Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux
An employee pours a sample of pre-fermented wine from a vat tap in Pomerol, France. (Photographer: Balint Porneczi/Bloomberg)

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

Over the past year, bats have gone from unloved animal to devastating threat, thanks to their suspected role as the original carriers of Covid-19 before the novel coronavirus hopscotched to humans.

Yet in Bordeaux, one of the world’s top wine regions, they’re being welcomed as heroes.

As the 2020 harvest started early, a lot is riding on the region’s vintage amid a spate of challenges. After U.S. President Donald Trump imposed a 25% tariff on several varieties of European still alcohol last October, the value of Bordeaux wine fell 46% in November, compared to the previous year, with total sales volume dropping 18% according to the Bordeaux Wine Bureau (CIVB).

Covid-19 has exacerbated these difficulties: For the 12-month period ending July 2020, Bordeaux exports fell 18% in value, compared to the year before. High-quality 2019 reds are going for as much as 30% less than the previous vintage, because the pandemic hobbled en primeur sales, which usually help drive competition for bottles. A 1999 Château Mouton Rothschild is now priced at around $330; it would ordinarily command almost $500 on the top tier. 

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

Then, as in such other regions as Champagne, decreasing grape yields are brought on by climate change and pests. The 2019 Bordeaux harvest was down 2.3%, compared to the 10-year average, and 28%, compared with 20 years ago.

The pests are what inspired Bordeaux winemakers to turn to local bats to help save the day. While studies are still determining how much the winged mammals have helped boost harvest yields and quality, the region’s winemakers have embraced them, figuratively speaking. Other renowned French wine regions are taking note.

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

Last fall, I traveled to Château Lapelletrie in Saint-Émilion to see the animal-assisted winemaking first-hand. Anne Biscaye, a ninth-generation vintner with the aspect of Juliette Binoche, led me underground, into a former quarry, to check out her collaborators. A pair of bats soon flew overhead. At night, dozens would join them to roam above the vineyard in search of insects.

Biscaye is one of several vintners installing wooden nesting boxes around their properties, adding watering holes and leaving grassy strips between vine rows to create a bat-friendly habitat. They are participating in a long-term scientific study to confirm the impact of local bats on two of the most invasive vineyard pests: the European grapevine moth and grape berry moth. Both lead to botrytis, a destructive gray rot.

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

Nocturnal Experimentation

At Château du Courlat in Lussac-Saint-Émilion, I meet Yohan Charbonnier, a scientist from France’s Bird Protection League, just before sunset under bats silhouetted against a purple-orange sky. As night fell, he and his headlamp-wearing team rigged nets among trees to catch various species: the gray long-eared bat, Kuhl’s pipistrelle, the greater mouse-eared bat. He tested each for any digested presence of the harmful moths before releasing them.

Charbonnier has been running these catch-and-release tests since 2017, working on 23 vineyard plots that include Biscaye’s Lapelleterie and Château du Courlat in five of Bordeaux’s most famed regions—Medoc, Saint-Émilion, Pessac-Léognan, Côtes de Bourg, and Côtes de Bordeaux.

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

“Nocturnal, insectivorous, and with an insatiable appetite, bats are designated to be the best animals to limit the moth pests from the vineyards,” Charbonnier says.

Because so many factors, including climate, affect grape yields, it has been difficult to pinpoint how much the animals help—or even to prove empirically that they do. But Charbonnier thinks he’s cracked it. He’s confirmed that the flying mammals successfully eradicate the destructive moths and is now in the process of quantifying the increase in yield, using data collected ahead of this year’s harvest. 

Cécile Mallié-Verdier isn’t waiting on the results. Already an enthusiastic believer, the winemaker at Château Brethous in Camblanes-et-Meynac says that by eliminating the moths that create gray rot, she can avoid the moldy grapes that might taint her wines, such as the merlot-cabernet sauvignon blend Cuvée Arpège. She thinks bats may improve overall wine quality and taste as well by obviating the need for some pesticides that risk harming  grapes’ aromatic profile

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

For Mallié-Verdier and other local winemakers, the use of bats dovetails with the CIVB’s push for winemakers to avoid pesticides labeled as carcinogenic. From 2014 to 2016, Bordeaux vineyards cut the use of several pesticides by 55%. Now, requirements are growing more stringent: The recently enacted agricultural EGalim Law requires winegrowers to uphold specific environmental standards by 2030.

“Nature has become a real partner of the Bordeaux winemakers,” says Bernard Farges, president of the CIVB. “Bats are the perfect example of a win-win situation.”

Bats Are the Newest Key to Producing a Fine Bottle of Bordeaux

Bat Plan Spreads Its Wings

The vineyards at which Charbonnier’s studies take place are just a few hectares in area, a fraction of Bordeaux’s 110,800 total. But they represent a variety of winemakers. And though most of the study’s participants have been avant-garde producers of natural wine, the initiative also has buy-in from such big winemakers as Château Figeac, the largest wine estate in Saint-Émilion, and the famed Château du Tertre. Both participated in the study.

Moreover, estates around the region can record bat colonies by taking advantage of an online bat observatory developed by the CIVB and an accompanying app and geolocation system. CIVB is also releasing a technical notebook, a printed pamphlet that outlines the usefulness of bats for vineyards, based on the study, with practical tips for improving the animals’ habitat.

Additional areas around France are taking note: Winemakers in Burgundy have participated in a study similar to Bordeaux’s; some in Dordogne have begun installing wooden bat houses on their vineyards. 

Château Lapelletrie’s Biscaye is firm in dismissing fears of bats caused by the coronavirus pandemic. “I decided to accept working with nature and—from it—let everything take its place,” she says. “Bats, just like birds, are our friends.”

©2020 Bloomberg L.P.

BQ Install

Bloomberg Quint

Add BloombergQuint App to Home screen.