Nonmedical Factors Associated With Feather Picking in Pet Psittacine Birds Author(s): Lori A. Gaskins, DVM, Dipl ACVB, Dipl ACAW and Laura Hungerford, DVM, MPH, PhD Source: Journal of Avian Medicine and Surgery, 28(2):109-117. 2014. Published By: Association of Avian Veterinarians DOI: http://dx.doi.org/10.1647/2012-073R URL: http://www.bioone.org/doi/full/10.1647/2012-073R
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Journal of Avian Medicine and Surgery 28(2):109–117, 2014 Ó 2014 by the Association of Avian Veterinarians
Nonmedical Factors Associated With Feather Picking in Pet Psittacine Birds Lori A. Gaskins, DVM, Dipl ACVB, Dipl ACAW, and Laura Hungerford, DVM, MPH, PhD Abstract: A nested case-control study was performed to determine nonmedical risk factors associated with feather picking in psittacine birds. Forty-two case birds, reported by their owners to pick their feathers, and 126 unaffected birds were compared. The odds of feather picking were higher in 2 species categories, African grey parrots (Psitticus erithacus, adjusted odds ratio [ORadj] ¼ 8.4, P , .001) and cockatoos (Cacatua species, ORadj ¼ 12.7, P , .001). The odds of feather picking also were higher for birds that were out of their cages more than 8 hours per day (ORadj ¼ 7.4, P , .001) and for birds that had been taken in by the owner as a ‘‘rescue’’ (ORadj ¼ 4.7, P , .01). The odds of feather picking decreased by almost 90% (ORadj ¼ 0.1, P , .005) for birds that interacted with people at least 4 hours a day. These findings identify characteristics that practitioners may want to include when asking bird owners about behavioral history and may be useful in focusing future research regarding this behavior. Key words: feather picking, feather destruction, behavior, avian, psittacine, bird
behavior.9 The diagnostic criteria for many of these disorders, in other species, can be found elsewhere.10,11 Better understanding of these behavioral disorders, which could manifest as feather picking, is needed to facilitate diagnosis and treatment of affected birds. In this case-control study, we explored the captive environment and husbandry of pet psittacine birds with the purposes of better understanding this condition and identifying characteristics that differed between featherpicking birds and unaffected birds.
Introduction Feather picking is a common complaint addressed by avian veterinarians and encountered by pet bird owners and has been reported in 10% to 13% of psittacine birds.1,2 Birds present with selfinflicted injury that includes feather damage or feather removal, and may include mutilation of the underlying skin and muscle. Feather picking may be a symptom of a behavioral or a medical condition, or both. Although few etiologic or epidemiologic studies of feather picking in pet birds have been done, the disorder has been characterized based on possible medical3 and nonmedical4,5 etiologies. For nonmedical or behavioral feather picking, the differential diagnoses that have been considered include, but are not limited to, separation anxiety,6 attention seeking,7 compulsive disorder,8 lack of mental stimulation,9 displacement behavior secondary to stressors,6,9 and prolonged reproductive
Materials and Methods Recruitment This study was based on information collected through an online survey of bird owners.2 Online surveys have been found to have results consistent with traditional methodologies12 and have been used in other studies for the collection of veterinary data.13,14 General avian websites likely to be frequented by bird owners were identified and requests were made to post links to the survey. Data were collected from February 2006 to August 2006. In this original survey, 512 responses were received from Africa, Asia, Australia, Canada,
From St Matthew’s University, School of Veterinary Medicine, PO Box 32330, Grand Cayman KY1-1209, Cayman Islands, BWI (Gaskins); and the Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA (Hungerford).
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Europe, South America, and the United States.2 After excluding those in which the respondent was less than 18 years old or was not the primary caregiver, 404 responses were available. These respondents were predominately women (88%) and represented a span of ages: 30% were 18 to 29 years of age, 32% were 30 to 45 years of age, 33% were 46 to 60 years of age, and 4% were older than 60 years of age. A subset of these 404 respondents served as cases and controls for the analysis of factors associated with feather-picking behavior. Survey design The online survey was developed by using the survey generation program, SurveySuite.15 Questions from the published survey that were used in the current nested case-control analysis were owner characteristics (age, sex, bird-owning experience), bird characteristics (species, sex, age, rescue, behavior, wing clip), some aspects of human/bird interactions (hours interacting per day, trick training, bathing/misting, behavior), and environmental characteristics (group caged/individually caged/not caged, cage size, hours outside cage, cage covered at night, cage/bird moved at night, other birds or animals in view). Questions were presented in multiple choice and yes/no fashion, and an ‘‘other’’ category was listed in many questions with space for respondents to provide explanations. Subjects In total, 47 birds were reported to pick their feathers by respondents to the survey. Many owners provided information about more than one bird. If there were multiple birds that picked their feathers in a household, one was selected randomly for inclusion. This resulted in 42 case birds remaining, 2 of which (an eclectus parrot [Eclectus roratus] and a conure [unknown species]) also exhibited self-mutilation of underlying skin or muscle tissue. A random sample of 3 control birds per case was selected from households without feather-picking birds, with only 1 control bird selected per household. A total of 126 control birds was selected, without matching on characteristics of cases.16 Statistical analysis Univariate analysis was first performed to compare factors between cases and controls, estimating odds ratios (ORs) for categorical data
and differences between means for quantitative variables, and to determine 95% confidence intervals (CI). P values were calculated when at least 10 birds were in a level of a variable, using Fisher’s exact tests for risk factors with 2 categories and tests for trend for more than 2 ordered categories.17 A t-test was used to compare means.16 Associations with P values .25 were evaluated further by using stratified analysis to evaluate potential interaction. Multivariable logistical regression then was used to calculate the adjusted OR (ORadj) and 95% CIs for risk factors for feather picking, adjusted for confounding. Best subsets method was used for model selection.18,19 Coefficients, standard errors, Wald statistics, 2tailed P values, and effects on other coefficients were considered when including and excluding variables from the best identified models of each size. Contribution of different variables to model fit was assessed using likelihood ratio tests. Potential interactions and confounders were considered, and influential observations were evaluated. The final model was selected based on biological plausibility, strength, and significance of associations, and model fit. Analyses were conducted with the statistical software program SAS 9.2 (SAS Institute Inc, Cary, NC, USA). Statistical significance in this study was defined at the P .05 level. Results Factors associated with feather picking were compared between case and control birds, and included bird characteristics, owner characteristics, some aspects of human/bird interactions, and environmental characteristics (Tables 1–4). In univariate analyses, 5 of the 20 factors were associated significantly with increased or decreased odds of feather picking. An additional 4 variables were selected for further consideration in the multivariable modeling based on the screening criterion of P .25. The final model included 4 of the 9 factors evaluated in the multivariate analysis: 2 bird characteristics, 1 human/bird interaction, and 1 environmental characteristic (Table 5). Feather picking was associated significantly with several variables. The odds of feather picking were 8 times higher in African grey parrots (Psittacus erithacus, ORadj ¼ 8.4, P , .001) and almost 13 times higher in cockatoos (family Cacatuidae, ORadj ¼ 12.7, P , .001) than in other species. Birds that had been taken in by the owner as a ‘‘rescue’’ (ORadj ¼ 4.7, P , .01) and birds that were out of their cages more than 8 hours per day
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Table 1. Survey results of pet bird owners regarding the association of bird characteristics with feather picking in 168 pet psittacine birds. Cases, n ¼ 42
Controls, n ¼ 126
Species/bird characteristic
No.
