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55
ORNITOLOGIA NEOTROPICAL 25: 55–61, 2014
© The Neotropical Ornithological Society
POST-FLEDGING SURVIVAL OF BLUE-FRONTED PARROTS
(AMAZONA AESTIVA)
Sarah Faegre1 & Igor Berkunsky2
1Rota Avian Behavioral Ecology Program, University of Washington, P.O. Box 1298,
Rota MP 96951, USA. E-mail: sfaegre@gmail.com
2Instituto Multidisciplinario sobre Ecosistemas y Desarrollo Sustentable, Universidad
Nacional del Centro de la Provincia de Buenos Aires. Campus Paraje Arroyo Seco,
7000 Tandil, Argentina. E-mail: iberkunsky@parrots.org
Resumen. – Supervivencia de volantones en el Loro Hablador (Amazona aestiva). – El Loro Habla-
dor (Amazona aestiva) se encuentra bajo una intense presión producto de la destrucción de su hábitat
y la remoción de adultos y pichones para el comercio de mascotas. Mientras que estimaciones de éxito
reproductivo y supervivencia de pichones han sido producidas en estudios previos, la supervivencia de
los volantones es desconocida. Entre enero y abril de 2007, equipamos con radio-collares y monitorea-
mos 18 volantones correspondientes a ocho nidos de Loro Hablador. Monitoreamos las aves con trans-
misores por un promedio de 33 ± 20.9 (SD) días (rango: 11–87) desde que abandonaron exitosamente
el nido hasta que murieron, desaparecieron del área de estudio o falló el transmisor. La supervivencia
durante este período fue 94% (n = 18) y la única muerte, que ocurrió 11 días posteriores al abandono del
nido, fue causada por un ave rapaz. Durante febrero, perdimos la señal de 15 de los 17 volantones
supervivientes a un promedio de 27.3 ± 7.3 (SD) días (rango: 16–37) posteriores al abandono del nido.
Perdimos las señales de los hermanos al mismo tiempo, indicando una dispersión de los grupos familia-
res desde el área de estudio. Las señales perdidas no pudieron ser relocalizadas durante el resto del
período de estudio. Estudios adicionales se necesitan para definir la supervivencia de los juveniles sobre
un periodo de tiempo mayor, asi como elucidar la dirección y distancia de viaje de las aves que abando-
nan el área natal después de la temporada reproductiva.
Abstract. – Blue-fronted Parrots (Amazona aestiva) are under intense pressure from habitat destruction
and removal of adults and chicks for the pet trade. While estimates of nesting success and nestling sur-
vival of Blue-fronted Parrots have been produced in previous studies, the survival of fledglings is
unknown. During January–April 2007, we monitored 18 radio-collared Blue-fronted Parrots from eight
wild nests. We monitored radio-collared birds for an average of 33 ± 20.9 (SD) days (range: 11–87) post-
fledging, until death, disappearance from the study area, or failure of the collar. Survival during this
period was 94% (n = 18) and the single mortality, which occurred 11 days post-fledging, was due to pre-
dation by a raptor. During February, we lost the signals for 15 of 17 surviving fledglings at an average of
27.3 ± 7.3 (SD) days (range: 16-37) post-fledging. We lost the signals for siblings concurrently, indicating
a dispersal of family groups from the study area. The lost signals could not be relocated during the
remainder of the study period. Additional studies are needed to define the survival of juveniles over a lon-
ger period as well as to elucidate the direction and distance of travel for birds that leave the natal area
after the breeding season. Accepted 23 May 2014.
Key words: Blue-fronted Parrot, Amazona aestiva, Argentina, Chaco, parrots, post-fledging movements,
survival, telemetry.
56
FAEGRE & BERKUNSKY
INTRODUCTION
Two important and little-studied aspects of
parrot conservation biology include seasonal
movements and mortality (Snyder et al. 2000).
