How many humans does it take to impregnate an elephant? Earlier this summer a crowd gathered at Seattle’s Woodland Park Zoo to help Chai, a 32-year-old Asian elephant, conceive a calf. Specialists from across the country were involved, but Chai’s male mate was noticeably absent. Only the bull’s sperm made the trip to the West Coast, while the potential papa remained hundreds of miles away in New Mexico’s Alburquerque Biological Park Zoo.
Artificial inseminations (AIs) like Chai’s are playing a growing role in maintaining a healthy and genetically-diverse “herd” of North American zoo elephants. Today’s AI success rates rival those of natural breeding, thanks to creative scientists, technological advances, and cooperation among the many institutions that elephants call home.
“We usually have semen coming in from three different places, because they might not be able to collect a sample from a particular bull or it might not be good quality,” said Suzan Murray, chief veterinarian at the Smithsonian National Zoological Park in Washington, D.C. “We have to arrange plane schedules, and fly insemination experts in, and time it all to the elephant’s ovulation cycle. It really is a large number of people who work very collaboratively towards the common goal of getting an elephant pregnant.”
Insemination Allows Elephants to Be Stay-at-Home Moms
Old-fashioned elephant breeding is complicated by a sexual imbalance in North American zoos—many institutions have only female elephants on hand. In the wild, the massive mammals live in matriarchal herds with females and juveniles together while mature males typically live alone. This social structure is typically reconstructed in zoos which means that designated facilities must be constructed to separate males—and these must be of a specially-designed type to safely house the powerful and more dangerous bulls. New facilities are required to accommodate males in this manner, but many zoos with older facilities simply don’t have any males on site—which means breeding has often involved an elephant road trip.
“Traditionally you’d send your female off to another institution where there is a bull for months or maybe a year, because they only ovulate three times in a year, to get pregnant,” said Nancy Hawkes, Woodland Park Zoo’s general curator and resident expert in elephant reproduction. “You can imagine the cost and the potential stress of doing that, sending an elephant away from her social group where she has to assimilate to another herd and breed with a bull that she doesn’t know and then travel back pregnant.”
But artificial insemination is putting an end to many of these high-mileage matings. “This technology allows us to just move sperm around, instead of moving animals around, so it’s a lot less stressful and a lot better for the animals,” Hawkes said. “And today artificial insemination is just as successful as breeding,” she added. “It results in a pregnancy roughly 60-70 percent of the time.”
Elephant matings are carefully arranged under the elephant Species Survival Plan (SSP), a cooperative program of the Association of Zoos & Aquariums (AZA) geared towards ensuring a stable, genetically diverse population of North American elephants. Representatives from AZA zoos across the continent work together under the plan to breed elephants for the greater good in the face of stiff challenges like the herpes virus that is causing significant fatalities among Asian elephants in captivity and in the wild.
“We work with 75 zoos that have elephants in North America and in total there are about 150 of each species, African and Asian,” said Nancy Hawkes.
“All of the Asian elephants in North America are managed as one genetic population and we make decisions about breeding and husbandry based on maximizing the genetic diversity of the population and keeping it as healthy as possible. We at the Woodland Park Zoo don’t make decisions in a vacuum.”
And though some of North America’s zoo elephants were once wild, very few new elephants still enter the population this way. Relocating them from the nations where they occur is a legal and logistical challenge that can take years and has become quite a rare event. That reality makes AI particularly attractive in terms of matching males with distant herds where their genes can freshen local pools even if there is a bull in residence.
Modern artificial insemination techniques for elephants, pioneered in the 1990s by Thomas Hildebrandt and colleagues at Berlin’s Leibniz Institute for Zoo and Wildlife Research, have led to leaps in artificial insemination success rates. Ultrasound is now a major key to success because it allows experts to get a non-invasive view of the elephant’s unique reproductive anatomy during the procedure itself. Hildebrant’s team perfected the procedure by performing it on carcasses of elephants culled during South African population controls.
A female elephant’s vaginal opening is located deep inside the animal—a full meter in fact—and the ovaries are another 2 meters beyond. “You’re talking about a reproductive tract that’s 10 feet long,” Hawkes said. “We have to get through the opening between the legs, called the vestibule, and very deep inside the animal.”
Male elephants are naturally equipped for this task but AI teams use a thin, flexible, insemination catheter to deposit the semen in the right place, which is up by the animal’s cervix. “It’s such a big animal that you can’t see where you’re going and the very large bladder is close to the very small cervix, but the ultrasound can help guide the catheter into the right place,” Hawkes explained.
If the procedure sounds like a job for experts, well, it most certainly is. There are only three groups worldwide who perform the procedure and one of them is the German team who perfected modern ultrasound AI for elephants. Dennis Schmitt, a professor of animal science at Missouri State University, trained under the Leibniz Institute team and recently traveled to Seattle to perform the insemination on Chai. Disney’s Animal Kingdom also has a veterinary team trained to perform AI. There are currently about 30 AZA zoos that participate in AI as part of their elephant breeding programs under the auspices of the SSP consortium.
