Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 January 2026 | 18(1): 28174–28185
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.9812.18.1.28174-28185
#9812 | Received 03 April 2025 | Final received 15 November 2025 |
Finally accepted 06 December 2025
Field observations and citizen
science reveal ecological insights into rare and threatened parrots in the
Philippines
Vince Angelo G. Gicaraya 1 & Carmela P. Española 2
1,2 Terrestrial Research in Ecology
and Evolution (TREE) Laboratory, Institute of Biology, University of the
Philippines Diliman, Quezon City 1101, Philippines.
1 vggicaraya@up.edu.ph
(corresponding author), 2 cpesapnola@up.edu.ph
Editor: Hem Sagar Baral,
International Snow Leopard Trust, Seattle, USA. Date of publication: 26 January 2026 (online & print)
Citation:
Gicaraya, V.A.G. & C.P. Española (2026). Field observations and
citizen science reveal ecological insights into rare and threatened parrots in
the Philippines. Journal of Threatened Taxa 18(1): 28174–28185. https://doi.org/10.11609/jott.9812.18.1.28174-28185
Copyright: © Gicaraya & Española 2026. Creative Commons Attribution 4.0
International License. JoTT allows unrestricted use, reproduction, and
distribution of this article in any medium by providing adequate credit to the
author(s) and the source of publication.
Funding: This research received financial support from the
Department of Environment and Natural Resources Foreign-Assisted and Special
Projects Service (DENR-FASPS) and the Oriental Bird Club (OBC Grant P1499).
Competing interests: The authors declare no competing interests.
Author
details: Vince Angelo G. Gicaraya studied Environmental Science at
the University of the Philippines Diliman, specializing in the biology and
ecology of cavity-nesting birds. He is a Conservation Leadership Program Future
Conservationist Awardee for 2025 and currently works on the
Vulnerable Northern Rufous Hornbill, integrating scientific knowledge and
community engagement for avian conservation. Dr. Carmela P. Española is an associate professor at the
University of the Philippines Diliman specializing in
wildlife biology and ornithology. With a PhD from Manchester Metropolitan
University, United Kingdom, she is a leading expert in the conservation of
Philippine terrestrial vertebrates. She teaches and conducts research in
conservation ecology.
Author contributions:
VAGG and CPE conceptualized the
study and developed the methodology for field observations. VAGG conducted the
investigation, performed the analyses and interpretation, and led the writing
of the manuscript. CPE was responsible for funding acquisition,
provided supervision, and performed critical review and editing of the
manuscript.
Filipino: Sa kabila ng kanilang
popularidad at nanganganib na “conservation status”, ang mga loro sa ilalim ng
genus Tanygnathus at Prioniturus ay nananatiling kulang sa
pag-aaral. Ang kanilang pagiging madalang at mailap ay balakid sa pagkalap ng
komprehensibong datos tungkol sa kanilang ekolohiya. Sa pananaliksik na ito,
aming inilalahad sa unang pagkakataon ang “breeding behavior”, “diet”, at “nesting
phenology” ng Blue-naped Parrot Tanygnathus lucionensis at Green
Racquet-tail Prioniturus luconensis gamit ang mga nakalap na obserbasyon
sa ilang at mga citizen science databases. Isinagawa ang mga obserbasyon sa
Subic Watershed Forest Reserve mula Pebrero-Hunyo 2022 at Marso-Agosto 2023.
Batay sa aming mga datos, ang T. lucionensis ay may mahabang breeding
period, paulit-ulit o maraming beses na pagtatalik, pagpapakain ng lalaki sa
babae sa pamamagitan ng regurgitation, at pag-aalaga ng parehong magulang sa
mga supling—mga katangiang naaayon sa gawi ng mga Old World parrots.
Gayunpaman, walang natagpuang aktibong pugad ng P. luconensis sa panahon
ng pag-aaral sa field. Bilang suplemento, sinuri namin ang 1,281 rekord ng mga
lorong ito sa eBird at Facebook mula Enero 2012 hanggang Enero 2025. Aming
napag alaman na ang P. luconesis ay nagpaparami buong taon, samantalang
ang T. lucionensis naman ay sa mga buwan ng tag-init. Ang parehong loro
ay kumpirmadong kumakain ng iba’t ibang bahagi ng halaman, partikular na ng mga
prutas, bulaklak, dahon, at maging balat ng puno. Kapansin-pansin na 73% ng mga
rekord ay mula sa mga katutubong puno, pagpapatunay ng kahalagahan ng
pagtatanim ng mga katutubong puno bilang mapagkukunan ng pagkain ng mga loro.
Ang aming mga natuklasan ay nagbibigay ng mahalagang batayang impormasyon na
maaring gamiting gabay para sa mga susunod na pananaliksik at mga programang
pangkonserbasyon para sa mga ibong ito.
Acknowledgements: We would like to thank the Department of Environment and Natural
Resources Foreign-Assisted and Special Projects Service (DENR-FASPS) and the
Oriental Bird Club (OBC Grant P1499) for funding this study and to Mr. Jayson
Mansibang for identifying our plant samples. We would like to thank
all citizen scientists, particularly Vinz Pascua, Caloy Dionela, Jorge De
Ramos, Chris Chafer, Fidel Sy, and Marilyn Gates, for generously granting us
permission to use their photographs in this manuscript.
