Taxonomy
Characteristics
shared between motmots and other members of the Coraciiformes order include
small feet relative to body mass, syndactyl toes, cavity nesting (typically
in cliffs, banks, rock crevices, or trees), and a primarily carnivorous
nature. With a wide geographic range and differing habitat usage, the
Blue-crowned Motmots have been classified into 20 distinct subspecies.
Some of
these subspecies are geographically isolated and display significant morphological
differences. These few subspecies may eventually be considered at a future
time for individual species status. An example of this possibility would
be Momotus momota bahamensis found only on the islands of Trinidad and
Tobago. Due to an apparent inability of motmots to cross large waterways
in flight, these two populations have been genetically isolated from each
other and the remaining 19 subspecies for approximately 11,000 years.
Closer examination of the DNA fingerprint of the island species may show
differences from the mainland population (del Hoya; 2001).
Another
example of a subspecies that may eventually qualify for species level
would be Momotus momota lessonii, ranging from southern Mexico to Panama.
Although the geographic range potentially overlaps with several other
subspecies, M.m. lessonii varies morphologically and vocally from other
forms found on the opposite side of the Andes Mountain range significant
enough to classify them as a distinct species (del Hoya; 2001).
The Motmotidae
appear to originate as an Old World family, primarily relating to a fossil
record of Protornis glarniensis, found in Switzerland. The recovery in
Florida of a yet to be named fossil motmot from the late Miocene period
that is physiologically and morphologically similar to the living motmots
of today changed theories on the appearance of motmots in the New World.
The connection between this fossil and the current living population of
motmots can be found in the proximal end of the humerus, which is distinctive
in the Momotidae and differentiates them from the remainder of the Coraciiformes
(Feduccia, 1996).
The study
of this fossil dates the appearance of motmots in North America as significantly
prior to any fossil records encountered in Central or South America. This
indicates that the origin of the Momotidae in the New World was not of
South or Central American origin as was once considered. Instead, it is
believed that motmots spread from North America into Central America initially,
and then into South America with the opening of the Central American Land
Bridge. Motmots then became restricted geographically from North America
due to inter-specific competition and climatic change (Feduccia, 1996).
Population
Status
At this
time the wild status of Blue-crowned Motmots is not listed as threatened
or endangered, in fact Blue-crowned Motmots are common throughout much
of their native range. The current living North American regional captive
population, numbering 50.47.17 in the North American Region, descends
from a limited parentage, and captive breeding has been inconsistent recently.
Two recent group importations have significantly improved the genetic
diversity of the captive population.
Population
Distribution
Ten species,
forty-seven taxa, and six genera of Motmots are found in Mexico, the majority
of South America (with the exception of Chile and Uruguay), and
most of Argentina. Blue-crowned Motmots inhabit a wide geographic range,
including Bolivia, Paraguay, Argentina, Brazil, Colombia, Ecuador, Peru,
Mexico, Trinidad, and Tobago. Throughout this range, Blue-crowned Motmots
are divided into twenty currently recognized subspecies, but captive management
in the population management plan will occur strictly at the species level.
Threats
Toward Survival
Due to a
wide geographic range, tolerance of intrusion by man, and numerous protected
areas comprising habitat Blue-crowned Motmots as a species should continue
to thrive.
Reproduction
Nest
Description
Nest tunnels
are generally dug during the rainy season when the soil is soft, which
over the geographic distribution ranges from August to October. Blue-crowned
Motmots generally prefer to excavate their tunnels into the sides of cliffs
or into horizontal ground, but will use rock crevices on occasion if suitable
nesting sites do not exist within the territory. Both the male and female
share relatively equally in the digging tasks. The excavation of the nest
tunnel system and the terminal nesting chamber can take as long as 2 ½
months to complete. The timing of the work is focused primarily on the
late morning until the late afternoon when the soil is typically the driest.
It is not unusual for the motmots to begin and abandon several nest tunnels
before settling on one particular area.
