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OSTRICH 2014: 1–9

Printed in South Africa — All rights reserved

Copyright © NISC (Pty) Ltd

O S T R I C H

ISSN 0030–6525   EISSN 1727-947X

http://dx.doi.org/10.2989/00306525.2014.931311



Ostrich is co-published by NISC (Pty) Ltd and Taylor & Francis

This is the fi nal version of the article that is 

published ahead of the print and online issue

Insights into the feeding ecology of the Seychelles Black Parrot Coracopsis 

barklyi using two monitoring approaches

Anna Reuleaux

1,2

*, Heather Richards

1

, Terence Payet

1

, Pascal Villard

1

, Matthias Waltert

2

 and Nancy Bunbury

1

1

 Seychelles Islands Foundation, Victoria, Mahé, Seychelles 

2

 Conservation Biology, Workgroup on Endangered Species, Georg-August Universität Göttingen, Göttingen, Germany

* Corresponding author, e-mail: anna.reuleaux@gmail.com

Feeding ecology is an important factor for the survival of a species and knowledge of its parameters is 

a prerequisite for successful conservation work. In this study we describe the feeding ecology of the endemic 

Seychelles Black Parrot Coracopsis barklyi on Praslin, Seychelles, the only island on which this parrot is resident. 

We compared two methods to evaluate feeding choices: incidental observations and feeding walks on 25 transects 

in all habitat types. Black parrots fed on 46 different species, bringing the total number of known food plants to 

53 species. They predominantly consumed endemic and native species (58% of observed feeding bouts), mainly 

their fruit pulp (in 68% of feeding bouts), followed by buds (15%) and seeds (37%) with occasional observations 

of leaves, bark and scale insects. The incidental method rendered many more observed bouts than the transect 

approach and the ratios of consumed species differed between methods but the transect results are regarded 

as more representative. The incidental method is not suitable for quantitative conclusions but complements the 

transect method, providing information about rarely occurring feeding events. 

Keywords: Coracopsis barklyi, feeding ecology, Indian Ocean, palm forest, parrots, Seychelles Black Parrot

 Successful conservation depends inter alia on preservation of 

feeding resources, since food availability influences popula-

tion numbers directly and indirectly via survival, mortality

fitness, productivity and breeding success (Saunders et al. 

1991; Jones 2004). Food preferences and foraging strate-

gies define species’ roles as pollinators, seed dispersers or 

predators, and determine competitive relationships with other 

species. Knowledge of identity and availability of feeding 

resources as well as foraging location, timing and habits are 

thus important prerequisites for conservation. Many conser-

vation projects collect data on feeding ecology, although 

methods vary and usually have to balance feasibility with the 

need to record sufficient feeding observations to draw conclu-

sions. Recording incidental observations produces many 

observations with limited effort (Bollen and van Elsacker 

2004; Ortiz-Catedral and Brunton 2009), but such observa-

tions, although providing insight into a species’ feeding 

ecology, are typically not representative and do not allow 

quantitative conclusions. Dedicated feeding transects permit 

comparisons over time and, depending on the sampling 

method, between areas (Pizo et al. 1995, Renton 2001). 

The Seychelles Black Parrot Coracopsis barklyi breeds 

only on the island of Praslin in the Seychelles, with a popula-

tion size of 520–900 birds (Reuleaux et al. 2013). Despite 

its tiny population size and distribution, C. barklyi acts as a 

flagship species for the rare palm forest habitat on Praslin, 

particularly the UNESCO World Heritage site of the Vallée 

de Mai. It is also the national bird and an avian cultural 

icon of the Seychelles. The Seychelles Black Parrot’s 

single island distribution makes it highly vulnerable to 

stochastic effects such as forest fires, disease outbreaks 

and climate change, which, among other impacts, may alter 

plant phenology cycles. Breeding is seasonal but does not 

occur every year (Reuleaux et al. 2014), which is likely to 

be linked to food availability. The fragility of the Seychelles 

Black Parrot population prompted the development of 

the Seychelles Black Parrot Action Plan (Rocamora and 

Laboudallon 2009), which proposes conservation measures 

and further research into areas including feeding ecology. 

Seychelles Black Parrots are known to feed on a variety 

of fruits and seeds of native and introduced plants (Gaymer 

et al. 1969; Rocamora and Skerrett 2001; Walford 2008; 

Rocamora and Laboudallon 2009), but observations have 

been incidental and limited in time and area. The main 

aims of this study were therefore to gain an objective 

understanding of Seychelles Black Parrot feeding ecology, 

assess the value of incidental feeding observations in small 

population monitoring, and provide information for future 

conservation efforts. To achieve these aims we applied 

and compared two data collection methods—incidental 

feeding observations and controlled-effort transects—to 

determine specifically (1) which plant species and parts 

are eaten by C. barklyi and to what extent and (2) whether 

results from incidental feeding observations can be used as 

a reliable indicator of the relative importance or preference

of food species. 

Introduction

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Reuleaux, Richards, Payet, Villard, Waltert and Bunbury

2

Materials and methods



Study site

The research was carried out on the island of Praslin in 

the Seychelles archipelago in the Indian Ocean (Figure 1). 

Praslin Island (4°19′ S 55°44′ E; 38 km

2

, 367 m highest 



point above sea level) is the second largest of the granitic 

Seychelles islands and is located at 44 km north of the 

largest granitic island Mahé. The climate is tropical with little 

variation in monthly mean temperatures of 25–28 °C (Walsh 

1984) or humidity (monthly mean 75–80%). Annual rainfall 

is 


2 000 mm. Praslin usually experiences a dry season 

from May to October and a wet season from December to 

March (Walsh 1984). 

