NESTING OBSERVATIONS OF THE YELLOW-HEADED CARACARA IN THE CERRADO REGION OF BRAZIL
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SHORT COMMUNICATIONS
General Biology
ORNITOLOGIA NEOTROPICAL 10: 211–215, 1999
© The Neotropical Ornithological Society
NESTING OBSERVATIONS OF THE YELLOW-HEADED
CARACARA IN THE CERRADO REGION OF BRAZIL
Carl A. Johansson1,3, Eric T. Linder1, Clayton M. White1,4 & Jose Carlos Lyra Fleury2
1
Department of Zoology, Brigham Young University, 574 WIDB Provo, Utah USA 84602.
2
Rua Estado De Goiaz, No. 18 Jpameri, Goias Brasil.
Key words: Yellow-headed Caracara, Milvago chimachima, breeding, nest, cerrado, Brazil.
INTRODUCTION Caracaras over a period of six breeding sea-
sons indicate that, at least near the center of
Although the Yellow-headed Caracara (Mil- it’s distribution, and in the ranch setting
vago chimachima) is widely distributed, common where we observed them, Yellow-headed Car-
birds in South America, little is known con- acaras always lay four eggs (previously
cerning their breeding biology. Bierregaard (in reported as 1–2). We are also able to report
del Hoyo et al. 1994) conducted an excellent previously unknown incubation and fledging
review of known data, but details are based rates, as well as to add to prey and food items
on fragmented observations, are incomplete, utilized by Yellow-headed Caracaras. It is
and often inferential (Mader 1981, del Hoyo et especially interesting to note that, while the
al. 1994). It is known that Yellow-headed Car- nests themselves are considered to be fairly
acaras typically lay 1–2 eggs per nest, and they well known (Bierregaard 1995), we were able
use of stick nests, as well as hills (termite to observe previously unreported nest data.
mounds?), as nesting sites (del Hoyo et al.
1994). While information on nest placement STUDY AREA AND METHODS
and structure is well known (greater than 15
reported), information on the breeding The cerrado region (located primarily in cen-
behavior to be almost completely unknown tral Brazil) is the second largest biome in
(Bierregaard 1995). South America. This region encompasses an
Our observations of nesting pairs (or a area about 1.6 million km2, or one half the
single pair repeatedly) of Yellow-headed size of Amazonia (Ab’Saber 1977, Furley &
______________ Ratter 1988). The vegetation types of the cer-
3
Present address: Biology Department, Fresno City rado region range from grassland (campo) to
College, 1101 East University, Fresno, CA 93741. dense savannah (cerradão). Gallery forests
4
Correspondence, Email: Clayton_White@byu.edu (mata galeria) occur in narrow bands along
211GENERAL BIOLOGY
rivers and streams, and dry forests (mata days and all four eggs hatched synchronously
mesofitica) occur in widely scattered small on 30 August. Fledging time for each young
and medium patches where soil conditions varied slightly (17–20 days), with the first
are appropriate. It is these bands and patches leaving the nest on 16 September, the next
of forest that are thought to be the critical ele- two on the 17th, and the last leaving on the
ment for the survival of many bird species in 19th. The fledglings remained in the area
the cerrado (da Silva 1995). Unfortunately the throughout the next few months and were fed
natural vegetation of the cerrado has been by both adults for approximately three weeks
badly fragmented by agricultural practices, after fledging. We observed fledglings being
including induced fire, which has resulted in a fed (n = 19), with various beetles, grasshop-
45% reduction in undisturbed cerrado habitat pers and crickets making up about 90% of the
in the past five years (N.G. da Silva Jr., pers. food items being delivered, with an occasional
comm.) lizard also being provided by the adults. On
All observations of breeding Yellow- 31 July 1993, we found adults nesting in an
headed Caracaras were recorded at a ranch empty 5-l oil can hanging on the inside wall of
located 43 km east of Caldas Novas, Goias, the second story of the ranch’s water tower.
