Analysis of Feather Damage in a Large Mixed Collection of Psittacine Birds AAV 1999

Susan Clubb, DVM, Dipl ABVP
Loxahatchee, FL

Carolyn Cray, PhD University of Miami
Miami, FL

Frank Enders Juan Anthonio Armas Garcia
Miguel Casares Loro Parque
Canary Islands, Spain

Session # 470


Feather destruction is a common and complex problem associated with the maintenance of psittacine birds in captivity. It is one of the most frequent reasons for presentation of pet birds to the avian practitioner. Despite the abundance of literature on the subject, few publications have involved detailed analysis of a large number of cases with common husbandry standards. If this study only serves to develop a systematic model for evaluation of data, it will be of value.

A database was established in order to collect uniform data that could be used to establish a baseline on feather damage in this collection. The database was designed to accommodate repeated examinations in order to detect trends, associated with various forms of intervention, which will be used in future studies. The preliminary report will illustrate findings of the initial examinations and historical assessment.

The Loro Parque Foundation collection contains 58 genera and over 300 species and sub-species of parrots. In this study 497 birds were examined, some birds were examined several times. Initial examinations were made during annual physical examinations from November 1996 to January 1997, with subsequent examinations in 1998 and 1999.

The parrot collection of the Loro Parque Foundation is housed outdoors with most birds housed in breeding flights or cages and in pairs. The Park is located in Puerto de la Cruz on the north side of Tenerife Island in the Canary Islands (28o23’N, 16o33’W). The altitude is approximately 50-100 meters above sea level. The climate is subtropical with a median daily temperature of 19oC (66oF) with maximum temperatures of approximately 26.7oC (80oF) (September) and lows of 12oC (53oF) (January). Average relative humidity is 74%. Average precipitation is 30.85mm with an average of 3.1 days with precipitation per month. Average daily hours of sunshine (without clouds) is 5.3 hours. Mornings and late afternoons are usually cloudy.

The diet used in the collection is varied and includes extruded formulated diets, seed mixes, fresh fruits and vegetables, and natural foods such as palm nuts, breads, nectars, and nuts as appropriate for the species. Birds are fed twice daily. Water supply is chlorinated, then cleansed by reverse osmosis.

The Database

Each bird was evaluated systematically. General information about each individual bird included its species, sex, age (if known or estimated), weight, identification, source (wild-caught, captive bred, etc), and cage number. More subjective individual information included subjective assessment of weight (normal, slightly thin, very thin, slightly fat, obese). General condition was classified as excellent, good, or poor.

A housing assessment was recorded and included the cage size and the number of years housed in the existing cage. The characteristics of the cage, such as orientation of the nest box (north, south, east, or west), and a subjective measure of disturbance and illumination of the cage was entered.

Health history was classified as no health history, excellent, good, poor, or chronic problems. Feather and skin history was classified as no history, no previous problems, sporadic problems, or chronic problems. Type of feather damage behavior was classified as picking self only, picking self and mate, picked by mate, mate picking both, or mate picking self, juveniles chewing own feathers, and juveniles chewing others feathers.

Reproductive history was graded as not paired, paired but no production, poor production, infertile eggs, broken eggs, same sex pair, housed with birds of another species. Rearing was graded as unknown, wild caught, parent- reared, hand-reared, and partially hand-reared.

Feather condition on each body part was evaluated systematically and data recorded separately for the head, neck, back, chest, abdomen, right wing, left wing, right leg, left leg, vent/pygostyle, and tail. In each area, the following determinations were made by type of feather damaged, and type of feather damage. Amount of feather loss or damage was graded as little, less than half, more then half, or all. Type of feathers damages were coverts, down, rectrices, or remiges. The type of feather damage included plucked, broken, stripped rachus, chewed edges, chewed shaft, color change, presence of grease, or feather fungus. Feather damage was judged to be either bilaterally symmetrical or asymmetrical.

Skin evaluation included dry skin, crusty or scaly skin, thickened skin, edema, erythema, scarred follicles, pustules, or pigmentation. An attempt was made to document whether birds had pruritus, but this proved difficult. The scale was no evaluation, no pruritis observed, slight, medium, and severe pruritis.

Materials and Methods

Data was evaluated using Microsoft Excel 5.0. Trends in the database were evlauated using bar graphs. Data were evaluated for all birds in the study as well as by genera. Specific areas of interest have been selected for presentation including:

  • Total frequency in collection
  • Frequency by genus ( percentage of the collection)
  • Frequency by sex
  • Frequency by rearing method.
  • Frequency in association with health history
  • Frequency in association with feather damage history
  • Frequency in association with reproductive history
  • Frequency in association with general condition
  • Frequency of bilateral vs unilateral presentation
  • Frequency of total by body part affected
  • Frequency by type of feather damage
  • Frequency and type of skin disorders

Laboratory Analysis of Blood Samples

Laboratory analysis of blood samples was performed at the Department of Comparative Pathology, University of Miami, USA. Blood samples were collected from 100 of the birds in the study. Samples were collected using standard venipucture techniques, then placed in lithium heparin; plasma was separated and frozen at –20o C. Samples with gross hemolysis were not included in the study. Appropriate CITES (Convention on International Trade in Endangered Species) as well as agriculture permits were obtained to allow transport of the blood from Spain to the United States.

