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First nesting records of the endemic slender-billed parakeet (Enicognathus leptorhynchus) in Southern Chile

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  • INIBIOMA, UNCo-CONICET

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We report the first data on nesting ecology of the Slender-billed Parakeet (Enicognathus leptorhynchus) from two wild nests in native temperate rainforests of southern Chile. Nests were located in natural cavities 19 m up in emergent trees. Posture reached up to ten eggs and clutched four and five nestlings, respectively. Incubation period extended around 30 days, and nestling period around 40 days. Nestlings presented mass recession before fledging and finished their development once out of the nest. They exhibited two successive downs before feather emergence, a similar pattern shared with species from high-elevated mountains in tropical Andes. This may be a strategy, for psittacines inhabiting cooler regions, to overcome low temperatures while in the nest. Our study points out the necessity to collect additional information on breeding biology in the wild for this and other southern temperate psittacines.
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ORNITOLOGIA NEOTROPICAL 22: 103–110, 2011
© The Neotropical Ornithological Society
FIRST NESTING RECORDS OF THE ENDEMIC
SLENDER-BILLED PARAKEET (ENICOGNATHUS
LEPTORHYNCHUS) IN SOUTHERN CHILE
Maurice Peña-Foxon1, Silvina Ippi2, & Iván A. Díaz3
1Instituto de Ecología y Evolución, Facultad de Ciencias, Universidad Austral de Chile,
Casilla 567, Valdivia, Chile. E-mail: maurice.pena@gmail.com
2Instituto de Ecología y Biodiversidad, Departamento de Ciencias Ecológicas, Facultad de
Ciencias, Universidad de Chile, Las Palmeras 3425, Ñuñoa, Santiago, Chile.
3Instituto de Silvicultura, Facultad de Ciencias Forestales y Recursos Naturales, Universidad
Austral de Chile, Casilla 567, Valdivia, Chile.
Resumen. – Primeros registros de nidos de Choroy (Enicognathus leptorhynchus) en el sur de
Chile. – Documentamos los primeros antecedentes sobre la nidificación del loro Choroy (Enicognathus
leptorhynchus) obtenidos a partir de dos nidos naturales ubicados en el bosque templado del sur de
Chile. Los nidos se encontraron en cavidades naturales a 19 m de altura en árboles emergentes del
dosel. La postura alcanzó hasta 10 huevos y eclosionaron 4 y 5 pichones, respectivamente. El período
de incubación duró aproximadamente 30 días, y los polluelos permanecieron en el nido alrededor de
otros 40 días. Los pichones tuvieron una pérdida de peso previo a abandonar el nido y siguieron cre-
ciendo una vez fuera. Los pichones desarrollaron dos plumones distintos antes de la aparición de las
plumas, un patrón previamente descrito para un loro endémico de la alta cordillera de Colombia. Esto
podría ser una estrategia de los psitácidos habitantes de zonas frías para combatir las bajas temperatu-
ras mientras permanecen en el nido. Nuestro trabajo confirma la necesidad de seguir estudiando la
biología reproductiva de los psitácidos que habitan las zonas templadas, en particular de Sudamérica.
Abstract. – We report the first data on nesting ecology of the Slender-billed Parakeet (Enicognathus lep-
torhynchus) from two wild nests in native temperate rainforests of southern Chile. Nests were located in
natural cavities 19 m up in emergent trees. Posture reached up to ten eggs and clutched four and five
nestlings, respectively. Incubation period extended around 30 days, and nestling period around 40 days.
Nestlings presented mass recession before fledging and finished their development once out of the nest.
They exhibited two successive downs before feather emergence, a similar pattern shared with species
from high-elevated mountains in tropical Andes. This may be a strategy, for psittacines inhabiting cooler
regions, to overcome low temperatures while in the nest. Our study points out the necessity to collect
additional information on breeding biology in the wild for this and other southern temperate psittacines.
Accepted 12 February 2011.
Key words: Slender-billed Parakeet, Enicognathus leptorhynchus, Psittacidae, Nothofagus forest, tem-
perate rainforest, Chiloé Island.
INTRODUCTION
The ecology of psittacines inhabiting temper-
ate ecosystems is barely known compared to
species present in tropical and subtropical
ecosystems. Species living in temperate or
high-elevated ecosystems show differences in
nesting biology with other psittacines. For
104
PEÑA-FOXON ET AL.
instance, high-mountain living species, such
as the Thick-billed Parrot (Rhynchopsitta pachy-
rhyncha) from Mexico and the Azure-winged
Parrot (Hapalopsittaca fuertesi) from Colombia,
have respectively higher nest success and
lower growth rate than counterpart lowland
psittacines (Monterrubio et al. 2002, Tovar-
Martínez 2009). In Argentina, nestlings of the
Patagonian Burrowing Parrot (Cyanoliseus pat-
agonus) remain longer in the nest than other
psittacines of similar weight (Masello & Quill-
feldt 2002). The growth of two consecutive
downs during nestling’s stage in high-moun-
tain psittacines species has also been high-
lighted (Collar 1997, Tovar-Martínez 2009).
Despite these evidences, so far studies have
been insufficient among psittacines living in
cooler environment, e.g., concerning the
question if their nesting biology stands out
from tropical species. Even less data are avail-
able to indicate whether characteristics pre-
sented by high-mountain living psittacines
can be applied to species inhabiting temperate
latitudes.
