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112 Hand-Rearing Birds

available aquatic invertebrates are available as both frozen and freeze‐dried. In most cases, the
frozen variety is preferred for sea ducklings as it sinks; most sea ducklings seek prey underneath
the surface of the water. Freeze‐dried invertebrates float on the surface of the water and may be
used in addition to frozen invertebrates to stimulate self‐feeding behavior. Of the commercially
available aquatic invertebrates, frozen krill tends to be the most versatile prey item and is readily
consumed by nearly all species of sea ducklings (smaller ducklings require that the krill be
chopped). Mergansers benefit immensely from live fish and are capable of capturing live prey (if
the fish are sized appropriately) from a few days old. Live fish can be obtained from a local bait
shop or pet store or can be harvested (depending on local regulations) from ponds and/or streams.
When feeding thawed frozen items (particularly fish), thiamine supplementation should be pro-
vided to avoid deficiencies (Miller et al. 2017). Feeder insects (primarily mealworms) should also
be incorporated into a sea duckling’s diet. Live insects create movement on the water surface
which can trigger self‐feeding behavior. Live insects should be maintained on an appropriate sub-
strate and should be gut‐loaded approximately 12–24 hours prior to feeding with a commercially
available gut‐loading diet to maximize nutrient composition prior to consumption (Fidgett and
Gardner 2014). Transitioning ducklings onto a staple diet may be challenging for some species
once acclimated to whole prey.
Certain species of sea ducklings (namely goldeneyes along with certain mergansers) along with the
majority of pochards and stifftails consume a moderate amount of aquatic plant material. In captiv-
ity, either duckweed (Lemna spp.) or chopped greens can be offered floating on the water surface.
The provision of an appropriate staple diet along with a variety of natural food items does not
necessarily indicate that the ducklings will eat sufficiently to maintain weight. Ducklings should
be weighed twice daily for at least the first week in care. Ducklings that lose weight in care have a
poor chance of survival without intervention. Intervention includes a combination of gavage feed-
ing and drip feeding. These interventions are intended to provide supplemental calories while
encouraging the ducklings to self‐feed in an effort to minimize any weight loss while the ducklings
are learning how to self‐feed. Gavage feeding and drip feeding can be alternated throughout the
day every 2–4 hours to maximize success. Whenever possible with critically debilitated animals,
one overnight feeding should be provided to reduce weight loss overnight. Supplemental nutrition
is generally provided for 7–10 days or until the ducklings are eating sufficiently on their own to
maintain weight. Adjustments are made throughout this time to the volume and feeding incre-
ments to slowly increase the amount of formula being administered per feeding while increasing
the time between feedings.

Gavage-Feeding
Use the same type of syringe with an attached cut urethral catheter. Gavage‐feeding small amounts
of formula will help ducklings maintain weight while they transition to self‐feeding. The two pri-
mary diets appropriate for gavage‐feeding sea ducklings are Mazuri® Nestling Handfeeding
Formula or Mazuri Waterfowl Starter. The Nestling Handfeeding Formula is a powder for reconsti-
tution with hot water. The Waterfowl Starter should be soaked in warm water and blended to a
paste consistency that can fit through the urethral catheter. Ducklings can tolerate gavage feedings
equal to 10% body weight every 2–4 hours. When gavage‐feeding, ensure that the cut urethral cath-
eter is primed with formula prior to feeding to avoid air administration. With practice, the process
of gavage‐feeding should take no more than 15 seconds per duckling. Both of the formulas above
can also be used for debilitated juvenile and adult waterfowl. Feeding equipment should be
thoroughly cleaned and disinfected between uses.