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142
Journal of Avian Medicine and Surgery 19(2):142–149, 2005
q
2005 by the Association of Avian Veterinarians
Historical Perspectives
Feral Parrots in the Continental United States and
United Kingdom: Past, Present, and Future
Christopher J. Butler, PhD
Introduction
In many cities across the United States (USA),
from Boston to Los Angeles and Seattle to Miami,
free-flying parrots and parakeets can now be seen.
Likewise, feral parakeets are now present in Eng-
land in the Greater London area, on the Isle of
Thanet in Kent, and in select cities along the south
coast. In some areas, these feral parrots have been
present for decades, whereas in others, parrots have
only been present for a few years. This paper sum-
marizes the historical changes in number and com-
position of psittacine birds in the USA and United
Kingdom (UK).
Native parrot species
The USA was formerly home to 2 native parrot
species—the Carolina parakeet (Conuropsis caroli-
nensis) and the thick-billed parrot (Rhynchopsitta
pachyrhyncha)—both of which disappeared from
the USA during the 20th century.
Carolina parakeets were formerly found through-
out the southeastern USA, north to New York and
west to North Dakota, Colorado, and Texas.
1,2
Car-
olina parakeets fed on a variety of fruits, buds, and
seeds and were not averse to sampling crops, a fact
that did not endear them to farmers.
2
In addition,
flocks tended not to flee when fired upon, particu-
larly if an individual in the flock called in distress.
2
Consequently, hunting or persecution probably had
a substantial impact on the population. Individuals
also were collected for the pet trade, which may
have hastened their decline.
2
By the mid-19th cen-
tury, Carolina parakeets were scarce throughout
much of their range and were considered to be
abundant only in Florida.
2
By the early 20th century, Carolina parakeets were
nearly extinct, but reliable sightings were reported
From University of the South, SPO, 735 University Avenue,
Sewanee, TN 37383, USA.
from Florida in 1904 and Missouri in 1905. A spec-
imen also was taken in Kansas in 1904.
1
The last
known Carolina parakeets were kept at the Cincin-
nati Zoo (where they had been kept for 32 years),
with ‘‘Lady Jane’’ dying during the summer of 1917
and her mate ‘‘Incas’’ on February 21, 1918,
1
al-
though unconfirmed sightings of Carolina parakeets
were reported in South Carolina until 1936,
1
and at
least 1 author suggests that they may have survived
until the late 1930s in Florida.
2
Thereafter, there have
been no credible reports of this species, and it is
believed to be extinct. The disappearance of the Car-
olina parakeet is presumed to be due to a combina-
tion of overhunting, habitat destruction, and disease.
2
Thick-billed parrots were formerly present in
southeastern Arizona and southwestern New Mex-
ico, extending south through the Sierra Madre Oc-
cidental of Mexico to northwestern Durango.
1,3
Un-
like the Carolina parakeet, the thick-billed parrot
fed primarily on pine seeds, although it also ate
acorns.
4
Heavy hunting pressure is blamed for the
decline of this species in the USA by the end of the
19th century. During the early 20th century, thick-
billed parrots were still present in reasonable num-
bers in southern Arizona and New Mexico, How-
ever, hunting pressure on these birds continued to
be intense.
4
Of 300 parrots seen in Pinery Canyon,
Arizona, during 1917–18, fully one third were shot.
4
By the 1930s, the population(s) of thick-billed
parrots in the USA had declined considerably. The
last credible sighting of thick-billed parrots in Ari-
zona was in 1938 at the Chiricahua National Mon-
ument.
4
A number of other species vanished from
the Chiricahua region of southeastern Arizona at ap-
proximately the same time, including elk (Cervus
elaphus), pronghorn (Antilocapra americana), big-
horn sheep (Ovis canadensis), and wild turkey (Me-
leagris gallopavo).
4
The last reliable sighting of
thick-billed parrots in New Mexico was in 1964.
4
A program to reestablish thick-billed parrots inthe
USA began in 1986. A total of 88 individuals (most
143
BUTLER—FERAL PARROTS IN THE UNITED STATES AND UNITED KINGDOM
Figure 1. Christmas Bird Counts of budgerigars in
Florida from 1963 to 2002.
of whom were recovered from bird smugglers) were
released into the Chiricahua Mountains of southern
Arizona between 1986 and 1993.