The Slender-billed Parakeet (Enicognathus
leptorhynchus) is one of the two psittacids
inhabiting the temperate rainforests of south-
ern South America (Fjeldså & Krabbe 1990,
Juniper & Parr 2003). The species is endemic
to Chile and ranges from Santiago (33°S) to
Aisén (45°S). Its populations have declined
since the 1950’s due to habitat loss, shooting,
and disease (Fjeldså & Krabbe 1990, Juniper
& Parr 2003, Forshaw 2006) although it is not
currently considered globally endangered
(IUCN 2010). Little is known about the ecol-
ogy and reproductive biology of this parakeet,
particularly in respect to its nesting require-
ments and breeding success. Herein, we
describe aspects of the breeding biology of
the Slender-billed Parakeet from two natural
nests discovered in a temperate rain forest of
southern Chile. We expect that this study will
contribute to the better understanding of the
ecology of southern temperate psittacines.
METHODS
This study was conducted in the north-east of
the Chiloé Island (41°S, 73°W). The land-
scape is a mosaic of old-growth and second-
ary native forest fragments in an
anthropogenic matrix of agricultural fields
(Willson & Armesto 1996, Hoffmann et al.
1999, Willson et al. 2005). In the area, vegeta-
tion belongs to the North-Patagonian forest
type with a canopy dominated by Tepualia sti-
pularis, Drymis winterii, Podocarpus nubigena,
Nothofagus nitida, and several species of Myrta-
ceae. Emergent N. nitida trees over 20 m
height were sparsely distributed (Aravena et
al. 2002). The climate is temperate with a
mean annual temperature of 10.0 °C and a
mean annual rainfall over 2097 mm, falling
almost all year round (Carmona et al. 2010).
Nests were located in two forest frag-
ments > 100 ha, one in the Senda Darwin
Biological Station (SDBS) and the other in the
locality of Caulín, 6 km east of SDBS, both at
sea level. At each site we accessed a nest of
the Slender-billed Parakeet using tree climb-
ing techniques (Perry 1978, Dial & Tobin
1994). Nesting trees were characterized by
their height (using a 50 m tape) and diameter
at breast height (DBH). For each nest, we
measured its height from the forest floor,
horizontal and vertical diameter of entrance,
cavity depth from the base of the nest lip,
minimum internal diameter, and cavity orien-
tation (Saunders et al. 1982).
Nests were visited almost once a week
after their discovery and until the last nestling
left the nest. Egg size as well as bill, wing, and
tarsus length of each nestling were measured
to the nearest 0.1 mm using digital callipers
and at each nest inspection following
hatching (Moreno et al. 2005). For compara-
tive purposes, we obtained similar morpho-
metric data from 26 adult skins in the
Ornithology Collection of the National
Museum of Natural History of Chile. We
105
SLENDER-BILLED PARAKEET NESTING IN CHILE
limited the measurements taken depending on
the quality of individual museum skins sam-
pled. Body mass of nestlings was also
recorded using 1.0 g precision Pesola balances.
Morphometric data are given as mean ± one
standard deviation.
RESULTS
Nests were found in two large living N. nitida
emergent trees, both 23 m high. Nest tree
DBH was 82 cm and 98.5 cm in SDBS and
Caulín, respectively. Trees were similar in
shape; long and straight trunk without
branches until at 19 m, height where several
limbs constituted an emergent crown. Nest
cavities were located just below the crown at
19 m. Entrance holes were almost rounded
shape and measured 16 cm high by 12 cm
width for SDBS and 12 cm high by 9 cm
width for Caulín. Nest deeps from bottom of
entrance were 43 cm and 26 cm in SDBS and
Caulín nest respectively, and the narrowest
inner diameters were 20 cm for SDBS and 23
cm for Caulín. The nest cavity bottom was
garnished with finely chopped pieces of
wood. No other added materials were present,
with the exception of few sparse feathers
from the belly. Entrance orientation faced
southwest for SDBS and northeast for Caulín.
The SDBS nest was monitored 13 times.
The first visit (22 November 2006) took place
when only two eggs were present. By 21
December, the first hatchling was present
(Fig. 1), and by the last visit (14 February
2007) all fledglings had left the nest. On the
first visit to the Caulín nest (11 January 2007),
five nestlings were present. This nest was vis-
ited five times and by the last one (4 February)
the two last fledglings were still present at the
nest. Based on this information, the incuba-
tion period extended for 26–28 days and the
nestling period for 42–45 days.
The SDBS nest had up to 10 eggs, seven
of which were laid in a seven-day interval, rep-
resenting a rate of one egg per day. Mean
length and width of these 10 eggs plus one
unhatched egg from the Caulín nest were 35.0
± 1.7 mm and 26.4 ± 0.6 mm, respectively.
Four nestlings (40 %) hatched asynchronically
in the SDBS nest. Five of six eggs from the
SDBS nest that failed to hatch presented signs
of cracks or were destroyed. The shells of
hatched eggs were not removed by adults but
they disappeared with time. At hatching,
chicks had a white thin hair-like down which
was replaced progressively by a shorter,
denser, and grey down (Fig. 1) around day 10.
The Caulín nest was discovered containing
five nestlings with feathers already emerged
from wings and one unhatched egg, suggest-
ing a minimum clutch of six eggs. Pre-fledg-
ing data of bill and wing length and body mass
come from Caulín as last visits were realized
much closer to fledging day (4 days gap
between last and second last visit) than in
SDBS nest (9 days gap), giving a better
approximation of prefledging data.