%
No.
%
OR
95% CI
P valuea
African grey parrot (Psitticus erithacus) Cockatiel (Nymphicus hollandicus) Cockatoo (various species) Conure (various species) Macaw, large (various species) Parakeet (unknown species) Amazon parrot (Amazona species) Budgerigar (Melopsitticus undulatus) Caique (Pionites species) Eclectus parrot (Eclectus roratus) Lorie (various species) Lovebird (Agapornis species) Macaw, mini (various species) Parrotlet (Forpus species) Pionus parrot (Pionus species) Poicephalus parrot (Poicephalus species) Quaker parrot (Myiopsitta monachus) Male Female Unknown 0–12 mo old 13–23 mo old 2–4 y old 5–10 y old 11–20 y old More than 20 y old Rescued bird Bird from other source Wings not clipped Wings clipped Doesn’t scream Screamsf No masturbationg/regurgitation Masturbation/regurgitation
10 3 11 5 2 1 1 0 0 3 0 0 1 2 1 1 1 15 18 9 1 3 7 22 8 1 11 31 20 22 31 11 35 7
23.8 7.1 26.2 11.9 4.8 2.4 2.4 0 0 7.1 0 0 2.4 4.8 2.4 2.4 2.4 35.7 42.9 21.4 2.4 7.1 16.7 52.4 19.1 2.4 26.2 73.8 47.6 52.4 73.8 26.2 83.3 16.7
12 17 6 18 12 10 7 3 1 5 3 9 5 6 2 6 4 48 42 36 20 17 39 33 11 5 10 116 49 77 98 28 99 27
9.5 13.5 4.8 14.3 9.5 7.9 5.6 2.4 0.8 4.0 2.4 7.1 4.0 4.8 1.6 4.8 3.2 38.1 33.3 28.6 15.9 13.5 31.0 26.2 8.7 4.0 7.9 92.1 38.9 61.1 77.8 22.2 78.6 21.4
3.0 0.5 7.1 0.8 0.5 0.3 0.4 0.4c 1.0c 1.9 0.4c 0.1c 0.6 1.0 1.5 0.5 0.7 1.0 1.3 0.8 1.0 3.5 3.6 13.3 14.5 4.0 4.1 1.0 1.0 0.8 1.0 1.2 1.0 0.7
1.2–7.5 0.1–1.8 2.4–20.7 0.3–2.3 0.1–1.8 0.0–2.3 0.0–3.5 0.2–8.2 0.4–24.6 0.4–8.1 0.2–8.2 0.0–2.5 0.1–5.2 0.2–5.2 0.1–17.1 0.1–4.2 0.1–6.8 Referenced 0.7–2.3 0.4–1.7 Reference 0.3–37.1 0.4–31.2 1.7–107 1.6–132 0.2–75.7 1.6–10.6 Reference Reference 0.3–1.4 Reference 0.6–2.8 Reference 0.3–1.8
.02b .27b ,.001b .70b .33b .21b
.54 .82 .001e
.005
.37 .67 .67
a
P values were only calculated when there were more than 10 birds per category. Compared with all birds not of that species. c OR estimated by adding 0.5 to each category because of categories with 0 birds. d Reference category for variable group. e Test for trend across categories. f Screaming was reported by survey respondent. g Rubbing cloaca/vent on objects or people. b
(ORadj ¼ 7.4, P , .001) also had higher odds of feather picking. Interaction with people at least 4 hours a day had a protective effect, with the odds of feather picking in these birds decreased by almost 90% (ORadj ¼ 0.1, P , .005). No other variables were significantly associated with feather picking in the model. One potential interaction between 2 variables was identified by stratified analysis. Longer contact with people did not decrease the odds of feather picking for rescued birds (OR ¼ 1.5, P ¼ 1.0), but did have a beneficial
association for birds acquired from other sources (OR ¼ 0.2, P ¼ .005). However, there were too few rescued birds (n ¼ 21) to include this interaction term in the regression model. Discussion Feather picking in pet psittacine birds often is a frustrating condition. The fact that some birds remain partially featherless all of their lives indicates that our knowledge of this disorder is
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Table 2. Survey results of pet bird owners regarding owner characteristics associated with feather picking in 168 psittacine birds. Cases, n ¼ 42 Owner characteristic
Female Male 18–29 y old 30–45 y old 46–60 y old Over 60 y old Owned birds 0–2 y Owned birds 3–5 y Owned birds 6–10 y Owned bird 11–15 y Owned birds .16 y a b
No.
Controls, n ¼ 126 No.
%
39 3 7 16 16 3 7 5 11 7 12
92.9 7.1 16.7 38.1 38.1 7.1 16.7 11.9 26.2 16.7 28.6
OR
%
107 19 32 50 39 5 21 38 23 17 27
84.9 15.1 25.4 39.7 31.0 4.0 16.7 30.2 18.2 13.5 21.4
1.0 2.3 1.0 1.5 1.9 2.7 1.0 0.4 1.4 1.2 1.3
95% CI
P value a
Reference 0.6–8.2 Reference 0.5–3.9 0.7–5.1 0.7–6.4 Reference 0.1–1.4 0.5–4.4 0.4–4.2 0.4–4.2
.29 .14b
.16b
Reference category for variable groups. Test for trend across categories.
incomplete. In this study, some nonmedical factors for feather picking were identified that may add to the knowledge base for this complicated disorder. Bird characteristics Similar to previous findings,3,4,20 results of the current study found feather-picking behavior to be significantly more common among African grey parrots and cockatoos than among other birds. Some investigators have speculated that this may be because African grey parrots are highly intelligent and, therefore, easily bored,20 which indicates these birds may be at risk for feather picking secondary to lack of mental stimulation.
Cockatoos have been characterized as needing extensive interaction with their human owners9 and being more predisposed to anxiety due to social deprivation, resulting in feather damaging behaviors (B. Speer, 2011, oral communication). A diagnosis of feather picking secondary to attention-seeking behavior or separation anxiety should be explored for these birds, along with other behavioral diagnoses. Although there were some interesting suggestions of other species differences, there were too few birds of other species in this survey to draw conclusions about their predisposition to feather picking. As social behavior has not been characterized for most psittacines in the wild, it is difficult to hypothesize about behavioral
Table 3. Survey results of pet bird owners regarding human/bird interactions associated with feather picking in 168 psittacine birds. Cases, n ¼ 42 Human/bird interactions
,2 h/d 2–4 h/d .4 h/d Taught tricks No tricks taught Bathed/misted daily Bathed/misted weekly Bathed/misted rarely Not aggressive to humans Aggressive to humansc Not afraid of humans Afraid of humansd a
No.
10 27 5 31 11 12 26 4 26 16 41 1
Reference category for variable group. b Test for trend across categories. c Lunging at/biting people. d Hiding/trembling/trying to get away.
%
23.8 64.3 11.9 73.8 26.2 28.6 61.9 9.5 61.9 38.1 97.6 2.4
Controls, n ¼ 126 No.
