Poison Hemlock as a Food Source for Birds

Monday July 29th, 12:00 pm

The heat has eased off today and there is a pleasant breeze as I walk along the riparian area in the center of the valley. It is alive with fledgling birds begging for food from their parents as usual. Along the fence there is a variety of young and old birds. I see Western Bluebirds, Chipping sparrows, Lazuli buntings, Dark-eyed juncos, Song sparrows, American goldfinches, Black Headed grosbeak, and of course the Black phoebes. It is such a pleasure to see all these birds interacting with each other, even if it seems they are mostly chasing the other away! there are fewer songs and some seem to be different, maybe the females singing.

I can also see the air is full of insects. They are a food source for all of these birds and they are busily finding their own food sources in the late blooming flowers and plants.

It is the sound that catches my attention first, a wonderful chick a dee dee, with a series of high scratchy gargles,then I look for that cutest of small birds, the Chestnut- backed chickadee, Poecile rufescens.  It s hanging upside down from one of our invasive and noxious weeds, Poison Hemlock, Conium maculatum. It is doing acrobatics as it is eating the seeds of this plant! I am very amazed at this but then remember I have seen Lazuli buntings eating these seeds also. Birds must not be affected by the very toxic chemicals found in this plant.

 Poison hemlock plant grows to 4-10 feet tall and has a smooth, non-hairy, hollow stem with red-purple streaks. According to the Maryland Poison Center newsletter,  these blotches are called the “blood of Socrates” as poison hemlock was reportedly used to kill Socrates. The small white flowers grow in 4-6 inch wide “umbels” or clusters that resemble umbrellas. The leaves have a lacy, fern-like appearance. The roots are creamy white and look like carrots or parsnips. When crushed, poison hemlock has an unpleasant, musty odor.  This is an important fact because other plants that it looks like do not have that acrid, bad smell! Poison hemlock closely resembles and has been mistaken for Queen Ann’s lace (wild carrot), parsley, wild celery, and fennel.  

The Maryland poison center newsletter went on to say that “all parts of the plant contain coniine and other piperidine alkaloids, especially the root. Coniine structure and pharmacological properties are similar to nicotine, directly affecting nicotinic receptors… A toxic dose is nearly impossible to predict due to variances in concentrations of the alkaloids in each plant. Coniine is rapidly absorbed in the GI tract, producing nausea, vomiting, abdominal pain, salivation, mydriasis and confusion as soon as 20 minutes after the ingestion.Deaths are due to respiratory depression and respiratory muscle paralysis.There is no antidote for poison hemlock exposures and treatment consists of supportive care (e.g. benzodiazepines for seizures, IV fluids, dopamine or norepinephrine for hypotension) and ventilatory support.”

The Chestnut-backed chickadee, or CBC as birders call it, is busily eating the toxic seeds of this plant and I am once again struck with how extraordinarily adaptable birds are. This bird has learned to eat the seeds of a plant that came to California from Europe. I wonder if chickadees in Europe also eat the seeds of Poison Hemlock and I think they probably do!

The water in Davis creek is still thankfully plentiful, merrily bubbling by, providing much needed sustenance for all.