Fledging changes everything.

Wing clipping before fledging–the important developmental stage when a bird learns to fly–has the potential to inflict the most serious and long-lasting consequences compared with a singular clip of equal duration at any other time in its life. Wing clipping that interferes with fledging effectively interferes with the normal development of a young animal. Every bird owner, current or future, deserves to know how a bird can be affected by this.

If you visit a place which sells birds–depending upon which one you visit, of course–you may see baby birds in small pens, bins, cabinets, or cages.  These enclosures are appropriate for baby birds who are not yet ready to leave the nest.  The trouble arises, however, when baby birds are clipped and/or remain confined within small spaces past the age they should be learning to fly.  In the wild, these fledgling parrots would be building flight skills, exploring their environments, following their parents, and learning how to be birds.  To put it simply, the baby birds who are clipped and/or confined do not experience a normal transition to adulthood.  I am going to show you why this is a very problematic and even unethical way of raising baby birds which is falling out of favour among reputable aviculturists.  I understand that the people still following the outdated “wing clipping method” of rearing may, in many cases, be true bird-lovers who believe they are doing the right thing (or at least causing minimal harm), but that does not mean we need to accept or support it.  There are many sources from which one can purchase parrots which have been raised flighted, but one must do one’s research.  Private breeders, pet shops, and bird stores should all be taken as individual entities as their views on flight and wing clipping can vary tremendously.

First, how does wing clipping before fledging affect the physical aspects of a bird’s development? A baby bird instinctively learns to walk, flap, and fly, similar to the way a baby human instinctively learns to crawl, “cruise”, and walk.  The role of wings in avian locomotion is so deeply ingrained that baby birds adopt the characteristic flapping stroke associated with flight well before their musculoskeletal systems have finished developing.  By using their legs and wings cooperatively while their muscles and bones develop, they are able to make a seamless transition to wing-based movement, or flight.¹  Conversely, human babies use their arms and legs cooperatively to help them transition to leg-based movement.²  In short, a parrot’s wings do for them what our legs do for us.

Without primary/flight feathers, however, the baby bird is unable to make this transition.  Flight feathers strongly affect wingspan, reduce drag, and contribute greatly to the production of thrust and lift.³, ⁴  Bird wings do come in slightly different shapes, but certain characteristics, like primary feathers and wing tip shape, remain quite similar across avian species.  These are “central to flight performance…because of their aerodynamic importance”.⁵  Thus, wing clipping and fundamentally altering their aerodynamic shape infringes upon a baby bird’s ability to learn normal locomotion.  How can a baby bird, whose flight muscles are still developing, achieve flight without a properly shaped wing?  How can it adequately build its flight muscles?  A recent study on pigeons found that the pectoralis muscle grew rapidly after fledging, all the way up until sexual maturity.⁶

If muscles aren’t properly developed and remain weak, they can’t place an appropriate burden on the bones they control, leading to negative effects on bone mass, size, and strength.⁷  The mechanical load placed on a bone while it is growing ultimately determines the strength of that bone⁸, ⁹, and the mechanical load imposed by wing exercise at the onset of flight prompts specific and rapid changes in bone strength.¹⁰  It stands to reason that if a bird’s wing bones do not experience the burden of flight during development, they will be weaker than those which have been subjected to flight during development.  Additionally, exercise during growth results in bones of higher mass and density.¹¹, ¹²  If exercise continues throughout the animal’s life, this increased initial bone strength can help reduce the risk of fractures as it ages.¹³

The effects of wing clipping on physical development may seem troubling, but perhaps even more troubling are the effects of wing clipping on brain development.  During an animal’s early life, there exist sensitive periods wherein its experiences (or lack thereof) have a profound effect on its brain.¹⁴  Animals raised in enriched environments which incorporate mental, physical, and social stimulation have more active, plastic brains, possessing a greater number of, and more complex, neural connections.¹⁵, ¹⁶  The baby bird navigating its environment by flying is learning a series of complex motor skills: taking off, flapping, gliding, ascending, descending, turning, avoiding obstacles, braking, landing, and so on.  In doing so, it is quickly interpreting visual data.  Compare this baby bird, who is following a normal developmental path, to the baby bird in the bin who cannot move beyond the same stationary flapping it would have done while still in the nest.  Studies point to a significant relationship between physical activity, motor skills, and overall cognitive function.¹⁷  Research also indicates that the presence or absence of physical exercise can determine just how enriched an environment is.

To quote a recent study conducted on mice, which are the standard lab animals for experiments in neuroscience, “As the brain matures, its ability to change declines, together with the ability to learn, memorize or recover from various brain injuries. One of the approaches shown to improve brain plasticity is enriched environment (EE)”.¹⁸  The study compared mice raised in standard cages to those raised in an enriched environment, one which was nine times larger than the standard cage, had two floors, a ladder, a maze, a slide, a tunnel, and three running wheels.  Scientists discovered that even a few days of being housed in a standard cage without a running wheel completely eliminated the type of brain plasticity they were studying, while the addition of a running wheel was able to preserve it.  The mice in the standard cages were able to walk but not run, similar to a clipped baby bird who is able to walk but not fly.  Biologically appropriate, sufficiently demanding physical exercise made the difference.  Studies also show that physical activity during critical periods results in better learning, concentration, memory, and intelligence.  (Source: see footnote 17.)  Based on this information, is it not logical to conclude that the baby bird who learns to fly will receive higher levels of environmental enrichment and exercise, and will therefore achieve a higher level of brain development, than the baby bird who is flight-restricted?