25 64 37 86 40 27 76 23 84 42 116 10
%
19.8 50.8 29.4 68.3 31.7 21.4 60.3 18.3 66.7 33.3 92.1 7.9
OR
1.0 1.1 0.3 1.0 1.3 1.0 0.8 0.4 1.0 1.2 1.0 0.3
95% CI
P value a
Reference 0.4–2.5 0.1–1.1 Reference 0.6–2.9 Reference 0.3–1.7 0.1–1.4 Reference 0.6–2.5 Reference 0.0–2.3
.02b
.56 .12b
.58 .30
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GASKINS AND HUNGERFORD—FEATHER PICKING IN PET PSITTACINES
Table 4. Survey results of pet bird owners regarding the association of environmental characteristics with feather picking in 168 psittacine birds. Cases, n ¼ 42 Environmental characteristic
Individually caged Group cagedb Not caged Same day/night location Different day/night location .8 h outside cage 5–8 h outside cage 2–4 h outside cage ,2 h outside cage Cage covered at night Cage not covered at night Birds in view Animals in view Birds and animals in view None in view Space per bird (cm3/g)d
No.
32 8 2 33 9 12 9 15 6 26 16 17 3 6 6 25
%
Mean
76.2 19.0 4.8 78.6 21.4 28.6 21.4 35.7 14.3 61.9 38.1 40.5 7.1 14.3 14.3 3161
Controls, n ¼ 126 No.
106 16 4 108 18 14 40 50 22 78 48 41 17 19 29 78
%
Mean
84.1 12.7 3.2 85.7 14.3 11.1 31.8 39.7 17.5 61.9 38.1 32.5 13.5 15.1 23.0
OR
Difference
95% CI
P value a
1.0 1.7 1.4 1.0 1.6 1.0 0.3 0.3 0.3 1.0 1.0 1.0 0.4 0.8 0.5 804
3965
Reference 0.6–4.2 0.4–4.6 Reference 0.6–4.0 Reference 0.1–0.8 0.1–0.9 0.1–1.0 Reference 0.5–2.1 Reference 0.1–1.6 0.3–2.2 0.2–1.5 2570–962
.31
.29 .04c
..99
.25 .79 .22 .37
a
Reference category for variable group. Caged with at least one other bird. c Test for trend across categories. d Among individually caged birds only. b
differences that may manifest as feather picking in pet birds. Further studies should focus on individual species, their social differences, and whether these needs are being met in the home environment. Birds adopted as rescues, meaning respondents indicated they obtained the bird as a rescue or from a rescue group, were more likely to pick their feathers than nonrescued birds. Being a rescued or rehomed bird may be a risk factor for separation anxiety, which could be the underlying cause of feather-picking behavior. Separation anxiety is more likely in dogs found as strays or adopted from shelters, presumably because of a history of traumatic separations from previous owners.21,22
Because long-term histories were not available for these birds, it is not possible to determine if they were feather picking before or after being rescued. Some study birds may have been rehomed due to feather picking, as this has been reported in 6% of relinquished birds according to another study.23 The present study was similar to others in finding that risk of feather picking is similar in male and female birds.3 One study found females to have significantly higher risk for feather picking than males,4 while another reported that feather condition scores were worse in feather-picking females than in males.5 Trichotillomania, or hair plucking in humans, which is considered a possible analogous condition,24 also is reported more
Table 5. Multivariate model of factors associated with feather picking from survey results of pet bird owners on feather picking in 168 psittacine birds. Variable
Beta coefficient
SE
ORadj
95% CI
P value
2.13 2.54 1.99 2.11 1.54
0.59 0.62 0.57 0.69 0.57
8.4 12.7 7.4 0.1 4.7
2.7–26.5 3.8–43.2 2.4–22.3 0.0–0.5 1.5–14.3
,.001 ,.001 ,.001 ,.005 ,.01
a
Species group of bird African grey parrot Cockatoo Out of cage .8 h Hours people interact with birdb Bird was rescued/rehomed
No interactions were identified between any of the 4 variables; the Hosmer-Lemeshow statistic P value was 0.83 a The calculated statistic represents the estimated odds of feather picking in birds of this species group compared with all other birds that were not either African grey parrots or cockatoos. b The calculated statistic represents the estimated decrease in odds of feather picking for birds with more than 4 hours of interaction.
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commonly in females. Reasons for this sex bias are not understood. Feather picking increased with bird age in the univariate analysis, but not in the final model after adjusting for species. Age of onset of feather picking was reported for most cases (34/42, 81%) and ranged from ,6 months to .20 years, with median age range of 2 to 4 years. Among 9 cockatoos with known age of onset, 3 were less than 1 year of age, while the others varied in age from 1 year to more than 20 years at the onset. Similarly, large age ranges were reported for initiation of feather picking among cockatoos in another study.25 However, in African grey parrots, 7 of 8 cases with known ages of onset initiated feather picking at less than 1 year of age. Recognition of the wide range of ages at which feather picking began, including very young birds, should encourage practitioners to ask owners about early behavioral history and to explore a range of potential behavioral diagnoses. Exaggerated or frustrated reproductive behavior has been suggested as a cause of feather picking in birds that may have no outlet for these instincts.26 The present study did not find an association between birds displaying sexual or pair bonding behaviors (regurgitation and/or masturbation) and feather picking, even when immature birds were excluded in a post hoc analysis (OR, 0.6; 95% CI, 0.2–1.5; P ¼ .26). In fact, most of the African grey parrots in this study started feather picking before sexual maturity. Others have reported that cockatoos were likely to present with feather picking of reproductive origin.27 Among the small number of mature cockatoos in the present study (2/10 birds that feather picked and 2/5 controls), sexual or pair-bonding behaviors were not more common among feather-picking birds than in nonaffected birds. In a behavioral study of African grey parrots, wild-caught birds were found to pick their feathers more than hand-reared or parent-reared birds.28 In this current study, there were too few birds to assess these factors, with only 4 birds reported to be wild caught, 9 parent-reared, and 13 partially parent-reared. In that same study of African grey parrots, birds that were unable to fly were almost 5 times more likely to feather pick than flighted birds. In the present study, overall and for African grey parrots alone in post hoc analysis (OR ¼ 1.6; 95% CI, 0.3–11.3; P ¼ .61), the odds of feather picking were similar for birds that were flighted or were wing clipped. Effects of wing clipping and how they may relate to feather picking may depend on many other characteristics, such as type of wing
clip, species, type of rearing, and housing situations. The limited numbers of birds in each category in the current study made it impossible to analyze these factors. Birds that were considered by their owners to scream excessively were not more likely to show feather-picking behavior than those whose owners did not consider them to scream excessively. However, vocalizations differ widely between species and owner tolerance may differ. Featherpicking birds that scream when left alone should be evaluated carefully for separation anxiety, in addition to other diagnoses. If vocalizations are excessive, this could indicate the bird is experiencing stress and decreased welfare,29 which may lead to feather-picking behavior. Further information on the function, frequency, and patterns of calls would be needed to better assess the relationship between screaming and feather picking. Owner characteristics The sex, age, or bird-owning experience of owners had no significant effect on feather picking. As was found in another internet survey,30 most respondent bird owners in the present study were older women who had owned birds more than 5 years. Older women may be overrepresented because they may acquire birds to provide companionship as child substitutes.30 Future studies might assess other demographics, such as the total number of people in the household, personality of the owner, and the presence and number of children, and how these impact the odds of feather picking. Human/bird interactions In the questionnaire, interactions between the bird and people were defined as ‘‘taking the bird out of the cage, talking to it, teaching it things, practicing tricks, carrying it around with you, and so forth.’’ Survey respondents were asked to report the average number of hours each day that the bird spent interacting with people in the household. In this study, the odds for feather picking were significantly lower for birds that interacted with people at least 4 hours a day. Because psittacine birds are social by nature, interaction with humans may prevent feather picking by providing social structure. If owners are not capable of providing this amount of interaction time, assessing a feather-picking bird for lack of mental stimulation may be warranted. An attention-seeking behavior also may be explored, as a bird with little opportunity for social interaction may be rein-
GASKINS AND HUNGERFORD—FEATHER PICKING IN PET PSITTACINES
