Feral birds can be unique and unexpected sightings, but they can be controversial for birders and non-birders alike. Understanding what feral birds are and the problems they can present is essential to keeping control of these species and ensuring they do not overwhelm native populations.

Defining Feral

A feral bird was originally a pet bird or domestic poultry but has escaped or been released to live in the wild far from its native range.

Releases may be deliberate, such as the irresponsible dumping of Easter chicks and ducks at local parks, but are more often accidental, such as pet birds escaping from their enclosures or poultry roaming away from its farm. Unlike vagrant birds, feral birds only reach their new wild destination with assistance from humans rather than simply straying on migration or otherwise leaving their established range.

A wide variety of feral birds can be found around the world, with some species forming breeding colonies in unlikely areas, while others remain as solitary celebrities that wander with local wildlife. Species that are regularly seen as feral birds include:

• Parrots and parakeets, including the budgerigar, ring-necked parakeet and monk parakeet
• Domestic duck breeds and exotic waterfowl such as the black swan and Chinese goose
• Game birds including Indian peafowl, helmeted guineafowl and several types of pheasants
• Exotic doves such as the spotted dove as well as escaped fancy doves or racing pigeons

Less common feral species include different types of finches and other passerines that may be popular as pet birds, as well as the occasional rare escapee from zoos and aviaries, such as a flamingo in a flock of more familiar wading birds. These unique birds can attract attention to the local birding community, raising awareness of an area's avifauna, and some communities even host festivals to celebrate their feral birds.

Problems With Feral Birds

While it may be exciting to see a feral bird, these non-native guests can cause a variety of problems if they establish long-term colonies, such as:

• Competition: Feral species may be more aggressive than native birds, and could present harsh competition for available nesting sites and food sources. This can push native birds out of an area or reduce their populations dramatically if the feral population continues to grow.
   
• Interbreeding: If feral birds are compatible with local wild species, interbreeding may dilute the genetic purity of native birds, which can become a grave conservation threat. The red junglefowl, for example, is threatened in many parts of its native range because of interbreeding with feral chickens.
   
• Pests: When a feral population grows, it can become a community pest. Excessive feces, noise, shed feathers, food waste and other debris can accumulate, and birds that are not native to an area – and thus have no natural controls on their population – may take to ripping up local crops, invading backyards or otherwise becoming a nuisance.
   
• Diseases: Exotic birds have immunities to diseases that they may carry, but if those diseases are introduced to local birds, the consequences can be disastrous. Because many feral birds are gregarious and will seek out local flocks, diseases can spread quickly among native birds.

In many cases, feral birds do not pose difficulties to the communities they adopt, but if problems do arise, it may be necessary to take step to cull the population or otherwise remove the feral colony so it does not become unmanageable.

Feral or Invasive?

Feral birds are often confused with invasive birds, but there are some key differences. A species is not considered invasive until it is causing consistent hardship to native flora or fauna, but feral species do not always cause such problems. Furthermore, the term feral is more often applied to previously domestic or pet birds, while invasive birds can originate from other sources, such as wild birds accidentally imported on ships or with cargo. Invasive birds also typically spread quickly and thoroughly, usurping large areas of habitat, while feral birds more often stay confined to their initial introduction area and rarely spread beyond a small territory. Finally, invasive species are generally difficult to eradicate once they have become established, but feral colonies could be easily removed and often die out naturally within a few years or a decade or two if no new members join the colony.

Controversies With Feral Birds

While feral birds can be exciting to see, they can be controversial. Not only are the problems feral birds can cause likely to create some tension in communities with large feral populations, but other issues can arise, such as:

• Are they lifers or aren't they?
  Birding organizations don't often recognize feral sightings as life birds for record-keeping purposes, but birders may all have their own individual definitions of what an acceptable lifer can be.
   
• Do they encourage irresponsible pet ownership?
  If feral birds are celebrated and enjoyed, a thriving feral colony may inadvertently encourage people to release unwanted pet birds into the environment with the mistaken belief that they will be safe and healthy as wild birds.
   
• How should they be controlled?
  When a feral colony poses community problems or begins to harm local wildlife, population control measures such as hunting, culling, trapping or other methods can seem brutal, and other types of control techniques may inadvertently harm wild species as well.

Feral birds can be an interesting part of a community's avifauna, but it is important to understand the problems these birds may cause in order to better understand how they fit into a new ecosystem.

Photo – Feral Chickens © key lime pie yumyum