as part of a commercial felling regime. For example, commercially thinned
40–45 year-old Douglas-firPseudotsuga menziesiistands in Oregon, USA, held
higher densities of six bird species compared to unthinned stands, including three
characteristic of old-growth forest, namely Hairy Woodpecker Picoides villosus,
Red-breasted Nuthatch Sitta canadensis, and Hammond’s Flycatcher Empidonax
hammondii. In contrast, only Pacific-slope Flycatchers Empidonax difficiliswere
more abundant in unthinned stands, as this species is associated with dense,
closed canopy forest (Hagar et al. 1996).
14.7.6 Increasing the quantity of dead wood
Dead wood is a particularly important component of forests managed for con-
servation and, by encouraging woodpeckers, creates more nest-sites for species
that use their old nest holes. Standing dead trees (snags) provide nest-sites for
cavity-nesting birds and foraging habitat for woodpeckers and other species.
Dead wood associated with large populations of ancient trees can also support
important assemblages of invertebrates. Trees can rot in two ways—from the
outside (sapwood decay) or the inside (heart rot decay). Heart rot decay is
generally better for cavity-nesting birds and supports a particularly specialized
invertebrate fauna. Standing and fallen dead wood and old trees should not be
removed unless they pose unacceptable safety risks.
Dead wood can be increased by killing parts of or whole trees by girdling
(making a continuous cut with removal of a ring of bark from around the
trunk), or by injecting with herbicide, or in the case of conifers, removing the
base of the live crown. These methods can be accompanied by inoculation of
fungi to speed up decay. Such techniques should only be used on younger trees,
preferably healthy ones, and not on older or partly dead trees that are important
in their own right. It is preferable to damage only part of the tree, since whole
dead trees fall over more quickly and thereby lose their value to cavity-nesting
birds. A recent study found no difference in decay characteristics and wood-
pecker activity in Douglas Firs killed by girdling, herbicide injection, and cut-
ting off of the base of the live crown with or without inoculation of fungi
(Brandeis et al. 2002).
14.8 Managing deep water
Few management techniques to benefit birds apply in water over about 1 meter
deep. The main ways in which deep waterbodies can be improved for birds are by
providing suitable nest-sites by creating islands or providing rafts (Section 14.9.5);
by creating shallow areas and emergent vegetation around the margins (see below).
Managing deep water| 351