Brazil (17°45’S, 48°35’W). This 3300 ha ranch Two eggs were already in the can and the next
has been returned (as much as possible) to two followed on consecutive days. Eggs were
pristine cerrado vegetation, while the sur- deposited on the can’s bare aluminum bot-
rounding landscape has been extensively tom. Incubation was again delayed until all
altered by fire and agriculture. During four eggs were present. All young hatched on
each breeding season, between 1992 and 24 August, with two fledging on 10 Septem-
1998, pairs were observed several times ber and two the following day (again 17–19
daily (from two to five times per day). Once a days).
nest was discovered it was visited briefly every During the breeding season of 1994, no
day until the fledging of the young. Observa- nest was located, but adult Yellow-headed
tions (dates, numbers, locations, behavioral Caracaras were observed in the same area.
traits etc) were recorded in daily journals. Young were never observed and we surmise
that either egg laying never took place or the
OBSERVATIONS AND RESULTS nest was depredated or otherwise lost.
In August 1995, Yellow-headed Caracaras
On 4 August 1992, a pair of Yellow-headed nested in a wooden box originally constructed
Caracara established a nest in a square plastic to attract snakes. The box was 35 cm. long, 25
bucket, ½ full of ground corn, with an open- cm. wide and 10 cm. tall, and open on the top
ing 20 cm on each side and a depth of 25 cm. (25 x 35 cm.) The wooden box attached to the
The bucket was attached to the wall of the side of the ranch house, 1.75 m. above the
ranch house (1.6 m. above ground) on the ground, just outside the kitchen window in an
house’s inner court. There was no evidence of area of frequent human disturbance. The eggs
the nest building with sticks or other material, were laid on consecutive days from 4–7
but ground corn was used as the nesting sub- August, and were deposited on the bare wood
strate. The first three eggs of a clutch of four of the box. Incubation began after the 4th egg
were laid on consecutive days (4, 5, and 6 was laid, and all four eggs hatched on 29
August) before skipping a day between the 3rd August. One of the four young appeared to
and 4th egg. Incubation began only after the be a “runt” throughout its development.
fourth egg was laid. Incubation lasted for 22 Despite their size differences, all four young
212SHORT COMMUNICATIONS
fledged 17 days after hatching (15 Septem- information concerning the nesting behavior
ber). of Yellow-headed Caracaras.
In 1996 a pair of Yellow-headed Cara- Bierregaard (1998) identifies Yellow-
caras were observed flying into and out of an headed Caracaras as having “unknown breed-
excavated cavity about 10 meters above the ing biology”. While the data presented here
ground in a tree, about 120 meters from the do not answer all questions concerning the
farmhouse. The cavity had been excavated breeding biology of the Yellow-headed Cara-
and used as a nesting site the previous two cara, it does provide a valuable starting point.
years by toucans. While the nest site was inac- In addition to the basic data and observations
cessible for direct observation we witnessed we recorded, we have found several facts
considerable activity in and around the nest which are unusual (and possibly unique) to
site throughout August, and two recently the Yellow-headed Caracaras breeding biol-
fledged young were observed in the first ogy. The consistent (and perhaps determi-
week of September. nant) laying of four eggs conflicts with the
A pair of Yellow-headed Caracaras was reported 1–2 eggs in del Hoyo et al. (1994).
observed using the same tree cavity in 1997, The onset of egg laying occurred over a vary
but no young were found. We did witness narrow range of dates: last week of July or
what we interpret as food begging by the first week of August. The delaying of incuba-
female. While calling to the male, she bowed tion until a full clutch of four eggs has been
her head, extended her wings behind her laid followed by synchronous hatching is
body, and rapidly fluttered her wings. We unusual for falcons. In fact, the superspecies
believe this is a pairbonding and mating rit- compatriot of the Yellow-headed Caracara,
ual, but were unable to remain on site to the Chimango Caracara (Milvago chimachima),
observe the selection of a nest or production begins incubation upon laying the first egg
of young. Food begging has been observed in (del Hoyo et al. 1994).
subsequent breeding seasons as well (unpubl. A relatively short incubation period (22
data). days) as compared to similarly sized raptors is
The female was always the primary incu- interesting, particularly in light of the incredi-
bator at the nest. She was occasionally (one bly short fledging period of 17 days. Again,
or two times per day) relieved by the male compare these numbers with that of the Chi-
who would call her off the nest. She would fly mango Caracara. While the female Chimango
to the calling male, who in turn flew into the Caracara is slightly lighter than the female
nest and settled on the eggs. The female Yellow-headed Caracara (320 vs 370 g aver-
would return a short time later (usually 5 to age weight), it has an incubation of 26–27
10 min) and incubating duties would again be days (4–5 days longer) and a fledging period
switched. We observed this behavior on a of 32–34 days (del Hoyo et al. 1994), twice as
daily basis (during incubation) and were typi- long as that of the Yellow-headed Caracara.
cally alerted to the event by the calling of the The Chimango Caracara is reported to typi-
male. cally lay 3 eggs, with up to 5 eggs being
reported occasionally (del Hoyo et al. 1994).