5
During the sum-
mer of 1988, a pair successfully fledged 2 offspring.
5
Although 3 pairs attempted to breed the following
year and another nest was attempted during the sum-
mer of 1993, all of these attempts were unsuccess-
ful.
5
The lack of consistent reproduction, coupled
with a relatively high rate of raptor predation, pro-
hibited the formation of a self-sustaining wild pop-
ulation of thick-billed parrots in the USA. It is un-
known if an individual bird seen in the mountains of
Sierra County, New Mexico, during 2003 was a wild
bird (thick-billed parrots still breed within 80 km of
the US border), a survivor from the experimental
release in Arizona, or an escapee.
6
Feral parrot populations in the 20th century
Although Carolina parakeets had declined (and
perhaps vanished altogether) by the early 1920s,
there were rumors of a ‘‘flock’’ of parakeets present
around the edge of the Everglades.
7
A specimen col-
lected in 1924 was identified as a green conure (Ar-
atinga holochlora).
7
Although this bird was be-
lieved to be part of a flock living in the wild for
several years, it was later reported that the bird was
a local escapee from 5 miles away.
8
Rumors of a
‘‘flock’’ of parakeets near the Everglades were nev-
er substantiated.
During the 1920s and 1930s, feral populations of
parakeets were reported in southern Florida and
southern Texas, although breeding was not con-
firmed. In Texas, a population of green-cheeked
Amazon parrots (Amazona viridigenalis) persisted
in La Feria (Cameron County) from the 1920s into
the early 1930s.
9
Rose-ringed parakeets (Psittacula
krameri) were reported in Florida during the
1930s.
10
Feral populations of breeding parrots were
established in southern California, southern Texas,
and Florida in the 1950s.
Florida
Budgerigars (Melopsittacus undulatus) were re-
leased along the Gulf Coast of west-central Florida
sometime after 1956. Breeding was reported in
1963,
10
and by 1977, budgerigars were widespread
along Florida’s Gulf Coast, ranging from Fort My-
ers (Lee County) in the south to Hudson (Pasco
County) in the north.
11
The population continued to
increase rapidly, and in 1978 a single roost con-
tained an estimated 6000–8000 birds.
11
Thereafter,
the population underwent a rapid decline, as illus-
trated by Christmas Bird Count data (Fig 1).
During the 1960s and 1970s, breeding popula-
tions of rose-ringed parakeets, nanday conures
(Nandayus nenday), and green-cheeked Amazon
parrots also were reported in Florida.
11,12
‘‘Canary-
winged parakeets’’ were first noted in southernFlor-
ida in the late 1960s.
13
Their numbers continued to
increase during the 1970s and a 1972 count of a
roost at Coconut Grove recorded nearly 700 indi-
viduals.
13
‘‘Canary-winged parakeets’’ are now rec-
ognized as 2 separate species; the white-wingedpar-
akeet (Brotogeris versicolurus) and the yellow-
chevroned parakeet (Brotogeris chiriri).
14
From 1986 to 1991, a concerted effort was made
to record the distributions of all birds breeding in
Florida for the Breeding Bird Atlas (BBA).
15
A total
of 17 species of breeding parrots was found, includ-
ing the red-masked conure (Aratinga erythrogenys)
and blue-fronted Amazon (Amazona aestiva). First
reported in Florida in 1985,
10
breeding mitred con-
ures (Aratinga mitrata) were confirmed in Miami
(Dade County) during the BBA.
14
The first published
report of feral chestnut-fronted macaws (Ara severa)
in Florida was during 1981.
10
During the 1986–91
BBA, breeding was confirmed in chestnut-fronted
macaws in Dade County, where they used old pile-
ated woodpecker (Dryocopus pileatus) cavities.
15
Only 9 parrot species were found breeding in
more than 1 atlas block (an atlas block was 7.5
93
7.5
9
) during the BBA.
15
Breeding rose-ringed para-
keets were confirmed in multiple counties in Florida
including Citrus, Pinellas, Collier, and Dade coun-
ties.