forced for picking behavior, if the act of feather picking increases the owner’s attention. Specific human/bird interactions that were evaluated in this study, such as trick training and misting, were not associated with decreased feather picking. Additional research on details of human/bird interactions is needed to elucidate the specific type, duration, and frequency of interactions that may affect feather-picking behavior. Unwanted exposure or contact with people has been postulated to be just one of the many stressors that could lead to feather picking as a displacement behavior.6 Displaying aggression to and fearfulness of humans may imply unwanted contact is occurring, but in this study these types of interactions were not associated with increased odds of feather picking. Further study of the qualities of the human–bird relationship, as it relates to feather picking, is warranted. Environmental characteristics Small cage size has been suggested as a cause of feather picking,31 and while space requirements for psittacine birds are unknown, recommendations on optimal lengths of cages do exist.32 Length of cages for study birds was not available, but total space allowance calculated for individually housed birds had no effect on the odds of feather picking. However, cage complexity, which was not evaluated, may be more important than cage size for maintaining behavioral health. Chronic confinement, which has been hypothesized to exacerbate behavioral disorders because it limits opportunities for birds to engage in normal species-typical behaviors,6 did affect feather picking in this study. Surprisingly, birds that were out of their cages for more than 8 hours a day were more likely to pick their feathers than those out for less time. One possible explanation is that birds that already were feather picking were left out of their cages for long periods to try to treat the disorder. Alternatively, birds that were unconfined for extended periods may have had a different quality of social interaction with their owners, which already was identified as a protective factor. These birds also may have had different types of interactions with cage mates or other animals, but the number of birds in these categories was not numerous enough to assess these effects. Other housing recommendations were explored. Using a different day and night cage, or moving the location of a single cage, have been recommended to simulate the natural behavior of foraging and roosting in different locations, and
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to increase human interaction when moving the birds.33 Housing in groups or with other animals in view may provide a more natural social environment compared to other housing arrangements. Providing less than 12 hours of darkness per day may cause psychological stress from sleep deprivation and also may increase sexual activity, both of which may manifest as feather picking.6,9 No differences in the odds of feather picking were found with any of these housing characteristics, but most study birds were housed alone and were not moved to a different location or cage at night. Limitations of the study This study was based on data collected in a cross-sectional survey. Birds that were reported to be currently feather picking were compared to unaffected birds, but the historical relationship between the onset of feather picking and presence of risk factors was not known. This would not be a problem for attributes that do not change over time, such as species. Other variables, such as extended time outside of cage, may predispose birds to develop feather picking, or may result from the owners’ attempts to treat birds with an existing feather-picking condition. For such factors, if owners changed their behavior or the bird’s management over time, the survey may not have captured the conditions that triggered feather picking. A longitudinal study would provide better information on temporal relationships between these factors and feather picking. The wide diversity among birds included in the survey made it a good source for study of risk factors for birds in general, but provided limited ability to assess specific subgroups, such as different species. Additional studies of featherpicking birds of a single species are warranted. For some owner and environmental characteristics, most responses were quite similar and there were not enough birds in all categories to make the comparisons of interest. Additional studies that sample to look at some of these specific relationships would help better elucidate risk factors. An additional limitation was that case birds were selected based on the owner’s report of symptomatic feather picking, instead of a definitive diagnosis. Some of the feather-picking cases may have had a primary medical or behavioral etiology, or a combination of both. This could have weakened the power to detect behavioral risk factors for feather picking and prevented detection of additional risk relationships. Future studies of bird populations with a known diagnosis for
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feather picking, particularly studies using newly occurring cases, would provide additional information on risk factors. Conclusions African grey parrots and cockatoos, as well as rescue birds, were over-represented among birds that picked their feathers. Counseling potential bird owners about these risks and monitoring these birds more closely for signs of anxiety and stress, and associated feather picking, may be helpful. Being out of the cage more than 8 hours a day increased the odds that a bird would pick its feathers, but interacting with people for more than 4 hours a day, for birds other than rescues, had a protective effect. Recommending that owners interact with their birds more than 4 hours a day may help prevent feather picking, and owners who cannot devote this amount of time to a pet bird might be counseled to consider species other than African grey parrots and cockatoos. Including questions about the length of time birds are allowed outside their cage and the interactions birds have with their owners during history taking will be helpful in assessing risk. The factors found to be associated with feather picking in this study identify characteristics that practitioners may want to include when asking owners about their bird’s behavioral history. These findings may provide new directions for studying the behavioral etiology of the feather-picking disorder. Acknowledgments: We thank Nicole Mason and Sarah Vaughan for helping with this paper.
References 1. Grindlinger HM, Ramsay E. Compulsive feather picking in birds. Arch Gen Psychiatry. 1991;48(9):857. 2. Gaskins LA, Bergman L. Surveys of avian practitioners and pet owners regarding common behavior problems in psittacine birds. J Avian Med Surg. 2011;25(2):111–118. 3. Garner M, Clubb S, Mitchell M, Brown L. Featherpicking psittacines: histopathology and species trends. Vet Pathol. 2008;45(3):401–408. 4. Briscoe J, Wilson L, Smith G. Non-medical risk factors for feather picking in pet parrots. Proc Annu Conf Assoc Avian Vet. 2001:131. 5. Garner J, Meehan C, Famula T, et al. Genetic, environmental, and neighbor effects on the severity of stereotypies and feather picking in orange-winged Amazon parrots (Amazona amazonica): an epidemiological study. Appl Anim Behav Sci. 2006;96(1– 2):153–168.
6. Seibert LM. Feather-picking disorder in pet birds. In: Luescher AU, ed. Manual of Parrot Behavior. Ames, IA: Blackwell Publishing; 2006:255–265. 7. Bordnick PS, Thyer BA, Ritchie BW. Feather picking disorder and Trichotillomania: an avian model of human psychopathology. J Behav Ther Exp Psychiatry. 1994;25(3):189–196. 8. Jenkins JR. Feather picking and self-mutilation in psittacine birds. Vet Clin North Am Exot Anim Pract. 2001;4(3):651–667. 9. Lightfoot T, Nacewicz CL. Psittacine behavior. In: Bays TB, Lightfoot T, Mayer J, eds. Exotic Pet Behavior: Birds, Reptiles, and Small Mammals. St Louis, MO: Saunders Elsevier; 2006:51–101. 10. Landsberg G, Hunthausen W, Ackerman L. Handbook of Behavior Problems of the Dog and Cat. 2nd ed. Edinburgh, UK: Elsevier Saunders; 2003. 11. Horwitz DF, Neilson JC. Blackwell’s Five-Minute Veterinary Consult: Canine and Feline Behavior. Ames, IA: Blackwell Publishing; 2007. 12. Gosling SD, Vazire S. Should we trust web-based studies? A comparative analysis of six preconceptions about internet questionnaires. Am Psychol. 2004;59(2):93–104. 13. Gobar GM, Kass PH. World wide web-based survey of vaccination practices, postvaccinal reactions, and vaccine site-associated sarcomas in cats. J Am Vet Med Assoc. 2002;220(10):1477–1482. 14. Tynes VV, Hart BL, Bain MJ. Human-directed aggression in miniature pet pigs. J Am Vet Med Assoc. 2007;230(3):385–389. 15. SurveySuite. Available at: http://intercom.virginia. edu/cgi-b in/cgiwr ap/intercom /S urveySui te/ ss_wizard.pl. Accessed September 2006. 16. Rothman KJ, Greenland S, Lash TL. Modern Epidemiology. 3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2008. 17. Fleiss JL. Statistical Methods for Rates and Proportions. 2nd ed. Hoboken, NJ: John Wiley & Sons; 1981. 18. Hosmer DW, Lemeshow S. Applied Logistic Regression. 2nd ed. Hoboken, NJ: John Wiley & Sons; 2000. 19. King J. Running a best-subsets logistic regression: An alternative to stepwise methods. Educ Psycho Meas. 2002;63(3):392–403. 20. Rosskopf WJ, Woerpel RW. Pet avian conditions and syndromes of the most frequently presented species seen in practice. Vet Clin North Am Small Anim Pract. 1991;21(6):1189–1211. 21. McCrave EA. Diagnostic criteria for separation anxiety in the dog. Vet Clin North Am Small Anim Pract. 1991;21(2):247–255. 22. Patronek GJ, Glickman LT, Beck AM, et al. Risk factors for relinquishment of dogs to an animal shelter. J Am Vet Med Assoc. 1996;209(3):572–581. 23. National Parrot Relinquishment Research Project. Available at: http://www.thegabrielfoundation.org/ documents/NPRRPReport.pdf. Accessed September 2006.
