If an orphaned bird or mammal is found, further information should be sought before attempting wildlife rehabilitation. The following is a general overview, and all species require more information for a full course of captive care. It is illegal to keep most species of North American wild animals as pets. Permits are required, even by veterinarians, to care for most wild species beyond initial medical care. The USA Fish and Wildlife Service and state natural resource agencies should be contacted for applicable rules. Injured limbs of wild animals should never be amputated without consultation with regulatory agencies.
The first step is to determine if young are truly orphaned. If chicks are returned to nests or mammals are left alone and monitored from afar, the parent may return and resume care. Human handling does not preclude most parents accepting returned offspring. Neonatal wildlife, especially unidentified species, have the best chance of survival if kept warm and taken to local wildlife rehabilitation centers. Skunks, raccoons, foxes, and bats should only be rehabilitated by professionals because of potential zoonotic diseases. Marine mammals and seabirds require specialized care facilities (see Management of Marine Mammals).
All neonates require physical examination and assessment of hydration, body temperature, and weight. When hand-rearing, warmth, hydration, and energy are critical. Because most orphans initially cannot maintain or regulate their body temperature, supplemental heat should be provided with heating pads, hot water bottles, incandescent light bulbs, or brooders. A heat gradient for ambulatory young allows orphans to select their own comfort zone. Thermal support of altricial species must be closely regulated. Most placental mammals and birds have normal body temperatures warmer than that of people, and should feel warm to the human hand. Maintaining humidity of 50–70% in housing avoids dehydration, and insulating orphans from direct heat prevents burns. Hypothermic orphans should be warmed until body temperature is near normal and administered warm fluids to maintain hydration. Once the infant is warmed and well hydrated, species-appropriate diets can be fed to provide energy. Initial feedings should be conservatively sized and dilute until it has been determined that the infant's excretory systems are functioning. Infants of most species have a stomach or crop capacity of ~50 mL/kg. Overfeeding may result in aspiration pneumonia or diarrhea. Once infants are stabilized, the advice of a permitted rehabilitator should be obtained. Euthanasia should be considered for any animal with injuries that preclude eventual release.
When hand-rearing for wild release, infants should be raised with conspecifics to avoid human imprinting, using techniques that reduce habituation. Wild infants should be isolated from domestic animals. Feathers, skin, and eyes should be kept free of spilled food, and foods maintained hygienically. Nests/housing should be cleaned regularly and secured against vermin.
Nest replacements should be constructed so as to provide nonambulatory chicks with a comfortable upright posture with the head elevated and legs underneath the body. Housing chicks on flat surfaces may result in splayed legs. Fractured bones are considered life-threatening injuries because of the requirement of functionality for release. Trauma to soft tissues can be minimized by stabilizing fractures promptly. Elbow, carpus, spine, stifle, and hock fractures or luxations carry a poor prognosis for release. Chicks may heal rapidly from seemingly severe soft tissue injuries or mid-shaft long-bone fractures. Lacerations should have primary closure to minimize time in captivity and reduce adverse effects on growing plumage. Antibiotic therapy against gram-negative bacteria is advisable for predator-injured chicks; it should be continued until wounds have completely healed.
Identification of species is important for determination of behavioral considerations, weaning diets, and adult fate. Nearly all North American species feed vertebrate or invertebrate prey to their chicks. Metabolic bone disease may develop quickly on inadequately supplemented diets. Growing chicks require a ratio of elemental calcium:phosphorus of ~2:1 by weight. Milk and bread, hamburger, condensed milk, or uncooked rice should not be fed. Soaked dog kibble and monkey biscuits are inadequate for most species. All species require 8–12 hr uninterrupted sleep. Self-feeding requires daylight-level lighting in diurnal species.