Praslin Island’s population of c. 8 500 people is primarily 

settled around the coast (National Bureau of Statistics 

2013). The coastal plain is relatively wide and heavily 

modified by humans for cultivation, residential areas, 

tourism and infrastructure. Large areas of the island have 

been damaged by fire and are covered by secondary 

vegetation (Meuwly 2002). Hillsides are usually covered in 

boulders and thick scrub vegetation, whereas hilltops are 

often eroded bare soil. Only remnants of native palm forest 

occur in the uplands; the largest of these is protected in 

the Praslin National Park. Within the National Park lies the 

Vallée de Mai (19.5 ha), which is dominated by the endemic 

Coco de Mer palm Lodoicea maldivica and has been 

protected as a UNESCO Natural World Heritage site since 

1983 and managed by a public trust, the Seychelles Islands 

Foundation (SIF), since 1989. This research was carried out 

as part of a broader research programme on the Seychelles 

Black Parrots run by SIF since 2008. 

Feeding observations

We used two methods to collect feeding data: incidental 

feeding observations from October 2009 to August 2013, 

and transects with controlled search effort during three 

periods: January–April 2011, February–April 2012 and 

March–August 2013. For logistical reasons the transect 

survey period fell at the end of or after the breeding season 

(November–February) every year. Weather during the study 

period was typical for the seasons, but October 2011 and 

January 2012 were unusually wet months. 

Consumed plants were identified with binoculars and by 

examining dropped food items (the latter required many 

dropped items to be found and collected to distinguish 

between accidentally dropped items and actively discarded 

plant parts). The following parameters were recorded for all 

feeding observations: time, location, observer, food plant 

species, plant part(s) consumed, number of parrots feeding, 

and duration of feeding bout. Following other studies we 

counted feeding observations in bouts; a ‘feeding bout’ 

consists of at least one parrot feeding on one or more parts 

of a certain species, without taking the number of parrots 

or the time spent feeding in account (Pizo et al. 1995; 

Renton 2001; Ragusa-Netto 2007). We also recorded the 

‘parrot feeding time’ or ‘resource exploitation’ for each bout, 

which is calculated from the number of feeding individ-

uals multiplied by the number of minutes spent feeding 

(Kristosch and Marcondes-Machado 2001) and is measured 

in parrots*feeding minutes. Although this measure is 

intuitively more representative of the importance of food 

resources, it is not widely used; most studies assume 

that number of bouts reflects resource use. We used this 

measure to check this assumption for our data. 



Figure 1: Study area with feeding transects, Praslin National Park and Vallée de Mai

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Ostrich 2014: 1–9

3

Incidental feeding observations were not randomised, 



i.e. all parrots seen feeding in the course of parrot fieldwork 

were recorded regardless of time or location. 

Due to the low density of parrots across most of 

Praslin Island, transects were located in areas of high 

parrot activity using results from a population survey 

(Reuleaux et al. 2013). Twenty-five transects of c. 800 m 

length were chosen in 13 locations with known parrot 

activity and presence of fruiting trees. Habitat type 

of the transects was determined in the field for each 

100 m section using the following categories: (1) palm 

forest (67–100% endemic palms, canopy height 

6 m, 


canopy cover 

30%); (2) mixed forest (any other forest 

with canopy height 

6 m, canopy cover 30%); (3) native 

scrub (majority of plants native, canopy cover 

30% 


and/or canopy height 

6 m); and (4) cultivated/residen-

tial (residential areas, farmland and other land uses). 

Transects were positioned to cover equal lengths of the 

four habitat types. In 2011, 19 of the 25 transects were 

surveyed and the ratio of habitat types for that year was 

corrected by randomly excluding data from transect 

sections of the over-represented habitat types.

Transects followed footpaths, firebreaks and roads 

because difficult terrain did not allow walking off-track while 

concentrating on detecting parrots. Due to the density 

of the vegetation the visually surveyed area per walked 

distance was limited and, in combination with the low 

density of feeding parrots, it was necessary to include aural 

detections in the survey. In 2011 each of the 19 transects 

was walked four times, twice in the morning (06:00–10:30) 

and twice in the late afternoon (15:30–18:30), during hours 

of high C. barklyi activity (Reuleaux et al. 2013). With 

increased knowledge of the parrots’ behaviour the methods 

were improved in 2012 and 2013 by including two more 

time slots in the middle of the day, to investigate potential 

diurnal movements between habitat types, resulting in 

four time slots at 06:00–09:30, 09:30–12:00, 12:00–15:30 

and 15:30–18:30, which were all surveyed once on each 

transect each year. Transects were not surveyed in 

moderate or heavy rain or strong winds. Walking speed 

was c. 1 km h

−1

. Attempts to locate parrots heard within 



50 m of the observer were made and transects were left for 

this if necessary. If the parrot was not found within 5 min 

the transect was resumed. Each feeding observation was 

counted as one feeding bout, regardless of the number 

of parrots. If the birds stopped feeding on one plant and 

moved to a different species or a tree of the same species 

20 m away, a new feeding bout started and was marked 

as a second record for the same individual(s). Feeding 

parrots were followed until they were lost. Non-feeding 

parrots were abandoned after 3 min. 

Between January and April 2011 both methods were 

carried out in parallel by two different observers. Only these 

data were used for comparison of the methods. 

Statistical analysis

All means are presented 

1 SD unless stated otherwise. 

We used two data sets: transect data (bouts observed on all 

transects) and incidental data (bouts observed incidentally). 

