Page 291 - Hand rearing birds second

280 Hand-Rearing Birds

generalities and specificities, a basic set of diet supplies can be stocked that will satisfy the nutri-
tional needs of all herons and egrets. This basic set must include an adequate stock of frozen blocks
of small fish (smelt or herring, in the 5–20 g size range), which comprise the basic captive diet, and
stocks of frozen mice and live insects. If only larger fish are available (30–40 g size range), the fish
can be cut diagonally into smaller strips so that both ends are pointed, simulating smaller fish.
Mealworms (Tenebrio molitor), mature mealworm beetles, and crickets provide more options for
diet diversity. The beetles make excellent live forage practice for birds in pre‐release flight aviaries.
Because young herons and egrets can eat their own body weight each day, it may be impractical to
rely on live food for the bulk of their diet. Live fish are useful, however, especially for getting reluc-
tant eaters to start eating. At all stages of orphan rearing, food should be sprinkled with crushed
calcium carbonate tablets or pills can be administered orally to improve calcium to phosphorus
ratios.
Thawed, quartered mice should be introduced into the diets of all herons and egrets as a comple-
ment to the basic diet of fish: one mouse per bird per day will give the birds a chance to sample
these nonfish foodstuffs. Rehabilitators can assess additional quantities based on species prefer-
ences and local species wild diets. Snails, lizards, and crayfish may form substantial portions of
wild diets.

Supplements
All chicks should receive vitamin and mineral supplements while in care to support healthy
growth, unless being fed strictly fresh, unfrozen fish with an excellent calcium‐to‐phosphorus
ratio. Nutrients of concern in piscivores fed frozen–thawed, or certain small‐bodied fish include
thiamin, vitamin E, vitamin D, and calcium. Commonly‐used vitamin supplements for piscivores
include #5M2G Mazuri® Auklet Vitamin Tablets (www.Mazuri.com) or SeaTabs (Pacific Labs) and
500–600 mg calcium (from calcium carbonate) tablets. When needed, vitamin D 3 gelcaps intended
for humans work well.
Supplement doses are intended to be administered per kilogram of fish consumed; but in prac-
tice, food intake may be hard to determine in a busy clinic. When heron and egret chicks are grow-
ing rapidly, they may eat their own body weight in fish daily; hence, a good rule of thumb for
multivitamins is one tab per kg of bird for hatchlings and nestlings, with reduced frequency as
chicks’ growth and food intake slows as they reach adult size. Although variation in nutritional
content of fish is seen seasonally and from year‐to‐year, as shown in Table 17.1 different fish spe-
cies vary widely in mineral profiles and require different amounts of calcium supplementation to
support chick growth. In poultry, calcium‐to‐phosphorus ratios of 1.6–2.7 are needed for growth
(Klasing 1999). Capelin has been found to be deficient in vitamin D compared to other fish as well
(Hoopes and Clauss 2016). If skeletal maturation problems are seen in multiple chicks, reconsider
supplementation regimens. Laboratory analysis of food composition may be informative if prob-
lems are persistent.

­ Feeding­Procedures

Dead fish should always be kept well‐refrigerated or frozen until immediately before being fed out,
and thawed–frozen fish should be fed within 24 hours of thawing. Uneaten fish in heated environ-
ments, such as presented for self‐feeding in an incubator, should be changed frequently because
hot temperatures encourage bacterial growth and spoilage. All chicks that are not yet self‐feeding