One is occasionally seen, each winter, on a specially planted seed crop for farmland birds.
Wheat is used for the republic's own needs, and corn is exported as a seed crop.
Sunflowers are likely the second-oldest domesticated seed crop in eastern North America.
He thinks the stock will meet this year's demands because of the bumper seed crop last year.
Canola is an oil seed crop that is used to make cooking oil, animal feed, cosmetics, biodiesel fuel and more.
Betty produced a huge seed crop this spring but most of it was blown away by Storm Katie before it could be collected.
And the heavy annual seed crop provides a source of food for a number of birds and rodents.
Pucek, Z., Jędrzejewski, W., Jędrzejewska, B. & Pucek, M. Rodent population dynamics in a primeval deciduous forest (Białowieża National Park) in relation to weather, seed crop, and predation.
Control of viral diseases of potato, for example, can be accomplished by growing the seed crop in northern regions where low temperatures are unfavourable for the aphid carriers.
For example, seed predators commonly scour the ground for each year's seed crop, eating most of the seeds produced by many different species each year.
It appears, then, that seed crop size is the primary cause of irruptions and that large population sizes may sometimes be a contributing factor.