All statements requiring representative sampling are based 

on the transect data set. For comparison of the methods 

we created two subsets: incidental feeding observation 

data collected from January to April 2011 were compared 

with the data collected from feeding transects during the 

same period. We used a two-sided Fisher’s exact test with 

simulated p-value (Monte Carlo simulation based on 2 000 

replicates) to compare frequency of plant species in number 

of feeding bouts between the two methods. To ensure that 

samples from the feeding transect data were independent, 

we used only the first bout of each individual and tree.   

Pearson’s product-moment correlation with log-

transformed variables was used to confirm if the number of 

feeding bouts reflects the parrots’ feeding time (or ‘resource 

exploitation’ 

 parrots*feeding minutes). 

Statistical analysis was performed using R version 2.10.1 

(R Development Core Team 2013) with packages ‘reshape’, 

‘chron’ and ‘psych’ (Wickham 2007; James and Hornik 

2013; Revelle 2013). Rarefaction and species accumulation 

curves were produced using the ‘vegan’ package (Oksanen 

et al. 2013) and the function ‘rarefaction’ (Jacobs 2009). A 

Lomolino model was fitted to the food species accumulation 

and used to calculate the asymptote for the number of food 

species (Lomolino 2000; Tjørve 2003). 



Results

A total of 1 903 incidental feeding observations were 

recorded between November 2009 and August 2013, 

predominantly in the Vallée de Mai. Over the whole study 

period the incidental method rendered more observations 

than the transect approach (148). During our study 46 plant 

species were observed to be eaten by C. barklyi, bringing 

the total observed (including previous studies) to 53 plant 

species from 43 genera and 28 families that have been 

documented to be consumed by C. barklyi (Table 1). The 

asymptote of a species accumulation curve produced by 

a Lomolino model using all observations is 73.4 species. 

Twelve of these food species were observed to be eaten 

only once by parrots. Twelve of the consumed plant species 

are endemic to Seychelles, 12 others are native and 29 

have been introduced. 

The transect method showed that the majority (58%) of 

feeding bouts was on endemic and native plant species 

(Figure 2). Endemic palm species accounted for almost 

one-quarter of parrot feeding bouts and Dillenia ferruginea

a widespread endemic broadleaf, was the most consumed 

species. 

Parrots were observed feeding on fruits, buds, seeds, 

flowers, leaf petioles, bark and scale insects. Fruits were 

targeted in 68% of the observations, buds in 15%, seeds 

in 38%, and flowers, leaves, bark and scale insects were 

each consumed in 

1% of observations. Percentage of 

fruits consumed was higher on endemics (81% on palms, 

79% on other endemics) than on introduced species (61%; 

aov F 

 3.03; Tukey HSD, adj 0.045). Fruits and seeds 

were eaten ripe (29%) or unripe (19%), while ripeness 

stage remained unknown in 52% of feeding bouts. Food 

processing habits were particularly notable on endemic 

palm fruit as little substance appeared to be consumed: for 

example, unripe palm fruit (Phoenicophorium borsigianum 

and  Nephrosperma vanhoutteanum) before seed develop-

ment were picked, punctured and then dropped; after picking 

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Reuleaux, Richards, Payet, Villard, Waltert and Bunbury

4

Family



Scientific name

Vernacular name

Status

Part eaten



Source

Anacardiaceae



Mangifera indica

Mango


I

Fr(ur,rp), Bd

2, 4, 5

Spondias dulcis

Golden apple

I

Fr(ur)


2, 3, 4

Asclepiadaceae



Tylophora indica

Indian ipecac

I

Fr

4



Bignoniaceae

Colea seychellarum

I

Fr



1, 2

Bombacaceae



Ceiba pentandra

Kapok


I

Bd, Fl


2, 4, 5

Caricaceae



Carica papaya

Papaya


I

Bd, Fl, Fr(rp)

4, 5

Casuarinaceae



Casuarina equisetifolia

Common ironwood

N

Sd, Fr(ur), 



3, 4, 5

Chrysobalanaceae



Chrysobalanus icaco

Coco plum

I

Fr

2, 5



Clusiaceae

Calophyllum inophyllum

Takamaka


N

Bd, Fl, Si

5

Combretaceae



Terminalia catappa

Indian almond

N

Fr (rp)


5

Cyperaceae



Lophoschoenus hornei

E

Sd



5

Dilleniaceae



Dillenia ferruginea

Red wood


E

Fr(ur,rp),Sd, Bd, Lf

2, 4, 5

Erythroxylaceae



Erythroxylum sechellarum 

E

Fr (ur), Lf, Bd



5

Euphorbiaceae



Phyllanthus acidus

Gooseberry tree

I

Sd, Si


5

Phyllanthus pervilleanus

Kastik


N

Fr(ur,rp), Bd, Sd

3, 5

Fabaceae


Delonix regia

Flamboyant

I

Fl

5



Pterocarpus indicus

Dragon tree

I

Bd, Ba


5

Tamarindus indicus

Tamarind


I

Sd, Fr


3, 5

Goodeniaceae



Scaevola sericea

Beach naupaka

N

Lf, Fl


5

Lamiaceae



Premna serratifolia

Premna


N

Bd

5



Lauraceae

Cassytha filiformis

N

Fr



5

Cinnamomum verum

Cinnamon


I

Fr, Bd


5

Melastomataceae



Memecylon eleagni

E

Fr(ur), Sd



5

Meliaceae



Azadirachta indica

Neem tree

I

Fr

5



Sandoricum koetjape

Santol


I

Fr(rp)


4, 5

Swietenia macrophylla

Big leaf mahogany

I

Bd

5



Swietenia mahagoni

West Indies mahogany

I

Bd

5



Mimosaceae

Adenanthera pavonina

Red sandalwood

I

Fr, Sd, Bd



5

Moraceae


Ficus bojeri

E

Fr



5

Ficus lutea

Giant-leaved fig

N

Fr, Sd


1, 5

Ficus rubra

Fig


N

Fr

2, 3



Syzygium cumini

Jamun


I

Fr(rp)


