Feeding the Hospitalized Bird of Prey

Key Points

  • Raptors ingest whole prey items. Indigestible material or “casting” like fur, feathers, and bones, are retained within the raptor ventriculus, compacted into a pellet, and regurgitated or egested.
  • Egestion can occur as soon as 12–18 hours after a meal. The bird should not be fed again until it has produced a pellet.
  • Emaciation is a common presentation in young raptors that have been unsuccessful hunters during their first year. Birds can also present in poor condition due to a variety of other causes, including inclement weather or chronic injury.
  • Anemia and hypoproteinemia are common findings in the chronically malnourished bird of prey.
  • While critical illness and stress often leads to a hypermetabolic state, metabolism slows in the malnourished or starving patient.
  • When compared to parrots or songbirds, birds of prey can survive food shortages for longer periods of time. Smaller raptors are less tolerant of starvation than larger birds.
  • Supportive care for the chronically malnourished raptor includes fluid therapy and supplemental heat. Minimizing stress is also critical for weak, emaciated patients.
  • As long as the patient possesses a functional gastrointestinal tract, enteral nutrition can generally be started once the patient is warm and adequately hydrated.
  • Withhold indigestible material or casting if the bird is thin, if medication is given multiple times daily, or if the bird is very young (less than 3 weeks of age).
  • Most raptors will eat any appropriate meat source when their preferred food is unavailable, as long as the food item is skinned, however ospreys often require hand feeding in captivity.
  • Although relatively expensive, mice and rats are commonly fed to birds of prey. Captive-raised mice and rats tend to be relatively high in fat.
  • When fed with the yolk sac intact, day-old chicks are an adequate source of protein and calcium and a good source of fat-soluble vitamins.
  • Pigeons and doves should not be fed to raptors, as several infectious agents can be transmitted.
  • The safest and preferred method for thawing potentially hazardous foods, such as frozen mice, is use of a clean refrigerator designated for thawing items over 24-48 hours.
  • Monitor the patient receiving nutritional support carefully, evaluating body weight, body condition score, droppings, and pellet production.
  • Free-ranging raptors acquire most of their daily water needs through their diet, however captive raptors should always have access to fresh drinking water.

All raptors consume a meat-based diet ranging from the specialist diet of the fish-eating osprey (Pandion haliaetus) to a generalist diet that can include insects, mammals, birds, reptiles, amphibians, and even carrion. Other than poultry, the exact nutritional requirements of birds are unknown, however the natural raptor diet is always relatively high in protein and fat and low in carbohydrates. Whole prey diets have a calcium/phosphorus ratio of 1.5:1 as the bird actually consumes the bones as well as the meat . . .

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Further Reading

Barton NW, Houston DC. A comparison of digestive efficiency in birds of prey. Ibis 135(4):363-371, 1993.

Braun EJ, Sweazea KL. Glucose regulation in birds. Comp Biochem Physiol 151(1):1–9, 2008.

Chaplin SB. Effect of cecectomy on water and nutrient absorption of birds. J Exp Zool Suppl 3:81-86, 1989.

Denbow DM. Gastrointestinal anatomy and physiology. In: Whittow GC (ed). Sturkie’s Avian Physiology, 5th ed. San Diego (CA): Academic Press; 2000: 299–325.

Duke GE, Bird JE, Daniels KA, et al. Food metabolizability and water balance in intact and cecectomized great-horned owls. Comp Biochem Physiol 68(2):237-240, 1981.

Duke GE, Fuller MR, Huberty BJ. The influence of hunger on meal to pellet intervals in barred owls. Comp Biochem Physiol 66(2):203-207, 1980.

Facon C, Beaufrere H, Gaborit C, et al. Cluster of atherosclerosis in a captive population of black kites (Milvus migrans subsp.) in France and effect of nutrition on the plasma lipid profile. Avian Dis 58(1):176-182, 2014.

Fuller MR, Duke GE, Eskedahl DL. Regulation of pellet egestion: the influence of feeding time and soundproof conditions on meal to pellet intervals of red-tailed hawks. Comp Biochem Physiol 62(2):433-438, 1979.

King AS, McLelland J. Digestive system. In: Birds: their structure and function. 2nd ed. London: Bailliere Tindall; 1984: 84–109.

Klaphake E, Clancy J. 2005. Raptor Gastroenterology. Vet Clin North Am Exot Anim Pract 8(2):307-327, 2005.

Migliorini RH, Linder C, Moura JL, et al. Gluconeogenesis in a carnivorous bird (black vulture). Am J Physiol 225:1389-1392, 1973.

Myers MR, Klasing KC. Low glucokinase activity and high rates of gluconeogenesis contribute to hyperglycemia in barn owls (Tyto alba) after a glucose challenge. J Nutr 129(10):1896-1904, 1999.

Orosz SE. 2008. Critical Care Nutrition for Birds. Proc Annu Conf MASSAV. Williamsburg, VA: 208-214.

Quesenberry KE, Maudlin G, Hillyer EV. 1991. Review of methods of nutritional support in hospitalized birds. Proc Annu Conf European Assoc Avian Vet. Vienna: 243-254.

Tabaka CS, Ullrey DE, Sikarskie JG, et al. Diet, cast composition, and energy and nutrient intake of red-tailed hawks (Buteo jamaicensis), great horned owls (Bubo virginianus), and turkey vultures (Cathartes aura). J Zoo Wildl Med 27(2):187-196, 1996.

Veiga JA, Roselino ES, Migliorini RH. Fasting, adrenalectomy, and gluconeogenesis in the chicken and a carnivorous bird. Am J Physiol 234(3):115-121, 1978.

To cite this page:

Daut E, Pollock C. Feeding the hospitalized bird of prey. January 19, 2016. LafeberVet Web site. Available at https://lafeber.com/vet/feeding-the-hospitalized-bird-of-prey/