GASKINS AND HUNGERFORD—FEATHER PICKING IN PET PSITTACINES
24. van Zeeland Y, Spruit B, Rodenburg T, et al. Feather damaging behavior in parrots: a review with consideration of comparative aspects. Appl Anim Behav Sci. 2009;121(2):75–95. 25. Seibert LM, Crowell Davis SL, Wilson GH, Ritchie BW. Placebo-controlled clomipramine trial for the treatment of feather picking disorder in cockatoos. J Am Anim Hosp Assoc. 2004;40(4):261–269. 26. Rosenthal K. Differential diagnosis of feather picking in pet birds. Proc Annu Conf Assoc Avian Vet. 1993:108–112. 27. Rosskopf WJ, Woerpel RW. Feather picking and therapy of skin and feather disorders. In: Rosskopf WJ, Woerpel RW, eds. Diseases of Cage and Aviary Birds. 3rd ed. Baltimore, MD: Williams & Wilkins Co; 1996:397–405. 28. Schmid R, Doherr M, Steiger A. The influence of the breeding method on the behavior of adult
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African grey parrots (Psittacus erithacus). Appl Anim Behav Sci. 2005;98(3–4):293–307. Bergman L, Reinisch US. Parrot vocalization. In: Luescher AU, ed. Manual of Parrot Behavior. Ames, IA: Blackwell Publishing; 2006:219–224. Anderson P. A bird in the house: an anthropological perspective on companion parrots. Soc Anim. 2003;11(4):393–418. Davis CS. Parrot psychology and behavior problems. Vet Clin North Am Small Anim Pract. 1991;21(6):1281–1288. Hawkins P. Laboratory birds: refinements in husbandry and procedures. Lab Anim. 2001;35(suppl 1):1–163. Luescher AU, Wilson L. Housing and management considerations for problem prevention. In: Luescher AU, ed. Manual of Parrot Behavior. Ames, IA: Blackwell Publishing; 2006:291–299.
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Journal of Avian Medicine and Surgery 28(2):109–117, 2014 Ó 2014 by the Association of Avian Veterinarians
Nonmedical Factors Associated With Feather Picking in Pet Psittacine Birds Lori A. Gaskins, DVM, Dipl ACVB, Dipl ACAW, and Laura Hungerford, DVM, MPH, PhD Abstract: A nested case-control study was performed to determine nonmedical risk factors associated with feather picking in psittacine birds. Forty-two case birds, reported by their owners to pick their feathers, and 126 unaffected birds were compared. The odds of feather picking were higher in 2 species categories, African grey parrots (Psitticus erithacus, adjusted odds ratio [ORadj] ¼ 8.4, P , .001) and cockatoos (Cacatua species, ORadj ¼ 12.7, P , .001). The odds of feather picking also were higher for birds that were out of their cages more than 8 hours per day (ORadj ¼ 7.4, P , .001) and for birds that had been taken in by the owner as a ‘‘rescue’’ (ORadj ¼ 4.7, P , .01). The odds of feather picking decreased by almost 90% (ORadj ¼ 0.1, P , .005) for birds that interacted with people at least 4 hours a day. These findings identify characteristics that practitioners may want to include when asking bird owners about behavioral history and may be useful in focusing future research regarding this behavior. Key words: feather picking, feather destruction, behavior, avian, psittacine, bird
behavior.9 The diagnostic criteria for many of these disorders, in other species, can be found elsewhere.10,11 Better understanding of these behavioral disorders, which could manifest as feather picking, is needed to facilitate diagnosis and treatment of affected birds. In this case-control study, we explored the captive environment and husbandry of pet psittacine birds with the purposes of better understanding this condition and identifying characteristics that differed between featherpicking birds and unaffected birds.
Introduction Feather picking is a common complaint addressed by avian veterinarians and encountered by pet bird owners and has been reported in 10% to 13% of psittacine birds.1,2 Birds present with selfinflicted injury that includes feather damage or feather removal, and may include mutilation of the underlying skin and muscle. Feather picking may be a symptom of a behavioral or a medical condition, or both. Although few etiologic or epidemiologic studies of feather picking in pet birds have been done, the disorder has been characterized based on possible medical3 and nonmedical4,5 etiologies. For nonmedical or behavioral feather picking, the differential diagnoses that have been considered include, but are not limited to, separation anxiety,6 attention seeking,7 compulsive disorder,8 lack of mental stimulation,9 displacement behavior secondary to stressors,6,9 and prolonged reproductive
Materials and Methods Recruitment This study was based on information collected through an online survey of bird owners.2 Online surveys have been found to have results consistent with traditional methodologies12 and have been used in other studies for the collection of veterinary data.13,14 General avian websites likely to be frequented by bird owners were identified and requests were made to post links to the survey. Data were collected from February 2006 to August 2006. In this original survey, 512 responses were received from Africa, Asia, Australia, Canada,
From St Matthew’s University, School of Veterinary Medicine, PO Box 32330, Grand Cayman KY1-1209, Cayman Islands, BWI (Gaskins); and the Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA (Hungerford).