15
Likewise, the breeding range of nanday con-
ures had expanded to include Bay, St John’s, Pi-
nellas, and Dade counties.
15
By 1994, 1 author con-
sidered the Pinellas County population of nanday
conures to be sufficiently large enough to be an es-
tablished (ie, self-sustaining) population.
10
In contrast, several parrot species continued to
have restricted breeding ranges in Florida. For in-
stance, it was estimated that there were 50–75
green-cheeked Amazon parrots in southeastern
144
JOURNAL OF AVIAN MEDICINE AND SURGERY
Figure 2. The numbers of budgerigars, house sparrows,
and common starlings recorded per party hour during the
Christmas Bird Counts in St. Petersburg, FL, USA. Note
that numbers of both house sparrows and common star-
lings initially peak in the early 1970s, whereas budgerigar
numbers peak in the late 1970s before a decline begins.
Florida in 1980.
10
However, during the 1986–91
BBA, it was apparent that this species was doing
poorly in the Miami area and breeding was not con-
firmed in Dade County. Breeding green-cheeked
Amazon parrots were confirmed in Broward Coun-
ty, Florida.
15
Likewise, ‘‘canary-winged parakeets’’
were confirmed breeders only in the Miami area
during the 1986–91 BBA.
15
During the 1986–91
BBA, breeding was not confirmed for blue-crowned
conures (Aratinga acuticaudata) in Florida,
15
al-
though the area where they are suspected of breed-
ing (Key Largo in Monroe County) was not sur-
veyed.
10
During the 1990s, the once-prolific budgerigar
population in Florida leveled off to approximately
100–200 birds (Fig 1).
16
Their range contracted as
well, and by 1995–96, budgerigars were limited to
southwestern Hernando and northwestern Pasco
counties.
15
It has been suggested that this population
decline may have been due to competition with
house sparrows (Passer domesticus) or common
starlings (Sturnus vulgaris),
10,16
but examination of
Christmas Bird Count data indicates that budgeri-
gars declined before either house sparrows or com-
mon starlings were particularly numerous (Fig 2).
California
In California, breeding nanday conures were re-
corded from 1969 until 1976 in San Bernardino
County, although the population during this time
did not exceed 6 birds.
12
‘‘Canary-winged para-
keets’’ (white-winged parakeets and yellow-chev-
roned parakeets) were first observed in Los Angeles
County in 1971. By 1974, 60–70 ‘‘canary-winged
parakeets’’ were estimated in Los Angeles County
and 200–250 individuals in the state of California.
12
White-winged parakeets dominated in coastal Los
Angeles County during the 1970s and 1980s.
17
However, by the late 1980s and into the 1990s, yel-
low-chevroned parakeets began to predominate in
southern California.
17
Mitred conures have also in-
creased in the Los Angeles basin since the 1980s,
and in the 1990s it was estimated that there were
several hundred to more than a 1000 individuals.
17,18
During the 1990s, numbers of green-cheeked
Amazon parrots also increased in southern Califor-
nia.
9
Between 1995 and 1997, a mixed roost of
green-cheeked and lilac-crowned Amazon parrots
(Amazona finschi) containing up to 750 individuals
was observed in Temple City.
19
By 1997, approxi-
mately 1080 individuals were estimated in thegreat-
er Los Angeles area.
18
That same year, estimates for
a variety of parrots in the Greater Los Angeles area
were published, including white-winged parakeets
(approximately 380 individuals), yellow-chevroned
parakeets (approximately 20 individuals), nanday
conures (approximately180 birds), rose-ringed par-
akeets (60 birds), red-masked conures (70 birds),
and blue-crowned conures (50 birds).
18
Texas
Feral green-cheeked Amazon parrots have been
present in southern Texas since the 1950s.
9
Green
conures became established in southern Texas dur-
ing the 1990s.
1,3
During fieldwork for the 1987–92
Texas BBA, breeding was confirmed in green con-
ures and green-cheeked Amazon parrots in the
Lower Rio Grande Valley.
20
The number of green
conures and green-cheeked Amazon parrots in the
Lower Rio Grande Valley was estimated to be at
least 400 individuals each in 1995.