It is impossible to know for sure whether a particular bird’s behavioural issues are due to this type of rearing or another cause entirely, but we can make the logical inference that abnormal development increases the incidence of abnormal behaviour.  Clipped baby birds are often advertised as “hand-raised” or “tame”, but many of them are fearful and averse to human contact.  The shortcut which circumvents socialising and training these birds is to physically disable them via wing clipping.  Because they are unable to fly, they cannot escape a customer who wants to hold them regardless of how fearful they may be.  When a bird is afraid, repeatedly forcing it to interact with us and removing all avenues of avoidance does not result in tameness or “bonding”; it results in learned helplessness.  Learned helplessness is a condition where an animal or person is first confronted by inescapable stress or pain.  Then, later on, even if it would be possible for them to escape the stress or pain, they don’t make any attempt to.¹⁹  Essentially, if we force a clipped bird to step up over and over, or if we pick it up off the ground every time it tries to flutter away, we are forcing it into a state of learned helplessness.  It’s still afraid, but it has given up.  This naturally leads to a more insecure, dependent bird who feels safe in a very limited range of situations–a “one-person bird” in the making.

The other, equally unfortunate, result of forcing interactions with birds is that some of them learn that when flying away is futile, biting works very well.  Instead of turning to their instinctive avoidance strategy, flight, they rely on other behaviours, like biting, to try and make perceived threats go away.  Flight-restricted birds can’t build the confidence that comes of having the power to fly away from something they don’t like.  Fully flighted birds can and do bite in many contexts, but they do not have the added stressor of a physical handicap or the psychological insecurity caused by that handicap encouraging them to bite in instances where they would otherwise elect not to.  Dr. Michael Doolen, avian veterinarian, suspects that a great deal of problem behavior he has seen in his patients results from “imprinted birds not being allowed to fledge and develop strong flight skills”.²⁰  He has also observed that flight skills cultivated later in life can reduce or resolve some of this problem behaviour.

The rearing of baby birds is obviously a complex issue and many factors, not just wing clipping, are at work here.  However, the denial of the fledging process most certainly influences a baby bird’s development by barring it from normal exercise and stimulation.  You may now wonder: can birds learn to fly if they were clipped before fledging?  After all, the adult brain does maintain a certain degree of plasticity.  (Source: see footnote 15).  Fortunately, they can usually learn to fly, and there are many people all over the world helping their clipped or previously clipped birds do just that.  But it isn’t as easy for these birds, and even with a great deal of effort, they may never become as skilled as birds who fledged at the natural age.

Why might this be?  If flight is natural, why is it so hard for these birds to learn later in life?  Well, there are a few reasons.  During sensitive periods of brain development, our experiences help shape our abilities.  The developing brain forms an overabundance of connections and is constantly making new ones based on the information it receives.  The connections being used become stronger, while the ones left unused are eliminated.²¹  Genie, a “feral child” who was not exposed to language from the age of about two to thirteen, ultimately did learn some spoken language but was never able to harness the grammatical skills normal children learn by the age of five.²²  Another individual, who was merely deaf and uneducated up until the age of fifteen (rather than abusively isolated as in Genie’s case), showed striking similarities to Genie in his language deficits.  After almost three years, he was still unable to comprehend verb tense, negation, pronouns, or prepositions.²³  People who learn to play musical instruments as young children acquire structural differences in their brains compared to non-musicians.  These differences allow them to perform better at certain motor tasks, musical tasks, and even language processing tasks.²⁴  Rats raised in the reduced gravity of low Earth orbit have more difficulty maintaining balance and righting themselves when they return to Earth compared to rats raised in normal gravity.²⁵  All of these examples, though of course not perfectly analogous with fledging,  illustrate long-lasting or permanent effects associated with sensitive periods of brain development.

The ability to learn and acquire new skills obviously continues throughout life, as evidenced by people who learn to play instruments as adults and by birds who learn to fly as adults.  However, the developmental periods before puberty are windows of opportunity that are not to be underestimated.  One paper on motor learning in children concludes that these time periods should “be used particularly intensively…especially with regard to coordination and speed”.²⁶  Although we don’t have any studies on how flight restriction during sensitive periods may impact flight later in life, we do have studies on other kinds of sensitive periods in birds, such as sexual imprinting,²⁷ sensorimotor integration during song-learning,²⁸ and auditory-spatial learning,²⁹ as proof of concept.  Because a clipped baby bird is unable to fly, its brain is unable to build the specific connections that flight would have “unlocked”.  Building these connections later, when the brain is no longer at peak plasticity, can pose a serious challenge.  Thus, wing clipping significantly complicates a process–learning to fly skillfully–that would otherwise be natural and intuitive.

This is especially true when it comes to outdoor free flight.  Many birds (particularly larger birds like macaws and cockatoos) have been trained, with professional help, for outdoor free flight even if they were clipped before fledging.  I think it is wonderful that those birds and trainers have accomplished such a feat.  However, the risk and difficulty level when training these birds outdoors increases substantially compared to training a bird who has experienced normal development; such an undertaking is certainly not ideal.  As free flight becomes more common and more people wish to fly parrots, it is paramount that the importance of fledging and the effects of wing clipping (in addition to working with a highly experienced mentor) be understood. 

How can wing clipping affect physical health throughout a bird’s life?

 

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