monitored elephants currently are. When researchers track elephant deaths by keeping track of which elephants have stopped appearing, they discover that the majority of elephant carcasses are not found (Moss, 2001; Wittemyer et al, 2005). If we have a difficult time with finding carcasses (which, after all, are immobile and last a fairly long time), it will be even more difficult to identify terminally ill or wounded elephants in time to help them. However, if monitoring of elephants improves, elephant euthanasia might be something to campaign for.

In conclusion, the evidence about how likely elephants are to die of molar loss is fairly low-quality. However, putting it together, it looks like very few elephants are likely to die from starvation after they lose their molars. For this reason, it is unlikely to be a good issue for advocates against wild-animal suffering to prioritize.

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1. The first number includes reports of carcasses only, while the second number includes all elephants which have not been observed for a period of time.