Tree hollow

Hollows form in many species of trees, and are a prominent feature of natural forests and woodlands, and act as a resource or habitat for fungi and a number of vertebrate and invertebrate animals.

Forces may include wind, fire, heat, lightning, rain, attack from insects (such as ants or beetles), bacteria, or fungi.

Animals may use hollows as diurnal or nocturnal shelter sites, as well as for rearing young, feeding, thermoregulation, and to facilitate ranging behaviour and dispersal.

Tree holes are important habitats for many animals, such as Ceratopogonidae, Chironomidae, the common merganser, toucans, woodpeckers, and bluebirds.

In North America, recovery of the eastern bluebird (Sialia sialis) has required nest boxes due to the loss of natural hollows.

The scarcity of dead, hollow-bearing trees in Scandinavian forests is a key threatening process to native bird life.

[1][10] Threats to hollows include: native forest silviculture, firewood collection, rural dieback (such as from inundation and salinity), grazing by cattle, and land clearing.

: Ursus thibetanus), in northern parts of their range, such as Russian province Primorye, China, and both Koreas, prefer spend winter periods in large tree hollows, where females also give birth to cubs.

Threats include massive deforestation in these countries, combined with direct poaching of wintering bears—with selective destruction of the best hollow trees.

[13] Unfortunately, only a small portion of all damaged trees can be restored in Primorye, where forests are basically logged without taking to account needs of large fauna.