Friday, January 10, 2014

European zoos castrating male gorillas for easier management

Update, 28 July 2014: Please sign this petition asking European zoos to stop castrating their gorillas.

What do you do with a male gorilla who is challenging the silverback in a zoo’s gorilla group? Do you do move him out to a “bachelor group” of all males, as we do in North America? Or do you castrate him, as is happening in European zoos? The answer, at first, seems clear: don’t castrate! Let the males develop into beautiful silverbacks! It tears at the heart.

To be fair, let’s look at the European position. The European Association of Zoos and Aquaria’s European Endangered Species Programme (EEP) is an intensive type of population management for a species kept in EAZA zoos. The gorilla EEP supports castration as a way to handle what are known as “surplus males,” the guys who can’t be kept in their maternal group because of the dynamics with the silverback.

“Hopefully these castrates can stay in their maternal group during their lives without big problems, or create fewer problems when growing up in a bachelor group,” is how Tom de Jongh explained it in the August 2010 EAZA publication Zooquaria.

The National Zoo moved Kojo and his brother into
their own "bachelor group" when tensions rose
between them and the silverback Baraka.
Baby sis Kibibi pictured here.
In North America, the Association of Zoos and Aquariums’ Species Survival Program (SSP) for gorillas does not condone castration as a management strategy. Instead, the SSP does tremendous work on strategies to create bachelor groups where the surplus males are put together – without a female to cause problems.

The SSP has had a great deal of success with this strategy, especially when following some specific guidelines regarding age of introductions and flexibility in management. AZA zoos manage 27 all-male groups and a recent a paper on the behavior of males in different gorilla SSP social groups (Stoinski, et al., 2013) shows that with proper management, all-male groups are a stable long-term strategy for housing males in zoos.

So why don’t the Europeans try the bachelor groups? They do. Over the last 20 years or so, they have established 19 bachelor groups. But they are evidently having trouble establishing more. “As we all know, good zoos willing to keep gorillas as they should do not grow on trees,” one British zoo official admitted in an email message.

I know that zoo people do not start out their day thinking, “I’ll think I’ll maim a perfectly healthy gorilla today.” I know they deal with tremendous problems, and sometimes there seems to be no good answers. If a gorilla is sent to a bachelor group, there is a risk that he may spend his life watching his back for attacks from the others. The cardiac stress and hypertension caused by the continual elevated cortisol levels under stress can be a very real concern. If he can’t fit in, he may end up as one more of those solitary gorillas living without any companionship whatsoever. If castration provides social stability and inner calm for the male who has nowhere else to live, and he can play with babies and be in a large group for a long time… then maybe the Europeans are right to consider the options.

If, if, if.. And yet…

We know castrations, especially those done at earlier ages, can cause behavioral deficiencies in apes, as an American ape expert explained to me. And the assumption that a castrate’s life may be longer and stress free is just a hypothesis without real data, unproven, since this would require hormone assays and cardiac monitoring over time. From a scientific perspective, we need facts about how well castration works to reduce aggression in gorilla families and bachelor groups. Unfortunately, getting those assays, monitoring, and behavioral data requires the castration of male gorillas.

The European zoos have put themselves into a Catch-22. Does castration hurt or help gorillas in the long run? They have to castrate the gorillas to find out. And the Europeans are castrating them without knowing if it helps or hurts the gorillas.

Ultimately then, it seems to come down to a question of values. I asked one former zookeeper what her thoughts were. “I am opposed to castrating any great ape unless his health is in danger,” she told me. “I dislike the concept for apes, their bodies are sacred, and as much as I can honor that, I will.”

On the Facebook page for Gorilla Haven - Gorilla Fans, Jane Dewar has posted the names of the ten males who have been castrated by European zoos thus far.

Kukuma #2089 - Belfast
Loango #1818 - Apenheul
D'jomo #1986 - Vallee des Singes
Zungu #1704 - Basel
Mosi #2040 - Gaiapark
Bembosi #2081 - Amsterdam
Shambe #2082 - Amsterdam
Mapenzi #2046 - Beauval
Mbula #2024 - Chessington
Mwana #2108 - Chessington

The EEP has recommended even more castrations – while their zoos continue to breed more gorillas. More male babies destined for the surgical knife in Europe, if the castration strategy remains in effect.

It would be nice to know, definitively, whether gorillas live longer lives with or without castration. It would be fantastic to know if they are happier. But we’ve been fighting against the use of chimpanzees in invasive research here in the States, so it’s not surprising that many American ape lovers rebel against the idea of castrating gorillas for research. The Europeans, though, would be the first to remind us that they aren’t castrating the gorillas for research. They are using a medical procedure to make it easier to control their populations. 