Abstract: Despite their charismatic appeal
and threatened conservation status, parrots of the genera Tanygnathus
and Prioniturus remain poorly studied throughout their range. Their
inconspicuous behaviour, elusive nature, and rarity further hinder efforts to
gather comprehensive ecological data. In this study, we describe the breeding
behaviour, diet, and nesting phenology of the Blue-naped Parrot Tanygnathus
lucionensis and the Green Racquet-tail Prioniturus luconensis,
combining field observations and citizen science data to acquire insights into
their ecology. Field observations were conducted at Subic Watershed Forest
Reserve from February to June 2022 and March to August 2023. Results show that T.
lucionensis exhibits a long breeding period, with multiple copulation
events, male-to-female regurgitative feeding, and biparental care—traits
consistent with the reproductive behaviour of Old World parrots. However,
fieldwork did not locate any nests of actively breeding P. luconensis
during the study period. To supplement field observations, we analyzed 1,281
media records of both parrots dating from 2012 to 2025, sourced from two citizen
science platforms: eBird and Facebook. These records revealed that P. luconensis
breeds year-round, while T. lucionensis breeds predominantly in
the dry season. Both species are confirmed as mixed plant resource feeders,
primarily consuming fruits but also feeding on flowers, leaves, and bark.
Notably, 73% of records were native plant species from diverse families,
asserting the importance of planting native species as food resources for
parrots. Our findings provide much-needed baseline information to inform future
ecological research and conservation strategies for these understudied parrot
species.
Keywords: Breeding biology, cavity-nesting
birds, eBird, Facebook, nest, Old World parrots, Prioniturus,
Psittaculidae, social media, Tanygnathus.
INTRODUCTION
Tanygnathus and Prioniturus
(Psittaculidae) are genera of Old World parrots restricted to the Philippines
and Indonesia. The genus Tanygnathus is currently represented by five
species, with three occurring in the Philippines. Meanwhile, Prioniturus
consists of 10 species, seven of which are endemic to the Philippines
(Billerman et al. 2022). Despite their charismatic appeal, information on the
breeding and diet for both genera remains limited, as they are particularly
challenging to study due to their inconspicuous and highly elusive nature,
along with their rarity and cavity-nesting behaviour — with even large parrots
now absent from virtually intact habitats (Española et al. 2013). Breeding and
diet are fundamental components of a species’ ecological niche. Together, they
offer valuable insights into a species’ natural history that can be of
significant conservation importance, especially for threatened and poorly known
taxa. Unfortunately, knowledge of breeding biology remains severely limited for
tropical forest bird species in Southeast Asia (Xiao et al. 2016). This gap is
particularly pronounced among specialized breeders such as cavity-nesting birds
in Asia (Cornelius et al. 2008; Cockle et al. 2012; Lammertink 2014),
especially in the Philippines (Gicaraya & Española 2024a; Gicaraya et al.
2025). Similarly, avian diet remains poorly documented in the Philippines,
mirroring a broader trend across tropical Asia (Sankamethawee et al. 2011).
Dietary observations exist for a few species such as those compiled in Birds of
the World (Billerman et al. 2022), with fewer species having dedicated
field-based observations as in the case of the threatened Philippine Cockatoo Cacatua
haematuropygia (Widmann et al. 2001) and hornbills (Gonzalez 2007; Widmann
et al. 2015; Gicaraya & Española 2024b). Nonetheless, comprehensive studies
are still lacking.
Luzon Island, located in northern
Philippines, is home to several large parrots, including the endangered Green
Racquet-tail Prioniturus luconensis and the near-threatened Blue-naped
Parrot Tanygnathus lucionensis (Española et al. 2013; Allen 2020). The
Green Racquet-tail (GRT), endemic to the island, appears monotypic but is
sexually dimorphic, with males appearing yellowish whereas females are
uniformly greener. Most information about its genus is based on a few species
(Billerman et al. 2022): Blue-crowned Racquet-tail P. discurus
with breeding observations in central (Negros-Panay) and southern (Greater
Mindanao) Philippines, Yellow-breasted Racquet-tail P. flavicans
in Sulawesi (Walker & Seroji 2000), and Buru Racquet-tail P. mada
in Buru, South Moluccas, Indonesia.
The Blue-naped Parrot (BNP),
formerly widespread across the Philippines, is now limited to a few islands in
the archipelago. This large, green parrot is distinguished by its red beak and
yellow-and-blue wing feathers. It has been reported to breed from April to June
in tree cavities (Collar et al. 2020) with further breeding data remaining
scarce. As with most Tanygnathus parrots, information on the genus is largely
limited to a handful of breeding observations in the wild and in captivity
(Billerman et al. 2020).
In this paper, we aim to provide
insights on the biology and ecology of the above-mentioned parrots in Luzon and
acquire baseline information for their conservation through field observations
and citizen science. Citizen science serves as a useful tool for studying
diverse taxa, offering opportunities to acquire data on specific species across
broad temporal and spatial scales—efforts that would otherwise be challenging
to achieve through traditional field observations alone (Hall et al. 2021).
Citizen science has been instrumental in elucidating the natural history of
lesser-known species and in understanding aspects of a species’ ecology (Lees
& Martin 2015; Zeng et al. 2018; de Souza et al. 2022; Díaz et al. 2024).
In recent years, social media platforms such as Facebook have emerged as a
valuable platform for citizen science. Through this social media platform,
researchers were able to improve our knowledge of cryptic species distributions
(Tabeta & Bejar 2025), enable the crowdsourcing of specimens to collect
historical records and biological data (O’Connell et al. 2025), and establish
an early warning system for potential new species invasions (Marcenò et al.
