Is your glass of wine poisoning wildlife?

By on April 27, 2018 with 9 Comments

The Humane Society of the United States has two affiliated wildlife centers that rescue and rehabilitate thousands of orphaned and injured animals each year. Holly Hazard, our senior vice president of programs and innovation, visits these facilities for discussions with their management teams about the state of wildlife rescue and rehabilitation, and about the current challenges facing those who work in this important area of direct care.

Recently, on a visit to the Fund for Animals Wildlife Center in Ramona, Calif., Holly found staff colleagues dealing with an unusual problem — an increase in the number of barn owls coming in with symptoms of poisoning. Today, on the blog, I’ve invited her to share her observations.

Holly Hazard

At the Fund of Animals Wildlife Center near San Diego, our staff treats and releases native California wildlife, including opossums, skunks, raptors, bobcats and bears. On a recent visit there, Christine Barton, director of operations at the wildlife center, told me about this season’s disturbing increase in barn owl poisoning intakes.

Barn owls are a predator species, native to California. Christine believes the burgeoning wine industry in San Diego County, which has doubled since 2010, may be the cause of the problem. Many vineyards, committed to traditional rodent control to protect their crops, use cruel and environmentally damaging rodenticides to poison rats and other animals foraging on grapes.

Newer poisons act slowly and owls have an opportunity to prey on the dying animals and then become poisoned themselves. Worse yet, they may bring their prey back to the nest and feed the poisonous rat, squirrel or gopher carcasses to their owlets. After eating the poison, the victim can suffer internal bleeding, which eventually leads to a slow, painful death. If the mother is the victim, the situation leaves the owlets behind as starving orphans.

Christine also worries that larger predators, like bobcats, coyotes and mountain lions, while not poisoned directly, are also eating the bodies of poisoned animals, and succumbing to mange and other ailments in increasing numbers.

A poisoned barn owl undergoing treatment at the wildlife center.

Ironically, some vintners have installed owl boxes to attract barn owls because they are known to assist with rodent control. Unfortunately, this practice attracts the owls to precisely the venue in which they can easily be poisoned by rodenticides.

There are other vintners, however, warning of the negative impacts of rodenticides and promoting alternatives that could both protect crops and spare native wildlife. Ramona Ranch Vineyard and Winery, for instance, is working with the wildlife center to educate the public and other wineries on the successful and environmentally friendly pest-control options its managers successfully use at their vineyard. These options include owl boxes, beneficial bugs and snakes. There are many organic and biodynamic wineries that do not use pesticides.

I’m pleased to know that the wildlife center and other non-profits in California are working to sensitize wine growers to the indirect cost of using poisons. It’s a good example of the vital role that wildlife sanctuaries play in helping to identify and address inadvertent and unintended threats to animals. By detecting the nature and scope of such dangers, we can forge strategies to spare wild animals from harm.

Wildlife/Marine Mammals

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  1. Amy Osajima says:

    Is there a list showing which do and do not use pesticides, or just a list of wineries that do not use pesticides?

  2. Michele OBrien says:

    This is extremely upsetting. I don’t live in California but we have wine growers in New York state and even in New Jersey. I would be interested in finding out how they control their rodent population. Of course so much wine does come from California. I hope that other Vintners and groups who deal with wildlife are spreading the word on the harm that the Vintners, who do use rodenticides are doing to wildlife, such as the owls, that actually help Vintners. It’s a very sad situation.

    I buy wine from a little farm in New Jersey that gets the wine from local wineries. I think I’m just going to try to inquire as to how they control rodents although I have a feeling I’m not going to like the answer. Thank you very much for bringing this to the attention of so many people.

  3. Emily Phillips says:


    I am a graduate student at University of California, Davis studying exactly this POTENTIAL problem. If you are interested, please email me directly.

    • Teri R Kerns says:

      Hi – I own Ramona Ranch Winery, San Diego’s only certified sustainable Vineyard and Winery, and one of only 3 in Southern California – getting certified is not an easy task, but one we take seriously along with our role to educate fellow farmers, who do care about the environment. We work with the WildLife Group, hosting classes and sharing information. I agree, education is the key and I’d like to learn more. You can learn about California Wine Sustainablity on the Wine Institute’s website, with a published list of who practices. Thanks for your support, Teri

  4. Holland VanDieren says:

    Even with five decades of animal advocacy and vegetarianism (now vegan, of course!) behind me, I had not given thought to how wine production could be hurting wildlife. Thank you HSUS for raising awareness on this.

  5. Stacey O'Brien says:

    There is another concern with these owl boxes in farming areas, even if rodenticides are not used. Fledging barn owl babies don’t learn to fly quickly or easily, and since they evolved from living in trees, they learn to fly by practicing “branching”, which means they hop from branch to branch, exercising their wings and learning what different wing movements do. They also spend time watching how their parents use their wings. If they fall, they can climb back up a slanted tree by hooking their talons into the bark, flapping their wings, and powering up. If they’re raised in a box on top of a pole, on their first trip out, they fall to the ground and can’t get back up. The simple solution is to put a ladder near the box (not right up to it) and wrap rope tightly around one of the slanted legs. Also, there need to be a few platforms up in front of the door of the box, but not right up to it, for the owls to hop and flap over to, and back. Without that, they will become more and more extinct as their babies fail to live through the fledging and learning to fly stage. Ignorance of this need means that although you’ll get rodent control for awhile, the very boxes insure that the barn owls will go extinct in your area. This has happened in several midwestern farm areas. By providing branching, farmers insure that they’ll have barn owls around in the future!

    • Ceil Slauson says:

      The promotion of branching techniques for owl boxes is much needed – especially with those businesses supplying nest boxes to the public. I’ve sent an email to the business Barn Owl Box Company since their pictures reflect no branching provided.
      This is an area that needs to be included in educational efforts.

    • Ceil Slauson says:

      I have since found out that owl boxes are designed from the standpoint of simplicity for human usage in an effort to get people on board to use them. This does not negate the need for branching, but it does modify my approach to increasing awareness.

  6. Tom Stephan says:

    If I may, There are three methods most employed to control rodents.
    1. Rodenticides.
    2. Trapping.
    3. Barn Owls.
    There are other fringe methods like vacuum trucks and propane charges but the effects don’t last long and the propane is dangerous.
    Rodenticides do not work. In fact, they make the problem worse. Only about a quarter of the population of rats that actually eat the poison die, not all the rats eat it. So that makes the rat mortality in the less than 10%tile range of the TOTAL population. Rats out reproduce that “overhead” by miles. Just the price of doing business. Also rodenticides kill every barn owl chic it comes into contact with, wiping out entire broods year after year. I was a raptor propagator for 14 years. Make a mistake with food, water or temperature and they all perish, everytime. So now there’s no recruitment of new baby BO’s and after the old pair in that territory and nest box pass on, they leave the property owner with NO protection at all. Even if it did work, which it does not, it wouldn’t work because the rats continually re invade from the neighboring properties 24-7.
    Trapping only works locally and must be constantly maintained as new rodents come onto the property nightly.
    Barn owls control as many as 2,000- rodents per year per pair, when feeding their young. They sometimes miss some gophers in heavier brush and landscape so some local trapping is needed to integrate the two methods. Everything is going great and then some uneducated or selfish person puts out a bait station, what they call “traps” but they all know it not a trap. Plus, what a distinctly inhumane thing to do to an animal by poisoning it. If they banned all rodenticides that ‘d be fine with me. barnowl boxes . com

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