To me, castration is wrong. It is lazy. If the European zoos can’t manage their apes, they should: 1) stop making more of them; and 2) let us know which are the evidently dwindling “good zoos willing to keep gorillas.” Those are the zoos that the public should support. We already have the names of the zoos (see list above) that don’t deserve the support of people who respect apes for who they are… and for who they can – and should – become.  


  1. As far as ape castrations go, I completely agree with this article. Other than that, this article is disappointing. Since when are zoo used as the benchmark for gorilla behavior and happiness? It is very sad what humanity has become and the baseline we use to rationalize our control of the natural world.

    1. I didn't mean to imply that zoos are a "benchmark" for happiness. (Some of my earlier posts describe my mixed feelings about zoos.) Zoos do own a thousand gorillas, however, and this is a blogpost about some of those zoos' management techniques.

  2. Don't be fooled: Castrations are cheaper and easier for zoos, plus it let's them keep making gorilla babies which are $$ makers for zoos. All male groups can be dynamic and fun - Warsaw's 2 unrelated silverbacks play frequently, even tho silverbacks don't always play at all. There is plenty of science about all male groups - they work, but they require better keeper knowledge/experience, more room and more flexibility. Castrations are like lobotomies of the past, robbing the individual of his "essence" to make it easier on the zoo, not the individual gorilla.

    We are spending MILLIONS on saving gorillas in the wild as an endangered species. How anyone can suggest maiming as a management tool when it's shown by US zoos it's unnecessary, just boggles my mind!

    Finally, not sure everyone can see this, but it's one of *many* examples of all male groups being a fun and viable alternative to castration: Warsaw Zoo has 2 unrelated males, Azizzi and M'Tongue, who were raised in their group until moved together:

  3. Castrating male gorillas as a method to change their natural behavior is disturbing. If it's OK to castrate, then why not pull their teeth as well since they can cause physical harm to other members of their troop if they bite? It's a slippery slope.

    The responsible assumption should be that if a breeding recommendation is made that the offspring will be male. Simply looking at a studbook and deciding that Joan and Jeff will make desirable babies because of their genetic diversity isn't enough. Where an adult male will live in 10 years, if the offspring is male, should be the first consideration.

  4. I've had long conversations with the individuals on the EEP making the decision to maim healthy gorilla boys, and they seem to believe a "shell silverback" (as I call a castrated adult male - there have only been two such individuals and I knew both) living in his natal group is a better life than an all male group or solitary life. But the point is gorilla groups are dynamic and always changing. The EEP is trying to create stable groups that don't change as often as might be necessary (thus costing zoos more money/effort to manage). My motivation is always about what's best for the *individual* gorilla, but zoos castrating their gorillas are all about what's easiest/cheapest for them (ie: the zoo) overall. With news of the license to hunt/kill an endangered black rhino, it seems the term "endangered species" has no meaning and laws allegedly designed to protect them are useless. So sad.

  5. Breeding gorillas is not just about money for the zoo, especially if they are EEP participants. You have a social animal that learns maternal behavior, and there is proof that having at least one offspring is necessary for long-term health for females. Females that have never given birth have a higher risk for issue with their reproductive tract. Also, the full range of behaviors for a gorilla troop is to have and interact with babies. So it's not just about cranking out kids for profit, there is a real reason why they continue to let these animals breed. Also, managing a bachelor group takes a lot of space and staff; some zoos don't have as much of either as even they would like. By boycotting zoos that are unable to manage a bachelor group, you're taking away resources (money) that could be spent on larger enclosures, better night houses, and better trained staff that could lead to them being able to manage a bachelor group in the future. I personally would like to see stress studies done on these males. If EEP is going to continue to castrate anyway, lets start collecting fecals and blood and doing heart exams on these castrated males plus intact males by themselves and intact males in bachelor groups to see if castration really is effecting their welfare. As someone who works with two lone silverbacks that can't live together or with females, I'm not sure that castration worse than having a social animal live his life by himself.

    1. The testing you speak of has already been do e -- in HUMANS. There is no need to duplicate it.

  6. ARRETONS la castration des gorilles mâles dans les zoos. Si ces gorilles mâles sont trop nombreux (argument en contradiction avec la soi-disant "mission" que se sont donnés les zoos de sauvegarde d'espèces en danger ou en voie de disparition), il existe d'autres solutions comme la contrôle des naissances par la contraception etc...
    Ce qui est sûr, c'est que l'HOMME est le destructeur et la honte de la planète.