Habitat
Red-knobbed
hornbills inhabit primary lowland forest and forest edge from sea
level to about 3,600 feet (1,097 m) in elevation. They occasionally
range up to 5,900 feet (1,798 m) in elevation. Radio-telemetry studies
have shown that red-knobbed hornbills may cover as much as 23 miles
(37 km) per day, passing through degraded habitat in search of fruiting
trees. |
Physical
Characteristics
The
adult male’s crown and back of head
are reddish brown, face and neck are pale red or cream-colored,
body and wings are black, and the tail is all white. A male’s
bill is yellow with orange-brown ridges (“chevrons”)
across the base of both mandibles, and features a tall red
wrinkled ridge (also called the casque ridge) on the upper
mandible near the eyes. The skin around the eyes is pale blue
and the eyelids are dark blue. The bare throat skin is dark
blue with a black band through the lower edge and turquoise
skin below the band. The male has orange or red eyes, while
legs and feet are black.
The
adult female is smaller than the male, with similar coloring.
The female’s casque is yellow,
while the head and neck are all black. The female’s
throat skin has a smaller black band and the eyes are brown
or orange.
Both
sexes of immature red-knobbed hornbills have plumage
like the adult male when first emerging from the nest cavity.
However,
their casque ridge is undeveloped and the bill is pale
yellow with a red wash at the base. Juveniles have pale facial
skin
and dark brown eyes with a yellow rim. At 10-13 months
of age, the casque of juveniles begins to develop and the female
begins
to molt into adult head and neck colors (i.e. black). The
juvenile male’s plumage remains the same with the casque
growing larger and redder. |
Life
Span
Life expectancy in the wild could be approximately
20-35 years. Researchers need information from long-term banding
studies to accurately know life expectancy.
Historical records of red-knobbed hornbills in captivity provided
misleading information, as husbandry issues were underdeveloped
and birds died after just a few years. Presently, the oldest
living bird in captivity is a wild-caught male that a zoo acquired
in 1989. Because it was wild-caught, its exact age is unknown.
Life expectancy in captivity probably exceeds that of wild birds.
With improved husbandry, more information on longevity will become
available on captive-hatched birds. |
Diet
In the wild:
In the wild: Various fruits (especially figs) are the major
part of their diet. Red-knobbed hornbills also eat small
invertebrates as a small part of their diet.
At
the zoo: Soaked
(dried) figs, apples, papayas, bananas, grapes, blueberries,
pear, melon, tofu, and cooked yams. |
Reproduction
Sulawesi red-knobbed hornbills probably reach sexual maturity at 5-6 years.
In Sulawesi, the breeding season normally occurs from June to September.
If the first clutch fails, the birds will re-nest and try again in
July or August. Most North American captive births result in hatchings
between April and June.
The birds
find a natural cavity (caused by lightning strikes, natural decay,
etc.) in a large tree and the female
seals herself inside. She creates
a mixture of feces, food, and feathers into a clay-like substance to
seal off the enclosure. A narrow vertical slit in this hard wall
provides space
for the female to defecate and the male to regurgitate food to the female
(and nestlings). She remains inside the nest, incubating two to three
white eggs for approximately 30-35 days. During incubation, the female
depends
entirely on the male to provide her with food. After hatching, the female
remains in the nest, brooding the chicks for approximately another 90
days.
Life Cycle
In the wild, the chicks emerge from the nest some 30-40 days after
the adult female has exited the nest cavity. It is rare that more than one
chick successfully fledges. After confinement inside the cramped nest for
as much as 130 days, the fledgling is not a strong flyer. It takes a day
or two of exercising its muscles to enable the fledgling to keep up with
its parents.Parents continue to feed the juvenile
as they forage together in the forests.
In the tropics, food resources
vary with space and time. Not all trees provide fruit during the same period
of time and fruiting trees
often grow
far apart.
During the non-breeding season, up to 50 hornbills may feed together
in the same tree. Eventually, juveniles begin eating on their own.
Adults
return
to the nest in the next breeding season, leaving immature and unpaired
birds to roam among fruiting trees.
Toucan or Hornbill?
While toucans and hornbills share many physical characteristics, they
are two completely different families of birds. Many people look at hornbills
and immediately call them “the Fruit Loops toucan.” This
confusion is understandable. Both groups of birds have long, sometimes
colorful bills. They both nest in cavities in tropical regions, and feed
predominantly on fruits. However, this is where the similarities end.
Toucans live only in Central and
South America; hornbills live only in Africa and Asia. Toucans are
more closely related to woodpeckers, while
hornbills are more closely related to kingfishers. The similar appearance
of toucans and hornbills is an excellent example of a phenomenon called
parallel evolution. This theory hypothesizes that two or more different
species from different families and geographically separated locations
have adapted similarly to fit an available niche in nature.
An Impenetrable Bond
Because
the female depends so much on the male to provide
(food) for her and the nestlings, courtship occurs
throughout the year to build and maintain strong
pair bonds. The male and female invest much time
developing this bond, so it is to their advantage
to remain together year after year, returning to
the same nest site to breed and raise their young.
|
Fascinating
Facts
- Hornbills
rarely drink standing water. They get most (if not all) of
their moisture from the foods they eat!
- Hornbills
are often heard before seen. They lack covert feathers that
cover gaps between flight feathers. In flight, the air goes
through the quills of the large flight feathers creating
a loud “whoosh, whoosh” sound as they fly above
the canopy of the forest!