Bill growth showed a linear increase (Fig.
2), reaching 26.4 ± 1.2 mm (N = 5) at fledg-
ing. Wing growth also showed a linear
increase in length during all the nestling
period, reaching 186.0 ± 7.2 mm (N = 5) at
fledging. Tarsus growth showed strong
increase during the first days until stabilizing
around day 25 in 27.0 ± 0.8 mm (N = 9, Fig.
2). Average bill length of adult skins from
museum collection was 33.8 ± 1.4 mm (N =
25) while wing length was 212.3 ± 6.2 mm (N
= 26) and tarsus length 26.3 ± 1.1 mm (N =
23).
The body mass of the SDBS nestlings
progressively increased to a mean of 298.2 ±
3.6 g around day 35, then decreased to 269.7
± 6.4 g (N = 3, Fig. 2) on the last visit. Thus
nestlings lost a minimum of 10 % (28.5 g in
SDBS) of their mass during the last 7 to 10
days in the nest. Weight previous to fledge
recorded by the last inspection in Caulín was
248.4 ± 5.3 g (N = 5).
106
PEÑA-FOXON ET AL.
DISCUSSION
This study provides the first records of nest
characteristics and breeding aspects for the
Chilean Slender-billed Parakeet in the wild.
Nest cavities and trees were very similar in
both cases: same tree species, similar tree
shape, nest at the same height, similar
entrance and depth. In addition, as both nests
were situated just below the tree crown, they
presented easy access and gave a large view
across the surrounding forest, since these
emergent trees were above the forest canopy.
The breeding period on Chiloé Island lasts
from November to mid-February and agrees
with data provided by Fjeldså & Krabbe
(1990). However, our results indicate that it is
considerably longer than previously reported
(Johnson 1967).
The Slender-billed Parakeet and the
Colombian high-mountain Azure-winged
Parrot hatchlings exhibit the same two suc-
cessive downs previous to the development
of feathers (Tovar-Martínez 2009). These
downs, in particular the second denser one,
are likely to be an adaptation of psittacine
chicks to the relatively low temperatures at
high altitudes (Collar 1997). Climatic rainy
and cold conditions on Chiloé Island at sea
level present similarities compared to 3000 m
high Andean forest of Colombia (Tovar-Mar-
tínez 2009). Thus the two consecutive downs
may be a strategy of psittacines living in cold
environments to have better thermal insula-
tion while in the nest.
The body-mass recession observed before
fledging has already been reported for some
others psittacines (Aramburú 1997, Masello &
FIG. 1. A twenty days nestling of Slender-billed Parakeet with a short grey and dense down. Lower left
insert shows a one day hatchling with a white thin hair-like down, both from the nest at Senda Darwin
Biological Station.
107
SLENDER-BILLED PARAKEET NESTING IN CHILE
Quillfeldt 2002, Renton 2002, Tovar-Martínez
2009). The weight at fledging (248 g for
Caulín) was close to the weight reported by
Forshaw (2006) for adults (240 g). In contrast,
bill and wing lengths did not reach their maxi-
mum size by the time birds left the nest. Bill
length of adult specimens was 22 % longer
than those of pre-fledging in the Caulín nest.
Similarly, pre-fledging wing length repre-
sented 88 % of the average wing length mea-
FIG. 2. Morphometric measures and body mass of the four nestlings in the nest at Senda Darwin Biologi-
cal Station during the breeding period.
108
PEÑA-FOXON ET AL.
sured in adult museums specimens. At
contrary, tarsus length was similar between
wild nestlings before fledging and museum
specimens. Thus, young birds continue their
development after leaving the nest.
The SDBS nest revealed an extraordinary
clutch size for the Slender-billed Parakeet,
outnumbering a previous report of three to
six eggs (Goodall et al. 1946). Based on the
allometric curve of Masello & Quillfeldt’s
study (2002), an adult parrot of 240 g, such as
the Slender-billed Parakeet (Forshaw 2006),
should have a clutch size of 3.5 eggs. A similar
clutch size of 10 eggs has only been reported
previously for the Green-rumped Parrotlet
(Forpus passerinus), a small psittacid of 30 g
(Beissinger & Waltman 1991). However, in
general tropical birds exhibit smaller clutch
sizes than counterparts of temperate latitudes
(Skutch 1953, Young 1994, Martin et al. 2000,
but see Yom-Tov et al. 1994), and as Masello
& Quillfeldt’s allometric curve is based on
many parrot species of tropical and subtropi-
cal latitudes it might explain our observation.
Nevertheless, the possibility of a second
female laying eggs in the same nest can not be
neglected as the laying average rate of one egg
per day for a 7-day period is uncommonly
high for the family Psittacidae (Collar 1997)
and also because two eggs presented severe
damages on their shelves. Even if nests were
not monitored during long-term session in
this study and so any evidence of a third bird
visiting the nest cavity is unproven, the phe-
nomenon of multiple females sharing the
same nest exists and has been reported for
another psittacine, the Horned Parakeet (Eu-
nymphicus cornutus, Theuerkauf et al. 2009). As
well, evidence of egg destruction and/or
infanticide due to conspecific intruders in
Green-rumped Parrotlet, Palm Cockatoo
(Probosciger aterrimus), Crimson Rosella (Platy-
cercus elegans), and Eclectus Parrot (Eclectus
roratus) nesting attempts have been observed
or suggested by authors (Beissinger & Walt-
man 1991, Waltman & Beissinger 1992, Krebs
1998, Heinsohn & Legge 2003, Juniper &
Parr 2003, Murphy et al. 2003) who mainly
attributed this behavior to the lack of nesting
sites. The island of Chiloé, especially the
north, has been highly deforested for agricul-
tural purposes (Carmona et al. 2009) and,
together with selective logging, this reduces
the number of available cavities for secondary
cavity nesting birds (Díaz et al. 2005, Corne-
lius et al. 2008) and thus might increase com-
petition among psittacines.