2021), demonstrating the potential of the platform as a data-rich hub that can
be tapped for biodiversity research. Here, we present the breeding behavior of
the parrots through field observations, ascertain their diet through citizen
science, and determine their nesting phenology by piecing together data from
field observations and citizen science to arrive at a comprehensive picture of
the two parrots’ breeding cycle.
MATERIALS AND METHODS
Study Site
Breeding observations were
conducted at the Subic Watershed Forest Reserve (SWFR), in the provinces of
Bataan and Zambales, Luzon Island, Philippines. SWFR is a semi-evergreen
lowland forest situated west of Luzon Island. It is characterized by vegetation
dominated by dipterocarps primarily Shorea contorta and deciduous tree
species Parkia timoriana, Pterocymbium tinctorium, and Dracontomelon
dao (Fernando et al. 2008; Gicaraya et al. 2025). Wherever the canopy is
open, thick bamboo thickets emerge. Subic Watershed Forest Reserve is a mosaic
of open and closed canopy forests, interspersed with industrial zones,
agricultural, and residential areas. The area has rugged terrain with
elevations ranging 0–300 m. West Luzon has distinct dry and wet seasons occurring
in January–May and June–December of every year, respectively. Precipitation
typically ranges 50–100 mm in the dry season and 400–800 mm in the wet season
(Corporal-Lodangco & Leslie 2017).
Fieldwork Procedures
A thorough nest hole search was
undertaken in all accessible areas of the SWFR, along pre-existing and
off-trail routes, for two consecutive breeding seasons—February–June 2022 and
March–August 2023—with efforts made to survey the site as comprehensively as
conditions allowed. Following Gicaraya & Española (2023) and Gicaraya et
al. (2025), trees were inspected for cavities either by tracking flying and
calling parrots or by observing potential nest trees for breeding-related
activities through a pair of 10 × 32 Solognac binoculars. In addition, we
interviewed local people and wildlife photographers for previously active nests
that we could monitor for possible occupancy. We confirmed active breeding from
sightings of parrots staying inside the cavity for prolonged periods of time
during the day. Focal nests per species were observed for breeding-related
activities in a blind of trees at least 50 m from the nest tree using a KOWA
spotting scope (TSN-60). Per observation period, we took note of the general
diurnal breeding behaviour, including visible activities within the nest
cavity, activities surrounding the nest tree, and when possible, sex roles and
parental care strategies. We categorized activities into six types: peeking,
preening, out of the nest, feeding, calling, and no visible activity. We then
recorded the number of hours spent on each activity per observation day and
calculated their respective proportions to understand how these activities vary
and change throughout one nesting period. Unfortunately, only the BNP proceeded
with breeding between the two parrot species among nests located. Most
breeding-related data for the GRT, as well as diet information for both
species, were obtained through citizen science.
Citizen Science Data Collection
To gather ecological data on the
parrots, citizen science data was used. Photographs and videos of GRT and BNP
were sourced from two citizen science platforms—eBird and Facebook. In these
platforms, we filtered available media from January 2010 to January 2025. In
eBird, we clicked on the ‘Explore’ bar and typed in ‘Prioniturus luconensis’
and ‘Tanygnathus lucionensis’. We filtered the location to “Philippines”
and manually searched for any media of feeding parrots located. In Facebook, we
clicked on the search bar and typed ‘Green Racquet-tail/Green Racket-tail’,
‘Blue-Naped Parrot’, ‘Prioniturus luconensis’ ‘Tanygnathus
lucionensis’ and ‘loro/pikoy/kalangay’ and manually examined photos of
feeding parrots posted as public by bird enthusiasts or photographers. We also
examined photos from Facebook groups dedicated to birdwatching and wildlife
photography: ‘Wildlife Photographers of the Philippines’, ‘Philippine Bird
Photography Forum-FB Group’, ‘Birdwatch Philippines Community’, and ‘Wild Bird
Photographers of the Philippines’. Administrators of these groups require
members to post photographs with date taken and general location, nonetheless,
we validated the said information from the content owner through Facebook
Messenger. We also asked each content owner for additional observations,
further fruit/tree descriptions, and possible identity of the fruit sample in
their photo. Similarly, for photos with a parrot perched on a fruiting tree, we
asked the content owner if the bird was feeding on it before or after the photo
was taken. All plants were verified and identified to the lowest taxonomic
level by an expert botanist from the University of the Philippines Diliman.
Similarly, we tried to construct
the nesting phenology of both parrots using similar methodology as stated
above. We searched for photos of parrots in any stages of breeding: copulation,
nest building, activity surrounding a nest, feeding of nestlings in a cavity,
adults feeding fledglings, or sightings of fledglings. We took note of the date
when the photos were taken and had the media owners verify their authenticity
and asked for any other observations regarding their record.
RESULTS
Breeding Behavior
Green Racquet-tail (GRT)
We observed a pair of GRT
visiting Nest A on 28 May 2022 (Image 1a) and Nest B on 6 March 2023 (Image
1b). Both nests were woodpecker-made cavities excavated on dead trees. In both
nests, we observed cavity inspection behaviour in which the female entered and
exited the cavity nest multiple times while maintaining vocal contact with the
male. The male parrot did not enter the cavity and was perched only in a nearby
tree. Nest inspection lasted 3–20 minutes after which the pair left the site
together. A summary of the key behaviours is presented in Table 1.
Unfortunately, both pairs did not proceed with nesting.
Copulation attempts of a
different pair were observed on 02 March 2023. Fledglings with short spatules
were also observed within the site on 3 April and 23 April. For both dates, two
juveniles were seen with the adults, suggesting a brood size of two. During
these dates, it was noticeable that the juveniles were more vocal than the
adults. We also observed an adult racquet-tail feeding a juvenile on 23 April
2023.