With the
intrusion of man-made structures into the habitat of Blue-crowned Motmots
has come the introduction of new nesting opportunities in the way of roadside
berms, banks, and cliffs. In some areas this intrusion has allowed the
motmots to attain a higher population density then was previously possible
in pristine habitat.
The excavation
efforts will result in a long, winding burrow typically measuring at least
5 feet in length, but ranging up to 14 feet in length and 3-4 inches in
diameter, with the unlined terminal nesting chamber measuring approximately
10 inches high, 10 inches in width, and 14 inches in length. The winding
nature of the tunnel system aids in the avoidance of nest predation by
shielding the nesting chamber from being viewed from the tunnel mouth.
This winding tunnel system may also be the result of obstructions such
as rocks or root masses being encountered and avoided during the excavation.
The entrance to the nesting burrow may be concealed by root masses or
overhanging vegetation.
Another
method used to attempt to limit nest predation is each parent undertaking
extended incubation bouts to limit the amount of activity around the entrance
to the nest tunnels. Typically, the incubation shift of each parent will
last at least 3 hours, with some shifts lasting more than 8 hours. There
have been reports of the motmots relieving each other only twice during
the course of the day, once at dawn and once at dusk. This behavior has
been observed in both the wild by Alexander Skutch and in the captive
population at various participating institutions.
After the
tunnel system is completed, including the nest chamber, the birds abandon
the area until the following March or April, the onset of the breeding
season. At this point, the birds will return to the area for the onset
of the nesting season. Motmots in the higher elevation regions have been
observed roosting in the nest burrow during the non-breeding season. This
behavior is thought to be climate dependant, since those motmots found
in more tropical regions of their distribution do not roost in the nesting
cavities during non-breeding seasons.
No recorded
evidence of nest sanitation by motmots has been observed, which would
explain the typical behavior of digging a new nest tunnel each breeding
season. It has been observed that motmots do not reuse the same nest site
in successive breeding seasons. Even with the absence of nest sanitation,
the motmot chicks exit from the nest tunnels in immaculate feather condition.
Egg Laying
After the
courtship rituals have concluded, copulation between the pair, which lasts
5 to 10 seconds based on captive bird observations, occurs in late April
to early May. The female will then lay 3 to 4 white eggs, each measuring
approximately 26 mm in length and 23 mm in width. Incubation lasts approximately
21 days, during which time one bird will incubate from early afternoon
until the following dawn, before being relieved by its mate for incubation
during daylight hours. By only relieving each other from incubation duties
twice daily, movement around the nest tunnel entrance is kept to a minimum.
Feeding
Behavior
Blue-crowned
Motmots generally sit quietly hidden in shady trees searching for prey
items, flycatching insects and pouncing on small land dwelling animals.
Blue-crowned Motmots also use their heavy set, deeply serrated bill to
brush away leaf litter and probe into the earth searching for prey items.
If the prey item eludes the motmot's first capture attempt, the motmot
may hop in pursuit. The prey species may include: small lizards, frogs,
birds, small rodents, arthropods, centipedes, spiders, butterflies, cicadas,
beetles, and mantis. Trace quantities of fruit will be consumed as a portion
of the diet. Research by Orejuela in the Yucatan Peninsula found that
84.2% by volume of the diet of Blue-crowned Motmots was comprised of insects.
The remainder was found to be gastropod mollusks, arachnids, and chilopods,
with a small portion of fruit and plant reproductive parts. This consumption
would be regionally influenced and would depend heavily on food items
available within the home territory of the motmots (Orejuela, 1975). A
study of the stomach contents of 52 Blue-crowned Motmots found that 61.5%
contained arthropods only, 21.2% contained arthropods and fruit, 15.4%
contained fruit only, and 1.9% contained unidentifiable mush.
