The bird requires hardwood deciduous trees that have been cut down in order to nest. Young birds are heavily predated by owls and hawks that hunt them in cleared forest areas. Climate change has led to a decline in insects. There is a shortage of old, diseased pine trees in which the birds nest. Isostatic uplift is taking place in all polar regions of the Northern Hemisphere.
Isostatic uplift is a rise in sea level relative to the land level.
Isostatic uplift occurs primarily in Glacial Periods. Drumlin formation is dependent on isostatic uplift. A steep rise in the abundance of birch and pine pollen. An increase in the presence of pollen from thermophilous trees. The rise in grass pollen at the expense of tree pollen.