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Cormorants 257

Table­15.1­ Supplement schedule and housing by chick weight, based on feeding small-bodied fish
with unknown or low calcium to phosphorus ratio.

Chick Auklet­Tab­amount­ Calcium amount
weight and frequency and frequency Housing location

<150 g 1/8–1/4 tab EOD 75–150 mg SID Incubator with nest
150–255 g 1/4–1/2 tab EOD 150–300 mg SID Wood‐sided pen with heat
255–900 g 1/2–1 tab EOD 300–600 mg SID Large “pelican box” with gradual heat
reduction, days in play pen outdoors
900–1500 g 1 tab EOD 600–1200 mg SID Large “pelican box” with gradual heat
reduction, days in play pen outdoors
>1500 g 1 tab EOD‐q7d 1200 mg SID‐q7d Outdoors, free‐roaming in large aviary
EOD = Every Other Day.
SID = Once Daily.

Cormorant parents begin feeding their young within hours of hatching by forcing tiny particles
of partially digested food into the mouths of the blind and helpless chicks. By 3 days old, chicks
place their heads into the adult’s mouth and bob excitedly to encourage the adult to feed them.
Chicks signal for food by tapping on a parent’s beak, drooping and quivering their wings, flailing
their heads, and uttering high‐pitched squeaks. This behavior becomes more exaggerated as the
birds grow. In the wild, parents feed the chicks 3 times a day for the first several days after hatch-
ing, and then increase the frequency to up to 10 times a day for days 6–25. After that, the parents
gradually decrease the number of feedings until the chicks fledge at about 10 weeks of age (Dorr
et al. 2014).
Chicks should not be fed fish with long and/or sharp bones or spines that could perforate
their esophagus or gut, regardless of their age. For young, down‐less chicks, offer slivers of fish
(with heads, tails, fins, and large bones removed) by forceps or puppet. It may be necessary to
use one hand to steady the bird’s head, and the other, puppeted or holding forceps, to offer the
fish (Figure 15.4). Chicks may need encouragement to open their mouths to feed; this can be
achieved by gently touching or pinching both sides of the base of the bill using the hand steady -
ing the head. Table 15.2 shows a feeding schedule for Double‐crested Cormorant chicks by age
and weight.
Increasingly larger slivers of fish should be offered to birds until they are large enough to con-
sume whole fish. Continue to hand‐feed the birds as they grow, but also encourage them to self‐
feed using two methods: fish school and assist‐feeding (Figure 15.5). Fish school consists of
splashing fish in the feeding dish or tossing fish at the bird’s feet to use the movement of the fish
to encourage self‐feeding. Assist‐feeding, which acts as a bridge between hand‐feeding and self‐
feeding, entails partially placing the fish into the bird’s mouth and giving it a chance to manipu-
late the fish and swallow it on its own. An adult cormorant decoy used as a large puppet is very
useful for inspiring a chick’s interest in fish. For chicks at older ages, live fish can be used to
encourage self‐feeding, although it should be remembered that cormorant chicks in the wild do
not encounter live fish until hunting on their own (unless a fish is still alive after being regurgi-
tated by the parent).
After about 3–4 weeks of age, when chicks begin to stand on their own, whole small (<6 in.,
<15 cm) fish may be dropped on the floor of the cage or in a dish and pointed to by a puppet or
decoy to encourage birds to self‐feed. When feeding groups consist of three or more birds, the