Blue-Naped Parrot (BNP)
We located and observed two nests
of actively breeding BNP, both in woodpecker-excavated cavities on dead trees.
On 27 March 2022, we observed a BNP occupying Nest C. The parrot remained
inside the cavity for most of the day and only left upon the arrival of one or
two other adult parrots. During these interactions, the pair or group flew to a
nearby tree, where the nesting parrot was fed through regurgitation. Copulation
was also observed, during which the nesting parrot was mounted, thereby
confirming it as the female.
The second nest, Nest D, was
observed from March to August 2023, which we have observed from cavity
inspection and courtship to fledging. Early observations were consistent with
those previously recorded on Nest C, that is social behavior with a group of
parrots, post-copulatory feeding, and male to female feeding through
regurgitation (Image 2b). We also noted multiple copulation events in which the
nesting parrot was mounted (Image 2a), thereby confirming it as the female.
Nest attendance of the female parrot was highest during the first six weeks of
observation (Image 2c, Figure 1), consistent with the onset of incubation and
brooding periods. Later observations indicated chick provisioning by the
female, evident from its messy mandibles, regurgitation behaviour, and
increased time spent outside the nest (Figure 1). The male parrot was not
observed provisioning for the brood but was consistently feeding the female and
likely foraging with her in the later weeks of observation. By 19 August 2023,
the nest had been completely vacated with the brood likely fledging between 4
July (Week 22) and 18 August (Week 28). A summary of the key behaviours is
presented in Table 2.
Diet
We assessed 1,281 photos of
parrots (n = 403 for GRT, n = 878 for BNP) dating from 2012–2025 across two
citizen science platforms, eBird and Facebook. eBird had the highest number of
records but Facebook had the greatest number of unique photos (Table 3). Many
eBird entries were deemed unusable in analyzing the nesting phenology as they
do not bear dates, unlike records in human-moderated Facebook groups that have
strict posting rules. Records of GRT only came from a single locality (SWFR)
whereas records for BNP came from three (SWFR, Palawan, and Zamboanga).
Nonetheless, despite having records from three localities, the majority of BNP
photos (86%) analyzed came from SWFR.
We identified 33 plant species
from 21 families consumed by both parrot species, 73% of which were native to
the Philippines (Table 4). The GRT consumed 14 plant species, of which eight
were exclusively recorded in its diet. BNP fed on 25 species, with 19 recorded
solely in its diet. Both parrots were observed feeding on six shared plant
species: Mangifera altissima, M. indica, Commersonia bartramia,
Macaranga tanarius, Mezoneuron latisiliquum, and Cratoxylum sumatranum.
Fruits were the most documented plant part used for consumption, followed by
flower/flower buds, leaves/leaf buds, seeds, and bark (Image 3). Between the
two parrots, only the GRT was recorded to consume leaf buds and seeds.
Nesting Phenology
We analyzed 24 photos of GRT and
23 photos of BNP in various breeding-related activities or stages of development
to construct the nesting phenology of the parrots. Photos were classified into
five categories: Adult in/inspecting nest, copulating, nesting, juvenile
spotted, and adult feeding young. GRT has been recorded inspecting or in nests
during both the dry and wet seasons (Figure 2a). Consequently, juveniles have
been observed in almost all months of the year. In contrast, breeding
activities of the BNP were recorded only in the first half of the year, with
copulation records coinciding with the dry season and sightings of juveniles
recorded mostly towards or during the wet season (Figure 2a). These citizen
science data agree with our field observations, which we have combined in
Figure 2a.
DISCUSSION
Old World parrots are generally
monogamous, with both parents contributing to chick-rearing activities
(Billerman et al. 2020); however, some species exhibit complex breeding systems
like polygynandry for the Greater Vasa Parrot Coracopsis vasa (Ekstrom
et al. 2007) and polygynandry-polyandry for the Eclectus Parrot Eclectus
roratus (Heinsohn 2008). Our findings suggest that BNP may potentially have
a complex mating system, evident from observations of several visiting parrots
that could either be mates or helpers. Parrots copulating with nesting females
could also be different individuals; regrettably, our field methods did not
allow for precise identification of individuals, despite our efforts to look
for distinguishing marks or features from each visiting parrot. Future studies
employing individual identification techniques are necessary to validate the
species’ mating system. Nonetheless, our observations of parrots partaking in
multiple copulation events, males feeding the females through regurgitation,
and biparental care are consistent with the typical reproductive behaviour of
Old World parrots (Billerman et al. 2020). Sex roles appeared to be unequal,
with most of the direct chick-rearing responsibilities undertaken by the female
BNP. In addition, BNP exhibited an extended nesting period lasting ≥4 months,
predominantly during the dry season. This observation agrees with the behaviour
of other well-studied parrots such as the Lilac-Crowned Parrot Amazona
finsch (≥ 3 months, Renton & Salinas-Melgoza 2004) and Cape Parrot
Poicephalus robustus (3–4 months, Wirminghaus et al. 2001), possibly as a
response to suitability in cavity-nesting conditions and resource availability
(Ekstrom et al. 2007).
