Page 268 - Hand rearing birds second

256 Hand-Rearing Birds

accomplished by creating and using special costumes, with everyone involved dressing from head
to toe whenever interacting with chicks, making sure to also always keep hands covered. In addi-
tion, audio tracks of cormorant colonies and vocalizations can be used to provide young birds with
auditory stimulation and to help cover up anthropogenic sounds associated with their care. These
tracks can be played on a loop throughout the day and turned off at night, when chicks normally
sleep. Feeding puppets specially painted to replicate a cormorant adult are helpful for feeding
times. If a chick has to be alone for any amount of time, a mirror should be provided such that the
chick can always see “another cormorant.” Regardless of how long or short the human–bird inter-
action, the human should always be completely costumed. The greater the use of puppets, decoys,
and colony sounds, the less likely the birds are to habituate or imprint.

Diet

In the wild, cormorants feed on a wide variety of fish specific to the areas they inhabit. In captivity,
rehabilitators often need to rely on sporadic fish availability. Options for commercially available
fish include night smelt (Spirinchus starrski), peruvian smelt (Atherinella panamensis), capelin
(Mallotus villosus), and various minnows, sardines, anchovies, menhaden, and mullet species. Fish
that may be too large for newly hatched cormorants to ingest may be cut or sliced into smaller,
more size‐appropriate pieces. It is good practice to cut these into pieces that are long and slender
(fish‐shaped) to best simulate smaller fish and allow for easy swallowing. The nutritional content
of these fish depends on season, freshness, alive versus dead, and whether they have been frozen.
Husbandry may need to be adjusted if feeding fattier fish, such as anchovies or sardines, to avoid
contaminating the bird’s feathers or substrate with fish oil from feedings or feces.
All cormorant 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 phospho-
rus ratio. Nutrients of concern in piscivores fed frozen–thawed, small‐bodied fish include thiamin,
vitamin E, vitamin D, and calcium. Commonly‐used supplements for piscivores include #5M2G
®
Mazuri Auklet Vitamin Tablets (www.Mazuri.com) or SeaTabs (Pacific Labs) and 500–600 mg cal-
cium (from calcium carbonate) tablets. When needed, vitamin D 3 gelcaps intended for humans
work well. Capelin, in particular, has been found to be deficient in vitamin D (Hoopes and Clauss
2016). Supplement doses are intended to be administered per kilogram of fish consumed; but in
practice, it is best to dose on a regular schedule of every other day while a chick is having frequent
interactions with caregivers (Table 15.1). Once a bird is living in an outdoor enclosure and no
longer requires assisted feeding, the frequency of handling and supplementation decreases.

Feeding Procedures

Emaciated chicks often need to be further stabilized prior to receiving solid foods. A critical care
formula, such as Emeraid Piscivore (EP, Lafeber Company, fed at 11% fat from added salmon
oil), works well for this purpose. When chicks are debilitated, a slow transition from fluids to the
critical care formula can be beneficial. For example, start with 2‐hourly tubings of 100% fluids,
and then move to two tubings of 75% fluids/25% EP, two tubings of 50% fluids/50% EP, and so on
until the chick is receiving 100% EP. Once the chick is more stable, it can be transitioned to
eating solid foods.