First, it should be stated that the single most significant
threat to bird populations is habitat destruction, in all of its
forms and with all of its causes. The various causes of
mortality outlined below kill individual birds directly, and can
certainly have an adverse effect on population size, but can
actually have a beneficial effect in some cases. Studies of
hunting have documented that in certain cases killing small
numbers of birds can improve the health and survival of the
remaining birds. As long as the habitat is intact, the
population has the potential to replace the lost birds. In
simplest terms, habitat destruction reduces the population by
reducing the available resources, denying birds the chance to
reproduce, and effectively putting a cap on the population size.
The problems outlined below are serious threats and are
implicated in the declines of many species. They should be
addressed. Window strikes – estimated to kill 97 to 976 million
birds/year – Millions of houses and buildings, with the