While data describing the breeding range and
nest success of many species, including Blue-
fronted Parrots (Amazona aestiva) have been
published (Fernandes-Seixas 2002, Berkunsky
& Reboreda 2009, Berkunsky et al. 2009),
information on seasonal movements and
fledgling mortality are lacking. In many psitt-
acines, the first two to eight weeks after fledg-
ing are characterized by limited mobility and
high mortality (Snyder et al. 1987, Lindsey et
al. 1991, Smith & Moore 1992, Myers &
Vaughan 2004, Salinas-Melgoza & Renton
2007). Post-fledging survival estimates are
important because they increase the accuracy
of population viability analyses and improve
the ability of managers to target conserva-
tions efforts to the most vulnerable life stages
(Holdsworth et al. 2011).
Due to habitat destruction and capture
for the pet trade, 19 of 30 Amazona species
are considered threatened (Critically Endan-
gered, Endangered, or Vulnerable; IUCN
2013). Other Amazona species remain rela-
tively widespread and abundant but many,
including the Blue-fronted Parrot, are experi-
encing local population declines (del Hoyo et
al. 1997, Berkunsky et al. 2012). The primary
causes of the decline of Blue-fronted Parrots
in Argentina are habitat destruction and
direct persecution by humans, including the
removal of chicks for the pet trade and cap-
ture or hunting of juvenile and adult parrots
at citrus orchards (Bucher et al. 1992, Berkun-
sky et al. 2012).
Blue-fronted Parrots inhabit the tropical
and sub-tropical dry forests and savannahs of
Argentina, Brazil, Paraguay, and Bolivia (For-
shaw 2006). The majority of Argentina’s Blue-
fronted Parrots breed in mature Chaco for-
ests (Berkunsky et al. 2012). Northern Argen-
tina’s Chaco province provides some of the
largest remaining areas of this threatened hab-
itat (Boletta et al. 2006). The regular, seasonal
fluctuation in abundance of individuals in
these forests between the breeding and non-
breeding seasons has led researchers to sug-
gest that a partial migration could be occur-
ring (Bucher et al. 1992). It is likely that Blue-
fronted Parrots leave the dry Chaco habitat,
where their foods become scarce during the
non-breeding season, possibly traveling north
or northwest to riparian and transitional for-
ests where other fruits and seeds are available
(Berkunsky et al. 2012).
From January to April of 2007 we esti-
mated post-fledging survival of fledglings in
their natal area and collected evidence for the
hypothesis of partial migration of Blue-
fronted Parrots breeding in mature, dry
Chaco forests.
METHODS
Study area and study subjects. The Loro Hablador
Provincial Park (25°28.19’S, 61°54.70’W, 173
m a.s.l.) occupies 300 km2 of dry Chaco forest
and savannah in Chaco province, northern
Argentina. The dry Chaco forests of South
America are considered a high priority for
conservation in the Neotropics (Dinerstein
et al. 1995), and the Park was created to
protect the breeding habitat of Blue-fronted
Parrots in Argentina. The climate is sub-
tropical, with distinct wet and dry seasons
and the highest maximum temperatures on
the continent, reaching 52 degrees Celsius
(Rabinovich 2004). The annual precipitation
averages 590 mm, of which 75% falls between
November and March (Berkunsky &
Reboreda 2009). The flat, dry landscape is
dominated by xerophilic forest with a dense,
thorny understory. Canopy vegetation aver-
ages 15 meters and is predominately com-
posed of hardwoods such the White
Quebracho (Aspidosperma quebracho-blanco,
57
POST-FLEDGING SURVIVAL OF BLUE-FRONTED PARROTS
Apocynaceae) and Red Quebracho (Schinopsis
lorentzii, Anacardiaceae), which provide nest-
ing cavities for Blue-fronted Parrots (Berkun-
sky & Reboreda 2009).
We chose to study nests for their proxim-
ity to an 18-meter tower, which we climbed to
locate distant radio signals. The tower was
located about 1 km from the Park Ranger
Headquarters. In December 2006, 19 chicks
from nine nests within a 7 km radius of the
tower were fitted with radio collars shortly
before fledging. One chick was depredated by
a boa constrictor (Boa constrictor occidentalis)
before fledging, which reduced the sample
size to 18 chicks from eight nests. The chicks
from these eight nests consisted of two 1-
chick nests, two 2-chick nests, and four 3-
chick nests. Most chicks were collared when
their primaries had fully emerged from the
sheath or upon reaching a wing chord (flat-
tened) of 200 mm. Two chicks were collared 1
week earlier because of their tendency to
climb up the nest cavity, avoiding capture. All
chicks had a mass of at least 350 g when they
were fitted with collars.