21
North America
During the late 1960s and the early 1970s, more
than 60000 monk parakeets (Myiopsitta monachus)
were imported into the USA, and escapes were re-
ported from New York to Puerto Rico.
22
The first
free-flying monk parakeets were observed during
1967 in New York City, and 8 nests were found in
that city by 1970.
23
By 1973 it was estimated that
4000–5000 free-flying monk parakeets were present
in the USA.
23
In response to this increase in feral
monk parakeet numbers, the US Fish and Wildlife
Service began overseeing an eradication program in
1973, particularly in the states of New York, Cali-
fornia, Virginia, and New Jersey.
23
It seems unlike-
ly, however, that the numbers estimated by the pop-
ular press were actually correct, because only 367
monk parakeets were confirmed.
23
145
BUTLER—FERAL PARROTS IN THE UNITED STATES AND UNITED KINGDOM
Parrots in the United Kingdom
The UK does not have any native parrot species,
although small parrots apparently were present dur-
ing the Eocene.
24
The first report of feral psittacine
birds in the UK was of rose-ringed parakeets in
1855 in Norfolk; however, this population soon dis-
appeared.
25
Rose-ringed parakeets were again reported in
England, this time in Epping Forest (Essex) in the
1930s but again this population did not persist.
25,26
Breeding populations of rose-ringed parakeets
were established in the 1960s. A family group of
parakeets was observed in Southfleet (Kent) in
1969.
25,26
During the 1970s, rose-ringed parakeets
expanded their range and nests were found at Stock-
port in Greater Manchester, Esher (Surrey), Wood-
ford Green-Highams Park (Essex), Margate (Kent),
as well as near Croydon (Middlesex) and Old Wind-
sor and Wraysbury (Berkshire).
25,27
The British Ornithologists’ Union accepted the
rose-ringed parakeet as an established exotic species
(Category C) in 1983 and estimated that the popu-
lation consisted of 500 birds.
28
The birds appear to
be a mixture of Psittacula krameri borealis and P
k manillensis.
26
Three years later in 1986, the pop-
ulation was estimated to consist of 500–1000
birds.
29
In 1996, a simultaneous count of the known
roosts revealed an increase in the rose-ringed par-
akeet population to 1508 individuals.
30
Since that
time, however, there has been a dramatic increase
in the numbers of rose-ringed parakeets. By 1999,
there were approximately 2500 parakeets at one
roost alone.
31
Similar to the rose-ringed parakeet, breeding bud-
gerigar populations were established in the 1960s.
In 1969, 4 pairs of budgerigars were deliberately
released on Tresco, in the Isles of Scilly, off Eng-
land’s west coast.
32
Six more pairs of budgerigars
were deliberately released on Tresco in 1970.
32
Food and nest boxes were provided for the birds,
and within 5 years the population consisted of 100
birds, including 35 breeding pairs.
32,33
However, the
resident at Tresco who had provided food for the
birds moved from the island in 1975 and thereafter
the population crashed.
32
One year later, only a sin-
gle individual was left and by 1977 the population
had completely vanished.
31
Parrots in the 21st Century
The American Ornithologists’ Union currently
recognizes 7 established feral parrot species in the
USA. These self-sustaining feral parrot populations
include the budgerigar, the rose-ringed parakeet, the
white-winged parakeet, the yellow-chevroned par-
akeet, the green-cheeked Amazon parrot, and the
monk parakeet.
3
In contrast, the American Birding
Association does not consider the rose-ringed par-
akeet established in the USA.
1
Currently, there is little official monitoring of
numbers of feral psittacine birds in the USA. Con-
sequently, data from Christmas Bird Counts were
used to evaluate trends in population size of estab-
lished parrot species in the USA. Christmas Bird
Counts have been conducted annually in North
America since 1900.
34
Participants count the num-
ber of individual birds encountered within a count
circle, which measures 24.1 km in diameter.
34
Many
counts have been conducted for decades. Therefore,
Christmas Bird Counts provide not only a long-term
data set, but the information provided is also wide
in scope. During the 103rd Christmas Bird Count
performed in 2002, there were 1981 count circles
and more than 55000 observers.