Much remains to be learned on the Slen-
der-billed Parakeet and other parrots of the
temperate Neotropics. Our results provide
information, albeit the small sample size, on
nesting phenology and nest site characteristics
and describe a clutch size extraordinarily large
for the size of this species (which must be
confirmed by further studies). Additional data
on the biology, ecology, and distributional
local movements of this parakeet are neces-
sary to plan and develop successful strategies
to enhance its conservation and also to com-
prehend better its relationship to man, as the
species is considered in some places as a pest
to crops (Juniper & Parr 2003). Future forest
management should consider the critical nest-
ing period to enhance the conservation not
only of the Slender-billed Parakeet but also of
the highly endemic and endangered avifauna
of this region (Stattersfield et al. 1998). Simi-
larly, selective logging recreating natural dis-
turbance regimes and keeping old and large
N. nitida trees (alive or dead) will provide
appropriate nesting sites for the numerous
cavity nesting community (Franklin & Arm-
esto 1996, Willson & Armesto 1996, Díaz et
al. 2005, Ojeda et al. 2007, Cornelius 2008).
As this study contributes to the knowledge on
Slender-billed Parakeet nesting biology but
arises new interrogations, we hope the infor-
mation reported herein will encourage addi-
tional studies to be done on temperate
Neotropical psittacines.
109
SLENDER-BILLED PARAKEET NESTING IN CHILE
ACKNOWLEDGMENTS
We are especially grateful to Juan Luis Celis
for his field support and friendship provided
during this study, and to Mary F. Willson for
the valuable comments done to the manu-
script and Juan J. Armesto for the develop-
ment of our field work. We thank also Marco
Mora for his assistance during fieldwork and
Juan Carlos Torres-Mura, bird curator from
the National Museum of Natural History
(Chile) to provide access to the avian collec-
tion. Comments of C. Cornelius, V. S. Ojeda,
and a third anonymous reviewer greatly
improved this manuscript. We thank to Fon-
decyt Grant 1050225, to Gary Machlis and
the generous support provided by The Canon
National Parks Science Scholars Program to
I.A. Díaz, and to CONICYT grant PDA-24.
SI acknowledges support from a CONICYT
scholarship. This is a contribution to the
Research Program of LTSER network at
Senda Darwin Biological Station, Ancud,
Chiloé.
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... Although considered of "Least Concern" globally (IUCN 2015), the Chilean government considers the species as "Vulnerable" in southern Chile due to an apparent population decline (SAG 2008), but there has been little research into the reasons for this decline. In fact, only recently some habitat requirements of this species have become known (Peña-Foxon et al. 2011;Carneiro et al. 2011Carneiro et al. , 2013, among which large, mature trees with ample cavities are essential. However, to date there has been no comprehensive quantitative description of the actual nesting cavities used by SBP in the central valley of southern Chile, an extensive area which has undergone dramatic landscape-level changes in habitat composition over the past century (Echeverría et al. 2006(Echeverría et al. , 2007Lara et al. 2012). ...
... Clutch and brood sizes of SBP were extraordinarily large. Peña-Foxon et al. (2011) also reported clutch sizes (n = 2) of six and ten for SBP nesting in Nothofagus nitida trees on Chiloé Island, approximately 140 km south of our study area. Moreover, Díaz and Kitzberger (2012) documented clutch sizes of 3-10 for the Austral Parakeet nesting in N. pumilio cavities in Argentina. ...
... At these higher latitudes, night-time temperatures during the SBP nesting season (November-January) often decline to 2-5 °C (DMC 2001). Peña-Foxon et al. (2011) reported that SBP nestlings exhibited two successive downs prior to feather development, with the second down being particularly dense and attributed this to adaptation to colder temperatures. If so, large broods may be an additional thermoregulatory adaptation, as the increased mass of additional nestlings may more effectively retain heat, especially during recurrent night-time low temperatures. ...
