Flight Mechanics & Ethical Concerns

juv macaw iStock cropped

Lecture objectives

parrot flight syncronicity Lecture topics will include:

  • Avian Welfare
    • Definitions
    • Scientific approaches
  • Flight Mechanics
    • Definitions
    • Feather anatomy
    • Down/upstroke
  • The Ethics of Wing Trims
    • The relationship between flight and bird brain development
    • Communication and education
    • Informed consent
  • Wing Trim Techniques


Flight in Companion Parrots – The Conflict:  Freedom vs Safety

Feather trimming birds in captivity has been a common practice performed for many reasons, including fear of loss, safety, and the ability to control and tame.  If the gold standard for animal welfare is freedom and feather destructive behavior is a reliable indicator of scientifically studied animal welfare, feather trimming impacts how the animal feels, functions, and prohibits natural responses to positive or aversive stimuli.  Perhaps it is time to reflect on the benefits and risks of feather trims through the lens of animal welfare. At a minimum, the degrees of severity of the current techniques need redressing when we consider the experience of the bird.



Download a PDF version of Dr. Drigger’s outline



  • What is the experience of life through the perspective of the bird?
    • Define animal (avian) welfare
      • Minimum
      • Ideal vs captive optimal (natural evolutionary biology)
  • Freedom versus safety
  • What have we normalized?
    • Unintentional neglect
  • What have we generalized?
    • The generic bird vs the evolutionary machine of uniqueness and sentient being
  • Scientific approaches to avian welfare
    • Feelings based
    • Function based
    • Nature based
  • Preventive avian welfare – increasing freedoms
    • Social/environmental enrichment
    • UV exposure-outdoors
    • Aviaries- indoor/outdoor connected
    • Allowing flight
    • Foraging opportunities
  • Avian Welfare as an afterthought
    • Physical and psychological stressors
      • Behavioral disorders
        • FDB
        • Screaming
        • Biting
        • Reproductive issues
    • Treatment is the same as the prevention+
    • Applied Behavior Analysis -losing the labels/creating action plans
      • Functional Assessment
        • Antecedent
        • Behavior
        • Consequence
    • Education not guilt
      • Guilt leads to stewards desire to rehome
      • Education is empowerment



  • Definitions
    • Airfoil
    • Lift
    • Drag
      • Induced
      • Profile (form)
      • Parasitic
    • Boundary layer
    • Stall
    • Turbulence
  • Feather Anatomy
  • Flight mechanics of downstroke
  • Flight mechanics of upstroke
  • Primary/secondary open and feather separation causes high pressure air under the wing to louver through to low pressure on top decreasing backstroke resistance – passive?
  • Forward thrust at primary/secondary separation at carpals with minor lift



  • Bird’s eye view (perspectives) on wing trims
    • Cut feathers poke (irritation)
    • Falling hurts (pain)
    • Afraid / can’t escape noxious stimuli (fear)
    • Unable to say yes or no by natural means (limit choice and increase fear learned helplessness)
    • Total dependence on human steward
  • Flight is how bird brains develop independence (avian education)
    • Never Trim Parrots Prior to Fledging
    • Flight is empowerment
    • Flight is their evolutionary design and biological right
    • They can’t respond naturally to noxious stimuli when trimmed aggressively.
  • Further physical and psychological health considerations
    • Cardiac and bone health.
    • Psychological wellness
      • To a bird in a cage with a wing trim
        • Yes means “I can’t”
        • No means “I can’t”
  • Perspectives
    • Cruelty?
    • Careful steward?
    • Fearful owners?
  • Flight ethics
  • DVM responsibilities
    • Flight ethics- communication, education, and informed consent
    • Not trimming and not educating will result in loss of a client*
    • Communication of both the risk and benefits of feather trimming and/or leaving the natural wing
    • Education/communication
    • Regarding flight- 2 way conversation DVM/Client
      • Education of Benefits/Risk
      • Listen and educate
        • Flight goals
        • Freedoms/enrichment
        • Risk factors (Client Fears)
    • Fear (of loss) is a Primary Client Motivator that “Justifies” Removing flight (the evolutionary response to fear in captivity or in nature)
  • Bird “owners” generally have great intentions.
    • Intention vs impact
    • Educate clients from fear-based decision to………
    • “How do we ensure birds live the best life possible” based decision
    • Client discussion topics (fear mitigation)
    • Ceiling fans
    • Household predators- cats, dogs, children, and wildlife
    • Individual habits of household- kids, doors, high ceilings, mirrors, windows, toilets, pools and other outside risk
    • Past flight experience and injuries
  • Long term:
    • Nerve and bone pain lead to osteomyelitis, nerve impingement;
    • Chronic pain leads to learned helplessness, mutilation, feather destructive behavior, obesity, cardiovascular disease, pododermatitis (bumblefoot), OCD
    • Increased risk over time to predation leads to early death (opportunity/time)
  • Physical examination
    • Species- body type, wing load, tail length
    • Body condition/weight
    • Past or current medical issues or disabilities