In contrast, the GRT appears to
breed all year-round, with an observed brood size of two. The species may be
reliant on woodpecker-excavated cavities in dead trees as nesting sites,
natural cavities in live trees (Realubit et al. 2022; Gicaraya et al. 2025), or
even cavities in arboreal epiphytic ferns (Walker & Seroji 2000). Both our
field and citizen science data failed to locate nests of actively breeding
racquet-tails, underscoring their highly elusive and inconspicuous nature, as
well as their aversion to human disturbance (Vince Angelo G. Gicaraya pers.
obs. 2022). They are also likely susceptible to the presence of more aggressive
cavity users, such as the Coleto Sarcops calvus, Dollarbird Eurystomus
orientalis, or even congeners, as evidenced by their displacement by
Blue-crowned Racquet-tails Prioniturus discurus in parts of their range
(BirdLife International 2024). Year-round nest surveys and telemetry studies
may prove fruitful in elucidating the breeding biology of this species.
In terms of diet, our findings
indicate that both parrots are mixed plant resource feeders, with BNP
exhibiting a broader dietary range compared to GRT. Leaf and seed consumption
by BNP was not recorded but may have occurred, possibly overlooked due to
citizen scientists’ limited ability to detect subtle feeding behaviours. Bark
consumption was observed for both species but has not been reported yet for
members of either genus. For well-studied parrots, this behaviour is often
associated with foraging for invertebrates, sap, and cambium (O’Donnell &
Dilks 1989; De Paula et al. 2017) or as a means to detoxify, digest, or absorb nutrients
(de Araújo & Marcondes-Machado 2011). Moreover, it is worth noting that
these parrots only consumed native plants (73% of records) from various plant
families, underscoring the importance of native vegetation as food sources for
native parrots. Nonetheless, both species were recorded consuming naturalized
plants indicating a degree of dietary plasticity.
There are several caveats that
should be considered when interpreting the results of this study. First, there
is a geographic bias towards SWFR, as it is a popular and easily accessible
birdwatching site for many enthusiasts. Second, although eBird contains
numerous records, many lacked dates and were, therefore, unusable, particularly
for analyzing nesting phenology. Third, although many of our findings agree
with the behaviour of Old World parrots, increasing the number of nests for
observation, along with the use of camera traps, could provide a sounder
understanding of the species’ breeding biology, particularly in estimating the
nesting period and defining parental roles. Nonetheless, as a preliminary
investigation, the current study was successful in four respects, in that it;
1) acquired a detailed account of the breeding biology of the BNP and its
behaviour within and surrounding an active nest through field observations; 2)
acquired insights on diet that could inform parrot-targeted habitat management;
3) constructed the nesting phenology of parrots using field and citizen science
data; and 4) demonstrated how citizen science could supplement data from field
observations and help acquire information on rare species, particularly when
field observations are limited by time and resources. Our findings offer a
valuable foundation for future research and conservation initiatives,
particularly those aimed at enhancing feeding opportunities for these rare and
threatened parrots through habitat enrichment, development of nest protection
measures, establishment of nest monitoring activities, and the meaningful
engagement of citizen scientists in biodiversity research and conservation
efforts.
Table 1. Key behavioural
observations in two nests of GRT. Effort in hours (h) pertains to observation
effort per day.
|
Nest code |
Date |
Effort (h) |
Key behaviors |
Breeding stage |
|
A |
28 May 2022 |
6 |
Female inspected cavity for 20
minutes; entered/exited multiple times; male perched on a nearby tree; both
birds vocalizing. The pair departed together after inspection. |
Nest establishment,
Pre-egg-laying |
|
A |
29 May, 03 June 2022 |
6 |
No activity observed. |
Nesting did not proceed |
|
B |
6 March 2023 |
2 |
Female inspected cavity for 15
minutes; entered/exited; both birds vocalizing. The pair departed together
after inspection. |
Nest establishment,
Pre-egg-laying |
|
B |
3 April 2023 |
2 |
Female inspected cavity for 3
minutes; both birds vocalizing. The pair departed together after inspection. |
Nest establishment,
Pre-egg-laying |
|
B |
18 May 2023 |
2 |
No activity observed. |
Nesting did not proceed |
|
B |
June 2023 |
0.5 |
Nest was found felled. |
|
Table 2. Key behavioural
observations in two nests of BNP. Effort in hours (h) pertains to observation
effort per day. Code: U = undetermined.
|
Week |
Nest code |
Date |
Effort (h) |
Key observations |
Breeding stage |
|
U |
C |
27 March 2022 |
8 |
Parrot stayed most of the time
throughout the day. Nesting parrot flew to a nearby tree and was met by an
adult parrot which fed it through regurgitation. Feeding lasted 5 minutes. |
Courtship, Pre-egg-laying |
|
U |
C |
31 March 2022 |
8 |
Two adult parrots visited the
nesting parrot. The small group flew to a nearby tree. One parrot copulated
with the nesting parrot twice lasting 3 minutes. Male fed the female
afterwards through regurgitation. |
Copulation, Pre-egg-laying |
|
1 |
D |
02 & 03 March 2023 |
24 |
Six parrots socializing on the
nest tree. Cavity inspection by an adult parrot. Two adult parrots attempted
to copulate but failed. Multiple nest visitations by the male in the
afternoons. Successful copulation (3-4 minutes) in two consecutive days.
Post-copulatory feeding (2-10 minutes). |
Courtship, Nest establishment,
Copulation, Pre-egg-laying |
|
4 |
D |
22 March 2023 |
12 |
Female parrot mostly stayed
inside the cavity nest. Left only thrice that day, usually accompanied by the
male. Female parrot was seen peeking through the cavity opening with either a
fruit or leaf. |
Onset of incubation; high nest
cavity attendance |
|
6 |
D |
3 April 2023 |
12 |
Female had ruffled belly
feathers. Nesting female was only out twice, joined by male. Male fed the
female. Male visited twice briefly. |
Brooding behavior evident; high
nest cavity attendance |
|
12 |
D |
18 May 2023 |
12 |
Female returned with messy beak.