Large food
items are caught and taken to a perch where the item will be repeatedly
bashed against the tree branch or rock to kill and tenderize the prey
item. After the pulverizing is complete, the food item is swallowed whole.
The observation
of wild motmot nests has shown that the chicks are not fed fruit until
the young were at an average of approximately 13 days old, and even from
that point on it was offered as a very small proportion of the overall
diet.
Vocalizations
Motmots
typically do not vocalize frequently, with the exception of during breeding
season. They are most vocal during the hours just prior to dawn and at
dusk. During this time, a variety of vocalizations can be used for territory
settlement, advertisement, courtship, pair bonding, and maintenance of
boundaries. The advertisement call by the male is a low frequency double
note represented as "hoot-hoot". This call can occasionally
be extended to a series of up to eight notes. The female generally will
respond to this advertisement call with a single note response represented
as "hoot".
Another
commonly heard vocalization is used during feeding to assemble small family
based forage groups. This call is a loud clucking sound similar to "kla-kla-kla-kla".
This vocalization is variable in intensity and can last from two to five
minutes in length.
During aggressive
interactions or territorial defense, the vocalization may include a hoarse,
dry, coughing bark. This may be repeated in a long series of chattering.
The parents,
upon entering the nest tunnels to feed, will utter soft vocalizations
along with feather ruffling sounds. The chicks will respond to these calls
with begging vocalizations. Initially the young in the nest tunnel system
are quiet, but as they grow their vocalizations increase in strength and
duration. After about 10 days of age, the young birds can be heard vocalizing
from a distance thirty to fifty meters from the nest entrance. (Orejuela,
1975).
Characteristics
Body
Measurements and Adult Weights
Blue-crowned
Motmots, depending on the subspecies involved, have a body length ranging
from 17-20" (43-50cm), including the tail length. Depending on the
subspecies involved, the normal body weight range for Blue-crowned Motmots
can vary from as little as 77 grams to as much as 175 grams. The largest
subspecies are those found in the tropical lowlands east of Andes, the
smallest subspecies being found in the peripheral parts of the range.
Physical
Description
Blue-crowned
Motmots are attractive birds with a similar color pattern to that found
in all ten Momotidae species found over a wide geographic range. This
pattern includes bright colors on the tail, face, and to a lesser extent
the wings. Similar arrangement of patterns and colors exist on the heads
of most species, with bright blue markings heightened by black contrasts.
An apostrophe-like black marking surrounded in some subspecies by a turquoise
border is found on the chest of most species. Body coloring is varying
shades of olive, light blue, rust, and
brown. Blue-crowned Motmots typically undergo a postnuptial molt, occurring
anywhere from July through October. All subspecies are primarily monomorphic,
with the males typically being slightly larger in body size and tail length.
Physical characteristics cannot be reliably used to determine sex.
The legs
of Blue-crowned Motmots are characterized by short tarsi and a syndactyl
foot, which is distinguished by a single rear facing toe, and a middle
toe almost completely joined to the inner toe. Blue-crowned Motmots, like
many cavity nesters and insectivores, have well developed tactile rictal
bristles which appear to originate from contour feathers. The rictal bristles
have a stiff rachis (shaft) and only have barbs near the base. It is likely
that the rictal bristles serve primarily as a sensory device for use in
the tunnel system and nesting chamber, but they may also assist in filtering
dust and dirt particles from the nares. Adult birds possess a red iris,
juveniles possess a dark brown iris. All Motmots have shared characteristics
including the possession of a beak that is short, down-curved slightly,
and heavily serrated along the edges of the upper and lower mandible running
the entire length of the beak. All representatives of the family Momotidae
have short, rounded wings which are not well suited for long flights.