  • Is it possible to trim feathers and achieve the goals of the owner and the not have an overwhelming impact on the bird physically or psychologically?
    • Technique sensitive?
  • IF trimming is deemed an acceptable risk with the…
    • Knowledge of flight mechanics
    • Benefit of clear communication and education of risk and benefit
    • Experience of a physical exam and history
    • Knowledge that aggressive trims based upon fear of loss may be responsible for many of the physical and psychological problems manifested in birds but short and long term
  • The right individual decision can be made with wisdom and informed consent
    • Consider a much lesser technique that mitigates many current negative trends that impact both client satisfaction with their avian companions and patient holistic health.
  • The new technique skinny trim
  • Skinny repeal trim
    • Biomechanics of this style of trim (skinny repeal)
    • Air compression on down stroke gradual loss of elevation (more stall but able to move wings more quickly)
    • Resistance on upward stroke (more rapid wing movements)
    • Wings move faster in both directions
      • velocity with wing movement = more exercise in a shorter period of time
      • Active control of landing impacted by feather length
      • Normal flight posture
      • Variable tip length to flight
      • In 5 years of performing this type of groom
    • Birds don’t poke themselves. Less picking and feather rachis shredding?
    • broken blood feathers- new feathers protected
    • trauma to tail vertebrae& feather osteomyelitis/nerve impingement
    • Molt cycle maintained/ normal torque germinal disc (where feather attaches to blood supply
    • No fractured beak tips, fracture keels, legs, lacerations, head trauma
    • Less psychological effects/confidence because more function is maintained
    • Less client guilt- more aesthetically normal
    • Better responses to noxious stimuli and desires
  • Not trimming feathers at all should always be considered when plausible.
  • Flight Ethics—A Compromise
  • As the veterinarian
    • Lead the conversations but listen
    • Be a patient advocate
    • Compromise is often necessary


About the presenter

Dr. Todd Eric Driggers has spent 25 years in practice evolving his understanding of flight and how/why we are influenced to remove the flight abilities of birds. Dr. Driggers interned at the Avian and Exotic Animal Clinic in Indianapolis and in 1996, he started Arizona’s first exclusive exotic animal practice.  He currently owns both a mobile practice and a stationary practice named The Avian and Exotic Animal Clinic of Arizona. Currently, he has both a mobile practice and a stationary 3-doctor practice named The Avian and Exotic Animal Clinic of Arizona [MORE]


Webinar recording

Shared media

Dr. Driggers has generously shared a video illustrating the skinny repeal technique (Slide 49) as well as one diagram and still images.


Driggers feather diagram

Slide 48. Feather diagram:  Trim the number of feathers you normally would (for your individual of interest) but only on the trailing edge. Trim only the primaries and do so symmetrically. Leaving more of the feather tip also provides more lift. Source:  Dr. Todd Driggers. Click image to enlarge.

skinny repeal macaw

Slide 50. Repeal trim in a blue and gold macaw (Ara ararauna). Note:  This image was originally oriented vertically and has been rotated to the right. Photo credit:  Dr. Todd Driggers. Click image to enlarge.


skinny repeal budgie Driggers

Slide 51. Repeal trim in a budgerigar parakeet (Melopsittacus undulatus). Photo credit: Dr. Todd Driggers. Click image to enlarge.