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Europe, South America, and the United States.2 After excluding those in which the respondent was less than 18 years old or was not the primary caregiver, 404 responses were available. These respondents were predominately women (88%) and represented a span of ages: 30% were 18 to 29 years of age, 32% were 30 to 45 years of age, 33% were 46 to 60 years of age, and 4% were older than 60 years of age. A subset of these 404 respondents served as cases and controls for the analysis of factors associated with feather-picking behavior. Survey design The online survey was developed by using the survey generation program, SurveySuite.15 Questions from the published survey that were used in the current nested case-control analysis were owner characteristics (age, sex, bird-owning experience), bird characteristics (species, sex, age, rescue, behavior, wing clip), some aspects of human/bird interactions (hours interacting per day, trick training, bathing/misting, behavior), and environmental characteristics (group caged/individually caged/not caged, cage size, hours outside cage, cage covered at night, cage/bird moved at night, other birds or animals in view). Questions were presented in multiple choice and yes/no fashion, and an ‘‘other’’ category was listed in many questions with space for respondents to provide explanations. Subjects In total, 47 birds were reported to pick their feathers by respondents to the survey. Many owners provided information about more than one bird. If there were multiple birds that picked their feathers in a household, one was selected randomly for inclusion. This resulted in 42 case birds remaining, 2 of which (an eclectus parrot [Eclectus roratus] and a conure [unknown species]) also exhibited self-mutilation of underlying skin or muscle tissue. A random sample of 3 control birds per case was selected from households without feather-picking birds, with only 1 control bird selected per household. A total of 126 control birds was selected, without matching on characteristics of cases.16 Statistical analysis Univariate analysis was first performed to compare factors between cases and controls, estimating odds ratios (ORs) for categorical data
and differences between means for quantitative variables, and to determine 95% confidence intervals (CI). P values were calculated when at least 10 birds were in a level of a variable, using Fisher’s exact tests for risk factors with 2 categories and tests for trend for more than 2 ordered categories.17 A t-test was used to compare means.16 Associations with P values .25 were evaluated further by using stratified analysis to evaluate potential interaction. Multivariable logistical regression then was used to calculate the adjusted OR (ORadj) and 95% CIs for risk factors for feather picking, adjusted for confounding. Best subsets method was used for model selection.18,19 Coefficients, standard errors, Wald statistics, 2tailed P values, and effects on other coefficients were considered when including and excluding variables from the best identified models of each size. Contribution of different variables to model fit was assessed using likelihood ratio tests. Potential interactions and confounders were considered, and influential observations were evaluated. The final model was selected based on biological plausibility, strength, and significance of associations, and model fit. Analyses were conducted with the statistical software program SAS 9.2 (SAS Institute Inc, Cary, NC, USA). Statistical significance in this study was defined at the P .05 level. Results Factors associated with feather picking were compared between case and control birds, and included bird characteristics, owner characteristics, some aspects of human/bird interactions, and environmental characteristics (Tables 1–4). In univariate analyses, 5 of the 20 factors were associated significantly with increased or decreased odds of feather picking. An additional 4 variables were selected for further consideration in the multivariable modeling based on the screening criterion of P .25. The final model included 4 of the 9 factors evaluated in the multivariate analysis: 2 bird characteristics, 1 human/bird interaction, and 1 environmental characteristic (Table 5). Feather picking was associated significantly with several variables. The odds of feather picking were 8 times higher in African grey parrots (Psittacus erithacus, ORadj ¼ 8.4, P , .001) and almost 13 times higher in cockatoos (family Cacatuidae, ORadj ¼ 12.7, P , .001) than in other species. Birds that had been taken in by the owner as a ‘‘rescue’’ (ORadj ¼ 4.7, P , .01) and birds that were out of their cages more than 8 hours per day
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Table 1. Survey results of pet bird owners regarding the association of bird characteristics with feather picking in 168 pet psittacine birds. Cases, n ¼ 42
Controls, n ¼ 126
Species/bird characteristic
No.
%
No.
%
OR
95% CI
P valuea
African grey parrot (Psitticus erithacus) Cockatiel (Nymphicus hollandicus) Cockatoo (various species) Conure (various species) Macaw, large (various species) Parakeet (unknown species) Amazon parrot (Amazona species) Budgerigar (Melopsitticus undulatus) Caique (Pionites species) Eclectus parrot (Eclectus roratus) Lorie (various species) Lovebird (Agapornis species) Macaw, mini (various species) Parrotlet (Forpus species) Pionus parrot (Pionus species) Poicephalus parrot (Poicephalus species) Quaker parrot (Myiopsitta monachus) Male Female Unknown 0–12 mo old 13–23 mo old 2–4 y old 5–10 y old 11–20 y old More than 20 y old Rescued bird Bird from other source Wings not clipped Wings clipped Doesn’t scream Screamsf No masturbationg/regurgitation Masturbation/regurgitation
10 3 11 5 2 1 1 0 0 3 0 0 1 2 1 1 1 15 18 9 1 3 7 22 8 1 11 31 20 22 31 11 35 7
23.8 7.1 26.2 11.9 4.8 2.4 2.4 0 0 7.1 0 0 2.4 4.8 2.4 2.4 2.4 35.7 42.9 21.4 2.4 7.1 16.7 52.4 19.1 2.4 26.2 73.8 47.6 52.4 73.8 26.2 83.3 16.7
12 17 6 18 12 10 7 3 1 5 3 9 5 6 2 6 4 48 42 36 20 17 39 33 11 5 10 116 49 77 98 28 99 27
9.5 13.5 4.8 14.3 9.5 7.9 5.6 2.4 0.8 4.0 2.4 7.1 4.0 4.8 1.6 4.8 3.2 38.1 33.3 28.6 15.9 13.5 31.0 26.2 8.7 4.0 7.9 92.1 38.9 61.1 77.8 22.2 78.6 21.4
3.0 0.5 7.1 0.8 0.5 0.3 0.4 0.4c 1.0c 1.9 0.4c 0.1c 0.6 1.0 1.5 0.5 0.7 1.0 1.3 0.8 1.0 3.5 3.6 13.3 14.5 4.0 4.1 1.0 1.0 0.8 1.0 1.2 1.0 0.7
1.2–7.5 0.1–1.8 2.4–20.7 0.3–2.3 0.1–1.8 0.0–2.3 0.0–3.5 0.2–8.2 0.4–24.6 0.4–8.1 0.2–8.2 0.0–2.5 0.1–5.2 0.2–5.2 0.1–17.1 0.1–4.2 0.1–6.8 Referenced 0.7–2.3 0.4–1.7 Reference 0.3–37.1 0.4–31.2 1.7–107 1.6–132 0.2–75.7 1.6–10.6 Reference Reference 0.3–1.4 Reference 0.6–2.8 Reference 0.3–1.8
.02b .27b ,.001b .70b .33b .21b
.54 .82 .001e
.005
.37 .67 .67
a
P values were only calculated when there were more than 10 birds per category. Compared with all birds not of that species. c OR estimated by adding 0.5 to each category because of categories with 0 birds. d Reference category for variable group. e Test for trend across categories. f Screaming was reported by survey respondent. g Rubbing cloaca/vent on objects or people. b
(ORadj ¼ 7.4, P , .001) also had higher odds of feather picking. Interaction with people at least 4 hours a day had a protective effect, with the odds of feather picking in these birds decreased by almost 90% (ORadj ¼ 0.1, P , .005). No other variables were significantly associated with feather picking in the model. One potential interaction between 2 variables was identified by stratified analysis. Longer contact with people did not decrease the odds of feather picking for rescued birds (OR ¼ 1.5, P ¼ 1.0), but did have a beneficial
association for birds acquired from other sources (OR ¼ 0.2, P ¼ .005). However, there were too few rescued birds (n ¼ 21) to include this interaction term in the regression model. Discussion Feather picking in pet psittacine birds often is a frustrating condition. The fact that some birds remain partially featherless all of their lives indicates that our knowledge of this disorder is
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Table 2. Survey results of pet bird owners regarding owner characteristics associated with feather picking in 168 psittacine birds. Cases, n ¼ 42 Owner characteristic
Female Male 18–29 y old 30–45 y old 46–60 y old Over 60 y old Owned birds 0–2 y Owned birds 3–5 y Owned birds 6–10 y Owned bird 11–15 y Owned birds .16 y a b
No.
Controls, n ¼ 126 No.
