When I wrote the book, most pet fur was still pretty natural. But now, flea
and tick preventatives, like the pill I give my dog Pip once a month, lace
the fur with pesticides. In the United States, there is virtually no
funding for the kind of research that can determine whether the danger to
birds using this fur might be offset by the possibility of reducing the
number of mites, lice, and flies hurting nestlings, so up until now, I
didn’t have a clue whether to amend my recommendation or not. A *2025 study
published in the U.K.
<https://substack.com/redirect/7406b3ec-50d4-42a8-8bac-1a0ea547fd2f?<j...>* clarifies the issue.
The researchers examined the fur lining in 103 nests of Eurasian Blue Tits
and Great Tits collected in 2020. The species were chosen because, like our
own chickadees and titmice, they virtually always line their nests with
fur.
<https://substack.com/redirect/bbed7fbb-4187-4f76-b07e-f061ba07b6da?<j...> I
photographed this Great Tit in Austria in 2014.
The scientists found that in *every single nest*, the fur was contaminated
with at least 2 pesticides—in some, as many as 11—each one in common
veterinary use to protect livestock and pets. But are these pesticides
actually dangerous for birds? The researchers discovered that the more of
these pesticides present in the fur incorporated into a nest, the fewer
eggs produced and the higher the chick mortality. So when it comes to
setting out fur from treated pets for your local nesting birds, please,
just say no.
In the nests examined, 100 percent contained the pesticide fipronil, which
is used to control ants, beetles, cockroaches, fleas, ticks, termites, mole
crickets, thrips, rootworms, weevils, etc., and is one of the ingredients
in Frontline and other popular anti-flea medications for pets. The nest
materials for the study were collected in 2020, before the product I now
use on my dog Pip (Simparica TRIO) was available. The three pesticides in
Simparica (sarolaner, moxidectin, and pyrantel) were not tested for in this
study, but based on fact that sarolaner is known to cause tremors, ataxia,
and seizures in some dogs, I can’t believe it’s safer than fipronil for
baby birds.
<https://substack.com/redirect/1882aecb-e5f7-412d-a39a-3d336beac681?<j...> Protecting
my dog Pip from heartworm and other insect-borne diseases is important to
me, but so is a pesticide-free environment. Weighing all the risks is not
at all easy to do.
Permethrin was another of the most prevalent pesticides found—it was in
slightly more than 89 percent of the nests. This pesticide is not just used
for pets—it’s in shampoos to treat head lice for humans, and is often
sprayed on clothing to protect us from bug bites.
When she was little, our daughter had a rare and dangerous reaction to
every single mosquito bite. We didn’t want to put repellants on her skin,
so we bought a can of permethrin to spray an over-sized shirt that we could
put over her clothes when she played outside. It worked, but Russ and I
both hated applying it. We obviously couldn’t spray it in the house, but
outdoors didn’t seem much better. We’d wait for a day with no wind and
drape the garment over our fence with newspapers beneath to catch as much
of the residue as possible so little would fall on our lawn where robins
fed and our dog walked, but it still felt dangerous. It wasn't until years
later that we discovered pre-treated “Buzz Off” clothing. That treatment is
safer, more effective, and much longer-lasting than spraying.
The *Insect Shield
<https://substack.com/redirect/077410f9-2545-4e0d-8361-62d13cbdb187?<j...>* company also provides that treatment to our own garments. Their process
binds permethrin to fibers in a way that spraying cannot, so a single
treatment stays effective for the life of the garment or up to 80 washes,
reducing the overall amount of permethrin used per garment. Before I went
to Peru and Uganda in 2016, I sent the company a few shirts and pants for
treatment. I'm still wearing those items, and they’re still protecting me
from insect bites. This year, before my trip to Guyana, I had a few more
items treated, including socks and lightweight sun-protection gloves. I
ended up with just one bite on the entire trip, on my wrist near my
watchband. Everyone else in our group got chigger bites—in some cases, a
*lot* of chigger bites—in the Georgetown Botanical Gardens. I didn’t get a
single one.
I tend to keep clothing for a long time—I still have, and wear, items I
bought back in the 1970s and 80s. Now that we know that permethrin really
is harming birds, when I do discard old clothing that was treated, I’ll be
very careful to wrap it tightly in plastic before putting it in the garbage
that will end up in the landfill. Wads of pet fur from brushing or trimming
a dog with any kind of flea-and-tick protection should be disposed of in
the same way. *Don't* set it out for nesting birds, and don’t compost it.
Environmental issues are growing ever more complex even as climate change
is making insect-borne diseases ever more prevalent. Yet profit-focused
corporate entities and anti-regulation billionaires keep pressuring
government to cut back on pesticide research and regulations even as our
Secretary of Health and Human Services closes his eyes to the evisceration
of the EPA to focus his attention on limiting our access to life-saving
vaccines. I sure wish I could tell him to buzz off.
<https://substack.com/redirect/99d79255-f7ea-44a1-8328-530b30f6887c?<j...>