The most
striking physical characteristic of Blue-crowned Motmots is their spatulate
shaped, racqueted tail, which is formed by the loss of barbs on the two
long, upper central tail feathers. The center retrices after molt are
feathered throughout the length, only becoming spatulate after the natural
loss of the barbs. At one time it was thought that the racqueted tail
feathers were a result of the birds themselves removing the feathers,
but it has been since found that the barbs are loosely attached at that
region of the retrix and detach from the feather shaft on their own. Members
of the genus Momotus are the only representatives of the family Momotidae
that possess 12 retrices, all other members of the family possess 10.
The center retrices in males tend to be slightly longer than those in
the females.
The fledged
young resemble the adults, but the crown is greenish-blue with indistinct
borders, the mask is sooty black and smaller than that of adults. The
fledglings also do not possess the distinct breast spot or tail racquets
of adults and have a dark brown iris as opposed to the red iris found
in adult birds.
Captive
Individual Identification Methods
In a large
free flight environment, Blue-crowned Motmots can be a challenge to identify
specific individuals. Motmots tend to perch with tarsi slightly bent,
blocking sight of bands. Brightly colored plastic bands may assist in
individual specimen identification if necessary. In addition to banding
for immediate visual identification, transponders should be injected into
the pectoral muscle. This can be useful not only for identification should
the band become lost, but provides another accurate method of identification
for cross-referencing in ISIS when a bird is shipped between institutions.
Capture
Methods
In small
exhibits, Blue-crowned Motmots are somewhat easy to capture using any
available soft, fine-meshed aviary capture net. The smaller the mesh size,
the less likely toenails will become entangled in the net. In large free
flight aviaries, the capture can be accomplished using one of many trap
cages designs. A trap that works well is a small enclosure constructed
with a non-automatic door. When the target bird enters the small enclosure,
the door can be manually closed from a somewhat remote location using
a pull string. Generally, allowing the birds time to adjust to the trap
and providing favorite food items during the acclimatization process will
aid in the capture. Once the motmot has been captured, care must be taken
in removing the toes from either the net or wire mesh to avoid injury.
Crating
and Transport
For shipping
between institutions, airline approved travel containers such as Vari-Kennels
with a natural perch firmly attached to the sides would be the preferred
method of transport. In order to lower the stress of shipping, the door
and windows of the kennel can be covered with a visual barrier (burlap,
shade cloth, etc). If a travel kennel is unavailable, a carrier can be
constructed using hardware mesh and plywood, ensuring that the door can
be securely fastened closed. Perching should be provided at a height to
limit contact between the tail and the bottom of the shipping crate.
Pest
Control
As in all
carnivorous species, any pest control methods must ensure a complete absence
of secondary toxicity. Boric acid, dish soap mixtures, or pyrethrin based
insecticides have been used successfully in the treatment against cockroaches
in several institutions and do not have the secondary toxicity associated
with most commercial treatments. Rodent control should be accomplished
through the use of snap traps (hidden and secured to prevent access by
the birds) or revolving live traps. Rodentecides should be avoided if
at all possible.
Enclosure
Design
Blue-crowned
Motmots can safely be housed in either mixed species free flight exhibits
or in smaller "jewel-box"enclosures. These are not particularly
active birds, and therefore can be housed in spaces as small as 8' x 8'
x 8' (or similar square footage). Larger allotted areas would be preferable
and likely would increase the instance of reproduction.
The construction
of the enclosure can be accomplished through numerous available designs.
The preference for wire mesh would be not larger than ½" x
3" x 18 gauge. Smaller mesh opening sizes are preferable to restrict
rodent and snake movement into the enclosure. Phantom mesh, Cascade Coil,
and Zoomesh are suitable for barriers, although these are more expensive
then standard galvanized after welded wire. Glass or plexiglass can also
be used, although care must be taken to lessen the likelihood of impact
when birds are introduced to the enclosure. Glass and plexiglass also
reduce airflow and could potentially lead to stagnant air and/or fungal
infestations of enclosures. Piano wire can be utilized, but it does offer
the potential for an escape route with motmots flying through the wire
if it is not small enough openings and under sufficient tension.