Article
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Background The Slender-billed Parakeet (Enicognathus leptorhynchus) is a psittacine endemic to southern Chile and an obligate secondary cavity-nester. In the central valley of southern Chile, most (94%) of the known Slender-billed Parakeet nests have occurred in large, mature southern beech (Lophozonia obliqua) trees (locally known as “pellines”). As relicts of the original old-growth forests of southern Chile, most pellines have been lost due to extensive land-clearing throughout the region, potentially threatening long-term persistence of the Slender-billed Parakeet. Methods We conducted our study in the central valley of southern Chile, near the city of Osorno during three consecutive nesting seasons (November–January, 2008–2011). Nest trees used by Slender-billed Parakeets were located by direct observation of parakeet activities and through interviews with local residents, some of whom were former parrot nest poachers. Nest cavities were accessed, inspected and measured using single-rope climbing techniques. We report means, standard errors, 95% confidence intervals and ranges for 11 cavity-related variables. We also report clutch sizes encountered in active nests, and age estimates of nest trees based on known growth rates of Lophozonia trees in southern Chile. Linear regressions were used to evaluate potential relationships between cavity-related variables and clutch size. ResultsWe located and measured 38 Lophozonia tree cavities used for nesting by Slender-billed Parakeets. Compared to those used by other psittacines, nest trees were relatively large, averaging 30.4 ± 1.1 m in height with a mean diameter at breast height of 134.5 ± 4.7 cm. Based on estimated annual diameter increment, ages of nest trees ranged from approximately 209–485 years. Nest cavities entrances averaged 12.5 ± 0.9 m in height above ground level. Cavity entrance widths averaged 51.0 ± 13.3 cm (vertical) by 11.5 ± 0.7 cm (horizontal). Cavity entrance orientations were apparently random, with no directional preferences detected. Nest cavities were also relatively large, with a mean internal diameter of 39.6 ± 2.4 cm and mean depth of 90.3 ± 24.2 cm. Clutch sizes (2–9) were unusually large for psittacines of this size (ca. 280–300 g) and broods of up to seven well-developed nestlings were observed. Conclusions We found that the deep and spacious cavities provided by pellines facilitate successful rearing of large broods, thereby maximizing productivity and fitness. The existence of pellines has apparently allowed Slender-billed Parakeets to adapt successfully to a wholesale loss of ancestral habitat to anthropogenic modifications. Immediate and strategic conservation measures, such as protection of existing pellines and the regeneration and recruitment of additional ones, are recommended for ensuring the survival of Slender-billed Parakeet populations throughout the central valley of southern Chile.
... Similar to other forest ecosystems in the world (Bednarz et al., 2004), most studies of cavity-nesting birds in TRSA have been focused at the species level (e.g. Ibarra et al., 2014Ibarra et al., , 2012Peña-Foxon et al., 2011;Ippi et al., 2012;Vergara and Marquet, 2007), and only a few have explored cavity-nesting birds at the community level (e.g. Ippi and Trejo, 2003). ...
... Similar to other forest ecosystems in the world (Bednarz et al., 2004), most studies of cavity-nesting birds in TRSA have been focused at the species level (e.g. Ibarra et al., 2014Peña-Foxon et al., 2011;Ippi et al., 2012;Vergara and Marquet, 2007) and only a few have explored cavity-nesting birds at the community level (e.g. Ippi and Trejo, 2003). ...
... for Nothofagus species matches the few studies at the cavity-nesting species level in other locations of TRSA. These studies, have reported similar occurrences of nests on Nothofagus species at coastal locations for A. spinicauda and Enicognathus leptothynchus (Peña-Foxon et al., 2011), in the central valley for Anas flavirostris (Jiménez and White, 2011) and E. Leptothynchus , and in Andean locations for G. nana (Ibarra et al., 2014), ...
... Similar conductual patterns are known for the medium-sized Austral pygmy owl (Glaucidium nana) (Ibarra et al., 2014). Two endemic parrot species depend on large decay cavities for nesting and roosting (occasionally in flocks), like the endangered slender-billed parakeet (Enicognathus leptorhynchus, 40-43 cm total length) (Carneiro et al., 2013;Peña-Foxon et al., 2011;White and Jiménez, 2017) and the Austral parakeet (Enicognathus ferrugineus, 35 cm total length) (Díaz and Kitzberger, 2013). Other habitatsensitive birds that depend on decay cavity availability are several tapaculos species (family Rhinocryptidae), mainly the black-throated huet huet (Pteroptochos tarnii, 22-25 cm total length) (De Santo et al., 2002). ...
Article
Maintenance of tree cavity supply is a global conservation priority for forest wildlife, which requires understanding the ecology and population dynamics of cavity-bearing trees. Explaining the occurrence of cavities in trees is particularly important in ecosystems where most secondary cavity-users (SCUs) are critically dependent on the slow formation of cavities by wood-decay processes. Our main objectives were (1) to explain the distribution of decay cavities in trees according to their individual attributes and, (2) to quantify the relative importance of each individual tree attribute to determine the presence of decay cavities. We focused on medium and large decay cavities (smallest entrance dimension ≥ 5 cm), which can limit populations of management-sensitive SCUs. We measured forest attributes and inspected cavities in trees (n = 860) and snags (n = 93) in six 0.5 ha plots from old- and second-growth Nothofagus dombeyi forest stands. We used generalised linear mixed-effects models (GLMM) to analyse the distribution of decay cavities in trees using data on their presence/absence, based on several tree individual attributes, across different sites. We applied an information-theoretical and multi-model inference approach to quantify the strength of alternative sets of hypotheses/models. We used model averaging, which allows estimating coefficients and making inferences that account for model and parameter uncertainty. Diameter at breast height (DBH), crown damage and decay, crown ratio (crown length • trunk length−1) and woodpecker foraging signs were important to explain the presence/absence of decay cavities in trees. Diameter at breast height, woodpecker foraging signs and a moderate-high crown damage and decay were positively related with decay cavity presence. The presence of medium and large decay cavities was also positively related with DBH, but trees with low crown ratios had relatively low probabilities of presenting these cavities, even with DBHs > 150 cm. Trees with DBHs smaller than 50 cm had very low probabilities (<0.25–0.30) to present decay cavities, while the probability of trees presenting decay cavities of medium and large sizes was very low for trees with diameters < 100 cm, even for trees with high crown ratios. Our results point out that conservation of large diameter trees with high crown ratios is important to maintain the supply of decay cavities required by management-sensitive SCUs in these forests. As these keystone structures are globally threatened by climate change induced disturbances (e.g. fires, droughts), they should be maintained/restored through forest management (e.g. retention of keystone structures) to achieve cavity-using wildlife habitat conservation in the long-term.