%
39 3 7 16 16 3 7 5 11 7 12
92.9 7.1 16.7 38.1 38.1 7.1 16.7 11.9 26.2 16.7 28.6
OR
%
107 19 32 50 39 5 21 38 23 17 27
84.9 15.1 25.4 39.7 31.0 4.0 16.7 30.2 18.2 13.5 21.4
1.0 2.3 1.0 1.5 1.9 2.7 1.0 0.4 1.4 1.2 1.3
95% CI
P value a
Reference 0.6–8.2 Reference 0.5–3.9 0.7–5.1 0.7–6.4 Reference 0.1–1.4 0.5–4.4 0.4–4.2 0.4–4.2
.29 .14b
.16b
Reference category for variable groups. Test for trend across categories.
incomplete. In this study, some nonmedical factors for feather picking were identified that may add to the knowledge base for this complicated disorder. Bird characteristics Similar to previous findings,3,4,20 results of the current study found feather-picking behavior to be significantly more common among African grey parrots and cockatoos than among other birds. Some investigators have speculated that this may be because African grey parrots are highly intelligent and, therefore, easily bored,20 which indicates these birds may be at risk for feather picking secondary to lack of mental stimulation.
Cockatoos have been characterized as needing extensive interaction with their human owners9 and being more predisposed to anxiety due to social deprivation, resulting in feather damaging behaviors (B. Speer, 2011, oral communication). A diagnosis of feather picking secondary to attention-seeking behavior or separation anxiety should be explored for these birds, along with other behavioral diagnoses. Although there were some interesting suggestions of other species differences, there were too few birds of other species in this survey to draw conclusions about their predisposition to feather picking. As social behavior has not been characterized for most psittacines in the wild, it is difficult to hypothesize about behavioral
Table 3. Survey results of pet bird owners regarding human/bird interactions associated with feather picking in 168 psittacine birds. Cases, n ¼ 42 Human/bird interactions
,2 h/d 2–4 h/d .4 h/d Taught tricks No tricks taught Bathed/misted daily Bathed/misted weekly Bathed/misted rarely Not aggressive to humans Aggressive to humansc Not afraid of humans Afraid of humansd a
No.
10 27 5 31 11 12 26 4 26 16 41 1
Reference category for variable group. b Test for trend across categories. c Lunging at/biting people. d Hiding/trembling/trying to get away.
%
23.8 64.3 11.9 73.8 26.2 28.6 61.9 9.5 61.9 38.1 97.6 2.4
Controls, n ¼ 126 No.
25 64 37 86 40 27 76 23 84 42 116 10
%
19.8 50.8 29.4 68.3 31.7 21.4 60.3 18.3 66.7 33.3 92.1 7.9
OR
1.0 1.1 0.3 1.0 1.3 1.0 0.8 0.4 1.0 1.2 1.0 0.3
95% CI
P value a
Reference 0.4–2.5 0.1–1.1 Reference 0.6–2.9 Reference 0.3–1.7 0.1–1.4 Reference 0.6–2.5 Reference 0.0–2.3
.02b
.56 .12b
.58 .30
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GASKINS AND HUNGERFORD—FEATHER PICKING IN PET PSITTACINES
Table 4. Survey results of pet bird owners regarding the association of environmental characteristics with feather picking in 168 psittacine birds. Cases, n ¼ 42 Environmental characteristic
Individually caged Group cagedb Not caged Same day/night location Different day/night location .8 h outside cage 5–8 h outside cage 2–4 h outside cage ,2 h outside cage Cage covered at night Cage not covered at night Birds in view Animals in view Birds and animals in view None in view Space per bird (cm3/g)d
No.
32 8 2 33 9 12 9 15 6 26 16 17 3 6 6 25
%
Mean
76.2 19.0 4.8 78.6 21.4 28.6 21.4 35.7 14.3 61.9 38.1 40.5 7.1 14.3 14.3 3161
Controls, n ¼ 126 No.
106 16 4 108 18 14 40 50 22 78 48 41 17 19 29 78
%
Mean
84.1 12.7 3.2 85.7 14.3 11.1 31.8 39.7 17.5 61.9 38.1 32.5 13.5 15.1 23.0
OR
Difference
95% CI
P value a
1.0 1.7 1.4 1.0 1.6 1.0 0.3 0.3 0.3 1.0 1.0 1.0 0.4 0.8 0.5 804
3965
Reference 0.6–4.2 0.4–4.6 Reference 0.6–4.0 Reference 0.1–0.8 0.1–0.9 0.1–1.0 Reference 0.5–2.1 Reference 0.1–1.6 0.3–2.2 0.2–1.5 2570–962
.31
.29 .04c
..99
.25 .79 .22 .37
a
Reference category for variable group. Caged with at least one other bird. c Test for trend across categories. d Among individually caged birds only. b
differences that may manifest as feather picking in pet birds. Further studies should focus on individual species, their social differences, and whether these needs are being met in the home environment. Birds adopted as rescues, meaning respondents indicated they obtained the bird as a rescue or from a rescue group, were more likely to pick their feathers than nonrescued birds. Being a rescued or rehomed bird may be a risk factor for separation anxiety, which could be the underlying cause of feather-picking behavior. Separation anxiety is more likely in dogs found as strays or adopted from shelters, presumably because of a history of traumatic separations from previous owners.21,22
Because long-term histories were not available for these birds, it is not possible to determine if they were feather picking before or after being rescued. Some study birds may have been rehomed due to feather picking, as this has been reported in 6% of relinquished birds according to another study.23 The present study was similar to others in finding that risk of feather picking is similar in male and female birds.3 One study found females to have significantly higher risk for feather picking than males,4 while another reported that feather condition scores were worse in feather-picking females than in males.5 Trichotillomania, or hair plucking in humans, which is considered a possible analogous condition,24 also is reported more
Table 5. Multivariate model of factors associated with feather picking from survey results of pet bird owners on feather picking in 168 psittacine birds. Variable
Beta coefficient
SE
ORadj
95% CI
P value
2.13 2.54 1.99 2.11 1.54
0.59 0.62 0.57 0.69 0.57
8.4 12.7 7.4 0.1 4.7
2.7–26.5 3.8–43.2 2.4–22.3 0.0–0.5 1.5–14.3
,.001 ,.001 ,.001 ,.005 ,.01
a
Species group of bird African grey parrot Cockatoo Out of cage .8 h Hours people interact with birdb Bird was rescued/rehomed
No interactions were identified between any of the 4 variables; the Hosmer-Lemeshow statistic P value was 0.83 a The calculated statistic represents the estimated odds of feather picking in birds of this species group compared with all other birds that were not either African grey parrots or cockatoos. b The calculated statistic represents the estimated decrease in odds of feather picking for birds with more than 4 hours of interaction.