2, 4, 5

Myrtaceae



Psidium cattleianum

Strawberry guava

I

Fr(ur,rp), Sd



1, 2, 5

Psidium guajava

Common guava

I

Fr, Sd


3, 4, 5

Syzygium jambos

Jambrosade

I

Fr

2, 5



Syzygium malaccense

Malay apple

I

Fr(rp), Fl



4, 5

Syzygium samarangense

Bell fruit

I

Fr, Sd


5

Syzygium wrightii

E

Fl, Lf



1, 2, 4, 5

Oxalidaceae



Averrhoa bilimbi

Bilimbi


I

Sd, Fr(ur,rp)

1, 2, 3,4,5,5

Averrhoa carambola

Star fruit

I

Sd, Fr(ur)



3, 4, 5

Palmae


Cocos nucifera

Coconut palm

N

Sd, Fr(ur)



3

Deckenia nobilis

Cabbage palm

E

Fr(ur,rp), Bd



1, 2, 3, 5

Nephrosperma vanhoutteanum

Seychelles palm

E

Fr(ur,rp), Bd



2, 5

Phoenicophorium borsigianum

Thief palm

E

Fr, Sd, Bd, Fl



2, 3, 5

Roystonea sp.

Unidentified exotic palm

I

Fr(ur)


5

Verschaffeltia splendida

Seychelles stilt palm

E

Fr(gr,rp)



2, 5

Passifloraceae



Passiflora edulis

Passion fruit

I

Fr, Sd


5

Passiflora suberosa

I

Fr (ur,rp)



5

Polygonaceae



Antigonon leptopus

Coral vine

I

Fl, Fr


5

Rubiaceae



Canthium bibracteatum

N

Fr, Fl, Bd



5

Craterispermum microdon

E

Fr(ur), Fl



4, 5

Paragenipa wrightii

E

Lf, Bd, Fr(ur,rp)



5

Sapotaceae



Pouteria obovata

N

Fr(ur,rp)



5

Table 1: Plant species documented to have been eaten by Coracopsis barklyi on Praslin Island showing status (E 

 endemic to Seychelles, 

 native to Seychelles, I  introduced to Seychelles), part eaten (Fr  fruit, ur  unripe, rp  ripe, bd  bud, sd  seed, lf  leaf [usually only 



the petiole], si 

 scale insect from leaf, fl  flower), and source (1  Gaymer et al. 1969, 2  Evans 1979, 3  Walford 2008, 4  Rocamora 

and Laboudallon 2009, 5 

 this study)

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Ostrich 2014: 1–9

5

ripe fruit, parrots would first extract and drop the seed before 



scraping the bill inside the fruit and then drop the pulp as 

well. Dropped fruit parts did not visibly lack any flesh. 

Among the food items, scale insects (Coccoidea), which 

the parrots scraped from leaves of Calophyllum inophyllum 

and  Phyllanthus acidus, were the most unusual observa-

tions. This is the only invertebrate documented to be 

consumed by C. barklyi.  

Larger exotic fruit targeted for its seeds (e.g. Averrhoa 



bilimbi and A. carambola) were regularly dropped before 

half the seeds had been extracted. Many fruits with a single 

bite mark were found underneath parrot feeding trees. 

Mangifera indica fruits were shared by several parrots. 

Average group size during feeding transects was 2.34 

 

1.73 (range: 1–9; 13 individuals was the maximum group 



size recorded during incidental observations). Feeding 

bouts lasted 529 

 505 s (range: 20–2 849 s) and each 

one comprised 26.0 

 48.9 parrot*feeding minutes (range: 

0.3–420, median 

 11.9). The results from feeding bouts 

and parrots feeding time (parrot*feeding minutes) were 

strongly correlated (r(27) 

 0.77,  p   0.00001), indicating 

that it is legitimate to use number of bouts as an estimate 

for the extent to which a resource is used.



Habitat and time of the day 

Despite equal sampling effort of transects in all habitat 

types, most feeding bouts were in palm forest (32%) and 

cultivated/residential areas (39%), followed by mixed forest 

(18%) and native scrub (11%). Food species and the 

proportion of endemics consumed depended on habitat 

type (Fisher’s exact test: p 

 0.001 and p  0.001, respec-

tively), with more endemics consumed in palm forest (82%) 

and native scrub (88%) than in mixed forest (52%) and 

cultivated/residential areas (9%). The share of endemic 

palms among the food plants was much higher in palm 

forest (45%) and much lower in cultivated/residential areas 

(2%) than the other habitats. 

The transect data show that observed feeding bouts were 

equally likely at all times of the day when pooling all habitats 

(



2



 

 3.73, df  3, p  0.29). The likelihood of observations 

over the day, however, was influenced by habitat (Fisher’s 

exact test: p 

 0.003): in palm forest, feeding observations 

occurred more often in the early morning and late afternoon 

than expected from the search effort, whereas in the middle 

of the day fewer bouts were observed (



2

 



 9.70, df  3, 

p 

 0.021). The other habitat types did not show significant 

differences to the expected daytime distribution.  

Comparison between incidental and transect methods

Between January and April 2011, the period when both 

methods were carried out in parallel, 311 incidental and 

53 transect observations were collected. This corresponds 

to 17 and 19 different food species, and 1 264 and 385 

parrot*feeding minutes, respectively. 

The proportions of plant species in the feeding bouts 

differed between the two methods (Fisher’s exact test: 



p 

 0.001; Figure 3). After removal of all observations 

obtained in the Vallée de Mai car park (55), which was 

walked past several times a day, the results from the two 

methods still differed (p 

 0.001). 