... In the majority (86 %) of these datasets, mean cavity depth was C50 cm, and just over one-third (38 %) of the datasets had a mean cavity depth of C1 m (Fig. 3). The shallowest nests, with a mean depth of \40 cm, were on the whole occupied by large parrots and macaws (Elliot et al. 1996;Cruz-Nieto 1998;Pinho and Nogueira 2003;Peña-Foxon et al. 2011;Rivera et al. 2012). Finally, in contrast to the other nest-cavity features, the mean diameter of cavity entrances showed a broad range, varying from 5 to 22 cm ( Fig. 3), which corresponded with a similar wide range in body sizes of the tree-cavity nesting species studied (Fig. 3). ...
Article
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Parrots (Order Psittaciformes) are secondary cavity-nesters that depend on existing cavities for nest sites, and consume plant resources of fruits, seeds, and flowers that are highly variable, but little is known of resource selectivity by parrots, or how they deal with variable environments. We reviewed published studies of nest-cavity use by parrots, and those evaluating parrot diet and their relationship with food resources. Most studies have been conducted within the last 20 years and these present data on resource use for only one-third of parrot species worldwide. However, basic information on resource requirements is lacking for the vast majority of Psittaciformes, particularly for species from the Asian region. Nesting studies have found that parrots use nest cavities in large trees, high above the ground, with large nest chambers, of 0.5–1 m deep, and entrance diameters related to body size of the parrot species. A few studies demonstrate that parrots select nest sites based on cavity characteristics, which may influence nest success, but a complete evaluation of adaptive nest site selection by Psittaciformes is lacking. Parrots have varied diets and may employ a combination of strategies of diet switching, habitat shifts, and movements to track food resources. This plasticity in diet and foraging strategy may influence the extent to which parrots can respond to anthropogenic pressures of global change. Parrots may also play an important functional role in forest ecosystems, yet little is currently known of plant–animal interactions of parrots, or the impact of parrot populations on forest dynamics. Based on our review of the literature, we suggest that to meet their resource requirements, parrots employ resource selection strategies of hierarchical nest site selection to increase the likelihood of nest success, and plasticity in diet and foraging strategy to track variable food resources. Future studies need to evaluate resource selection and the consequences of this for fitness in order to assess the potential impacts of global change on parrot populations, and to identify characteristics which make species vulnerable to human pressures
... fungal decay, branch breakage and insects attacks). Natural cavities used for nesting were in large trees, and commensurate with the findings of Goodall et al. (1946), Díaz et al. (2005) and Peña-Foxon et al. (2011) for its congeneric E. leptorhynchus, which was almost exclusively founded in old growth forest. However, natural cavities are the only nesting and refuge sites available in A. araucana trees, highlighting the critical conservation value of large A. araucana individuals to Austral parakeets. ...
Article
Full-text available
Identifying habitat or nesting microhabitat variables associated with high levels of nest success is important to understand nest site preferences and bird–habitat relationships. Little is known about cavity availability and nest site requirements of cavity nesters in southern hemisphere temperate forests, although nest site limitation is suggested. Here we ask which characteristics are selected by the Austral parakeet (Enicognathus ferrugineus) for nesting in Araucaria araucana–Nothofagus pumilio forest in Argentine Patagonia. We compared nest plot and tree characteristics with unused plots and trees among areas of different A. araucana–N. pumilio density. We also examine whether nest plot and tree use and selection, and the associated consequences for fitness of Austral parakeets are spatially related to forest composition. Austral parakeets showed selectivity for nests at different spatial scales, consistently choosing isolated live and large trees with particular nest features in a non‐random way from available cavities. Mixed A. araucana–N. pumilio forests are ideal habitat for the Austral parakeets of northern Patagonia, offering numerous potential cavities, mainly in N. pumilio. We argue that Austral parakeet reproduction and fitness is currently very unlikely to be limited by cavity availability, although this situation may be rapidly changing. Natural and human disturbances are modifying south temperate forests with even‐aged mid‐successional stands replacing old growth forests. Cavity nesting species use and need old growth forests, due to the abundance of cavities in large trees and the abundance of larvae in old wood. Neither of the latter resources is sufficiently abundant in mid‐successional forests, increasing the vulnerability and threatening the survival of the Austral.
... leptorhynchus) puede así usar un procesos jerárquico de selección de lugares de anidación; después que un parche de hábitat es elegido, los pericos pueden entonces inspeccionar arboles de manera individual en búsqueda de lugares The family Psittacidae is the world's most threatened group of birds, with at least 28% of the species in this family facing some risk of extinction (Collar 1997, 2000, Snyder et al. 2000, Cockle et al. 2007). Slender-billed Parakeets (Enicognathus leptorhynchus; locally known as choroy) are endemic secondary cavity nesters of the south-temperate forests of Chile and little is known about their natural history (e.g., Peña-Foxon et al. 2011). Early reports indicated that the species was widely distributed throughout the lowland Nothofagus forests of southern Chile (Philippi 1864, Hellmayr 1932, Goodall et al. 1957, which have been fragmented and degraded by humans for agriculture and livestock grazing during the past 150 yr (Echeverría et al. 2006). ...