Chicks should be warmed to normal body temperature, hydrated until droppings are produced, and then fed. Tiny, unfeathered chicks require environments as warm as 100°F (37.8°C); larger feathered chicks do well initially in temperatures of 90–95°F (32.2–35°C). Overheated chicks may hold perpetual open-mouthed postures, droop heads over nest edges, and cease producing droppings if dehydrated. Not all species gape/beg (swifts, nightjars). Some species stop begging when full (corvids), some do not and may dangerously overeat (finches, goldfinches). Crops should empty between feeds; not all species have crops (insectivores, owls). Hatchlings require more water than older chicks. Common problems that cause lack of gaping include too cold, hot, weak, or dehydrated; untreated illness or injury; and misidentified species. Puréed high quality kitten or ferret kibble is an acceptable temporary food for most altricial chicks, supplemented with 150 mg/kg calcium glubionate, PO, bid until on a balanced diet. Puréed, skinned prey animals (quail or adult mice, including bones and organs, minus feet and heads) form an adequate diet for many species. Bone fragments must be completely pulverized to avoid GI trauma. Thawed-frozen prey require vitamin supplementation. Higher protein/fat, lower carbohydrate diets are desirable for most species.
Songbirds and Woodpeckers
A simple hand-feeding diet consists of 1 cup (116 g) Purina Pro-Plan kitten kibble, 1.25–1.5 cup (300–360 mL) water, 2 tbsp (14 g) powdered egg white, 750 mg calcium from CaCO3, and ½ tsp (1.4 g) Avi-Era powdered avian vitamins (Lafeber). Do not delete or substitute ingredients haphazardly, soak kibble and blend until smooth, and feed with appropriately sized syringe. Hatchlings/nestlings: feed 50 mL/kg every 20–45 min (by age) 12–14 hr/day, 16 hr/day for insectivores. Fledglings; hand-feed 50 mL/kg every 1–2 hr, 12 hr/day, offering appropriate self-feeding diet.
These chicks should be transferred to an experienced caregiver immediately. A temporary diet consists of 1 part water to 6 parts table sugar or 5% dextrose, fed every 20 min. Do not spill sugar water on the bird.
Doves and Pigeons
Commercial diets for hatchlings are Roudybush Squab and Lafeber Emeraid Carnivore; for nestlings/fledglings, Kaytee Exact Hand Feeding Formula. Crop capacity is 100–120 mL/kg. Birds should be fed when crop empties, 12–14 hr/day: every 1–2 hr until eyes open, every 3 hr until ambulating and ingesting seed. Palpating the crop before each feeding will prevent overfilling.
Hatchlings can be fed small pieces of warm, water-dipped meat every 2 hr, 12 hr/day with blunt-tipped forceps; tiny bone pieces can be included by day 3 post-hatch, and casting material (skin/hair) by day 5. The crop should empty between meals. Most species will pick up chopped prey from a dish by day 14. Feeding with a puppet parent can be done once the eyes open.
Herons and Egrets
Thawed-frozen fish (5–20 g, sliced diagonally if larger), live insects, or thawed-frozen chopped mice, should be offered hourly until self-feeding, then several times daily. Food should be sprinkled with calcium powder. Hatchlings may require force feeding; older chicks may eat from a dish.
Once warm and secure, many species drink and eat independently. Solitude stresses chicks; a mirror, small stuffed animals, clean feather duster, or closely related species chicks can be companions. Uncommon species and debilitated hatchlings require professional rehabilitative care for a positive outcome. Placing pebbles in water dishes can prevent quail/ducklings from drowning. Hatchling quail/killdeer require 95–100°F (35–37.8°C) habitat brooders.
Shorebirds (Killdeer, Sandpipers, Avocets)
Live, fresh-frozen, and freeze-dried small invertebrate prey (tubifex worms, brine shrimp, mosquito larvae, tiny krill, small freshly shed mealworms, fly larvae, or cichlid mini-pellets) should be offered in shallow water at least 4 times daily.
Waterfowl (Geese, Ducks, Swans)
Natural duckweed or watercress, small invertebrates, crushed hard-boiled egg, small minnows, and waterfowl starter (Mazuri) should be offered. Access to shallow water should be controlled; chicks must be able to easily exit water to warm under a heat source.
Gamebirds (Pheasants, Quail, Turkeys)
Soaked puppy kibble, small-bodied invertebrates, small clumps of grass or weeds with soil, or commercial gamebird starter can be offered.
