Here’s how the Smithsonian Zoo grows bamboo for its pandas

FRONT ROYAL, Va. — On a wet Thursday morning in rural Virginia, a buzzing noise emerges from a patch of tall, green trees. A group of five workers, dressed in thick pants and boots and armed with chain saws and loppers, gather around a truck. “Bamboo Procurement Team” is written on the side. The workers listen to instructions on how many stalks they’re cutting — today, it’s about 400.

Here at the 3,200-acre Smithsonian Conservation Biology Institute in Front Royal, Virginia, is where more than 13,000 stalks of bamboo, are harvested by the zoo each year.

The bamboo feeds several species, including gorillas, red pandas, and Asian elephants, but the bulk of it will go to National Zoo’s most famous animals — their giant pandas. It’s a process that the zookeepers are now ramping up after the arrival of two new pandas, Bao Li and Qing Bao, on Tuesday.

Harvesting bamboo is “the most physically taxing activity at the zoo,” said Mike Maslanka, senior nutritionist and head of the Department of Nutrition Science for the National Zoo. “It doesn’t matter what the weather is, we go and harvest bamboo,” Maslanka said. “Pandas can’t survive and thrive without it.”

While pandas have the same digestive system as carnivores, bamboo is the only thing they eat. They absorb the little nutritional value of the bamboo (each bamboo stalk is about 12 calories) and immediately pass it. This means in a day, pandas typically eat about 70 to 100 pounds of bamboo — and leave about 50 to 100 piles of panda feces for zookeepers to clean.

“[Bamboo] is 99.9% of a panda diet. It just is. They’ve evolved to eat this … Our pandas are healthier, GI [gastrointestinal] tract-wise, when they eat this,” Maslanka said.

According to a zoo spokesperson, the zoo has grown bamboo for about 52 years. The harvesting work starts in earnest in the spring, when bamboo shoots emerge from the ground. The team purchases shoots for planting and as treats for the pandas. Jennifer Adams, an animal keeper at the zoo and part of the Bamboo Procurement Team, says the shoots are “yummy” to the pandas.

“[Pandas] kind of change what they eat throughout the year in the wild. Here, if we can give them that variety, we’ve got a limited window to do that, but we’ll take them and we’ll try to freeze some too so that they can have it for a little bit longer,” Adams said.

Upon sprouting, the bamboo grows to its full height and then stops. A team that usually consists of about two people cut down the 20-to-25-feet-tall trees. Currently, the team harvests from the campus about two to three days a week. This will increase to four days now that the pandas have returned.

The zoo also sources bamboo from about 20 to 30 other stands throughout the region, including some located at the zoo. Maslanka says the labor used to supply the bamboo to the zoo, along with vehicle costs and the purchase of new rootstock, make up most of the financial costs.

The process has gone mostly smoothly, except for 2009, when the Smithsonian found itself with an unexpected shortage of bamboo. The team clear-cut a stand of bamboo to its rootstock with the assumption that it would grow back to its full height. Instead, the bamboo was stunted and could not be harvested.

Maslanka and his team put out a request to local landowners and farmers with bamboo, asking whether they would let them harvest and manage their crop. In a testament to the love for the giant pandas, the request led to an overload of emails from fans of the zoo, according to Maslanka, who was new to the National Zoo at the time.

“I was sorting through literally hundreds of emails from people who wanted to help us out so much. It was ‘yes, we’ve got some bamboo. We want to help the zoo. We love the zoo.’”

The National Zoo has strict criteria for donated bamboo. The 2009 request states that stands must “comprise a minimum of one acre, be within a 25-30 mile driving distance of the Zoo, be at least 100 feet from a roadway, and have not been treated with herbicides or pesticides.” Given the amount of bamboo that the zoo actually requires, Maslanka said that going to people’s houses would’ve been more costly and time-consuming. Most of the offered bamboo sources were too small, and the zoo would’ve had to harvest from multiple places just to hit their usual amount.

In the end, the team decided to change some of its cutting practices and add additional sources.

Now, the workers cut the bamboo patch in alternating zigzags to avoid a repeat of the 2009 incident. “It’s healthier to cut 30%, maybe 25% of a stand and leave the rest to allow regrowth from year to year,” Maslanka said.

Adams, the zookeeper, began working at the zoo as an intern 10 years ago but returned last year. She has experience harvesting bamboo at other facilities, but said the National Zoo’s program is “a lot more intensive.”

“We don’t go to the gym much, because this is enough,” Adams said.

Adams is small but lifted the heavy bamboo stalks with a practiced ease.

“For how much everybody loves the pandas, we put twice as much work into that to keep taking care of them,” she said. “I hope everyone just knows how much we love the pandas and how much we do for them.”