Over the four-year study period, species accumulation 

and rarefaction curves show that the incidental data set 

comes closer to an asymptote of total number of consumed 

species (Figure 4). 



Discussion

The large number of plant species and parts on the list of 



C. barklyi’s food items indicates that it is a generalist frugiv-

orous-granivorous-herbivorous feeder, similar to several 

other parrot species (Galetti 1993; Vaughan et al. 2006; 

Contreras-González et al. 2009). Since 12 of the plant 

species were only observed to be eaten once it is likely that 

further research will reveal more infrequently consumed 



Figure 2: Percentage of the most important food species of C. barklyi based on 148 observations on transect walks (2011–2013) with equal 

coverage of all habitat types; dark fill: endemic palm species; medium grey: other endemic and native species; light grey: introduced species

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Reuleaux, Richards, Payet, Villard, Waltert and Bunbury

6

species, which is congruent with the asymptote of the 



species accumulation curve. The number of consumed 

species observed in this study is larger than in earlier 

studies of Seychelles Black Parrots (Gaymer et al. 1969; 

Evans 1979; Walford 2008; Rocamora and Laboudallon 

2009) as expected with the longer survey period and 

substantial search effort. Bollen and van Elsacker (2004) 

found a similar number of species (40) to be consumed by 

C. nigra in Madagascar. 

The Black Parrot’s assumed tolerance for high tannin 

contents, known from C. nigra in south-eastern Madagascar 

(Bollen and van Elsacker 2004), makes them independent 

of ripeness in most fruits. This is an advantage for avoiding 

competition with other frugivores and granivores that rely 

on ripe fruit. According to the definition by Hulme and 

Benkman (2002), the Black Parrot should be considered 

a pre-dispersal seed predator for most species as it takes 

fruits before they are ripe and the seeds are either eaten 

and digested or destroyed. This is true for all regularly 

consumed introduced species. The consumption of ripe 

endemic palm fruit is a different case as the seeds are 

viable and are not consumed but usually dropped directly 

underneath the tree, making the parrot an inefficient seed 

disperser. The Black Parrot has potential to disperse seeds 

of the endemic Verschaffeltia splendida, D. ferruginea and 

Ficus lutea because the fruits are eaten when ripe and 

occasionally carried before consumption; the seeds of the 

latter two species are small and often stick to the bill. 

The proportion of plant parts consumed in this study 

differs from findings of C. nigra in Madagascar. Of the plant 

species observed to be consumed there, 68% of bouts were 

on seeds, 22% seeds and pulp, and 10% only pulp (Bollen 

and van Elsacker 2004). The proportion of species eaten 

for their seeds is much lower in our study. The vegetation in 

south-eastern Madagascar is fundamentally different from 

Praslin Island’s and the overlap in food species is minimal 

(one). The low importance of seeds and in particular 

endemic palm seeds in the diet of C. barklyi is notable. In 

other parrot species, seeds often account for more than 

half of consumed plant parts (Forshaw 1989; Galetti 1993; 

Matuzak et al. 2008). Seeds have a high energy content 

and their consumption increases foraging efficiency (Hulme 

and Benkman 2002), so the fact that endemic palm seeds 

passed through the parrots’ beaks but were then regularly 

discarded instead of consumed is surprising. In Seychelles, 

the fruit pulp of native plants is generally lower in energy 

content than invasive species (Kueffer et al. 2009), which 

may explain the parrot’s attraction to introduced species. 

Inefficient foraging would explain food stress despite 

year-round availability of most consumed food plants. 

In Bollen and van Elsacker’s (2004) study of C. nigra, 

flowers played a similarly minor role as in C. barklyi, whereas 

Hampe (1989) described a shift from pure fruit consumption 

to c. 80% flower consumption in the course of his three-week 

study period in C. nigra in western Madagascar. Insectivory 

in parrots is not a new observation (e.g. Forshaw 1989; 

Figure 3: Percentage of total number of feeding bouts of each food 

species observed in transects and incidental observation methods 

(based on data from January–April 2011; n 

 53 [transects] and 



n 

 314 [incidental])



Figure 4: Seychelles Black Parrot food species accumulation 

curve (a) with increasing number of transects (exact method, 

100 permutations), (b) rarefaction curves comparing number of 

consumed species between methods of data collections and 

(c) between habitats in the overall transect data set

EXACT


MEAN SPECIES RICHNESS

500


10

10

15



15

5

5



0

0

0



1 000

1 500


20

20

10



15

5

0



20

25

25



30

10

0



20

30

40



50

10

0



20

30

40



50

TRANSECTS

OBSERVATIONS IN SUBSAMPLE

OBSERVATIONS IN SUBSAMPLE

Transect data

Incidental data

Mixed forest

Cultivated/residential

Palm forest

Native shrub

SyzJam

35

30



25

20

15



10

5

0



Transects

Incidental

PhoBor

DilFer


DecNob

A

veBil



ManInd

PteInd


PouObo

CarPap


CasEqu

FicLut


NepV

an

PapW



ri

SanKoe


A

veCar


CanBib

CeiPen


MemEli

PasSpp


SyzMal

V

erSpl



ErySec

PhyPer


PsiCat

ScaSer


SyzJam

PERCENT


AGE (%)

Downloaded by [Anna Reuleaux] at 01:52 01 September 2014 



Ostrich 2014: 1–9

7

Greene 1998; Renton 2001), including Poicephalus spp. 



(Perrin 2012), but it has never been documented for any 

C. nigra,  C. barklyi or C. sibilans population. Kearvell et al. 

(2002) report that Orange-fronted Parakeets Cyanoramphus 



malherbi and Yellow-crowned Parakeets C. auriceps in New 

Zealand also consume scale insects. 

