Perils Past and Present

Major Threats to Birds Over Time

International

Migratory

Bird Day

(IMBD),

held annually

on the second

Saturday in

May, is an

invitation to

celebrate and

support

migratory bird

conservation.

IMBD Information

web - http://birds.fws.gov/imbd

phone - 703 /358-2318

IMBD Sales

web - http://www.BirdDay.org

phone - 1-866/334-3330

January 2003

Of the challenges faced by bird

populations, the majority are related to

human activities. Some of the most

significant threats of the past century

have been overcome due to increased

advocacy for wildlife and the passage of

numerous laws protecting birds and their

habitats. However, major threats persist,

putting numerous species at risk and

requiring our attention and action.

Habitat Loss and Degradation

Past

By 1900, millions of immigrants had

arrived in North America, clearing

forests, draining wetlands, and

converting native grasslands for farming,

grazing and fuel. With widespread

conversion of natural habitat to human

uses, it’s no wonder that many forms of

once-abundant wildlife, such as the wild

Turkey, became scarce in settled areas.

People now generally recognize the

importance of conserving habitat in order

to conserve wildlife. Natural habitat is

protected in the form of Migratory Bird

Sanctuaries and National Wildlife Areas

in Canada; National Wildlife Refuges and

State wildlife management areas in the

U.S., and the System of Protected

Natural Areas in Mexico. In North

America, 2.5 million km2

 (618 million

acres) of land, freshwater, and marine

areas – equalling nine percent of the

continent – have been dedicated as

wildlife habitat. Public lands held for

other purposes, such as forestry, grazing,

and even military exercises also set aside

for wildlife, as are millions of acres by

private landowners.

Present

The fact is that despite the areas set

aside for wildlife, some bird populations

are still at risk from habitat loss. Much

of the landscape continues to undergo

degradation and conversion due to human

development and disturbance. We are

still experiencing a net loss of wetlands in

North America, for example. In addition,

growing numbers of birds are killed due

to collisions with human structures and

equipment, including power lines,

communication towers, wind turbines,

glass windows, and automobiles. Our

challenge is to manage landscapes,

control development and alter our

activities in such as way that people and

birds can coexist.

Overexploitation

Past

Wild birds were once sold for food in

restaurants and markets across North

America. All types of birds were

harvested, including shorebirds, seabirds,

even songbirds, in addition to those

considered “game birds” today (such as

ducks, geese, doves, turkeys, pheasants).

Wild birds were also harvested for their

skins and feathers to supply the millinery

(hat making) trade. In 1886, American

Museum of Natural History ornithologist

Frank Chapman surveyed ladies’ hats

during two walks in New York City and

discovered the bodies or body parts of

wild birds on 542 out of 700 hats.

The commercial trade in birds depleted

some species to the point of extinction.

Fortunately, public campaigns, stronger

regulations, and changing fashion

stopped the slaughter. These days, most

birds are under some form of protection.

It’s even illegal to possess most wild bird

feathers without a permit. For species

still harvested, well-regulated hunting

serves as a tool for conservation rather

than a threat.
Present

Some species of birds are still threatened

by commercial exploitation; most notably,

parrots targeted for the exotic pet bird

trade. Trade in wild-caught parrots,

coupled with habitat loss, has resulted in

the parrot family having more globally

threatened species than any other family

of birds. The U.S. used to be the largest

consumer of parrots, legally importing

250,000 mostly wild-caught parrots a

year. This changed with the passage of

the U.S. Wild Bird Conservation Act,

which controls trade in parrots listed

under the Convention on International

Trade in Endangered Species, and with

Mexico’s ban on exporting parrots. The

Act also helped reduce smuggling, but

illegally-caught parrots still flow across

the border. The black market and the

legal trade still occurring in many

countries are cause for great concern.

Consumers should take care to never buy

a wild caught parrot: for every one that

reaches a store, four will have died along

the way.

Present

Birds are still victims of pesticide exposure. Each year, about 67 million birds

die from direct exposure to pesticides on

farmlands in the U.S. An estimated 7

million bird deaths are attributed to

homeowner use of pesticides. These

figures do not include birds that perish

after a period of illness, that die after

feeding on poisoned insects, rodents, or

other prey, or losses due to failed reproduction (eggs left unhatched or nestlings

left to starve). The impact on birds from

pesticide use in areas outside the U.S. is

unknown. Exposure is likely to be higher

in Latin American countries where

migratory birds spend their winters and

the permissible types and quantities of

pesticides are less regulated.

Homeowners have many opportunities to

lessen the impacts of pesticides on birds

and minimize bird deaths. Currently,

homeowners use up to 10 times more

chemical pesticides per acre on their

lawns than farmers and spend more per

acre, on average, to maintain their lawns

than farmers spend per acre on crops.

Moreover, a 1992 survey revealed that

more than 63 percent of the households

surveyed had 1 to 5 pesticides in storage.

Homeowners can improve this situation

by practicing pest prevention, planting

native vegetation, encouraging birds to

visit, using non-chemical controls where

possible, and carefully following application and disposal instructions.

Introduced Species

Past

Purposefully or accidentally, people have

introduced new plants and animals

around the world, some of which have

proven very harmful to native birds. A

famous intentional introduction was the

1890-91 release of 80 to 100 European

Starlings in New York City by an

organization seeking to introduce to

North America all birds mentioned by

Shakespeare. Starlings proliferated and

now compete with native birds for

nesting sites. Unintentional

introductions occur when new species are

transferred unknowingly or accidentally.

For instance, Black Rats and Norway

Rats from Europe were stowaways on

early ships arriving in the Americas.

Rats prey on many native bird species, as

well as being a serious pest to humans.

Introduced species may adversely affect

native bird populations in ways other

than predation or competition. Introduced herbivores and exotic plants can

degrade habitat quality; other introduced

species serve as carriers of disease. The

effects of introduced species are most

severe on islands, since island-bound

birds such as nesting seabirds or resident

species evolved to be flightless are

especially vulnerable to introduced

species such as rats, snakes, hogs, foxes,

and goats. Ninety percent of historical

bird extinctions have occurred on islands.

Present

Today, numerous regulations and campaigns exist to remove harmful introduced species and prevent new introductions. For example, authorities in Hawaii

vigilantly search port facilities to avoid

introduction of the Brown Tree Snake,

responsible for the decimation of birds on

Guam. However, some introduced

species are here to stay. In fact, one of

the most dangerous introduced predators

is the domestic cat. Tame and feral cats

kill hundreds of millions of songbirds and

other avian species each year. A study in

Wisconsin estimated that in that state

alone, rural housecats kill roughly 39

million birds annually. Add the deaths

caused by feral cats, or domestic cats in

urban and suburban areas, and this

mortality figure would be much higher.

Responsible cat owners, by spaying and

neutering and keeping cats indoors,

prevent unwanted, uncared-for cats; have

healthier pets; and save the lives of

millions of birds each year.

Pesticides

Past

From the 1940s to 1960s, the pesticide

dichloro-diphenyl-trichloroethane (DDT)

was used in numerous countries to

vanquish malaria and other insect-borne

diseases, saving human lives, and to

control agricultural pests, boosting food

production. Unfortunately, DDT and

many other pesticides were frequently

over-applied and inappropriately used.

DDT and other hydrocarbon pesticides

accumulated in the bodies of birds of prey

via the food chain, affecting eggshell

production and causing nesting failure.

The result was a drastic decline in

Brown Pelicans, Ospreys, Bald Eagles

and other birds of prey. Due to public

outcry, authorities in the U.S. and

Canada banned DDT in the early 1970s

and enacted stronger regulation of

pesticide production and use.