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Euthanizing Marius the giraffe: zoos, genetics, and conservation

On Feb. 9 staff members of the Copenhagen Zoo euthanized an 18-month-old giraffe named Marius, dissected his body in front of a live audience, and fed his remains to the lions. This has sparked a debate about the decisions zoos must make in the name of conservation.

Zoo staff members were refreshingly upfront about their plans to euthanize the giraffe, and this predictably created an uproar from some animal lovers. Some even started a petition to save Marius (they solicited 27,170 signatures—just a bit short of their 28,000 goal). And a few other zoos  supposedly agreed to take the giraffe. I'll admit that even I, pragmatic scientist that I am, was a bit taken aback when I first heard of the zoo's plans. In fact, I heard about this story on Feb. 8th just a few hours after visiting the giraffes at my local zoo with my family.

The truth of the matter is that zoos often euthanize animals—either to end their suffering when they're injured, sick, or dying or as a matter of conservation. The latter is what came into play in the decision to euthanize this young giraffe. Giraffes are large animals (duh), so there are a limited number that can be kept in captivity. Even if another European zoo agreed to take Marius, the Copenhagen Zoo staff decided that this was not in the best interest of giraffe conservation. This is because Marius was related to several giraffes already in captivity and therefore would not have added to the genetic diversity of captive giraffes.

In short, Marius was killed to prevent inbreeding. And this makes sense—international zoo-breeding programs exist to maintain the genetic diversity of captive populations. When inbreeding occurs, it reduces the health of the overall giraffe population—putting members at risk for genetic diseases and poor immune systems. It may sound heartless, but Marius was taking up valuable space that can now go to a giraffe that will actually add to the genetic variation of the giraffe population at the Danish zoo.

What I found curious—and I'm not alone—is why the zoo decided to allow Marius to be born at all, knowing that breeding his parents would not add genetic diversity to the population. Visiting our local zoo just before learning about this story, I happened to have a lengthy conversation about this subject with an educator there. At our zoo we have two adult females and one three-year-old male who is the son of one of the females (you can see them on camera here). I asked how they prevent the male from mating with his mother or the other older female, and the educator said the female giraffes are on birth control. The zoo is considering bringing in a younger female from another zoo to mate with the young male—Jaffa Prince—in a few years. (This educator also mentioned that it is very difficult to move full-sized giraffes).

So why wasn't Marius's mother on birth control? Or did her birth control fail? No contraceptive method is perfect, after all. The real answer is that the Copenhagen Zoo has a different philosophy from our zoo. The staff see breeding and caring for offspring as an essential part of giraffe behavior. The Zoo's website says, "It [caring for offspring] is a 24-hour job in longer periods of their lives and we believe that they should still be able to carry out this type of behaviour also in captivity." The same website mentions that contraceptives can have "unwanted side effects on the internal organs."

It's difficult for me to say which giraffe population control method has more merit. Certainly, my local zoo's prevention philosophy is easier to swallow, but I also understand the arguments made by the Copenhagen Zoo. Balancing the need to maintain genetic diversity in captive giraffe populations with the desire to let these giraffes experience normal animal behavior—like birthing and raising offspring—is a difficult question with no clear answer. I will say that I appreciate that the Copenhagen Zoo made the best of a less than pallatible situation by hosting a public teaching autopsy and by feeding the giraffe's remains to the zoo's lions. If they had chosen to euthanize Marius with a drug, feeding his body to the lions would not have been possible and the meat would have gone to waste. Most importantly, by being open and transparent about their animal welfare decisions, the Copanhagen Zoo has also spurred conversations about the role of zoos in the conservation of large mammals.

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