Between 10 January and 28 April 2007 we
tracked radio-collared fledglings in the Park
and surrounding private properties. During
March 2007, we also conducted searches in
four areas outside of the Park area, where
flocks of Blue-fronted Parrots were larger
and more common during the non-breeding
season (IB pers. observ.). These areas
included sites near: 1) The towns of Pompeya
(24º55’S, 61º28’W) and Wichi (24º36’S,
61º27’W), along the Bermejito and Bermejo
rivers, 75 and 110 km northeast of the Park;
2) The Ingenio Tabacál (23º15’S, 64º18’W),
Salta province, 340 km northwest of the
Park; 3) Finca Las Varás (23º21’S, 64º05’W)
Salta province, 320 km northwest of the Park
and 4) Cachipunco and the citrus orchards
of Santa Clara (24º16’S, 64º38’W), Jujuy
province, 307 km west-northwest of the
Park.
Telemetry equipment. Birds were tracked using
R-1000 receivers (Communications Specialists
Inc.) and 3-element collapsible yagi antennas
(Telenax Inc.). Our radio-collars, TX-203C
(Telenax Inc.), weighed 13.5 g, approximately
4% of an adult parrot’s body mass. Each col-
lar was equipped with activity/inactivity and
mortality sensors. The mortality sensors were
programmed to give a double-beep after four
hours of inactivity. Our order was custom
made to maximize detection range and thus
the battery life of our transmitters was only
3.5 months. The detection range was 1–3 km
from the ground and 3–6 km from the top of
the 18-m tower. The reception range was
strongly affected by the height of parrots in
the vegetation and varying density of foliage.
Search techniques. Once the collars were in
place, we determined the status of each chick
daily until fledging. The signals of fledged
chicks were checked at least once per day,
when weather conditions allowed, by noting
the strongest bearing from the closest, acces-
sible ground location. We searched for signals
from access points on roads and trails, or
from the nest tree and/or from the top of the
tower. Daily searches were confined to a 7 km
radius around the tower. On four occasions
we were able to physically locate fledglings
during the first week post-fledging however,
unless otherwise noted, our discussion of
movements is based on radio signal locations.
Radio signal locations were plotted as occu-
pancy of a semi-circular plot, created using
the maximum possible detection distance of
the signal from the observer (3 km) and our
maximum directional error (± 15 degrees).
Location plots were not detailed enough to
employ meaningful statistical calculations and
thus we limit our discussion of the move-
ments of tagged birds to anecdotal observa-
tions.
We conducted vehicle searches from
14–26 March 2007 to search for lost signals in
58
FAEGRE & BERKUNSKY
a larger area. The first week was spent search-
ing systematically along all drivable roads
within a 20 km radius of the tower. We
stopped every 2 km and conducted a search
for each frequency with the antenna held
approximately 3 m above the ground. We
scanned individual frequencies for 30-45 s
each by holding the antenna steady for 5 s
before moving it 45 degrees and waiting
another 5 s. After concluding the vehicle
searches in the vicinity of the Park, we con-
ducted final searches in areas that have been
suggested as likely wintering grounds for the
Blue-fronted Parrots breeding in the Park.
These areas where chosen because they have
historically shown a seasonal increase in num-
bers of parrots, with large flocks appearing in
the winter (IB pers. observ.).
We tracked all birds until death, disappear-
ance of the signal from the study area, or bat-
tery failure of the collar. Upon detecting a
mortality signal, we located the bird and
determined the cause of death. When a signal
was not found we commenced a search, stop-
ping to scan for the signal every 500–1000
meters on roads within a 7 km radius of the
tower, or by scanning for the signal from the
top of the tower. A signal was considered to
have disappeared from the study area after it
had been missing for a minimum of 29 days.
