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Hi All,
Most birds in Nova Scotia are migratory and thus occupy four different kinds
of habitat over the course of a year; breeding habitat, aerial habitat,
stopover habitat, and winter habitat. Birds are subject to increasing levels
of human-induced mortality in all of these habitats.
Mortality in breeding habitats is particularly worrisome since it can
involve the death of all the young of local populations as in the case of
clearcutting. The relationship between local and regional populations is not
well understood or documented. There is scientific evidence that adult
forest birds show fidelity to a breeding site while yearling birds disperse.
We don't know how resilient these adult birds are to landscape changes when
they return in the next breeding season, and if there is a threshold of
change at which resilience is no longer possible.
Since a great part of our migratory birds are neotropical migrants, they
spend a very large part of the year flying to and then flying back from
Mexico, and Central and South America. One has only to look at a satellite
photo of North America at night to see how this aerial habitat is highly
polluted by lights which disorient migrants, causing death by exhaustion or
from collision into wind turbines, gas flares, and urban buildings. Birds
from all types of breeding habitats are represented in this aerial habitat
and the piles of dead birds collected in a morning on a city block represent
birds of the fields, forests, and wetlands.
During this voyage, the Nova Scotia birds must come down in the morning to
refuel. As they get further from Nova Scotia, the availability of habitat
similar to their breeding habitat may decline or refueling for long-distance
flight might require quite a different diet than one for nourishing
nestlings, and hence quite a different type of habitat. At the Mount Auburn
Cemetery in the middle of the city of Boston, one will find hundreds of
forest birds in the ornamental trees surrounding the groomed lawns and quiet
pools of the large cemetery. In these stop-over habitats birds may be
particularly vulnerable to predation by cats and other predators, like the
Peregrine, that specialize in hunting in open areas like cities and coastal
thickets.
Birds spend the winter in habitats that are under increasing levels of
destruction and disturbance through the growth of coffee plantations, other
types of deforestation, mining, tourism, and urbanization. Mortality in
these winter areas is not well understood but appears to be very substantial
for some species.
Finally, on top of all these threats to birds, is climate change which
drastically affects all four of their habitats.
Conservation efforts are required on a very broad front, and habitat
preservation and restoration are a continent-wide problem affecting the
survival of Nova Scotia's birds.
John
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vlink=3Dpurple><div class=3DWordSection1><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'>Hi =
All,<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'>Most birds =
in Nova Scotia are migratory and thus occupy four different kinds of =
habitat over the course of a year; breeding habitat, aerial habitat, =
stopover habitat, and winter habitat. Birds are subject to increasing =
levels of human-induced mortality in all of these =
habitats.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'><o:p> </=
o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'>Mortality in =
breeding habitats is particularly worrisome since it can involve the =
death of all the young of local populations as in the case of =
clearcutting. The relationship between local and regional populations is =
not well understood or documented. There is scientific evidence that =
adult forest birds show fidelity to a breeding site while yearling birds =
disperse. We don’t know how resilient these adult birds are to =
landscape changes when they return in the next breeding season, and if =
there is a threshold of change at which resilience is no longer =
possible.<o:p></o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'><o:p> </=
o:p></span></p><p class=3DMsoNormal><span =
style=3D'font-size:12.0pt;font-family:"Calibri",sans-serif'>Since a =
great part of our migratory birds are neotropical migrants, they spend a =
very large part of the year flying to and then flying back from Mexico, =
and Central and South America. One has only to look at a satellite photo =
of North America at night to see how this aerial habitat is highly =
polluted by lights which disorient migrants, causing death by exhaustion =
or from collision into wind turbines, gas flares, and urban buildings. =
Birds from a