Motmots
have not proven to be exceptional escape artists. Only 19 out of 504 (3.77%)
specimens listed in the historical studbook have escaped to the wild at
one time or another. Of those that have escaped, 7 were recaptured. An
additional 16 birds were listed in the North American Regional Studbook
as having escaped their enclosure into and being recaptured from a secondary
containment area. The enclosure should have a double door safety cage
if it is an outdoor system due to the distinct threat of escape through
a single door system. The bottom of the enclosure should be protected
through the use of wire or concrete to keep predators from digging into
the enclosure and keep motmots from digging out. There have been multiple
cases of the escapes being linked to birds digging out of the enclosure.
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Riverbanks
Zoo Breeding Enclosure Gallery
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Bronx
Zoo Breeding Enclosure Gallery
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Nestbox
Design
If an artificial
nest box design is to be used, the construction is fairly simplistic and
straightforward. A rectangular plywood box with a 3" PVC tube connection
to simulate the tunnel can be constructed. The measurements are not critical
as long as sufficient space is provided within for the two adult birds
and the potential of 4-5 offspring. Ease of maintenance and access should
be considered due to the fairly infrequent nest maintenance procedures
undertaken by the adult birds.
Group
Composition
For breeding
purposes, the ideal group composition would be 1.1 Blue-crowned Motmots,
as it is extremely likely that the pair will become territorial and aggressive
towards any con-specifics sharing the enclosure during breeding season.
In rare cases, large free-flight aviaries may successfully house mixed
gender groups of birds during the non-breeding season, but this is not
ideal and usually will necessitate the removal of all but the dominant
pair during breeding season. Most institutions that have attempted to
house multiple pairs in the same aviary have needed to remove all but
the dominant pair when sexual maturity and breeding season were reached.
There have been several institutions that have successfully housed single-sex
groups long term in the same enclosure long term without any significant
aggressive interactions.
Offspring
may be left in the exhibit with parents through the non-breeding season
if necessary, however they should be removed prior to the onset of the
following breeding season, beginning with the excavation of the tunnel
system in early fall. Typically the aggression from the adult pair towards
the juveniles has escalated to necessitate the removal of the offspring
when the juveniles reached approximately four to five months in age. Based
on captive breeding records, this occurs between September and November
in the majority of incidences.
Introductions
Feeding
Methods, Diets
A wide variety
of diets have been used successfully by institutions, all of which are
similar in basic components. The diets are based on a combination of proprietary
pellets, bird of prey meat, insects, pinky mice, and a small portion of
minced fruits/vegetables. Location of the diet does not appear to influence
the consumption levels as motmots routinely feed on both arboreal and
ground dwelling food items. A sample diet previously in use is listed
below:
Blue-crowned
Motmot Sample Diet (Per Pair) - 140 gram birds
Diets
Fed Out Twice Daily - Each feeding contains:
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Non-Breeding
Season
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Breeding
Season
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Chick-rearing
(Feed Ad Lib)
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1.5
tbsp (11g) Hills Science Diet Feline Maintenance Pellets, soaked
after measuring
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2.25
tbsp (17g) Hills Science Diet Feline Maintenance Pellets, soaked
after measuring
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Hills
Science Diet Feline Maintenance Pellets, soaked
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1
tsp bird of prey meat
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1.5
tsp bird of prey meat
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Bird
of prey meat
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4
Mealworms (.6g)
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6
Mealworms (1.0g)
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Mealworms
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4
Waxworms (1.0g)
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6
Waxworms (1.6g)
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Waxworms
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4
Crickets (1.0g)
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6
Crickets (1.5g)
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Crickets
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2
Superworms (1.0g)
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2
Superworms (1.0g)
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Superworms
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2
whole Pinkies (6.0g)
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2
Whole Pinkies (6.0g)
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Diced
Pinkies increasing in size as chicks age
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½
tsp Bird Mix (2g) (variety of minced fruits/veggies)
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½
tsp Bird Mix (2g) (variety of minced fruits/veggies)
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Bird
Mix (variety of minced fruits/veggies)
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Water
Supply
Motmots
are generally fond of bathing, and should be provided with a water source
with a sufficient width and depth to allow free access. Many institutions
have provided water movement through the use of streams and/or waterfalls
within the exhibit, and the motmots have shown themselves to use the moving
water regularly for bathing and consumption.