Head movements inside the cavity nest suggest feeding of nestlings. Coleto Sarcops
calvus briefly inspected the cavity then left. |
Nestling stage; nestling
provisioning behavior evident |
|
18 |
D |
15 June 2023 |
12 |
Two feeding events. Feeding was
done by the female while perched at cavity rim. The nest was left unattended
for 5.8 hours that day. |
Nestling stage; nestlings
likely older; reduced cavity nest attendance |
|
22 |
D |
3 July 2023 |
12 |
Female peeked through the cavity
opening during Dollarbird Eurystomus orientalis visit (no usurpation).
Regurgitation inside the cavity nest. Rapid exit-return movements (3x). |
Late nestling to fledging
stage; reduced cavity nest attendance |
|
28 |
D |
19 August 2023 |
12 |
No visible activity |
Presumed fledging completed |
Table 3. Feeding and breeding
records of parrots obtained in different citizen science platforms.
|
Citizen science platform |
GRT |
BNP |
||||
|
Number of photos |
Foraging |
Breeding-related activities |
Number of photos |
Foraging |
Breeding-related activities |
|
|
eBird |
195 |
3 |
0 |
512 |
12 |
0 |
|
Facebook- Birdwatch Community
Philippines |
83 |
8 |
9 |
118 |
11 |
5 |
|
Facebook- Wild Bird
Photographers of the Philippines |
79 |
8 |
8 |
95 |
22 |
8 |
|
Facebook- Philippine Bird
Photography Forum-FB Group |
19 |
1 |
7 |
48 |
13 |
6 |
|
Facebook- Wildlife
Photographers of the Philippines |
20 |
0 |
0 |
91 |
7 |
4 |
|
Facebook- Personal Public Post |
1 |
1 |
0 |
2 |
2 |
0 |
|
Requested from Enthusiasts |
6 |
6 |
0 |
12 |
12 |
0 |
|
Total |
403 |
27 |
24 |
878 |
79 |
23 |
Table 4. Plant species consumed
by parrots identified using citizen science.
|
Plant species |
Conservation status |
Family |
Plant part |
GRT |
BNP |
||
|
SWFR |
SWFR |
Palawan |
Zamboanga |
||||
|
Buchanania arborescens |
Native |
Anacardiaceae |
Fruit |
|
x |
|
|
|
Mangifera indica |
Native |
Anacardiaceae |
Fruit |
x |
x |
|
|
|
Mangifera altissima |
Native |
Anacardiaceae |
Fruit |
x |
x |
|
|
|
Polyscias nodosa |
Native |
Araliaceae |
Flower/peduncle |
|
x |
|
|
|
Spathodea campanulata |
Introduced |
Bignoniaceae |
Flower Bud |
|
x |
|
x |
|
Garuga floribunda |
Native |
Burseraceae |
Fruit |
|
|
x |
|
|
Commersonia bartramia |
Native |
Byttneriaceae |
Fruit |
x |
x |
|
|
|
Kleinhovia hospita |
Native |
Byttneriaceae |
Fruit |
x |
|
|
|
|
Calophyllum inophyllum |
Native |
Calophyllaceae |
Fruit |
|
|
x |
|
|
Trema orientale |
Native |
Cannabaceae |
Fruit |
|
x |
|
|
|
Casuarina equisetifolia |
Native |
Casuarinaceae |
Fruit |
|
x |
|
|
|
Terminalia catappa |
Native |
Combretaceae |
Fruit |
|
|
|
x |
|
Coccinia grandis |
Cryptogenic |
Cucurbitaceae |
Fruit |
|
x |
|
|
|
Tetracera sp. |
Native |
Dilleniaceae |
Flower Buds |
x |
|
|
|
|
Endospermum peltatum |
Native |
Euphorbiaceae |
Fruit |
|
x |
|
|
|
Macaranga tanarius |
Native |
Euphorbiaceae |
Fruit |
x |
x |
x |
|
|
Melanolepis multiglandulosa |
Native |
Euphorbiaceae |
Fruit |
|
x |
|
|
|
Intsia bijuga |
Native |
Fabaceae |
Bark |
|
x |
|
|
|
Leucaena leucocephala |
Introduced |
Fabaceae |
Flower Buds |
x |
|
|
|
|
Mezoneuron latisiliquum |
Native |
Fabaceae |
Fruit |
x |
x |
|
|
|
Parkia timoriana |
Native |
Fabaceae |
Flower |
|
x |
|
|
|
Pterocarpus indicus |
Native |
Fabaceae |
Fruit |
|
x |
|
|
|
Tamarindus indica |
Introduced |
Fabaceae |
Fruit |
x |
|
|
|
|
Cratoxylum sumatranum |
Native |
Hypericaceae |
Fruit |
x |
x |
|
|
|
Gmelina arborea |
Introduced |
Lamiaceae |
Fruit |
x |
|
x |
|
|
Unidentified |
NA |
Lamiaceae |
Fruit |
|
x |
|
|
|
Ficus sp. |
Native |
Moraceae |
Leaf buds |
x |
|
|
|
|
Psidium guajava |
Introduced |
Myrtaceae |
Fruit |
|
x |
|
|
|
Syzygium cumini |
Introduced |
Myrtaceae |
Fruit |
x |
|
|
|
|
Bambusa sp. |
NA |
Poaceae |
Seeds |
x |
|
|
|
|
Guioa sp. |
Native |
Sapindaceae |
Fruit |
|
x |
|
|
|
Pterocymbium tinctorium |
Native |
Sterculiaceae |
Flower/Fruit |
|
x |
x |
|
|
Cissus repens |
Native |
Vitaceae |
Fruit |
|
x |
|
|
|
Unidentified |
NA |
NA |
Bark |
x |
|
|
|
For
figures & images - - click here for full PDF
REFERENCES
Allen, D. (2020). Birds of the
Philippines. Lynx Edicions, Barcelona, 400 pp.
