Appendix A: Aging in Macaws - A Study by Susan Clubb

In 1992, Susan Clubb submitted a paper to the Association of Avian Veterinarians for publication and presentation at the annual conference proceedings. This paper, "Aging in Macaws," documented the review of health records of a group of macaws whose ages were known in order to provide information about the aging process and longevity of macaws in captivity and in the wild.

She states that macaws are known to be "hardy and long-lived... with few natural predators," ¹² and she estimates their natural lifespans are at least 60 years. At the time, however, there had been very little documentation of their life spans or aging processes in academic literature. Her work was done at Parrot Jungle and Gardens in Miami, Florida, which had been in existence since 1936.

The 57 birds used in this study were at least 25 years old and were examined yearly for a period of three years. Twenty-six were captive-bred and ranged from 25 to 52 years of age. Thirty-one were wild-caught birds which had lived at the facility for at least 20 years. The oldest bird there at the time, a 57-year-old military macaw, had been recently euthanized due to frequent and severe seizures. It had been blind and had suffered from a chronic neurological disorder for many years.

As of the writing of Clubb’s paper in 1992, the first macaw that had hatched at Parrot Jungle, and was still in the collection, was 52 years old. Seven other captive-bred birds in the collection were between 41 and 49 years old. "All had various stages of cataracts and degenerative diseases related to senescence, including arthritis, loss of skin tone and elasticity, muscle wasting, and degenerative neurological disease. As with most mammalian species, aging macaws show physical signs of aging around the time that their reproductive potential has passed. Macaws are known to be capable of reproducing from four to thirty-five years of age. The most productive years were the late teens and early twenties."

After 40, the onset of all degenerative changes began to occur. For the birds in this collection, lack of exercise led to weight loss and muscle wasting since these birds were sedentary. “Birds which had always been free-fliers reverted to walking or resting in a secure location most of the day." Clubb states that their posture had not significantly changed; most remained upright when perching unless they had had skeletal injuries in the past. Arthritis, with its joint stiffness and limited range-of-motion, was evident in birds over 40 years of age. "Some birds over 40 developed twisting deformities of the flight feathers of the wings, similar to the Angel Wing disorder."

Since macaws have no feathers on their faces, dermatological changes were obvious in birds over 40. "The skin on the face developed pigmented spots, polyps, wart-like blemishes, cysts, and wrinkling. The skin on the face and feet became thin, and the facial feathers at the edge of the skin began to thin out; in addition, the skin on the feet began to develop spotty depigmentation. Feathers in general began to lose condition and luster at this point as well."

Most macaws developed degenerative eye disorders, primarily cataracts, after age 35. "The external ophthalmic changes included lid laxity. The lids lost tone and became thickened and wrinkled. The corneas remained relatively clear unless there had been some interocular trauma in the past. Most birds in this collection were blind in at least one eye after age 45." These older macaws in this collection died as a result of tumors, renal failure and other degenerative diseases. "Many had died long before their natural lifespans has been reached due to malnutrition and husbandry-related disease. Once a bird develops cataracts and is unable to see well, his survivability in the wild is limited since cataracts limit his ability to forage." Most macaws over 35 years of age developed cataracts, just as they develop in other species of birds. "Cataracts may develop suddenly, and this can lead to uveitis and blindness. In macaws, age-related cataracts are seen in the center of the lens. Surgery to remove them is possible and sometimes performed."

What is interesting is that these birds were tracked in the late 1980’s to early 1990’s, and at that time, the macaw’s maximum lifespan was only in the 40’s and 50’s. Since then, only a little over 20 years later, due to improved diet and husbandry practices, the maximum lifespan has extended to 50-90 years of age in some species.