- In Indonesia, the Sulawesi red-knobbed hornbill is
known as “Burung Tahun,” or the Year Bird. The
red chevrons on the sides of the base of the bill are thought
to tell the age of the bird with a new stripe acquired with
each year. However, some of these plates shed or fall off,
and are not an indicator of the bird’s true age.
|
Sulawesi red-knobbed hornbills
are on exhibit in the large enclosure north of the Conservation Aviary
in the Temperate Forest. The Temperate Forest also includes the Family
Farm, “Bug” World, Wetlands, and Asian Cranes. Other
birds on exhibit in the Conservation Aviary include: various pheasant
species, curassows and trumpeters from South America, and several
softbills (jays, laughing thrushes, turacos, whistling thrushes,
birds of paradise, mynahs).
Red-knobbed hornbills are not an endangered species and are common
throughout their range.** Other species of hornbills are not so fortunate,
as at least four species are listed as endangered.
The Sulawesi red-knobbed hornbill is endemic to the island of Sulawesi,
which is slightly larger than the state of North Dakota and encompasses
just 73,057 square miles (189, 216 km2). Therefore, the red-knobbed
hornbill’s habitat is restricted and the small size of Sulawesi
limits its future survival. Today, the biggest threat to this hornbill
is logging, which results in loss of habitat. Excessive logging removes
the required large trees with naturally occurring cavities. To fully
assess the status of this species, researchers need more studies to
determine if the population is stable or declining.
Hornbills
are important because they help disperse seeds throughout the forest.
They regurgitate
larger seeds, and pass smaller seeds through
their feces. It may be that forests need hornbills as much as hornbills
need forests. The presence of nesting hornbills is a sign of a healthy
Asian tropical rain fore.
Woodland Park Zoo is Helping - With Your Support!
Each
in-situ project supported by the zoo aims to provide
a broad, holistic approach to conservation,
encompassing research, education, habitat and species
preservation. This includes comprehensive, cooperative
strategies to link the needs of animals with the
people who share their ecosystems.
Woodland
Park Zoo (WPZ) supports Dr. Randall Kyes of the University
of Washington. Each year, Dr. Kyes
offers a lengthy field biology course to students
from Manado University in northern Sulawesi. They
live for several weeks in Tangkoko Dua-Sudara Nature
Preserve, learning various field techniques while
observing Celebes black apes. The most obvious
avian species in this preserve is the red-knobbed hornbill,
which the students learn about. It is hoped that
through these field classes, local Indonesians
will take on future responsibility as guardians of their
local flora and fauna.
Since
1999, WPZ staff, volunteers, members and friends have adopted more
than 186 hornbill nests
in southern
Thailand. This is a win-win situation for all
involved: the hornbills get protected, the researchers obtain
data, and the villagers get much needed cash
to improve their lives.
An outcome
of the above program was the construction and staffing of the Conservation-Education
Center
in Tapoh Village, Narathiwat Province in southern
Thailand. WPZ has supported this Education
Center since 2001.
How You Can Help!
The effort to save animal species requires cooperation and support
at the international, national, regional and individual levels.
You can help in this cause. Join and become active in WPZ and other
conservation organizations of your choice. Let your elected representatives
know your views on protecting endangered species and wild habitats.
Please do not buy products made from wild animal parts.
Contact
the WPZ at 206.615.1030 to find out how you can adopt a hornbill
nest. One hundred percent of the adoption money (at a
price of $120 per nest per year) goes directly to the villagers
who guard nests in neighboring Budo-Sungai Padi National Park.
Along with protecting the birds and nest sites, they collect
valuable data for the Hornbill Research Foundation. At the end of
the breeding
season, nest results are sent to each adopter. Included with
these results are colored photos of the birds at the nest and the
local
villager who protected it.
Learn other ways you can help conserve
wildlife and the habitats they require for survival, by calling
the zoo's Education Center
at 206.684.4800.
Sources and Suggested
Reading
del Hoyo, J., Elliot, A. & Sargatal, J. eds. 2001. Handbook
of the Birds of the World, Volume 6. Mousebirds to Hornbills.
Lynx Edicions, Barcelona, Spain. 589 p.
Kemp, A.C. 1995. The Hornbills. Oxford University Press, Oxford, UK.
302 p.
Kinnaird. M.F. 1995. North Sulawesi:
A Natural History Guide. Wallacea Development Institute,
Jakarta, Indonesia. 83 p.
Kinnaird, M.F. & O’Brien, T.G. 1993. Preliminary
observation on the breeding biology of the endemic Sulawesi
red-knobbed hornbill (Rhyticeros cassidix). In: Tropical Biodiversity.
1:107-112.
Kinnaird, M.F. & O’Brien,
T.G. 1999. Breeding ecology of the Sulawesi red-knobbed hornbill,
Aceros cassidix. In: Ibis 141: 60-69.
Kinnaird, M.F., O’Brien, T.G. & Suryadi,
S. 1996. Population fluctuation in Sulawesi red-knobbed hornbills:
tracking figs in space and time. In: Auk 113(2): 431-440.
Kowalczyk, E. 2006. North American
Regional Studbook: Genus Aceros. (unpublished but distributed to
ISIS and AZA facilities). 114 p.
Michi, H. 1993. Der Celebeshornvogel.
Gefierderte Welt. 117(3): 78-83.
Poonswad, P. 1993. Forest flagships.
In: World Birdwatch 15(3): 14-17
Other Resources
Taxonomic Advisory
Group
Hornbill
Research Foundation
* Taxonomic classification varies between references. Classification
information used in this fact sheet was taken from: A Complete Checklist
of the Birds of the World, 2nd edition, by Richard Howard and Alick Moore,
1994. Academic Press Inc., San Diego, CA. 630 p.
**There are several
international and federal agencies that determine the endangered status
of species. WPZ designates a species as endangered
if it is listed as endangered on the IUCN (International Union for
the Conservation of Nature) Red List, the U.S. Fish & Wildlife Service's
Endangered Species List, or on Appendix I of CITES (Convention on the
International Trade of Endangered Species of Flora and Fauna).. |