With a passing grade of 70% or higher, you will receive a continuing education certificate for 1 hour of continuing education credit in jurisdictions that recognize AAVSB R.A.C.E. approval.

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Expert Q+A

Although Dr. Driggers was able to answer many questions during the live event, the remaining questions were answered by email and are posted below:


What [are the flight mechanics of] goshawk type birds that are ridiculously maneuverable at speed? 

For a more thorough review of Form and Function of bird wings, Birds by King and McLelland will help to answer your question.  Over time, the functional need helps determine the successful form.  



Is the purple line where you are clipping?

Driggers feather diagram

The interior of the purple is the removable portion.  


How many feathers do you trim on the skinny trim?  

Depends on the bird’s flight experience, body condition, molt, feather condition, and the flight goals. Generally speaking to the skilled person that already trims feathers, trim no more than you do regularly but seriously ask yourself if a bird has the need to be trimmed first.  

LafeberVet’s Grooming Companion Birds also includes some specific recommendations on this matter.


Can you trim all the primary feathers with the Skinny trim?? or should you leave the first two intact??  

I never leave the first two [primary feathers] intact on any birds because they give the most amount of lift and speed.  


What is the adequate % removal  of the trailing edge that  is appropriate on each feather. 

Perhaps 50% on average leaving the tip around 10% on average.  But really evaluate the individual bird, not the average bird. It is an individual.  


What extension of the length of the feather trailing edge should be trimmed in order to be effective?  

Depends on the individual characteristics of each bird…Thin bodied birds need more trimmed. Heavy bodied species need more wing load (weight dispersed over more feathers).

LafeberVet’s Grooming Companion Birds also includes some specific recommendations on this matter.

Do you trim in this way all the 1st primary feather?

Depends on bird’s flight experience, body condition, molt, feather condition and the flight goals. Generally speaking to the skilled person that already trims feathers, trim no more than you do regularly but seriously ask yourself if a bird has the need to be trimmed first.  

LafeberVet’s Grooming Companion Birds also includes some specific recommendations on this matter.


I am going to do a skinny repeal on my grey parrot and Amazon parrot from now on.  What is the optimal trim for these two species? 

Usually no more than five feathers for grey parrots.  Amazon body size can vary a lot so more or less may need to be considered.


Dr. Driggers, in the realm of parrot rescue and rescue facilities can wing trimming be avoided?  

Yes. I would encourage leaving [birds] flighted unless an exception is necessary for the individuals’ good.  


How often do you recommend trimming the birds wing? 

When the risk of harm from flight become greater than the risk of benefit from the trim.

LafeberVet’s Grooming Companion Birds also includes some specific recommendations on this matter.


Does wing trimming affect the molting cycle? 

Not in my subjective observation


[B]irds with short wing trims molt MORE often or LESS often? (since the torque is changed)? 

Less torque on germinal tissues means short feather rachus stays in longer (in my subjective opinion).  


I have a 1-year old cockatiel that is very sweet and healthy. He had a very aggressive wing trim and by the time the feathers grew out he is still not able to have controlled flight. From the floor he will takeoff and fly up and backwards until he hits a wall so when I take him out of his cage I have to contain him so he won’t hurt himself. I am not happy with this situation.

He has to re-fledge.  In severe cases I anesthetize and pull primary stubs to stimulate feather growth faster so as not be cause more physical or phycological problems.  

This owner was encouraged to take this reply to his avian veterinarian.


If we choose to complete a trim is there any concern with trimming a growing feather? 

Just the fact that you are trying to be symmetrical and consider flight mechanics. 

Also consult the section “What if I find a blood feather” in LafeberVet’s Grooming Companion Birds.