Courtship
Behavior
Although
the nest chamber is unlined, courtship rituals between the pair still
include the male offering leaves, twigs, grass, and flowers to the female.
This courtship offering behavior has been observed regularly in both the
wild population and in captive settings and appears to reinforce the pair-bonding.
Penduluming
of the tail increases in speed, frequency and duration when the birds
are excited, whether that is due to pair bonding and courtship behavior,
feeding behavior, or territory defense.
Enrichment
Several
enrichment ideas have been attempted with motmots, although the most successful
have been food-based initiatives. Slow-release insect feed stations utilizing
mealworms, crickets, or waxworms can be constructed out of end-capped
PVC with access holes drilled if appearance is not an issue. If the appearance
of the feeder is of importance, bamboo sections with access holes can
be used.
Captive
Reproduction
Development
Blue-crowned
Motmots are completely altricial, and thus the parents must provide for
all needs. Feather shafts will begin to emerge from the hatchlings altricial
bodies at approximately 7-9 days of age, and the eyes will begin to open
at approximately 14-15 days of age. After 29-31 days in the nest, the
offspring will begin to make their way
up the tunnels towards the entrance, by which time they will look identical
to the parents, with the exception of lacking the racketed tail. After
exiting the nest tunnels, the fledglings are extremely weak flyers and
exhibit difficulty in perching due to their subterranean development.
This quickly fades, as the fledglings develop these skills within the
first day or two post-fledging. The young gain independence relatively
soon after fledging, some being observed self-feeding within 3-4 days.
Approximately two weeks after leaving the nest tunnels, the young are
consistently self-feeding, and 3-5 weeks post fledge the offspring will
have gained complete independence from the parents.
Blue-crowned
Motmot Chick Development Gallery
Reproduction
Both males
and females in captivity have shown themselves to be capable of reproduction
at one year of age, but reliable reproduction generally does not occur
until both are three years of age.
In captivity,
the oldest recorded breeding male was 24 years old. Females in the captive
records appear to become post-reproductive at 15 years old.
Offspring
Care
After hatching,
the parents alternate brooding, with the female being primarily responsible
for the brooding and the male providing most food items. When the offspring
are approximately one week old, both parents will be out of the nest occasionally
hunting for food. Initially, the feeding will occur at 2-5 minute intervals,
with the parents focusing almost exclusively on live food such as crickets,
mealworms, waxworms, and earthworms. The frequency of feeding will decrease
as the hatchlings age, with the trips into the nest dropping to 5-6 per
hour within two weeks post hatching. The parents begin to offer a variety
of live insects, pinky mice, and other protein-based food items almost
immediately post hatching, and pelleted food items at approximately day
12-14 post hatching, although live food continues to be the overwhelming
preference.
Hand-Rearing
In captivity,
Blue-crowned Motmots have proven to be excellent parents and hand-rearing
is rarely, if ever, necessary. If this must be undertaken, care is similar
to that of many soft-billed birds and an example of a hand-rearing protocol
can be seen here.
Blue-crowned
Motmot offspring are offered a diet similar to that given to adult birds,
with the overwhelming majority consisting of protein based items. This
can be soaked pellets, soaked cat food, soaked dog food, bird of prey
meat, mealworms, waxworms, crickets, earthworms, pinky mice, etc. Trace
amounts of fruits can be added to round out the diet.
Due to their
altricial nature, hatchling motmots require supplemental heat and humidity
until feather development allows the birds to thermoregulate.
Bibliography
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