Billerman,
S.M., B.K. Keeney, P.G. Rodewald & T.S. Schulenberg (2020). Old World Parrots
(Psittaculidae) version 1.0. In: S.M. Billerman, B.K. Keeney, P.G. Rodewald
& T.S. Schulenberg (eds.). Birds of the World. Cornell Lab of
Ornithology. https://doi.org/10.2173/bow.psitta4.01
Billerman,
S.M., B.K. Keeney, P.G. Rodewald & T.S. Schulenberg (eds.) (2022). Birds of the World.
Cornell Laboratory of Ornithology.
BirdLife
International (2024). Species factsheet: Green Racquet-tail Prioniturus luconensis.
Downloaded from https://datazone.birdlife.org/species/factsheet/green-racquet-tail-prioniturus-luconensis
19 March 2025.
Cockle, K.L.,
K. Martin & G. Robledo (2012). Linking fungi, trees, and hole-using birds in a
Neotropical tree-cavity network: Pathways of cavity production and implications
for conservation. Forest Ecology and Management 264: 210–219. https://doi.org/10.1016/j.foreco.2011.10.015
Collar, N.,
G.M. Kirwan & P.F.D. Boesman (2020). Blue-naped Parrot (Tanygnathus
lucionensis). In: del Hoyo, J., A. Elliott, J. Sargatal, D. Christie &
E. de Juana (eds.). Birds of the World. Cornell Lab of Ornithology. https://doi.org/10.2173/bow.blnpar1.01
Cornelius,
C., K.L. Cockle, N. Politi, I. Berkunsky, L. Sandoval, V. Ojeda, L.O. Rivera,
M. Hunter, K. Martin, F.S. Darwin & P.S. de Pino Paraná (2008). Cavity-nesting birds in
Neotropical forests: Cavities as a potentially limiting resource, https://api.semanticscholar.org/CorpusID:54893354
Corporal-Lodangco,
I.L. & L.M. Leslie (2017). Defining Philippine Climate Zones Using Surface and High-Resolution
Satellite Data. Procedia Computer Science 114: 324–332. https://doi.org/10.1016/j.procs.2017.09.068
De Araújo,
C.B. & L.O. Marcondes-Machado (2011). Diet and feeding behavior of
the Yellow-Faced Parrot (Alipiopsitta xanthops) in Brasilia, Brazil. Ornitologia
Neotropical 22: 79–88.
De Paula,
G.A., R. Laps & E. Fischer (2017). Hyacinth Macaws (Anodorhynchus
hyacinthinus, Psittacidae) feeding on termites. Ornitología Neotropical
28: 187–190. https://doi.org/10.58843/ornneo.v28i0.247
de Souza, E.,
J. Lima-Santos, O.M. Entiauspe-Neto, M.M. dos Santos, P.R. de Moura & E.
Hingst-Zaher (2022). Ophiophagy in Brazilian birds: a contribution from a collaborative
platform of citizen science. Ornithology Research 30(1): 10. https://doi.org/10.1007/s43388-022-00082-5
Díaz, A., E.
Amanqui, K.G. Saravia-Llaja, J.R. Mandujano Collantes, M. Jiménez, R.
Zárate-Gómez & F. Condo (2024). Breeding records of 325 bird species from Peru over
21 years based on citizen science data. Ecological Research 39(5):
789–799. https://doi.org/10.1111/1440-1703.12496
Ekstrom,
J.M.M., T. Burke, L. Randrianaina & T.R. Birkhead (2007). Unusual sex roles in a highly
promiscuous parrot: the Greater Vasa Parrot Caracopsis vasa. Ibis
149(2): 313–320. https://doi.org/10.1111/j.1474-919X.2006.00632.x
Española,
C.P., N.J. Collar & S.J. Marsden (2013). Are populations of large-bodied
avian frugivores on Luzon, Philippines, facing imminent collapse? Animal
Conservation 16(4): 467–479. https://doi.org/10.1111/acv.12018
Fernando,
E.S., M.H. Suh, J. Lee & D.K. Lee (2008). Forest Formations of the
Philippines. ASEAN-Korea Environmental Cooperation Unit (AKECU), Korea, 232
pp.
Gicaraya,
V.A.G. & C. Española (2023). Notes on the breeding biology and nesting behaviour
of the Coleto Sarcops calvus in the wild. Journal of Asian
Ornithology 39: 26–29.
Gicaraya,
V.A.G. & C.P. Española (2024a). Observations on the breeding biology of the Luzon
Flameback Chrysocolaptes haematribon (Wagler 1827) (Piciformes: Picidae)
with notes on active nest defense against dollarbird Eurystomus orientalis
(Linnaeus 1766) (Coraciiformes: Coraciidae). Natural History Sciences
12(1): 84–88. https://doi.org/10.4081/nhs.2024.748
Gicaraya,
V.A.G & C.P. Española (2024b). Breeding biology of the Luzon Hornbill Penelopides
manillae manillae (Aves: Bucerotidae) on Luzon Island, Philippines. Ornithological
Science 23(2): 91–101. https://doi.org/10.2326/osj.23.91
Gicaraya,
V.A.G., C.P. Española, E.S. Quijano, K. Soriano, E.S. Torio & D.R.D. Naguit
(2025). Cavity
characteristics explain the differences in realized nest niches among tree
cavity-nesting birds in a lowland tropical forest in Luzon Island, Philippines.