We scanned for the frequencies of missing
signals from the top of the tower and from
roads within 7 km of the tower on most days
during this 29-day period. The last 7 days of
this period included intensive searching from
all roads within a 20 km radius of the tower.
Battery failure of the collar was considered a
possible outcome only in the cases where
individuals had collars in place for close to 3
months before disappearance of the signal.
RESULTS
For the population of Blue-fronted Parrots
breeding in the vicinity of the Park we found
a 94% survivorship of birds during the 33 ±
20.9 (SD) days (range: 11–87) over which the
birds were tracked. Six of eight family groups
disappeared from the study area before bat-
tery failure of the collar. Only one fledgling
died before radio signals were lost. This mor-
tality occurred 11 days after fledging and
approximately 1 km from the nest. The feath-
ers surrounding the plucked remains lacked
teeth marks, indicating a raptorial predator.
The signals from 15 of 17 surviving parrot
chicks (six of the eight family groups) disap-
peared from the study area between 7 Febru-
ary and 20 February 2007, at an average 27.3
± 7.3 (SD) days after fledgling (range: 16–37
days), and could not be re-located. The
remaining chicks, two single chicks from dif-
ferent nests, were tracked for 86 and 87 days.
They remained within 5 km of their nests for
the duration of the study.
Post-fledging mobility varied considerably
among family groups. Two chicks from one
family group moved more than a kilometer
within 1 hour of fledgling; three chicks from
another family group remained within 200
meters of their nest for two weeks after fledg-
ing. Of three chicks that were observed on
the day that they fledged, two were found on
the ground. They did not fly during our
observations, however they were active and
climbed into nearby vegetation. The third was
in a small tree, about 2 meters off the ground,
and remained still throughout the observa-
tion. All of these fledglings survived without
intervention and we do not believe that the
radio collars significantly affected their mobil-
ity. Siblings generally stayed close together
after fledging and were often found near to
fledglings of one or more other family
groups. Each family disappeared from the
study area as a separate unit, even when leav-
ing from a local area shared by multiple fami-
lies. No two family groups disappeared on the
same day, and all chicks of each family group
disappeared on the same day.
59
POST-FLEDGING SURVIVAL OF BLUE-FRONTED PARROTS
After the disappearance of all but two of
the collared fledglings, we conducted searches
by vehicle in an attempt to locate the lost sig-
nals. None of the missing subjects were
detected during searches conducted from all
roads within a 20 km radius of the tower.
From the roof of the vehicle, the detection
range for our radio-collars was 3 km. This
range, combined with the 5 km average range
from the top of the tower, allowed us to be
certain that the radio-collared individuals were
not present in approximately 35% of the area
searched.
After our local searches, we attempted to
locate the lost signals among flocks of parrots
on their suggested wintering grounds. During
the searches at Finca Las Varás in northern
Salta province, a flock of approximately 200
Blue-fronted Parrots was located, roosting
near citrus orchards, however the radio-col-
lared individuals from Chaco were not among
them. We were unable to locate any Blue-
fronted Parrots at the three other sites we
searched.
DISCUSSION
In many psittacines, the first two to eight
weeks after fledging are characterized by lim-
ited mobility and high mortality (Snyder et al.
1987, Lindsey et al. 1991, Smith & Moore
1992, Myers & Vaughan 2004, Salinas-Mel-
goza & Renton 2007). During this stage of
development fledglings usually remain in a
secure location, either with siblings or with
fledglings from other family groups, while the
adults forage nearby, returning periodically to
feed their young.
In Lilac-crowned Parrots (Amazona finschi),
first year survivorship was 73% (n = 68) and
all mortalities occurred during the first five
weeks post-fledging; mortality was the highest
during the first two weeks post-fledgling
when chick mobility was limited (Salinas-Mel-
goza & Renton 2007). A study of Puerto
Rican Parrots (Amazona vittata) found an 87%
survivorship of fledglings during the first four
weeks (n = 15; Lindsey et al. 1994). A six-year
study of Western Long-billed Corellas (Caca-
tua pastinator) and Major Mitchell Cockatoos
(Cacatua leadbeateri) found respective survival
rates of 83% (n = 164) and 80% (n = 155)
during the first month post-fledging (Smith &
Rowley 1995). In comparison, while our
radio-collared Blue-fronted Parrot fledglings
showed a trend of limited movements during
the first weeks post-fledgling, they did not
suffer high mortality during this period.
