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174 Hand-Rearing Birds

Grebes should be offered live feeder fish and insects such as crickets and mealworms. Various
small‐sized live feeder fish may be obtained from a bait or pet store and easily kept in a 30 l or larger
aquarium with a filtration system. Live crickets can typically be found at most pet stores. It is
always best to add as much diversity into the diet as possible to encourage food recognition and
good self‐feeding behaviors, as well as to provide nutritional variety. Appropriate live fish include
rosy reds, minnows, fingerling carp, threadfin shad, crayfish, herring, and small smelt. Insects that
may be fed include crickets, mealworms, water fleas, and water beetles. Pools and water containers
should always be treated with a dechlorinating agent 20 minutes before adding live fish, if the
water has chlorine in it. Live fish should be kept in water that matches the temperature of the pool
to which they will be added so they do not die quickly.
Live food is ideal but not always available, and may be expensive. Thawed frozen fish can be
used but this does not help teach the chick hunting skills. Dead fish should always be supple -
mented with 35 mg of thiamine and 100 mg of Vitamin E per kilogram of fish. The optimal cal-
cium‐to‐phosphorus ratio is 2 : 1 and small‐bodied fish may have poor ratios similar to
mealworms. Deboned fish is very high in phosphorus and low in calcium, so extra calcium will
need to be provided to make up the deficit if deboned fish is being fed. Twelve grams of calcium
carbonate powder (4800 mg of elemental calcium) should be added to each kilogram of deboned
fish, resulting in 0.4–0.8% of the complete diet (Perlman 2016). Deboned fish are also deficient
in many other nutrients, as the organs are the primary sources of many vitamins such as A and
D. If small pieces are needed to feed a particular chick, be sure to feed the viscera in addition to
muscle tissue. Similarly, young chicks eat fish roe eagerly, but it is also deficient in many nutri-
ents, especially calcium.
If tube‐feeding is necessary, a slurry can be made by blending fish in a food processor until a
consistency is achieved that will easily move through a syringe and orogastric tube. The addition
of insects will add nutritional diversity to the diet. Prepared diets should always be fed at room
temperature, refrigerated if not used immediately, and used within 24 hours. Cold food can be
allowed to sit out for a short length of time to take the chill off; however, slurry should not be
heated to warm it up since fish cooks at very low temperatures and heating will affect the bioavail-
ability of the nutrients in the diet.
Grebe chicks are regularly fed soft contour feathers by their parents beginning shortly after
hatching, and they continue to consume them throughout adulthood. Feathers are mainly obtained
from the parents’ own bodies while they preen, but occasionally they are found floating on the
water and taken either by one of the parents or by the self‐feeding chick. The consumed feathers
form into a compacted mass that creates a plug in the gizzard. This plug slows food passage and
allows more chemical digestion to occur before further passage. A second distinct mass of feathers
is typically found in the pyloric pouch, which finally prevents indigestible matter from entering
into the intestine. Research suggests that the purpose of eating feathers is to slow down the diges-
tion process (Jehl 2017). The undigested material and some of the feather matter are regularly
regurgitated as cast pellets, which may assist in minimizing the presence of gastric parasites
(Piersma and Van Eerden 1989). Feathers have been found to comprise over 50% of the stomach
content for several species of grebe, indicating that their consumption is intentional and relevant
to the grebe’s digestive system (Muller and Storer 1999). Since grebes seek out notable quantities of
feathers to feed to their chicks, these should be made available to grebes at all stages of their care
in captivity. Donor feathers should be small clean contour feathers and can be obtained from
grebes that did not survive rehabilitation or older current patients. Chicks will usually eagerly eat
these feathers (Figure 10.3).