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304 Hand-Rearing Birds

Figure­18.8­ White-faced Ibis (WFI) chick in indoor housing that allows movement and exposure to natural
substrates. Source: photo courtesy of International Bird Rescue.

­ Preparation­for Release­and Release­Criteria

Ibis should not be directly interacted with other than during routine health checks once self-feed-
ing. All supplemental heat should be discontinued for several weeks prior to release. Once chicks
are living outside and eating independently, they should maintain weight and be within the species
norm. Ibis have a prominent keel and may feel thin subjectively, but should have palpable muscle
mass on each side of the keel. Ibis propagated or rescued with the intent to release into wild habitats
should meet established release criteria for the species, such as flight feathers fully grown in, plum-
age in good condition and waterproof, behavior appropriately wary of people, and blood parameters
within normal limits. Birds should be healthy and free of injury prior to release. Birds with poor
waterproofing should not be released without addressing plumage issues. Birds should be able to fly
and demonstrate the ability to forage and feed unassisted and without soliciting caregivers for food
by begging as a chick would to its parents. Ibis should have reached their asymptotic weight and
then lost weight as they fledged. As colonial birds, they may learn additional behaviors, such as
predator avoidance and breeding behaviors, from adult birds in wild colonies. Release ibis into
appropriate habitat with established colonies or in the vicinity of other ibis when possible.
Many American AZA accredited institutions support field conservation programs related to spe-
cies recovery and have established guidelines or taxon advisory groups eager to share information
and experiences regarding this complex aspect of propagation (Association of Zoos and Aquariums
(AZA®) 2018).

­ Acknowledgments

Thank you to Christine Simeone, Linda Henry, Stephanie Costelow, Wendy A. Turner, Hannah Bailey,
Christopher Holmes, and Susie Kasielke for their insights into hand-rearing birds. Thank you to
Elizabeth Koutsos for sharing her knowledge about nutrition in fish-eating birds. Thank you to Justin
Brackett for compiling weight loss data. Thank you also to SeaWorld San Diego for sharing unpub-
lished hand-rearing data. Last, but not least, thank you to my SeaWorld editor, Dr. Judy St. Leger.