In the present study, 17 of 18 Blue-fronted
Parrot fledglings survived during the 33-day
mean tracking period. However, the multi-
year studies described above found significant
differences in survival rates between years.
For example, the first-month survival rates of
Cacatua pastinator and Cacatua leadbeateri varied
from 56% (n = 18) to 93% (n = 29) and from
55% (n = 11) to 93% (n = 30), respectively,
over the six-year period (Smith & Rowley
1995). Consequently, while the difference in
first-month survivorship between Blue-
fronted Parrots and other psittacine species
may be biologically significant, more years of
survivorship data for Blue-fronted Parrots
will be needed before conclusions can be
drawn. Furthermore, while survivorship data
for any discrete life stage, such as a “limited
mobility fledgling period”, can illuminate age-
specific vulnerabilities, survivorship data from
other life stages is needed to create an accu-
rate projection of population trends.
Expansive home ranges, nomadic behav-
ior, and the difficulties of capturing and
re-sighting marked individuals have kept the
seasonal movements of forest-dwelling par-
rots largely illusive. Only two of 356 parrot
species, both Australian, are known to be
completely migratory (IUCN 2013), while
several other Australian species are partially
migratory. Among New World parrots, long-
distance, seasonal migration has been docu-
60
FAEGRE & BERKUNSKY
mented only in Thick-billed Parrots (Rhyncho-
psitta pachyrhyncha) in Mexico (Snyder et al.
1999) and Mealy Parrots (Amazona farinosa)
in Guatemala (Bjork 2004). While seasonal
altitudinal movements and nomadic wander-
ings have been documented in many Amazona
parrots, only Mealy Parrots, among the 30
Amazona species, are known to make long-
distance migratory movements of up to 190
kilometers from their breeding grounds
(Bjork 2004). The discovery of long-distance
migration of Mealy Parrots in a lowland forest
habitat highlights the need for increased
research on seasonal movements of other
lowland Amazona parrots, especially where
seasonal fluctuations in populations are
observed.
In the present study, the signals from 75%
(6 of 8) of the radio-collared Blue-fronted
Parrot family groups disappeared from the
study area during February. It is possible that
these individuals dispersed locally and were
concentrated in the portions of the study area
that we could not reach. However, the disper-
sal of family groups to a more distant location
is also likely, considering the observational
evidence that very few Blue-fronted Parrots
occur anywhere along the perimeter or inte-
rior of the 300 km2 Park between late-Febru-
ary and August (the non-breeding season).
Our data are consistent with observations
that each year most of the Blue-fronted Par-
rots in and surrounding the Loro Hablador
Natural Park depart at the end of the breed-
ing season, during February and March (IB
pers. observ.). Future efforts should employ
the use of aircraft or satellite telemetry to dis-
criminate between the occurrence of discrete,
long-distance migrations and the ranging,
nomadic movements that are more typical of
the Amazona genus. Since the long term sur-
vival of this species can only be ensured
through the protection of habitat used during
both breeding and non-breeding seasons, the
seasonal movements of Blue-fronted Parrots
breeding in the dry Chaco continues to be an
important area for future study.
ACKNOWLEDGMENTS
This study would not have been possible
without the financial support of The Ama-
zona Society (U.S. and U.K. divisions), Parrots
International, The World Parrot Trust, and
numerous private donors. I.B. was supported
by fellowships from Consejo Nacional de
Investigaciones Científicas y Técnicas de
Argentina (CONICET). We thank R. Rojas,
R. Ruggera, K. Jones, and J. Carrera for their
assistance in monitoring nests, and James
Melton, Wilson Morales, and Alberto Cor-
doba for their assistance in monitoring radio-
collared parrots. We also thank the Dirección
de Fauna, Parques y Ecologia of Chaco Prov-
ince for granting permission for research. We
are grateful to Donald Kroodsma and Steve
Seibel for their constructive comments on
early drafts of this manuscript.
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