Article
Full-text available
South American temperate rainforests, a global biodiversity hotspot, have been reduced to nearly 30% of their original extent and most remaining stands are being degraded. Cavity-nesting vertebrate communities are dependent on cavity-bearing trees and hierarchically structured within nest webs. Evaluating the actual degree of cavity dependence (obligate, non-obligate) and the preferred attributes of trees by cavity nesters is critical to design conservation strategies in areas undergoing habitat loss. During three breeding seasons (2010–2013), we studied the cavity-nesting bird community in temperate rainforests of Chile. We found the highest reported proportion of tree cavity nesters (n = 29 species; 57%) compared to non-cavity-using birds for any forest system. Four species were excavators and 25 were secondary cavity nesters (SCNs). Among SCNs, ten species were obligate and 15 were non-obligate cavity nesters. Seventy-five percent of nests of SCNs were located in cavities produced by tree decay processes and the remaining 25% were in cavities excavated mainly by Pygarrhichas albogularis and Campephilus magellanicus. Nest web structure had a low dominance and evenness, with most network interactions occurring between SCNs and large decaying trees. Tree diameter at breast height (DBH) was larger in nest-trees (57.3 cm) than in available trees (26.1 cm). Cavity nesters showed a strong preference for dead trees, both standing and fallen (58% of nests). Our results stress that retaining large decaying and standing dead trees (DBH [ 57 cm), and large fallen trees, should be a priority for retention in forest management plans in this globally threatened ecosystem.
Article
Species in the family Psittacidae may be particularly vulnerable to anthropogenic habitat transformations that reduce availability of suitable breeding sites at different spatial scales. In southern Chile, loss of native forest cover due to agricultural conversion may impact populations of Slender-billed Parakeets (Enicognathus leptorhynchus), endemic secondary cavity-nesting psittacids. Our objective was to assess nest-site selection by Slender-billed Parakeets in an agricultural-forest mosaic of southern Chile at two spatial scales: nest trees and the habitat surrounding those trees. During the 2008-2009 breeding seasons, we identified nest sites (N= 31) by observing parakeet behavior and using information provided by local residents. Most (29/31) nests were in mature Nothofagus obliqua trees. By comparing trees used for nesting with randomly selected, unused trees, we found that the probability of a tree being selected as a nest site was positively related to the number of cavity entrances, less dead crown, and more basal injuries (e.g., fire scars). At the nesting-habitat scale, nest site selection was positively associated with the extent of basal injuries and number of cavity entrances in trees within 50 m of nest trees. These variables are likely important because they allow nesting parakeets to minimize cavity search times in potential nesting areas, thereby reducing energetic demands and potential exposure to predators. Slender-billed Parakeets may thus use a hierarchical process to select nest sites; after a habitat patch is chosen, parakeets may then inspect individual trees in search of a suitable nest site. Effective strategies to ensure persistence of Slender-billed Parakeets in agricultural-forest mosaics should include preservation of both individual and groups of scattered mature trees. © 2013 The Authors. Journal of Field Ornithology
Article
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We studied a chronosequence of forest fragments in northern Chiloé Island, southern Chile, with the aim of assessing ecosystem recovery patterns following anthropogenic disturbance. Hypotheses regarding successional trends in tree species richness, the replacement of shade-intolerant by shade-tolerant species, and the impact of disturbance on soil properties were evaluated in nine forest stands. The chronosequence encompassed two early (minimum stand age <15 years), three mid-successional (30-60 years), three late-successional (129-134 years), and one old-growth stand (ca. 200 years). Stand ages were estimated by coring a minimum of 30 canopy trees in each stand. Early and mid-successional stands showed evidence of human disturbance by fire of moderate intensity, with few scattered old trees surviving the fire. We determined densities and basal areas of all trees in a 50 x 20 m plot, and densities of saplings and seedlings in subsamples of each plot. Soil pH, total carbon (C) and nitrogen (N) contents, available N, and bulk density were used to characterize soil processes across the chronosequence. In contrast to the hypothesis that predicts a decline in tree species richness during the course of succession due to competitive exclusion of pioneers, species richness of canopy trees increased from 3 to 13 through the chronosequence. This trend was accompanied by a more even distribution of species importance values in late succession. Changes in richness were unrelated to stem densities, which were highest in mid-successional forests. The number of species of woody seedlings and saplings did not change with stand age. Most tree species, both shade tolerant and intolerants, were present as seedlings in all the stands, but canopy dominance shifted from shade-intolerants in early and mid-successional forests to shade-tolerant species in late-successional and old-growth stands. We did not observe a complete replacement of these two groups of species, as shade-intolerant trees were still present in the canopy and/or understory of older stands. The successional trend fits Egler's Initial Floristic Composition Model, whereby differences in life history attributes among tree species account for major changes in dominance through succession. Soil properties were generally similar across the chronosequence of stands, suggesting that both ecosystem processes and tree regeneration were fairly resilient to moderate-intensity fire. We conclude that because of the relatively short history of human impact in the area, largely limited to the 20th century, and the carry over of structural elements such as snags, logs, and large living trees in disturbed stands, lowland forest patches in northern Chiloé show resilience to human disturbance. However, as forests in the area become increasingly isolated, affected by recurrent fire, and other forms of human impact, their ability to recover their original structure and biodiversity will probably be impaired. Threshold levels of deforestation, at the landscape scale, that would impinge on successional trends at the patch scale remain an important open question for land managers.