DISCUSSION Falconids of similar size found outside of
South America also appear to have consider-
Several things we have observed over a ably longer incubation and fledging periods.
period of six breeding seasons appear to be in For example, the Australian Hobby (Falco lon-
direct contrast with previously published gipennis) (female weight about 295 g, Dunning
213GENERAL BIOLOGY
1992), which is reported to lay 2–4 eggs, incu- Why are our observations about egg numbers
bates for 28–35 days and has a fledging and nest construction and location so differ-
period of 34–38 days (del Hoyo et al. 1994). ent than those previously reported? We think
Eleonora’s Falcon (Falco eleonorae) (female that this may be an artifact of previous obser-
weight about 390 g), normally lays 2–3 eggs vations of Yellow-headed Caracaras being
which it incubates for 28–30 days, while the done on the extreme periphery of it’s South
fledging period is about 37 days (del Hoyo et American distribution, while our observations
al. 1994). Clearly the very short incubation were from the center of their known range.
period of the Yellow-headed Caracara (22–23 At the range periphery, a species is experienc-
days) and incredibly short 17–18 day fledging ing ecological, and probably physiological,
period (less than half of the time required by limitations. The differences found in clutch
other falconids of similar size) is an aspect size may be linked to the readily available
that merits further study. We can think of no food supply provided by conditions at the
reason why these times should be so much ranch. Consequently, it is unclear if the larger
shorter than similar falconids. clutch sizes we observed are attributable to
Mader (1981) noted that young fledged differences in position within its geographic
during the wet season. His interpretation was range (center vs. peripheral), or unique to
based upon two observations from the litera- conditions created at the ranch. This is one
ture. In the first, Renessen (in Haverschmidt, aspect, of many, of the Yellow-headed Cara-
1968) described finding a “nearly fledged bird caras breeding biology that needs to be
at the end of the dry season”. Similarly, Fried- addressed. Lastly, our new information on a
mann & Smith (1950) described finding a common South American raptor serves to
recently fledged bird during the wet season in highlight the extreme lack of information
Venezuela, although it is not clear at what available on South American raptors (Bierre-
phase of the wet season it was found. Taken gaard 1995, 1998).
with our own observations, we suggest that
Yellow-headed Caracaras fledge at the start of ACKNOWLEDGMENTS
the wet season, or even prior to, prepared to
exploit this food-abundant period. We are exceedingly grateful to FURNAS-
We suspect that previous reports of stick- Centrais Eletricas S.A., for providing the
nests may have been the opportunistic use of, opportunity for gathering the data used in this
or commandeering of, other species stick study and to Hamilton Garboggini for help in
nests. In fact, Sick (1993) reports the use of various aspects of logistics and general infor-
piles of sticks gathered by both the Fire-wood mation of the study site. We also thank the
Gatherer (Anumbius annumbi) and the Monk Universidade Catolica de Goias (UCG) and
Parakeet (Myiopsitta monachus) as nest sites for particularly Dr. Nelson Jorge de Silva Jr., as
the Yellow-headed Caracara. Our findings of without them we would have never had a
the use of man-made structures, as well as chance to visit and work in Brazil. This manu-
cavity nesting by Yellow-headed Caracaras, script has benefited from the reviews of R.
add new information to an area previously Bierregaard and an anonymous reviewer.
considered quite well known.
Our data suggest several interesting ques- REFERENCES
tions. Why would the incubation and fledgling
periods be so short for Yellow-headed Cara- Ab’Saber, A. N. 1977. Os dominios morphoclimat-
caras? We can think of no compelling reason. icos da America do Sul. Premeira aproximacao.
214SHORT COMMUNICATIONS
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