Escaped Pet Parrots Are Now Established In 23 U.S. States
Bird watchers and citizen scientists have spotted 56 different parrot species in 43 US states, with 25 of those species breeding in urban areas in 23 different states, a new study finds
Although two species of parrots originally lived in the United States, one species, the iconic Carolina parakeet, Conuropsis carolinensis, was quickly shot into extinct by white settlers (more here). Soon afterwards, the thick-billed parrot, Rhynchopsitta pachyrhyncha, was persecuted out of the desert southwest and back into Mexico by a combination of uncontrolled shooting, unregulated logging, and runaway development.
Thanks to the pet trade, parrots became increasingly available in the United States starting in the 1960s, mostly as companion pets. But wild parrots are difficult to tame, so some either managed to escape or were intentionally released by frustrated owners. Some of these liberated parrots survived and even thrived, particularly in urban areas where food was plentiful and wild predators were relatively few. As a result, parrots were living freely in the USA once again.
But how many of those immigrant parrot species managed to establish breeding populations in the continental United States?
That was one of the many questions that occurred to behavioral ecologist Stephen Pruett-Jones, now an associate professor at the University of Chicago, after he first saw the famous monk parakeets in Chicago’s Hyde Park in 1988. These parrots were first spotted in Hyde Park in 1968 and they built their first nest in 1970 (ref).
It didn’t take long for Professor Pruett-Jones to envision some of the research opportunities these birds presented to him and his students.
“I have never actually held a wild parrot in the United States,” Professor Pruett-Jones said in a press release. “But indirectly, I’ve become the spokesperson for parrot research here because when I saw the monk parakeets in Chicago, I realized nobody else was working on them.”
How many introduced parrot species are breeding in the USA?
To answer this basic question, Jennifer Uehling, an undergraduate at the time (she now is a graduate student at the Cornell Laboratory of Ornithology), collaborated with Professor Pruett-Jones and bioinformatics expert, Jason Tallant, who works at the University of Michigan Biological Station, to compile and analyze two databases of bird sightings reported by bird watchers and citizen scientists from 2002 through 2016. These data included 118,744 observations from 19,812 unique locations.
One data source was the Christmas Bird Count, a citizen science census organized by the National Audubon Society. This annual census is conducted during a one month period during the Christmas holidays and it provides a snapshot of which bird species are present in the dead of winter, and their numbers (more here). The second data source was eBird, a real-time online checklist where birders report all bird species seen at any time during the year, along with their numbers and locations.
After analyzing these data, Ms. Uehling and her collaborators found that the most common parrot species in the United States today are monk parakeets, Myiopsitta monachus, which accounted for more than one-third of all reports. This species is most notable for its large and untidy multi-occupancy nest, which it often builds on utility pole transformers.
The second most common established parrot species was the red-crowned Amazon parrot, Amazona viridigenalis, which accounted for 13.3% of all sightings. The nanday parakeet, Aratinga nenday, was the third most common established parrot species, accounting for 11.9% of reported sightings.
All together, this study revealed that 56 species of parrots have been observed so far in 43 states, and 25 of those species are breeding in 23 states.
“Of course, not every species is breeding in every state in which they are observed, but three states combined (Florida, California, and Texas) support breeding populations of all 25 known breeding species,” Ms. Uehling and her collaborators noted in their paper.
“But many of these species are perfectly happy living here and they’ve established populations,” Professor Pruett-Jones added. “Wild parrots are here to stay.”
Although Ms. Uehling and her collaborators found that many of these parrots dwell in the warmer regions of the United States, they did find sizeable populations in colder urban areas, such as New York City and Chicago (Figure 1).
Where did these parrots come from?
“Many of them were escaped pets, or their owners released them because they couldn’t train them or they made too much noise — all the reasons people let pets go,” Professor Pruett-Jones explained in a press release.
Ultimately, the pet trade made parrots into one of the more species-rich orders of established birds that are breeding in the USA. But the number and diversity of parrot species present are unlikely to increase further because legal importations of parrots have mostly ceased due to international regulations and agreements.
Although the data used for this study “are certainly not perfect records of all non-native parrot species sighted in the USA,” as Ms. Uehling and her collaborators point out in their report, this study still raises interesting questions: Why are established populations of parrots found in some places but not others? Is there a correlation between concentrations of particular species of captive parrots and their naturalized populations? How do they manage to thrive in foreign habitats?
Ms. Uehling and her collaborators are already examining which ecological factors have the greatest influence on the distribution of established parrots in the US. They’ve found that the most important limiting factor is the minimum January temperature. This is not surprising since most parrots originate in tropical areas and generally cannot survive in regions that are strongly seasonal with cold winters. But monk parakeets are the one exception: it appears their ability to survive cold climates is at least partially dependent upon their magnificent nests, which they build on human-made as well as natural structures, and their ability to change their diets so they can survive extreme cold.
The density of people is another important factor that impacts parrot survival in foreign landscapes. Some people intentionally feed birds, at least in the winter, their buildings can serve as shelters against the worst weather, and cities themselves are generally warmer than the surrounding rural areas. This explains why established populations of parrots are almost always found in or near urban areas, particularly in southern Texas, southern Florida and southern California, where large human populations are concentrated.
Considering that at least a few introduced species end up causing tremendous harm to native wildlife, it’s important to establish whether any naturalized parrots harming native species, particularly native frugivores, which are most vulnerable. Fortunately for the parrots and for the people who love them, there is currently no evidence they are harming any native species.
Studying the natural history of established parrots in the USA could provide important insights into fundamental aspects of their ecology and conservation. Further, some of these naturalized species, such as the red-crowned Amazon parrot, are endangered in their native ranges. But this parrot’s population is increasing in the United States — so much so that there now are more red-crowned Amazon parrots living freely in US cities than in its native range in northeastern Mexico (more here). This raises the possibility that established populations of endangered parrots may be used as source populations to bolster future conservation efforts (more here).
“Because of human activity transporting these birds for our own pleasure, we have inadvertently created populations elsewhere,” Professor Pruett-Jones said. “Now for some of these parrots, they may become critical to the survival of the species.”
Jennifer J. Uehling, Jason Tallant, and Stephen Pruett‐Jones (2019). Status of naturalized parrots in the United States, Journal of Ornithology, published online on 15 May 2019 ahead of print | doi: 10.1007/s10336–019–01658–7
Originally published at Forbes on 21 May 2019.