Hypothermia and dehydration should be corrected. Hairless neonates require ambient temperatures of 85–90°F (29.4–32.2°C), while haired infants can be housed at cooler temperatures depending on maturity and body condition. Once warm and hydrated, milk replacer (MR) should be introduced using this regimen: 100% oral electrolyte solution, gradually increasing strength of MR in one to several feedings to ¼ strength, then ½, then ¾, and finally full strength MR. During this process, if the neonate develops digestive upset (vomiting, diarrhea, bloating), feeding should return to the last well-tolerated ratio. Neonates can be stimulated to eliminate by gently stroking the perineal area with warm moist gauze or tissue. Dorsal side up is normal nursing posture; infants should not be put on their backs to feed. The environment should be quiet.
Fawns should be raised in groups with minimal human contact. If they are in the veterinary clinic temporarily, they should be kept away from dogs. Newborn to 2-day-old fawns should be fed colostrum, such as Colostrx (Schering-Plough), for the first 24–48 hr. After reconstitution, one 454-g package can be administered via bottle or stomach tube over 8–10 hr (5 meals/day). Acceptable MR include Fox Valley Milk Replacer, Lamb's Milk Replacer, or goat's milk. Fawns 2–7 days should be fed qid. At 1 day old, each meal should consist of 30–40 mL/kg, gradually increasing to 50 mL/kg from 2–6 wk of age, reaching a maximum of 480 mL tid. At 4–6 wk, feeding frequency is decreased to bid, and solid food added (eg, goat chow, calf manna, and alfalfa hay). Indigenous natural browse should always be available. By 7 wk, fawns should be eating solid food and fed one 480 mL bottle daily. By 8–10 wk, fawns should eat solid food exclusively.
Syringe-feeding is preferred; Catac® nipples work well. Eastern gray and fox squirrel neonates should be fed every 2 hr until 2 wk old. From 2–3 wk, feeding should be every 3 hr, 8 times/day. At 4 wk, the late-night feed is eliminated. At 5–6 wk, feedings are reduced to 5 and then to 4 times/day, at 7–8 wk to 3 times/day, and at 10 wk to once a day. Weight should be monitored daily, and the squirrel fed 50 mL/kg per meal until it weighs 100 g, gradually increasing to 70 mL/kg. Acceptable MR (ratios by volume) include 2 parts Fox Valley 32/40 and 3 parts water, or 1:½:2 parts of Esbilac, MultiMilk, and water. When eyes are open and squirrels are ambulatory, natural foods and rodent block can be offered; fruit should be strictly limited. Ground squirrels wean at 6 wk old, and Western gray squirrels at 12 wk.
Rabbits and Hares
Neonatal rabbit stomachs hold 100–125 mL/kg. Feeding 1–4 times/day is needed; use of a slip-tip syringe is preferred. If suckling response is poor, tube-feeding should be reduced by 30% and an extra feeding added to ensure adequate caloric intake. Acceptable MR (ratios by volume) include 3 parts Esbilac liquid and 2 parts MultiMilk (powder) or 1 part Esbilac powder; 1 part MultiMilk powder to 1.5 parts water; and 1 part Esbilac powder, ½ part heavy cream, and 1 part water (fur rabbits). When the eyes open, a variety of chopped leafy greens and grass (orchard, timothy, or oat) hay should be provided. Fruits and high-sugar vegetables (eg, carrots) should be avoided.
Infants weighing <20 g have a poor prognosis. Infants weighing 20–35 g should be fed 50 mL/kg 6 times/day, those weighing 40–100 g, 50–60 mL/kg 5 times/day. An acceptable MR (ratio by volume) is 1 part Esbilac, ½ part MultiMilk, and 2 parts water. Tube-feeding is preferred, and a size 3.5 French red rubber catheter measured to the caudal rib can be used. If syringe feeding, a cut smoothed Tomcat catheter can be attached to the syringe and the infant fed drop-wise. When the eyes open (around 45 g) infants can be taught to lap formula from a shallow dish. When infants weigh ~60 g and are walking, kitten kibble soaked in Esbilac can be offered. Once the infant is eating the soaked kibble (~80–100 g), 10% other natural food items (crickets, worms, chopped mice, local fruits, high-calcium vegetables) can be introduced. Most opossums self-feed by the time they weigh 100–120 g. Adequate calcium intake must be ensured to prevent metabolic bone disease.
Last full review/revision July 2011 by Rebecca S. Duerr, DVM, MPVM; Laurie J. Gage, DVM, DACZM