EAZA Hornbill Management and Husbandry Guidelines

Familiarity with food items can greatly influence their acceptability to hornbills. For
example, six great hornbills from the other zoos remaining six weeks at a “dating center”
at Arnhem Zoo never lost their preference for items that they were fed in their resident
zoos (M. Damen, pers. comm.). It is therefore important to give hornbills ample time to
adapt to new dietary items.
5.1.3 Colors
P. Poonswad (pers. comm.) noted that Asian hornbills in the wild select fruits which are
predominantly red, orange, dark purple/black. Sunda wrinkled hornbills Aceros
corrugatus at Arnhem Zoo were noted to show a stronger preference for red items when
feeding young (Luttenburg and Bisselink, in press). Reddish to blackish fruits may be
high in cartenoids, flavenoids and other colored pigments that have been shown to affect
plumage and skin color in many bird species. Potential studies on this topic can be found
in Section 8.1.1: Dietary issues.
5.1.4 Fiber
Further investigation of wild fruits provides useful directions for possible diet
improvement. Field researchers M. Kinnaird and P. Poonswad have noted that fiber
content of Asian hornbill diets is far higher than in captive diets, and suggested that fiber
in captive diets should be increased (Sheppard and Worth, 1997). A low amount of
insoluble fiber may provoke a tendency towards watery feces. Increasing dietary fiber
has proven beneficial in some cases with other birds. Addition of ground chitin or wheat
bran improved feces of rollers and bee-eaters at the New York Bronx Zoo and allowed
the bee-eaters to show normal casting behaviors when kept on a non-insect diet. A
pheasant that consistently plucked its own feathers stopped the behavior when fiber was
added to the diet.
P. Poonswad (pers. comm.) noted that many fruits eaten by hornbills contain large
pits/seeds that the hornbills regurgitate, and that this behavior may be important for
healthy functioning of the hornbill digestive system. Uncured olives might serve as
replacement for wild seeds, however, the nutritional value of olives has to be evaluated.
5.1.5 Protein
A study on nitrogen requirements of captive Aceros (three species) and Buceros (two
species) hornbills was carried out at the Wildlife Conservation Society. It was found that
the hornbills could maintain body mass on a diet containing 10.8% crude protein (4
Kcal/g dry matter). The results also suggested that Aceros and Buceros hornbills have
similar nitrogen requirements. More work needs to be done before these values can be
verified (Foeken and de Vries, 2001).
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