But success requires a much larger team of experts who begin work 6 months to a year before any insemination attempt. Their first step is to make a female elephant comfortable with a procedure that may take 15 minutes but could last longer, during which she’s not sedated or tranquilized in any way.
Trainers use time to acclimate an elephant to the process, which begins when the animal enters a chute used for other medical procedures.
“She has to be good about standing still for say up to an hour and also having a lot of people around her back end,” Hawkes said. “And of course she has to accept the ultrasound, endoscope and the insemination catheter. So we work with them slowly over a long period of time, taking baby steps, getting them used to getting into this position and having the equipment around and then step by step inserting pieces of equipment.”
Positive reinforcement is key, Hawkes said, and Chai especially enjoyed munching on tasty treats like carrots and cantaloupe. “But in my experience almost every elephant I’ve worked with most loves just being the center of attention and having all of their keepers around and getting lots of praise.”
Because the elephant’s welfare is always the primary concern, and because the procedure can’t succeed without her full cooperation, a female is always given the option of whether or not to enter the chute and participate in insemination activities. They rarely decline, Hawkes said, and in fact seem to enjoy the attention once acclimated to the process. “You hear a lot of happy vocalizations,” she noted.
Of course, even when only one partner of an elephant pair is on site it does take two to reproduce. So on insemination days other specialists are hard at work at distant locales.
“Some days you have everything in line and you’re just sitting around praying that some bull will produce a sample that you’re able to use,” said reproductive physiologist Janine Brown, of the Smithsonian National Zoological Park’s Conservation and Research Center in Front Royal, Virginia.
Unlike some other animal semen, elephant sperm doesn’t freeze well—at least with current technologies. So it must be collected daily and transported by rush delivery in refrigerated “equitainers,” like those used for horses. Gathering it is a very extensive procedure and one for those not afraid to get their hands dirty.
“Basically you have a keeper who has an arm up the rectum, massaging the accessory glands, and you have another keeper encouraging the penis to drop and basically causing an erection,” explained Woodland Park Zoo’s Hawkes. “Still another attaches a palpation sleeve, the big long examination glove that a vet uses, onto the penis and the elephant ejaculates into that.”
The process takes patience and skill, and is “more of an art than a science.” Sometimes samples simply can’t be collected or they may become contaminated with urine. “They set up a microscope right there in the barn and look at the sample,” Hawkes said. “Only if it looks good will they prepare to ship.”
Timing is Everything
Considering the rather arduous task of collecting semen, and the logistics required to get one of the world’s few expert elephant insemination experts on site for a procedure, timing is critically important. It’s also crucial if the insemination is to have a good chance of actually impregnating the female.
That’s where Janine Brown comes in, with her colleagues at the Smithsonian Conservation Biology Institute’s endocrinology laboratory in Front Royal, Virginia.
Brown’s group times both artificial and natural breeding opportunities because elephants have a 3.5 to 4-month estrous cycle, which means there aren’t a lot of chances for conception in a given year. ““We run a diagnostic lab where other zoos send samples for fertility assessments and hormone measurements in order to time artificial insemination. Our biggest clientele, if you will, are the elephants,” she said.”
“You only get so many shots and you really need to be able to time it very precisely,” Brown said. “They are only fertile for a day and a half or two days, so the fertility window is very short and you have to know exactly when she’s going to ovulate.”
But Brown and her colleagues consider themselves lucky because it turns out that elephants have a hormonal signal, extremely unusual in mammals, that allows experts to predict periods of fertility with striking success.
Elephants have two surges of luteinizing hormone (LH), which Brown documented, meaning an initial hormonal surge is followed some three weeks later by a second which actually induces ovulation.
”We don’t even know exactly what the first surge is for, but when we see the first surge we know that ovulation is going to occur 20 days later,” Brown said. “We can pretty much pinpoint it down to the day and whoever is coming to do the artificial insemination has about 3 weeks to purchase their plane tickets and get ready.”
“Women only have one LH surge so they just pick up the phone and say honey come home. But we couldn’t just call Germany and say please get on the plane. So this was, for us, an incredible gift that we just stumbled on and it really broke things open so that we could effectively time the insemination.”
But despite all the best efforts of science, Mother Nature still plays a major role in pregnancy and things don’t always work out as planned. Chai, for example, has been inseminated during several (nine) ovulation cycles since 2005, but only one resulted in pregnancy—and that was terminated by an early miscarriage.
Scientists won’t know for about 15 weeks whether the elephant is currently pregnant from her June 8 insemination. But they have high hopes. If the procedure was successful and Chai carries her pregnancy to term the elephant and her human handlers will welcome a new baby in Spring 2013.