Annales Zoologici Fennici 62(1): 51–64. https://doi.org/10.5735/086.062.0105
Gonzalez,
J.C. (2007). Ecology and
distribution of the Polillo Tarictic Hornbill Penelopides manillae subnigra
in the Polillo Islands, Philippines, pp. 345–355. In: Kemp, A. & M. Kemp
(eds.). Proceedings of the 3rd International Hornbill Workshop, The Ecology
of Hornbills: Reproduction and Populations. Hornbill Research Foundation,
Bangkok, 364 pp.
Hall, M.J.,
J.M. Martin, A.L. Burns & D.F. Hochuli (2021). Ecological insights into a
charismatic bird using different citizen science approaches. Austral Ecology
46(8): 1255–1265. https://doi.org/10.1111/aec.13062
Heinsohn, R.
(2008). Ecology and
evolution of the enigmatic Eclectus Parrot (Eclectus roratus). Journal
of Avian Medicine and Surgery 22(2): 146–150. https://doi.org/10.1647/2007-031.1
Lammertink,
M. (2014). Trends in
threat status and priorities in conservation of the woodpeckers of the world. Acta
Ornithologica 49(2): 207–219. https://doi.org/10.3161/173484714X687109
Lees, A.C.
& R.W. Martin (2015). Exposing hidden endemism in a Neotropical forest raptor using citizen
science. Ibis 157(1): 103–114. https://doi.org/10.1111/ibi.12207
Marcenò, C.,
J. Padullés Cubino, M. Chytrý, E. Genduso, D. Salemi, A. La Rosa, A.S.
Gristina, E. Agrillo, G. Bonari, G.G. del Galdo, V. Ilardi, F. Landucci &
R. Guarino (2021). Facebook groups as citizen science tools for plant species monitoring.
Journal of Applied Ecology 58(10): 2018–2028. https://doi.org/10.1111/1365-2664.13896
O’Connell,
M., D. Spennemann, J. Bond, R.K. Kopf, N. McCasker & P. Humphries (2025). Fishing on Facebook: Using
social media and citizen science to crowd-source trophy Murray cod. Citizen
Science: Theory and Practice 10(1): 5. https://doi.org/10.5334/cstp.718
O’Donnell,
C.F.J. & P.J. Dilks (1989). Sap feeding by Kaka (Nestor meridionalis) in
South Westland, New Zealand. Notornis 36: 65–71.
Realubit, N.,
L. Afuang, J. Acay & C. Española (2022). Habitat associations of five
endemic and threatened Philippine parrot species present in Bataan Natural Park
and Kingfisher Park, Busuanga Island, Palawan. Sylvatrop 32: 88–113.
Renton, K.
& A. Salinas-Melgoza (2004). Climatic variability, nest predation, and
reproductive output of Lilac-Crowned Parrots (Amazona finschi) in
tropical dry forest of western Mexico. The Auk 121(4): 1214–1225. https://doi.org/10.1093/auk/121.4.1214
Sankamethawee,
W., A.J. Pierce, G.A. Gale & B.D. Hardesty (2011). Plant-frugivore interactions in
an intact tropical forest in north-east Thailand. Integrative Zoology
6(3): 195–212. https://doi.org/10.1111/j.1749-4877.2011.00244.x
Tabeta,
M.S.G. & S.G.F. Bejar (2025). Improving our understanding of a cryptic primate, the
Philippine Tarsier (Carlito syrichta), through social media. International
Journal of Primatology 46(3): 737–762. https://doi.org/10.1007/s10764-025-00495-1
Walker, J.S.
& M. Seroji (2000). Nesting behaviour of the Yellowish-breasted Racquet-tail Prioniturus
flavicans. Forktail 16: 61–63.
Widmann, P.,
I.D. Lacerna & S.H. Diaz (2001). Aspects of biology and
conservation of the Philippine Cockatoo Cacatua haematuropygia on Rasa
Island, Palawan, Philippines. Silliman Journal 42(2): 129–147.
Widmann, P.,
I.L. Widmann, M.F. Plazos & R. Antonio (2015). Aspects of breeding biology and
conservation of the Palawan Hornbill Anthracoceros marchei in the
Palawan faunal region, Philippines. Malayan Nature Journal 67: 130–143.
Wirminghaus,
J.O., C.T. Downs, M.R. Perrin & C.T. Symes (2001). Breeding biology of the Cape
Parrot, Poicephalus robustus. Ostrich 72(3–4): 159–164. https://doi.org/10.2989/00306520109485310
Xiao, H., Y.
Hu, Z. Lang, B. Fang, W. Guo, Q. Zhang, X. Pan & X. Lu (2016). How much do we know about the
breeding biology of bird species in the world? Journal of Avian Biology
48(4): 513–518. https://doi.org/10.1111/jav.00934
Zeng, Q., Q. Wei & G. Lei
(2018). Contribution
of citizen science towards cryptic species census: “many eyes” define wintering
range of the Scaly-sided Merganser in mainland China. Avian Research
9(1): 6. https://doi.org/10.1186/s40657-018-0098-5