From the book
The Birds of British Columbia (Campbell et al)
For the full text describing the invasion of the European Starling into British Columbia, see:
http://www.royalbcmuseum.bc.ca/nh_paper ... rling.html
There has been concern that the introduction of large numbers of European
Starlings to the ecosystems of North America has caused the numbers of
some native species to decline. The starling is a cavity-nesting species.
In British Columbia, when away from an urban setting, it frequently nests
in cavities excavated by the larger woodpeckers. These cavities are also
used by such native species as Mountain and Western bluebirds, Tree and
Violet-green swallows, Purple Martin, House Wren, American Kestrel,
Northern Pygmy Owl, Northern Saw-whet Owl, Western Screech-Owl,
Bufflehead, Barrow's and Common goldeneyes, Wood Duck, and woodpeckers.
A study of nest cavities previously used by the Northern Flicker,
Mountain Bluebird, and Tree Swallow at Westwick Lake (near Williams Lake),
found that the proportion usurped by the starling increased from 40% to 80%
over 3 years (Myres 1957). In the same region, European Starlings usurped
nest cavities previously occupied by Buffleheads (Erskine 1972).
However, there has been no detailed study to determine the impact of the
starling in British Columbia as a major competitor of the native species
for scarce nest sites. An anecdotal account from California (Weitzel 1988)
describes the experience in a small area (0.35 ha) on which 14 pairs of
native species had nested before the European Starling invasion.
The native species included American Kestrel, Mountain Bluebird,
Northern Flicker, Olive-sided Flycatcher, Mourning Dove, Tree Swallow,
House Wren, House Finch, and House Sparrow. The European Starling displaced
all of them by nest takeover or harassment, and none nested on the property
for 5 years. After the starlings were removed, the native species returned.
The US Fish and Wildlife Service promotes "elimination" of non-native, unprotected
House Sparrows and European Starlings.
From their online pamphlet
MIGRATORY SONGBIRD CONSERVATION at:
http://library.fws.gov/Bird_Publication ... l#Sparrows
House Sparrows and Starlings - Every Spring, birds that nest in cavities compete with
each other for a limited number of nest sites. The neotropical migrants that nest in cavities
- purple martins, tree swallows and great-crested flycatchers - have adapted to competition
from chickadees, titmice and woodpeckers.
The "rules of competition" changed around the turn of the century when we humans
imported two European cavity nesting species: house sparrows and starlings.
House sparrows eliminate nest competitors by attacking the adults and killing the young
when they are on the nest. Starlings eliminate nest competitors by taking over cavity
nesting sites. Our native birds don't seem to be able to defend themselves from house
sparrow and starling attacks. So, if you put up a nest box to help bluebirds, martins,
chickadees, titmice, woodpecker, wrens or flycatchers, you must monitor the box and
eliminate house sparrows and starlings.
The United States Geological Survey recommends the use of traps to "eliminate" non-native,
unprotected House Sparrows and European Starlings.
From
http://www.npwrc.usgs.gov/resource/1999 ... exotic.htm
A major factor leading to the decline of eastern bluebird populations has been nesting
competition with non-native species, specifically European starlings and house sparrows......
Trapping and eliminating the adult bird in the box is more effective
than simply removing the nests. Trapping with inside-the-box traps or bait-type traps
such as those made by Trio, and Hav-a-hart, is recommended. If uncomfortable with
removing the birds or nests, another option is to vigorously shake the eggs, or addle them,
for 60 seconds and leave them in the nest so that the female will continue to expend
reproductive energy without hatching success. This also prevents the exotic species
from attempting to take over another box.