Routine chemistry determinations were performed using a Johnson & Johnson DT-60 apparatus (Rochester, NY, USA). Quality control samples were run before and during machine operations and reagents were prepared from the same lot, as documented by lot numbers. Determinations included aspartate aminotransferase (AST, also known as SGOT), uric acid, and calcium. Additional tests were preformed as sample volume allowed. Total protein was determined by refractometer.

Protein electrophoresis was performed as previously reviewed.1 Briefly, the Beckman Paragon electrophoresis unit and reagents were utilized. Gels were analyzed by laser densitometry for the fractionation of six bands corresponding to pre albumin, albumin, and alpha-1, alpha-2, beta, and gamma globulins. Fractions were quantitated as percent of total protein and normalized using the refractometer total protein to be presented as g/dl.

Additional testing was performed using ELISA systems for the determination of the following antibodies to Aspergillus, antibody to Candida, antibody to Mycobacterium, Aspergillus antigen, histamine, and antibody to human allergy panels. In addition, antibody to Chlamydia was evaluated by indirect immunofluorescent assay (IFA). This test has been utilized in this laboratory for several years.2 Antibody and antigen assays for Aspergillus were performed as previously described.3,4 All other assays were newly implemented for this study.

The tests were selected in order to assess the frequency of common infectious diseases that may be associated with feather destruction. Specific diseases for which antibody (and with aspergillosis, also antigen) detection tests were performed included Chlamydiosis, Aspergillosis, Mycobacteriosis, and Candidiasis. Basic chemistry profile was selected to find underlying liver or kidney disease.

Feather problems that may be included in assessment of feather damange include chronic inflammatory changes with decrease in beta globulins, and acute inflammation associated with infection (like aspergillosis) with an increase in beta globulins.

Histamine is a common test used with IgF levels, in humans, for the determination of allergy. As no method has yet been formulated to evaluate IgF levels in birds, the authors tried to detect histamine levels.

Allergen panels are commonly used in humans and some domestic animals in which detectable levels of antibody to certain environmental allergens can be detected. These allergens are associated with allergic reactions involving respiratory, gastrointestinal, and skin disorders. In this study, commercial human assays were adapted and selected to represent groups of allergens such as other animals, grains, grasses, molds, weeds, and inhalants.


Results will be presented at the conference and in future publications. Ongoing evaluation includes attempts to establish chronicity and to select birds that have irreversible damage to follicles. These birds will be fitted with collars and observed for feather regrowth in scarred, pigmented areas.


Examination of these data revealed a few points of great interest that are somewhat supportive of the widely-held belief that self-induced feather destruction has a strong behavioral component, which may be associated with the relationship of the bird to its mate and its reproductive success.

Attempts were made to identify birds with long-term, chronic changes to the skin and feather follicles. In these birds, changes in behavior cannot be corrective in physical appearance; however, continued monitoring can establish whether destructive behavior progresses. A special area was established at Loro Parque for such birds where they could be monitored and other corrective attempts could be evaluated without disturbing breeding birds.

In order to enhance the surroundings of the birds in the Loro Parque collection, a new breeding facility was established in 1998. This facility provides excellent housing and enrichment for the inhabitants. Ongoing dietary studies are in progress. Other ongoing projects are in progress. Other ongoing projects include reevaluation of pairing and social interaction between birds and neighbors, etc.


Feather destruction is one of the most frequent reasons for presentation of pet birds to the avian practitioner, yet few publications have involved analysis or a large number of cases with common husbandry standards. The present study may find value as a model for future studies. Corrective attempts to feather destruction may include changes in housing, the need for enrichment, reevaluation of diet, and consideration of the pairing of birds and social interaction between birds and neighbors.


1. Cray C, Tatum LM. Application of protein electrophoresis in avian diagnostics. J Av Med Surg 1998;12(1):4-10.

2. Cray C, Zielezienski K. Clinical comparison of chlamydiosis diagnostic tests. Proc Annu Conf Assoc Avian Vet 1998:93.

3. Cray C, Zielezienski K. Application of aspergillosis antigen testing to the diagnosis of aspergillosis. Proc Annu Conf Assoc Avian Vet 1997:219.

4. Zielezienski K, Cray C. An update to the application of aspergillosis antigen diagnostic testing. Proc Annu Conf Assoc Avian Vet 1998:95.