This is bird note.

Do you ever see flocks of birds in your yard that show up in droves one year, but are completely absent the next?

Take this flock of pine ciskins swarming around a thistle feeder, their wings briefly flashing yellow as they flit about.

Rather than adopting the common north and south itinerary, you might associate with

migrating songbirds, these Siskins take a more nomadic approach. Their movements depend on

the availability of food and habitat. It's called eruptive migration.

In years when conifer seeds are scarce in the boreal forests of Canada,

pine ciskins might hang around in lower latitudes, say, southern California or Tennessee.

The location and timing of these eruptions change from year to year.

And sometimes, by chance, gigantic flocks of

pine ciskins get funneled into the same regions, leading to backyards full of ciskins.

While these flocks are a delight for bird watchers, the dense groups of ciskins can easily transmit

diseases such as salmonellosis to each other and to other birds.

It's a good reminder to keep bird feeders clean for our feathered visitors that can

always social distance when diseases spread.

For Bird Note, I'm Ariana Rimmel.

This episode is brought to you by Wild Delight Bird Food,

which aims to support wild bird populations with clean, nutritious ingredients in every blend.

Available at chewy.com.