I am a Bird Watcher: Why should I care about invasive species?
It is estimated that half of all the birds threatened with imminent extinction are
threatened either wholly or partly by introduced plant and animal species. 1
Invasive plants affect birds in many ways. They replace
native vegetation needed for food, shelter and nesting.
Invasives, such as multiflora rose, produce fruit that
may be of lower nutritional value to our native birds
than native shrubs, like blackberry, blueberry and
dogwood species. Invasive plants are also likely to be
unpalatable or even toxic to our native insects. What
negatively affects insects, will negatively affect birds.
Many native song birds feed their young on insects, so
fewer insects means that fewer young birds will reach
maturity.
Amur honeysuckle, Lonicera maackii
Chuck Bargeron, University of Georgia, Bugwood.org
Other studies have shown that certain
species of birds, such as Northern
robin and the wood thrush, are lost to
predation when they nest in invasive,
exotic shrubs, such as Amur
honeysuckle or common buckthorn,
as opposed to nesting in native
shrubs with which they have
co-evolved.2
Multiflora rose, Rosa multiflora
Barry Rice, Bugwood.org
Ground-nesting birds, as well as other groundnesting animals, are negatively affected by the
presence of the red imported fire ant. Red imported
fire ants originated in South America. As anyone
from the Southern U.S. knows, they are extremely
aggressive and have a powerful sting. Fire ants have
been shown to attack bird eggs, juveniles, and
adults. Newly hatched chicks can be completely
engulfed by an onslaught of fire ants. Fire ants have
been shown to reduce bobwhite quail chick survival
and, in one study, 38% of chick deaths were
attributed to fire ant stings. The populations of the
golden-cheeked warbler and the black-capped vireo
are also seriously affected by red imported fire ants.
1
Red imported fire ant, Solenopsis invicta
Barry Rice, Bugwood.org
European starling, Sturnus vulgaris
Lee Karney, U.S. Fish and Wildlife Service, Bugwood.org
European starlings are native to Europe
and were introduced into New York in
1890. These invasive birds are extremely
abundant. Population levels in North
America have reached approximately 200
million. Starlings invade any habitat that
has suitable nesting sites, including
woodlands, farmlands and cities.
European starlings nest earlier than many
native cavity nesters, creating serious
competition for suitable nesting sites.
They also destroy the eggs and nestlings
of tree swallows, woodpeckers, purple
martins, great crested flycatchers and
eastern blue birds.
West Nile virus has been detected in over 250 species
of birds in the United States. It has now spread across
the U.S. and is present in every state except Alaska,
Hawaii and Washington. The virus was first detected in
the United States in New York City in 1999. The
American crow, blue jays, and fish crow are
particularly at risk. Infected birds become weak and
can lose the ability to fly or walk. Deaths attributed to
the virus have been noted in almost 60 species of
birds in the Northeastern United States. The disease is
spread to humans from infected Asian tiger
mosquitoes which were accidently introduced to the
United States. Symptoms range from mild and flu-like
to no symptoms at all. However, if the virus enters the
brain it can cause swelling of the brain and spinal cord
and lead to death. No specific vaccines are available
for the virus at this time.
Asian tiger mosquito, Aedes albopictus
Susan Ellis, Bugwood.org
What can Bird Watchers do to help prevent the spread of invasive species?

Avoid spreading seed of invasive plants, learn to recognize infestations, and
avoid passing through them.

Clean equipment, boots, and gear between trips, or preferably before leaving
an infested area. Make sure to remove all seeds and other plant parts.

Report any invasive sightings to the local land manager.

Change the water in bird baths often to prevent mosquitoes from breeding.
1
Simberloff, D. 2007. Aliens among us. Conservation Magazine 8 (2). pp 18-19.
2
Schmidt, K.A. and C.J. Whelan. 1999. Effects of exotic Lonicera and Rhamnus on songbird nest predation. Conservation Biology 13 (6). pp 15021506.
K.A. Rawlins, 2013. Why should I care? Series: I Am A Bird Watcher, Why should I care about invasive species? The University of Georgia Center
for Invasive Species and Ecosystem Health,, Tifton GA, BW-2013-113. 2 p.
This publication based on: Midwest Invasive Plant Network. 2008. Why should I care about invasive plants? How invasive plants impact hunting,
fishing, boating, gardening, hiking, biking, horseback riding, and other recreational activities in the Midwest. From MIPN.org/InvasivesBrochure.pdf
2