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commonly in females. Reasons for this sex bias are not understood. Feather picking increased with bird age in the univariate analysis, but not in the final model after adjusting for species. Age of onset of feather picking was reported for most cases (34/42, 81%) and ranged from ,6 months to .20 years, with median age range of 2 to 4 years. Among 9 cockatoos with known age of onset, 3 were less than 1 year of age, while the others varied in age from 1 year to more than 20 years at the onset. Similarly, large age ranges were reported for initiation of feather picking among cockatoos in another study.25 However, in African grey parrots, 7 of 8 cases with known ages of onset initiated feather picking at less than 1 year of age. Recognition of the wide range of ages at which feather picking began, including very young birds, should encourage practitioners to ask owners about early behavioral history and to explore a range of potential behavioral diagnoses. Exaggerated or frustrated reproductive behavior has been suggested as a cause of feather picking in birds that may have no outlet for these instincts.26 The present study did not find an association between birds displaying sexual or pair bonding behaviors (regurgitation and/or masturbation) and feather picking, even when immature birds were excluded in a post hoc analysis (OR, 0.6; 95% CI, 0.2–1.5; P ¼ .26). In fact, most of the African grey parrots in this study started feather picking before sexual maturity. Others have reported that cockatoos were likely to present with feather picking of reproductive origin.27 Among the small number of mature cockatoos in the present study (2/10 birds that feather picked and 2/5 controls), sexual or pair-bonding behaviors were not more common among feather-picking birds than in nonaffected birds. In a behavioral study of African grey parrots, wild-caught birds were found to pick their feathers more than hand-reared or parent-reared birds.28 In this current study, there were too few birds to assess these factors, with only 4 birds reported to be wild caught, 9 parent-reared, and 13 partially parent-reared. In that same study of African grey parrots, birds that were unable to fly were almost 5 times more likely to feather pick than flighted birds. In the present study, overall and for African grey parrots alone in post hoc analysis (OR ¼ 1.6; 95% CI, 0.3–11.3; P ¼ .61), the odds of feather picking were similar for birds that were flighted or were wing clipped. Effects of wing clipping and how they may relate to feather picking may depend on many other characteristics, such as type of wing
clip, species, type of rearing, and housing situations. The limited numbers of birds in each category in the current study made it impossible to analyze these factors. Birds that were considered by their owners to scream excessively were not more likely to show feather-picking behavior than those whose owners did not consider them to scream excessively. However, vocalizations differ widely between species and owner tolerance may differ. Featherpicking birds that scream when left alone should be evaluated carefully for separation anxiety, in addition to other diagnoses. If vocalizations are excessive, this could indicate the bird is experiencing stress and decreased welfare,29 which may lead to feather-picking behavior. Further information on the function, frequency, and patterns of calls would be needed to better assess the relationship between screaming and feather picking. Owner characteristics The sex, age, or bird-owning experience of owners had no significant effect on feather picking. As was found in another internet survey,30 most respondent bird owners in the present study were older women who had owned birds more than 5 years. Older women may be overrepresented because they may acquire birds to provide companionship as child substitutes.30 Future studies might assess other demographics, such as the total number of people in the household, personality of the owner, and the presence and number of children, and how these impact the odds of feather picking. Human/bird interactions In the questionnaire, interactions between the bird and people were defined as ‘‘taking the bird out of the cage, talking to it, teaching it things, practicing tricks, carrying it around with you, and so forth.’’ Survey respondents were asked to report the average number of hours each day that the bird spent interacting with people in the household. In this study, the odds for feather picking were significantly lower for birds that interacted with people at least 4 hours a day. Because psittacine birds are social by nature, interaction with humans may prevent feather picking by providing social structure. If owners are not capable of providing this amount of interaction time, assessing a feather-picking bird for lack of mental stimulation may be warranted. An attention-seeking behavior also may be explored, as a bird with little opportunity for social interaction may be rein-
GASKINS AND HUNGERFORD—FEATHER PICKING IN PET PSITTACINES
forced for picking behavior, if the act of feather picking increases the owner’s attention. Specific human/bird interactions that were evaluated in this study, such as trick training and misting, were not associated with decreased feather picking. Additional research on details of human/bird interactions is needed to elucidate the specific type, duration, and frequency of interactions that may affect feather-picking behavior. Unwanted exposure or contact with people has been postulated to be just one of the many stressors that could lead to feather picking as a displacement behavior.6 Displaying aggression to and fearfulness of humans may imply unwanted contact is occurring, but in this study these types of interactions were not associated with increased odds of feather picking. Further study of the qualities of the human–bird relationship, as it relates to feather picking, is warranted. Environmental characteristics Small cage size has been suggested as a cause of feather picking,31 and while space requirements for psittacine birds are unknown, recommendations on optimal lengths of cages do exist.32 Length of cages for study birds was not available, but total space allowance calculated for individually housed birds had no effect on the odds of feather picking. However, cage complexity, which was not evaluated, may be more important than cage size for maintaining behavioral health. Chronic confinement, which has been hypothesized to exacerbate behavioral disorders because it limits opportunities for birds to engage in normal species-typical behaviors,6 did affect feather picking in this study. Surprisingly, birds that were out of their cages for more than 8 hours a day were more likely to pick their feathers than those out for less time. One possible explanation is that birds that already were feather picking were left out of their cages for long periods to try to treat the disorder. Alternatively, birds that were unconfined for extended periods may have had a different quality of social interaction with their owners, which already was identified as a protective factor. These birds also may have had different types of interactions with cage mates or other animals, but the number of birds in these categories was not numerous enough to assess these effects. Other housing recommendations were explored. Using a different day and night cage, or moving the location of a single cage, have been recommended to simulate the natural behavior of foraging and roosting in different locations, and
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to increase human interaction when moving the birds.33 Housing in groups or with other animals in view may provide a more natural social environment compared to other housing arrangements. Providing less than 12 hours of darkness per day may cause psychological stress from sleep deprivation and also may increase sexual activity, both of which may manifest as feather picking.6,9 No differences in the odds of feather picking were found with any of these housing characteristics, but most study birds were housed alone and were not moved to a different location or cage at night. Limitations of the study This study was based on data collected in a cross-sectional survey. Birds that were reported to be currently feather picking were compared to unaffected birds, but the historical relationship between the onset of feather picking and presence of risk factors was not known. This would not be a problem for attributes that do not change over time, such as species. Other variables, such as extended time outside of cage, may predispose birds to develop feather picking, or may result from the owners’ attempts to treat birds with an existing feather-picking condition. For such factors, if owners changed their behavior or the bird’s management over time, the survey may not have captured the conditions that triggered feather picking. A longitudinal study would provide better information on temporal relationships between these factors and feather picking. The wide diversity among birds included in the survey made it a good source for study of risk factors for birds in general, but provided limited ability to assess specific subgroups, such as different species. Additional studies of featherpicking birds of a single species are warranted. For some owner and environmental characteristics, most responses were quite similar and there were not enough birds in all categories to make the comparisons of interest. Additional studies that sample to look at some of these specific relationships would help better elucidate risk factors. An additional limitation was that case birds were selected based on the owner’s report of symptomatic feather picking, instead of a definitive diagnosis. Some of the feather-picking cases may have had a primary medical or behavioral etiology, or a combination of both. This could have weakened the power to detect behavioral risk factors for feather picking and prevented detection of additional risk relationships. Future studies of bird populations with a known diagnosis for
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feather picking, particularly studies using newly occurring cases, would provide additional information on risk factors. Conclusions African grey parrots and cockatoos, as well as rescue birds, were over-represented among birds that picked their feathers. Counseling potential bird owners about these risks and monitoring these birds more closely for signs of anxiety and stress, and associated feather picking, may be helpful. Being out of the cage more than 8 hours a day increased the odds that a bird would pick its feathers, but interacting with people for more than 4 hours a day, for birds other than rescues, had a protective effect. Recommending that owners interact with their birds more than 4 hours a day may help prevent feather picking, and owners who cannot devote this amount of time to a pet bird might be counseled to consider species other than African grey parrots and cockatoos. Including questions about the length of time birds are allowed outside their cage and the interactions birds have with their owners during history taking will be helpful in assessing risk. The factors found to be associated with feather picking in this study identify characteristics that practitioners may want to include when asking owners about their bird’s behavioral history. These findings may provide new directions for studying the behavioral etiology of the feather-picking disorder. Acknowledgments: We thank Nicole Mason and Sarah Vaughan for helping with this paper.
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