In contrast to the results of this study, Evans (1979) 

concluded from his observations of parrot distribution 

(concentrated at the Vallée de Mai) that the endemic palm 

V. splendida was an important food source and could be 

a crucial factor for parrot feeding and distribution. We 

found no support for this claim. Only 2% of incidental 

and less than 1% of transect feeding observations were 

on  V. splendida making it the least consumed of the four 

endemic palm species in our study. Seasonality may play a 

role; Evans’ (1979) study period in August falls in our least 

surveyed period and 70% of our incidental observations 

on  V. splendida were between October and December, 

when the fruits were ripe. Our data may underestimate the 

importance of this species as a food item; however, it is 

unlikely that a single species, which peaks in fruit produc-

tion at the same time as most other food species, and is 

only moderately consumed when available, limits the distri-

bution on a small island such as Praslin, where parrots 

travel half the island’s width regularly. 



Relative importance of native and exotic species

Despite covering a variety of habitats, the two species 

most commonly consumed by C. barklyi,  comprising 

more than one-third of all observed feeding bouts, were 

endemics: P. borsigianum and D. ferruginea are particularly 

important due to their year-round high availability in most 

habitats. Some native species (e.g. N. vanhoutteanum 

and Paragenipa wrightii) seem to be preferred but are 

relatively rare and bear few fruits at one time: parrots in 

these trees rarely leave before all ripe fruits or buds have 

been consumed. Other species, such as F. lutea and 

A. carambola, promote communal feeding as they bear 

many fruits that ripen simultaneously, attracting large groups 

of parrots. Most but not all parrot food species are available 

year-round but neither of our methods covered the annual 

cycle sufficiently to allow conclusions across the whole year.

The relatively large proportion of introduced species in 



C. barklyi’s diet (39%) contrasts with the diet of C. nigra 

in Madagascar, which is only recorded to include one 

introduced species (Hampe 1989; Bollen and van Elsacker 

2004). This could indicate a shortage of native food on 

Praslin Island or simply reflect availability, or a combina-

tion of both. Madagascar is a much larger island with 

higher species richness, a lower proportion of invasive 

plants and relatively higher availability of native species 

(Simberloff 1976; Kueffer et al. 2009). Coracopsis sibilans 

in the Comoro Islands shows similar habitat preferences 

to  C. barklyi and feeds on introduced species in gardens 

(Stevens et al. 1992). 

An increase in introduced plant species has been 

proposed as a reason for the increase in C. barklyi numbers 

and range (Rocamora and Laboudallon 2009) but not 

enough is known about the history of the Black Parrot’s 

feeding habits in gardens and on farmland. Furthermore, 

conflicts with fruit farmers are thought to be a threat for 



C. barklyi (Watson 1984; Rocamora and Laboudallon 

2009). Particularly owners of A. carambola trees, which are 

more valuable than A. bilimbi and are eaten more wastefully 

than M. indica, complain about parrot damage to their fruit, 

demand compensation (Rocamora and Laboudallon 2009) 

and threaten to take action against the crop pest (AR, HR 

and TP pers. obs.). 

Diurnal feeding patterns

It is common practice to conduct parrot feeding studies 

in hours of high parrot activity (Renton 2001; Ragusa-

Netto 2007; Matuzak et al. 2008), which may be problem-

atic if the study species prefers certain habitat types at 

different times of the day. Evans (1979) noted regular 

diurnal movements between the Vallée de Mai and coastal 

regions, which concurs with our observations of parrot 

traffic in the mornings and afternoons. Restricting our study 

to early mornings and late afternoons would have favoured 

palm forest species and underestimated the importance 

of garden species. Frequency of feeding observations is 

linked to detectability: in more open habitats parrots are 

detected more easily, even when not calling. Black Parrots 

call more frequently in the mornings and evenings (Gaymer 

et al. 1969; Reuleaux et al. 2013), making them easier to 

detect in closed habitats, such as palm forest. It is therefore 

possible that the low number of feeding observations in 

palm forest in the middle of the day was caused not by the 

absence of feeding parrots, but by our inability to detect 

them. Detectability does not, however, explain the absence 

of feeding parrots in native scrub in the late morning.  



Comparison between incidental and transect methods 

Incidental feeding observations render more observa-

tions per time unit because locations with the highest 

parrot feeding activity are targeted repeatedly. The much 

higher number of feeding observations from this method 

(six times as many bouts as in the transect approach) and 

its rarefaction curve, which approaches the asymptote, 

show that incidental observations are useful if the aim is 

to compile a list of consumed species. One should not 

conclude from incidental observations, however, that the 

results accurately reflect proportion of observed food 

species or plant parts in the diet, feeding duration or flock 

size. For example, in this research, a few favoured parrot 

feeding trees (Carica papaya), at the entrance to the 

Vallée de Mai, concentrated observers’ efforts and had 

a clear impact on the incidental feeding observation data 

in that this species was substantially over-represented. 

If quantitative information is required, it is important to 

control for, or record, search effort, across habitats and 

times of the day (and season). 

Incidental observation data has its uses, however, 

and with little additional effort can be collected alongside 

other work. One strength of this method is anecdotal 

information about rare incidents that can be important for 

small populations. Feeding on scale insects, for example, 

would not have been found had we only focused on 

transects. Furthermore, incidental observations can 

increase understanding of how food items are processed, 

e.g. determining exactly which plant part is eaten may 

require multiple observations and a good view, which is not 

Downloaded by [Anna Reuleaux] at 01:52 01 September 2014 


Reuleaux, Richards, Payet, Villard, Waltert and Bunbury

8

always possible from transects. Having different observers 



could have caused some differences between the methods 

but the divergence between them was so marked that it is 

unlikely to be the only reason.