35
There is also
standardization of reporting methodology and re-
porting of observer effort.
16
Nonetheless, data from
Christmas Bird Counts should be used with caution.
Although observers are supposed to report all in-
dividuals of each bird species recorded, in practice
Christmas Bird Counts have somewhat erratic cov-
erage of exotic species.
17
In addition, the ranges of
some introduced species may not overlap with
Christmas Bird Count circles.
16
Because the number
of people involved and the amount of effort ex-
pended in a count circle may vary from year to year,
Christmas Bird Counts analyses are typically per-
formed on the number of birds per party-hour.
16
Based on Christmas Bird Counts, none of the es-
tablished feral parrots are declining, although bud-
gerigars and ‘‘canary-winged parakeets’’ do not
show a significant increase (Table 1). Rose-ringed
parakeets, green conures, green-cheeked Amazons,
and monk parakeets all exhibit significant linear in-
creases in population (Table 1).
Rose-ringed parakeets are officially established
only in southern Florida; however, this species may
also be self-sustaining in southern California. Bud-
gerigars are established in southwestern Florida.
White-winged parakeets and yellow-chevroned par-
akeets are established in southern Florida and Cal-
ifornia, whereas green conure numbers are self-sus-
taining only in southern Texas. Green-cheeked Am-
azon parrots are officially established in southern
Texas and southern Florida. In addition, it seems
likely that green-cheeked Amazon parrots may be
established in southern California as well, with a
total of 619 individuals recorded in California dur-
ing the 2003 Christmas Bird Count, and an esti-
mated 2003 population of 2800 individuals.
36
Monk parakeets are most widely established with
146
JOURNAL OF AVIAN MEDICINE AND SURGERY
Table 1. Populations of feral psittacine birds in the United States that are considered established or self-sustaining by
the American Ornithologists’ Union based on data from Christmas Bird Counts.
Species Year first detected Number detected in 2002
Budgerigar 1963 117 (count circles)
Rose-ringed parakeet 1972 241 (3 count circles)
Monk parakeet 1970 4155 (45 count circles)
Green conure 1978 336 (6 count circles)
‘‘Canary-winged’’ parakeet 1971 562 (324 yellow-chevroned in 7
count circles, 238 white-winged
in 3 count circles)
Green-cheeked Amazon parrot 1971 468 (9 count circles)
Table 2. A summary of monk parakeets recorded during
the 2003 Christmas Bird Count.
State Number
a
Florida
Connecticut
Illinois
Texas
2834 (19)
1091 (5)
175 (4)
266 (6)
New Jersey
New York
Louisiana
Total
42 (2)
32 (3)
12 (1)
4452
a
Number of count circles is given in parentheses.
self-sustaining, breeding populations in southern
Quebec, Illinois, Michigan, Connecticut, Rhode Is-
land, southern New York, New Jersey, Texas, and
Florida.
3
Since the US Fish and Wildlife Service’s
eradication program was halted, monk parakeet
numbers have more than recovered (Table 2). In
fact, during the 2002 Christmas Bird Count, 4155
birds were detected (Table 1). Currently, monk par-
akeet populations are doubling in size every 4.8
years.
37
However, it should be noted that popula-
tions are not increasing in every state. For instance,
in Oregon, monk parakeet numbers peaked in the
late 1980s and early 1990s and thereafter began to
decline.
38
In addition to the species recognized as estab-
lished by the American Ornithologists’ Union, 5
species show significant increases and may be in the
process of becoming established in the USA (Table
3). Of those 5 species, nanday conures are most
numerous, being recorded in Christmas Bird Counts
from both California and Florida. During the 2003
Christmas Bird Count, 500 individuals were record-
ed in a single count circle in St Petersburg (Pinellas
County), FL, USA.
35
Of nonestablished species, the second most com-
monly encountered during Christmas Bird Counts
is the mitred conure, which also is also reported in
Florida and California. The largest numbers found
(n
5
85) were in the Kendall area of Dade County,
Florida.
35
Examination of Christmas Bird Count
data indicates that although their numbers are in-
creasing significantly, blue-fronted Amazon parrots
are currently limited to southeastern Florida, as are
chestnut-fronted macaws and blue-crowned con-
ures. (Small numbers of blue-crowned conures also
have been reported from St Petersburg, FL, USA).
