Here's the latest from my gorilla doctors blog. . .

Mushya's Case, Part 2: Hands-on with Icyizere and Mushya

Mushya's Case, Part 1

One-Health Partners

So Much for the Rule of Threes

Sad Week in Rwanda

Forgive me for not blogging over the last few weeks, and for returning with a sad report about the deaths of several gorillas.  We didn’t have the opportunity to treat these individuals, but we did do post mortem exams on three of the four.  If the rule-of-threes holds, the good news is we won’t have another dead gorilla for a while.

The first two deaths were newborns.  The day had started off with great news.  Veronica, the coordinator for Karisoke Research Center, called to say twins had been born in Pablo Group!  The babies looked healthy and strong (only one set of twins has survived since monitoring of the mountain gorillas began years ago.  See 2007 blog post about Mugeni in Kwitonda Group - here’s the link).  Then she delivered the bad news: the twins’ mother had only recently rejoined the group.  I gasped, and asked about Cantsby, the lead silverback, wondering why he hadn’t killed them.  Veronica said he seemed calm. But when she called back an hour later, I almost didn’t need to hear the words over the phone—her voice was enough.  At least it had happened before everyone had time to get excited about the birth of the twins.

Later that day, the trackers were able to recover one of the infants so that we could do a routine post mortem analysis.  It was a female with a crushed skull (sorry to be so graphic).  We guessed that she had died instantly.

Since I’ve worked here, infanticide has been the outcome every time an infant sired by a male in another group has been born to a newly transferred female.  It’s also happened when there have been interactions between lone silverbacks and family groups.  In that case, the intruding male makes the kill.  I don’t know if anyone will ever understand exactly how a silverback recognizes an infant that doesn’t belong to him.  The Karisoke researchers think the timing of the transfer is the main factor.  If the female is in early pregnancy when she joins a new group, her babies can be born and left alone.  (The same theory holds for chimpanzees.)  It could be that the silverback remembers whether or not he mated with the female.  Maybe she behaves differently in some way toward him, or the infant smells or looks different in some way.  Some trackers have told me they think the silverback kills only male infants, but this one was a female, and other female babies have been killed since I’ve been here.

One thing is certain: clearly the silverback recognizes infants who are not his.  But what about the female?  I can’t help wondering what in the world this new mother of twins was thinking—or not thinking.  It’s hard to believe she didn’t sense the risk of returning to her former group late in pregnancy.  Or maybe she did, but food and protection and other advantages mattered more in her scheme of things.

The day the twins were born and killed ended on an even more negative note.  The Karisoke trackers couldn’t find Shinda, the silverback in charge of the group bearing his name.  We’d been monitoring Shinda for lethargy and decreased appetite.  Magda had just visited him the day before.  He was alert and eating, though slowly, and appeared to be experiencing pain in his back or hips.  We’d made a plan to check him again if he didn’t improve.  When he disappeared, we assumed the worst, though it was true that he’d rebounded from similar episodes of lethargy before.  Perhaps he’d rejoin his family the next day.  Four days later, the trackers found Shinda dead.

Continued...Sad Week in Rwanda