Thus, the two methods are not mutually exclusive alterna-

tives, but complementary. Deciding which method to adopt 

depends on the aims of the research. A transect survey 

provides data for quantitative questions, including identifi-

cation of key food species, feeding preferences, group size 

and times of day, while incidental feeding observations 

can produce supporting information, help to clarify feeding 

strategies, and assist in compiling a non-prioritised list of 

food species in a short time, especially in cases where very 

little is known about a species’ feeding ecology. Parameters 

such as feeding duration and number of individuals did not 

produce reliable information from incidental observations

in this study. 



Conclusions and conservation recommendations

Our research underlines the importance of endemic 

palm species for the Seychelles Black Parrot, not only as 

breeding habitat, but also as ideal feeding habitat. Exotic 

species also play a role in the parrots’ diet and may 

compensate for seasonal fluctuations in availability of native 

species. Year-round transect survey feeding data would 

determine seasonal changes in parrot feeding habits and, 

in combination with ongoing phenology monitoring, provide 

more insight into seasonal food shortages and potentially 

breeding fluctuations. 

To ensure sufficient year-round food availability for 



C. barklyi on Praslin, and for potential translocations to 

other islands, the abundance of palms and native food 

species in mixed forest and scrub should be increased. 

For apparently preferred native species with locally limited 

availability, e.g. N. vanhoutteanum, F. lutea and P. wrightii

supplementary planting should be considered. Planting 

exotic fruit trees to increase food availability, as has often 

been suggested by the general public, is not recommended. 

Not only are endemic and native trees more important 

food sources for the parrots, planting of exotics counter-

acts the principle of a flagship species and may increase, 

not lessen, conflict with local farmers. Increased public 

education efforts would help to raise awareness among fruit 

tree owners that parrot-caused damage is relatively limited 

and may trigger greater understanding and appreciation of 

the Seychelles’ national bird. 



Acknowledgements   — We thank the Seychelles Islands 

Foundation and Vallée de Mai staff, particularly Jovani Simeon, 

for help with field work, and Frauke Fleischer-Dogley, Wilna 

Accouche, Marc Jean-Baptiste, Marcus Pierre, Dainise Quatre and 

Nathachia Pierre. We are also grateful to the many Praslinois who 

permitted access to land, including the Seychelles National Parks 

Authority, Praslin Development Fund, Fond Ferdinand and the 

Coco de Mer Hotel. Many thanks to Christopher Kaiser-Bunbury 

for statistical advice, to the Seychelles Bureau of Standards and 

Seychelles Environment Department for approving and supporting 

the research, and to the Environment Trust Fund Seychelles for 

financial support. We are grateful to two anonymous referees 

for reviewing and improving this article. Part of this study was 

funded by the German Academic Exchange Service DAAD and 

the Gesellschaft für Tropenornithologie GTO. MW is currently 

supported by a grant from the Volkswagen Foundation, Germany. 



References

 Bollen A, van Elsacker L. 2004. The feeding ecology of the Lesser 

Vasa Parrot, Coracopsis nigra, in south-eastern Madagascar. 

Ostrich 75: 141–146.

 Contreras-González A, Rivera-Ortíz F, Soberanes-González 

C, Valiente-Banuet A, Arizmendi M. 2009. Feeding ecology of 

Military Macaws (Ara militaris) in a semi-arid region of central 

México. Wilson Journal of Ornithology 121: 384–391.

 Evans PGH. 1979. Status and conservation of the Seychelles Black 

Parrot. Biological Conservation 16: 233–240.

 Forshaw JM. 1989. Parrots of the world. Willoughby: Lansdowne.

 Galetti M. 1993. Diet of the scaly-headed parrot (Pionus 

maximiliani) in a semideciduous forest in southeastern Brazil. 

Biotropica 25: 419–425.

 Gaymer R, Blackman RAA, Dawson PG, Penny M, Penny CM. 

1969. The endemic birds of Seychelles. Ibis 111: 157–176.

 Greene TC. 1998. Foraging ecology of the red-crowned parakeet 

(Cyanoramphus novaezelandiae novaezelandiae) and yellow-

crowned parakeet (C. auriceps auriceps) on Little Barrier Island, 

Hauraki Gulf, New Zealand. New Zealand Journal of Ecology 22: 

161–171.


 Hampe A. 1989. Field studies on the Black Parrot Coracopsis 

nigra in western Madagascar. Bulletin of the African Bird Club 

5: 108–113.

 Hulme PE, Benkman CW. 2002. Granivory. In: Herrera CM

Pellmyr O (eds), Plant–animal interactions: an evolutionary 



approach. Oxford: Oxford University Press. pp 132–154.

 Jacobs J. 2009. Rarefaction. R function. Available at http://www.

jennajacobs.org/R/rarefaction.txt.

 James D, Hornik K. 2013. chron: Chronological objects which can 

handle dates and times. R package version 2.3–43. Available at 

http://CRAN.R-project.org/package

chron.

 Jones CG. 2004. Conservation management of endangered birds. 



In: Southerland WJ, Newton I, Green RE (eds), Bird ecology 

and conservation: a handbook of techniques. Oxford: Oxford 

University Press. pp 269–301.

 Kearvell JC, Young JR, Grant AD. 2002. Comparative ecology of 

sympatric orange-fronted parakeets (Cyanoramphus malherbi

and yellow-crowned parakeets (C. auriceps), South Island, New 

Zealand. New Zealand Journal of Ecology 26: 139–148.