35
Two species (red-masked conures and peach-
faced lovebirds [Agapornis roseicollis]) also may be
in the process of becoming established, but their
populations are not being adequately monitored by
Christmas Bird Counts. Red-masked conures in San
Francisco, CA, USA, are believed to be both repro-
ducing and increasing.
39
The population increased
from 26 individuals in 1993 to 130 individuals by
2003.
40
Peach-faced lovebirds were first reported
breeding in Phoenix, AZ, USA, in 1998, when a
breeding pair was found at a saguaro cavity in
Scottsdale (G. Clark, written communication, No-
vember 2004). A Web site was set up to track sight-
ings of this species and it soon became clear that
the population size was considerable.
41
Currently, it
is estimated this population consists of hundreds of
individuals in the greater Phoenix area, and it is
possible that the total population may number in the
low thousands (G. Clark, written communication,
November 2004).
In the UK, rose-ringed parakeets are the only of-
ficially established feral parrot and their numbers
have increased dramatically since 1996. By 2003, a
single roost contained 6918 rose-ringed parakeets
(J. Wheatley, written communication, November
2004). It is estimated that the 2004 population of
rose-ringed parakeets in the UK is approximately
10000 individuals.
42
Their range is continuing to
spread and breeding parakeets can now be found in
Surrey, Berkshire, Buckinghamshire, Middlesex,
Hertfordshire, Sussex, Hampshire, and Kent.
42
147
BUTLER—FERAL PARROTS IN THE UNITED STATES AND UNITED KINGDOM
Table 3. A summary of populations of feral psittacine birds not currently recognized as established in the United States
that are increasing significantly based on data from Christmas Bird Counts.
Species Year first detected Number detected in 2002
Nanday conure
Blue-crowned conure
Blue-fronted Amazon parrot
Chestnut-fronted macaw
Mitred conure
1973
1982
1982
1982
1984
546 (9 count circles)
80 (1 count circle)
103 (1 count circle)
44 (2 count circles)
347 (9 count circles)
In addition to rose-ringed parakeets, 3 other par-
rot species breeding in England may become estab-
lished or self-sustaining in the near future: monk
parakeets, alexandrine parakeets (Psittacula eupa-
tria), and blue-crowned conures.
31
Monk parakeets
were found breeding in Borehamwood (Hertford-
shire) in 2001.
31
These birds have been present since
at least 1993, and by 2002 the population consisted
of 32 birds.
31
Most nests are on private property
where birds regularly visit bird feeders, and it seems
likely that the population will continue to grow.
31
Since 1997, alexandrine parakeets have bred at
Fazackerley (Merseyside) and the population con-
sisted of 12 birds by 1998.
31
However, in 1998,
many of the birds were shot, although 1 pair sur-
vived to breed again in 1999.
31
In addition, a nest
of hybrid alexandrine parakeets (apparently crossed
with rose-ringed parakeets) was discovered in 2001
in Kent, and 2 nests of hybrid birds were discovered
in 2002.
31
These 3 hybrid birds (1 male and 2 fe-
males) as well as 3 apparently pure alexandrine par-
akeets can routinely be seen roosting with rose-
ringed parakeets at the nearby Lewisham Crema-
torium.
31
In 1997, a pair of blue-crowned conures was ob-
served coming to a feeder in Bromley (Kent).
43
By
1999, the number of birds coming to the feeder had
increased to 8, and a flock of 15 birds was seen
nearby.
43
The first nest of this species was discov-
ered in 2001,
43
and the population is believed to be
increasing (G. Hazlehurst, written communication,
July 2004).
What the future may hold
Introduced species may have a detrimental effect
on native species through predation, habitat alter-
ation, introduction of diseases such as psittacosis or
Newcastle’s disease, hybridization, competition for
nest cavities, or a combination of these. There is
also concern that introduced species may cause eco-
nomic loss due to crop damage.
44
To date, however, few of these potential negative
effects have materialized, although rose-ringed par-
akeets in England have been observed feeding upon
grapes in a vineyard.