Article
We conducted a study of the breeding biology of the Thorn-tailed Rayadito (Aphrastura spinicauda) in secondary forests on the continental island of Chiloé (42° S), southern Chile. Rayaditos are small insectivorous furnariids inhabiting the south-temperate forests of Chile and Argentina. We followed the reproduction of rayadito pairs breeding in nest-boxes. Rayaditos build their nests mainly of rhizomes and stems of epiphytic vines, grasses, and hairs during periods of at least a week, and show a marked population asynchrony in laying dates of more than two months (October–December). Rayaditos lay clutches of 3–6 eggs with a mode of 4 and laying occurs on alternate days. Eggs are 50% larger and hatchlings are 30% larger than expected from allometric equations. Most broods hatch synchronously. Nestling growth curves adjust well to logistic functions and at 2 weeks nestlings attain masses similar to asymptotic values. Nestling growth, which occurs over 3 weeks, is 27% slower than expected from allometry. Fledglings attain adult size with respect to tarsus length, but have less developed plumage and higher body mass than adults. Rayaditos exhibit clutch and brood reduction, suggesting possible food limitation. The protracted breeding periods may preclude second breeding attempts for most pairs in Chiloé. There is evidence for declines in parental quality with season. The low seasonal fecundity, large eggs, and prolonged dependence periods of a truly south-temperate species like the Thorn-tailed Rayadito reflect a ‘slow’ life history similar to that of tropical passerines. Biología Reproductiva de Aphrastura spinicauda (Furnariidae) en Bosques Lluviosos Templados Meridionales de Chile Resumen. Realizamos un estudio de la biología reproductiva del Rayadito Aphrastura spinicauda en bosques secundarios de la isla continental de Chiloé (42° S), sur de Chile. Este pequeño furnárido insectívoro habita los bosques templados meridionales de Chile y Argentina. Seguimos las actividades reproductivas de parejas de rayaditos que utilizaron cajas artificiales para nidificar. Los rayaditos construyen sus nidos utilizando rizomas, hierbas y pelo durante períodos de al menos una semana, y muestran una marcada asincronía a nivel de población de más de dos meses (octubre a diciembre) en el inicio de la puesta. Las puestas incluyen de 3 a 6 huevos, con un tamaño modal de 4 huevos, los cuales son puestos en días alternos. Los huevos son 50% más grandes y los polluelos recién eclosionados 30% más grandes de lo esperado según ecuaciones alométricas. La mayoría de las nidadas eclosionan sincrónicamente. Las curvas de crecimiento se ajustan bien a funciones logísticas y el peso alcanza valores asintóticos a las dos semanas. El crecimiento de los polluelos, que ocurre durante un período de permanencia en el nido de tres semanas, es un 27% más lento de lo esperado por alometría. Los volantones alcanzan el tamaño adulto con respecto a la longitud de tarso, pero presentan un plumaje menos desarrollado y un mayor peso que los adultos. Esta especie presenta casos de reducción de la puesta o de la nidada, lo que sugiere posibles limitaciones en la disponibilidad de alimentos. Los prolongados períodos de reproducción pueden impedir el inicio de segundas puestas en Chiloé. Hay evidencia de disminuciones estacionales en la calidad parental. La baja fecundidad anual, el gran tamaño de los huevos y el prolongado periodo de crecimiento del Rayadito refleja una historia de vida ‘lenta’ similar a la de paseriformes tropicales.
Book
This volume consist of eight main sections. Initially origins and evolutionary relationships are examined, followed by a brief section on the classification of the parrots. Next a section reviews the natural history of the parrots, briefly covering: general behaviour; distribution; habitat; movements; social behaviour; diet; breeding; and nocturnal species. Conservation status ics covered next. The main threats to parrots are then outlined and discussed: habitat loss; live bird trade; introduced species; persecution and hunting; and storms'climatic change. A brief section then looks at captive breeding. The mian body of the book is taken up with colour plates and a systematic section. The systematic section contains the following information, for each species: identification notes; voice; distribution and status (including distribution maps); ecology; description; sex/age; measurements; geographical variation; and references.
Article
The Azure-winged Parrot (Hapalopsittaca fuertesi) is an endemic and critically endangered species from Colombia for which biological information that might aid conservation efforts is largely lacking. In this study, I present data on growth of 25 nestlings of H. fuertesi obtained in January-July 2005 in a high Andean forest area in depto. Quindío. I described growth in body mass, primary feather length, bill length and tail length using a logistic equation, and compared my data with those available for other species of psittacids. In addition, I described the sequence in which true feathers appear on the head, body, wings, and tail during the permanence of chicks in the nest (average 58.8 days). Body mass reached an asymptotic value during an early phase of the nestling period, as in other psittacids of similar size. However, the growth rate observed in H. fuertesi was more similar to that of lowland species of psittacids of larger size, which might be due to reduced food availability in high Andean areas. The growth curves obtained for body measurements, together with patterns of plumage development described in this study, are useful tools to estimate the age of nestlings of unknown age and can be useful for captive breeding programs.