As we go about our lives, the rest of the world keeps moving. Seasons change, animals and plants enact glorious revivals, tremendous gatherings and movements, that we take various approaches to noticing. All too often we miss great natural events in urban spaces, either because we are simply too distracted or don’t know where or when to look. Sometimes it’s simply that our spaces don’t support such events.

And sometimes we do notice, because they’re too hard to miss. The Eastern Cottontail Rabbit population explosion of the past couple years. Or this winter: the initial joy of Pine Siskin flocks at our bird feeders — a moment that quickly backpedaled into dismay.

If you don’t feed birds or don’t watch them as religiously as some, I wouldn’t put it past you to have missed the bevies of tiny finches. However, if during this dark winter, you were constantly at home you might have found new (or renewed) relief in bird feeding. It’s entirely likely that a few people reading started feeding birds for the first time in 2020, realizing how fun it can be to see our neighbors up close and personal. This isn’t just a posit: during the spring of 2020 Instacart searches for “Bird Food” rose by as much as 450%.

The birds
Pine Siskins are small, brownish finches with embellishments of yellow in their wings and tails. They are extremely gregarious, exploding into noisy flight, filling the tops of alder and conifers to find the winter seeds they subsist on. Siskins flocks are hard to miss once you know their intensity.

Though they are a northerly species, they are year-round residents on the Hill (though most head for the forest in summer) and mountainous areas of western North America all the way into northern Mexico enjoy them as such also. Siskin populations are deeply influenced by coniferous seed crops, so much so that in some years we have huge numbers and others they are entirely absent. Many finches have similar ways of responding to the variability of food and live irruptive, nomadic lives across much of their ranges.

Especially epic eruptions of finches are called “superflights.” Not only do Pine Siskins show up, but their enticing cousins do as well. Redpolls, crossbills, and grosbeaks, all are reliant on cone crops in winter. Only sometimes that food isn’t there.

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Spruces in the boreal forests in northern Canada and Alaska fluctuate their cone production regularly, probably to avoid predation by squirrels. Seeds are important in winter, but fresh insects are summer food, easier to squish into the mouths of hungry youngsters. Spruce budworms, a moth whose caterpillars eat spruce, had a banner year in 2020. This further increased the breeding success of many finch species, primarily Evening Grosbeaks but also Pine Siskins. Thus, lacking a winter larder, the stage for a great many mouths to surge south.

The outbreak
Though these kinds of movements are undoubtedly impressive, they can also be acts of desperation. The Pine Siskins that have descended on our region are probably malnourished, a toehold for disease. When reports of sick and dead siskins started in December, wildlife professionals knew what we were probably in for: an outbreak of salmonellosis.

Salmonella is a bacteria that regularly occurs in birds, reptiles, and amphibians. Though not all birds are carriers, they can all suffer from the bacteria, (so can mammals). Pine Siskins are a known carrier of the bacteria, a normal part of their intestinal flora. This becomes an issue when there’s an imbalance, and already weak birds come into contact with fecal matter carrying salmonella. A decent comparison are e coli outbreaks in humans although we too suffer from salmonella infections, most commonly transmitted from eggs and poultry.

So the Pine Siskins dropping like flies this winter are suffering from salmonellosis. The good news is that we can decrease the spread of salmonella by taking down our seed feeders right now, regardless of seeing Pine Siskins there. This recommendation made by the Washington Department of Fish and Wildlife may seem extreme, but it’s a temporary measure that could do much. And with luck, it would also decrease opportunities for other birds at our feeders to become infected.

People will continue to feed birds through this outbreak, so if you are disinclined to cease feeding consider cleaning daily while avoiding certain types of bird feeders. Because the main source of transmission is fecal to oral, platform bird feeders are a no no, but at least hummingbird feeders are totally fine. Feeding birds, even having a birdbath, comes with a responsibility and regardless of outbreaks we should be cleaning them regularly (at least weekly). This means using warm, soapy water, disinfecting with a 10% bleach solution, and thoroughly drying before refilling with seed.

The bad news is that bird feeding is just a contributor to this outbreak, not the cause. So while it’s important to take this temporary step, we can’t entirely stop salmonellosis, and it will crop up again. And though this is a particularly bad year, Pine Siskins appear to have been weathering these outbreaks long before we were aware of them, or for that matter the true causes of our own ailments. They are well known for huge population fluctuations and salmonellosis is a part of that story.

Wrapped up in these events are questions that I do not have absolute answers for: how much does salmonellosis impact siskin populations? Could this be exacerbated by climate change? Is it ethical to be feeding birds at all? Or, is feeding birds, when done properly, a benefit to birds in places with reduced habitat?

Some of these questions are deeply entwined in our emotions and our experiences with birds and nature on the Hill and in the rest of our lives; difficult things to step away from. Nor should we be trying to completely. At the end of the day, I can tell you that I took down my bird feeders for the sake of individuals, and not because I fear for the entire species. I can’t quite convince myself that this is a natural rhythm worthy of excitement. But it certainly got my attention.

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