45
Interestingly, despite the po-
tential for crop losses, naturalized rose-ringed par-
akeets in the UK are protected under the Wildlife
and Countryside Act of 1981.
46
It also appears that many people enjoy seeing
parakeets.
22
For instance, a PhD study on feral rose-
ringed parakeets in the UK found that most people
enjoyed seeing parakeets at bird feeders or in the
park.
42
Because introduced parrots and parakeets fre-
quently visit feeders, it has been suggested that feral
parrots may rely on human intervention survival.
Budgerigars in Florida were apparently heavily de-
pendent upon both bird feeders and nest boxes to
survive.
11
Likewise, feral budgerigars in England
disappeared after the woman providing food
moved.
32
Monk parakeets in Illinois were observed
feeding heavily upon sunflower seeds during the
winter months.
47
However, at least 1 author has sug-
gested that rose-ringed parakeets in the UK do not
need feeders to survive, because a population in
Brighton apparently did not learn how to use feed-
ers for 8 years.
48
Feral parrots are typically found in urban and
suburban areas, which also may suggest a reliance
upon humans. However, it is also possible that the
presence of parrots in urban and suburban areas
may be due to a relatively larger pool of potential
escapees in these locations. There are probably
more pet parrots per unit area in an urban or sub-
urban setting than in a rural setting. Rose-ringed
parakeets in the UK are now breeding in rural areas
of Berkshire, Buckinghamshire, and Surrey,
42
whereas monk parakeets have a small population in
rural Scio (Linn County), OR, USA.
38
This obser-
vation suggests that feral parrots are not necessarily
restricted to urban and suburban areas as long as
adequate food is available and temperatures do not
drop too low.
Most feral psittacine birds roost in the open and
may not be able to survive prolonged exposure to
cold temperatures. Rose-ringed parakeets intro-
duced into New York City suffered from frostbite
during the winter.
49
Likewise, a naturalized popu-
148
JOURNAL OF AVIAN MEDICINE AND SURGERY
Figure 3. Monk parakeets detected on Christmas Bird
Counts in Connecticut from 1972 to 2002.
lation of rose-ringed parakeets in Belgium has suf-
fered mortality during winter months.
50
However, it appears that there are few places too
cold for monk parakeets to survive in the USA and
UK. This species is increasing in numbers not only
in southern cities but also in northern states such as
Connecticut and Illinois. Monk parakeets were first
reported in Connecticut in 1972. By 2002, a total
of 799 birds were recorded in Connecticut (Fig 3).
Monk parakeets are apparently able to survive cold-
er winters because they do not roost in the open,
but rather sleep in their nests. These nests may be
up to 4.6
8
C warmer than the ambient air tempera-
ture during the winter.
51
Although the populations of several established
parrot species are increasing rapidly, most of these
species have relatively restricted ranges. In part this
may be because of restrictions imposed by climate
and food supplies; however, this also may be due
to limited dispersion from the natal site. Monk par-
akeets in Argentina, for example, traveled only
1230 m on average from their natal site to their first
breeding site.
22
More than 95% of green-rumped
parrotlets (Forpus passerinus) dispersed less than
500 m from their fledging site.
52
The short dispersal
distance leads to a relatively slow rate of expansion.
In England, it was discovered that although rose-
ringed parakeets in the Greater London area were
increasing at approximately 30% per year, the range
was only increasing at a rate of 0.4 km/y.
38
The USA has lost 2 native parrot species during
the 20th century (the Carolina parakeet and the
thick-billed parrot) but gained 7 species of feral par-
rots during the second half of the century. The UK
did not lose any native parrots during the same pe-
riod (because there were no native parrots) but feral
rose-ringed parakeets became established. It seems
possible that an additional 7 species in the USA and
an additional 2 or 3 species in the UK may become
established during the next few decades. The im-
plications of this are unclear, although it has been
suggested that further introductions may have det-
rimental effects on native species due to competi-
tion for nest cavities and the introduction of disease.
There is also the potential for economic damage.
Despite this, the relatively slow rate of range ex-
pansion observed in feral parrots suggests that most
will still have relatively restricted ranges in the de-
cades to come.
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