Any drawbacks or differences vets should warn owners about with the skinny repeal vs trimming of the primaries only previously? For example:  are those feathers more easily broken, etc.?

More frequent refresher grooms are often necessary.  


Do you use a scissor to cut the feathers for this trim? Any special type?

I use a long blade scissors to increase the speed of feather removal.  The main thing is that the scissors are comfortable and functional.


Any good references for medications to help birds with anxiety during their visit for exam +/- wing trim?

 Mans C, Sanchez-Migallon Guzman D, Lahner LL, et al. Sedation and physiologic response to manual restraint after intranasal administration of midazolam in Hispaniolan Amazon parrots (Amazona ventralis).  J. J Avian Med Surg 26(3):130-9, 2012.



I do not understand the question about blood feathers:  Is it the physical trauma of cutting the feathers that causes new blood feathers or is for the autotraumatise of the bird?

Blood feathers that grow in on the wings, where other feathers are trimmed short, are subject to trauma because they do not have other feathers to protect them. This predisposes blood feathers to trauma and breaking. 

LafeberVet’s Presenting Problem:  Broken Blood Feather also includes some information on this matter.

The image below also illustrates the potential vulnerability of the blood feather.

Blood feather Dr. Ed Ramsay

The image illustrates the potential vulnerability of the blood feather. Photo credit: Dr. Edward Ramsay. Click image to enlarge.



Do you have any suggestions for getting over the situation you described with [the] tail bone?  11- year old Timneh [grey parrot] whose wings were trimmed in a foster home.  Primaries are mostly grown out now but falling before they grew in resulted in all tail feathers broken off except one.  I am hoping the tail feathers will grow back in normally but she is over-preening that area.  Do you recommend [following] up with my vet or should I wait and see if they grow back?

I [suggest that you] work with your veterinarian.  I sometimes pull a lot of feathers that are cut, damaged and frayed. [This should be performed] under your vet’s care, of course. with anesthesia.  Cage rest, anti-inflammatories, etc…until feathers grow back in.  Other considerations would be based on your vet’s clinical findings.  


When you are assessing wing injuries, based on your computed tomography (CT) findings, would you still put merit in radiography or would you move straight to CT?

The CT is the Michael Jordon (MJ) of orthopedics.  The radiograph is Dennis Rodman (DR)…..  LOL. 

[In other words], radiographs are good, but I tell my staff never keep MJ on the bench and try to win the game with DR.  The one thing that I do tell my staff is if an effusion is suspected, use the ultrasound (another role player) but better than the survey radiogrpah.  



I see the similarity to this issue to declawing cats and spaying dogs and cats and so forth.  When does it seem that the veterinary client relationship should be private and respected and when should it be regulated?

With respect to cruelty?  I suppose this is one of those grey areas!.  Keep in mind, this is more an education issue not a legal issue.  Most people get birds already trimmed and assume it as normal. 


What is the best size for a free flight aviary? 

The sky.  [This is a] very species-specific question.  Bird size, foot size, habitat/niche……should also be [considered]. 

During the live webinar and Q+A, Dr. Driggers also discussed his clinic aviary, which measures 22.86 x 4.57 m (75 x 15 ft). He has two clinic birds, a rose-breasted cockatoo (Eolophus roseicapilla) and a Goffin’s cockatoo (Cacatua goffiniana). The birds are allowed outside to exercise in the aviary.



Is the new book “Thinking Like a Parrot” advised reading?  

Yes.  I have it and It is interesting and informative.  


RACE approval

This program 776-41764 is approved by the American Association of Veterinary State Boards (AAVSB) Registry of Continuing Education (R.A.C.E.) to offer a total of 1.00 CE credits to any one veterinarian and/or 1.00 veterinary technician CE credit. This RACE approval is for Category Two: Non-Scientific Clinical using the delivery method of Non-Interactive Distance. This approval is valid in jurisdictions which recognize AAVSB RACE; however, participants are responsible for ascertaining each board’s CE requirements. RACE does not “accredit” or “endorse” or “certify” any program or person, nor does RACE approval validate the content of the program.