 Kristosch GC, Marcondes-Machado LO. 2001. Diet and feeding 

behavior of the Reddish-bellied Parakeet (Pyrrhura frontalis

in an Araucaria forest in southeastern Brazil. Ornitologia 

Neotropical 12: 215–223.

Kueffer C, Kronauer L, Edwards PJ. 2009. Wider spectrum of fruit 

traits in invasive than native floras may increase the vulnerability 

of oceanic islands to plant invasions. Oikos 118: 1327–1334.

 Lomolino MV. 2000. Ecology’s most general, yet protean pattern: 

the species-area relationship. Journal of Biogeography 27: 

17–26.

 Matuzak GD, Bezy MB, Brightsmith DJ. 2008. Foraging ecology of 



parrots in a modified landscape: seasonal trends and introduced 

species. Wilson Journal of Ornithology 120: 353–365.

 Meuwly C. 2002. Fire and vegetation in Praslin and in the Fond 

Ferdinand. MSc thesis, Eidgenössische Technische Hochschule, 

Geobotanisches Institut, Zürich, Switzerland.

 National Bureau of Statistics. 2013. 2013: Population and vital 



statistics Seychelles. Statistical Bulletin no. 2. Available at http://

www.nsb.gov.sc.

 Oksanen J, Blanchet FG, Kindt R, Legendre P, Mininchin PR, 

O’Hara RB, Simpson GL, Solymos P, Stevens MHH, Wagner H. 

2013. vegan: Community ecology package. R package version 

2.0-8. Available at http://CRAN.R-project.org/package

vegan.

 Ortiz-Catedral L, Brunton D. 2009. Notes on the diet of the critically 



endangered orange-fronted parakeet (Cyanoramphus malherbi

on Maud Island. New Zealand Journal of Zoology 36: 385–388.

Downloaded by [Anna Reuleaux] at 01:52 01 September 2014 


Ostrich 2014: 1–9

9

 Perrin M. 2012. Parrots of Africa, Madagascar and the Mascarene 



Islands: biology, ecology and conservation. Johannesburg: Wits 

University Press. 

Pizo MA, Simáo I, Galetti M. 1995. Diet and flock size of sympatric 

parrots in the Atlantic forest of Brazil. Ornitologia Neotropical 6: 

87–95.

 R Development Core Team. 2013. R: a language and environment 



for statistical computing. Vienna: R Foundation for Statistical 

Computing. Available at http://www.R-project.org.

 Ragusa-Netto J. 2007. Feeding ecology of the Green-cheeked 

parakeet (Pyrrhura molinae) in dry forests in western Brazil. 



Brazilian Journal of Biology 67: 243–249.

 Renton K. 2001. Lilac-crowned parrot diet and food resource availa-

bility: resource tracking by a parrot seed predator. Condor 103: 

62–69.


 Reuleaux A, Bunbury N, Villard P, Waltert M. 2013. Status, distribu-

tion and recommendations for monitoring of the Seychelles black 

parrot Coracopsis (nigrabarklyiOryx 47: 561–568.

Reuleaux A, Richards H, Payet T, Villard P, Waltert M, Bunbury N. 

2014. Breeding ecology of the Seychelles Black Parrot Coracopsis 

barklyiOstrich 85(3). 

 Revelle W. 2013. psych: Procedures for personality and psychologi-

cal research. R package version 1.3.2. Evanston: Northwestern 

University. Available at http://CRAN.R-project.org/package

psych.

 Rocamora G, Laboudallon V. 2009. Seychelles Black Parrot 



Coracopsis  (nigra)  barklyi conservation assessment and action 

plan. 2009–2013. FFEM Project ‘Réhabilitation des Ecosystèmes 

Insulaires’. Seychelles: Island Conservation Society and MENRT.

 Rocamora G, Skerrett A. 2001. Seychelles. In: Fishpool L, Evans 

MI (eds), Important bird areas in Africa and associated islands

Newbury: BirdLife International. pp 751–768.

 Saunders DA, Hobbs RJ, Margules CR. 1991. Biological conse-

quences of ecosystem fragmentation: a review. Conservation 



Biology 5: 18–32.

 Simberloff D. 1976. Experimental zoogeography of islands: effects 

of island size. Ecology 57: 629–648.

 Stevens J, Herremans M, Louette M. 1992. Conserving the 

endemic birds on the Comoro Islands, II: population fluctuations 

on Ngazidja. Bird Conservation International 2: 81–91.

 Tjørve E. 2003. Shapes and functions of species–area curves: a 

review of possible models. Journal of Biogeography 30: 827–835.

 Vaughan C, Nemeth N, Marineros L. 2006. Scarlet Macaw, Ara 

macao, (Psittaciformes: Psittacidae) diet in Central Pacific Costa 

Rica. Revista de Biología Tropical 54: 919–926.

 Walford EP. 2008. An insight into the ecology of an isolated 

Psittacid: the Seychelles black parrot (Coracopsis nigra barklyi).

MSc dissertation, University of East Anglia, Norwich, UK.

 Walsh RPD. 1984. Climate of the Seychelles. In: Stoddart DR 

(ed.), Biogeography and ecology of the Seychelles islands. The 

Hague: Dr W Junk. pp 39–55.

 Watson J. 1984. Landbirds: endangered species of the granitic 

Seychelles. In: Stoddart DR (ed.), Biogeography and ecology of 



the Seychelles islands. The Hague: Dr W Junk. pp 515–516.

 Wickham H. 2007. Reshaping data with the reshape package. 



Journal of Statistical Software 21: 1–20.

Received 1 September 2013, revised 6 April 2014, accepted 13 May 2014

Associate Editor: Lizanne Roxburgh 

Downloaded by [Anna Reuleaux] at 01:52 01 September 2014 




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