Nest Characteristics of Little Black Cormorant

(Phalacrocorax sulcirostris) at Tanjung Rejo, North Sumatera

Erni Jumilawaty, T. Alief Aththorick

Department of Biology, Faculty of Mathematics and Natural Sciences, Universitas Sumatera Utara, Medan, Indonesia

Keywords: Cormorant, Mangrove, Nest, Phalacrocorax sulcirostris

Abstract: Breeding season of avifauna is initiated from mating choice and nesting step. Nest is an important aspect in

cormorant survivability. Prior entering breeding season, male cormorant construct nest to lure the females.

Size and composition of nest directly determine the success of breeding and birdlings survivability. In this

study, we examined nest constructions within 5 plots consisted of 15 stands for nest occurrence and 10

stands for nest characteristics at Tanjung Rejo, Deli Serdang, North Sumatera. The results showed that black

cormorant preferred to place their nests on 4 stand species: Exocoecaria agallocha, Rhizopora apiculata, R.

mucronata,and R. stylosa. Black cormorant nests shaped like concave bowl and placements are not

considered specific to certain site of stands. Twig characteristics are from straight-branched, straight-

unbranched, branched, falciform-branched and falciform-unbranched. The conclusion of this study is that

selection upon nest tree species, placement and structures are important part of the breeding success of black

cormorant.

1 INTRODUCTION

Black cormorant is one species of water bird from

Phalacrocoracidae. The breeding season of these

species begin as follows: partial nest construction by

males, invitational dance by males, finding a mate,

and complete nest construction from both sexes.

(Jumilawaty 2002).

Nest is a material that greatly determines the

breeding success and survival of birds. Nests have

various functions including laying eggs, incubating

eggs, raising and nurturing birdlings and protecting

offsrprings from weather and predators. The shape

and arrangement of the nest is a characteristic of

each species intended for protection and safety needs

for the young.

Material composting the nest of each species also

varies according to the availability of nature. The

process of building nests in birds is one of the

factors that determine the existence of a species,

which is largely determined by the process of

selecting available resources from the environment

(Ayas, 2008). Generally birds build a bowl-shaped

nest that is open at the top, for birds with large nest

material most often used are large-sized twigs

(Campbell and Lack, 1985).

In addition to the material of the nest material,

the success of birds breeding are also determined by

the choice of nest location, nest tree species and

wind factors. In Tanjung Rejo, North Sumatra, the

selection of places to nest and nest trees greatly

affects the success of breeding from more than 2500

pairs of water birds consisting of 6 species of water

birds that use these locations as breeding sites.

Generally, each species of water bird will build and

utilize natural resources around it to avoid

competition in choosing nesting sites and nest

material. The study aims to determine the

characteristics of the nest tree by black cormorants

that breed in Tanjung Rejo, North Sumatera.

2 MATERIALS AND METHODS

2.1 Materials

The tools used in this study were: Global Positioning

System (GPS) device, scales, tape measure, colored-

cloth ribbons, ropes, compass, calipers, binoculars,

cameras and stationeries.

140

Jumilawaty, E. and Alief Aththorick, T.

Nest Characteristics of Little Black Cormorant (Phalacrocorax sulcirostris) at Tanjung Rejo, North Sumatera.

DOI: 10.5220/0009899100002480

In Proceedings of the International Conference on Natural Resources and Sustainable Development (ICNRSD 2018), pages 140-143

ISBN: 978-989-758-543-2

2.2 Nest Tree Characteristics

Characteristics of the nest tree species utilized by

black cormorants, were obtained by measuring 15

trees samped randomly. To avoid the resampling of

the trees, each stands is marked using colored-cloth

ribbons. The nest tree species parameters measured

including:

1. Species of tree used as nesting place

2. H

tree

(tree height) nesting place.

3. H

trunk

, tree height from roots / rhizopor

4. D

tree

, the diameter of the nesting tree, is measured

by using a tape measure on a stem with a height of

1.30 m from the ground or water surface or 10 cm

from the top of the buttress root.

5. N

nest

, the number of nests on one tree

6. Distance

, the nest distance to the main stem

7. Distance

out

, the nest distance to the edge of the

canopy

8. Distance

nest

, the distance to the nearest nest in one

nest tree

9. Top, the distance of the nest to the top of the

canopy

10. Distance

edge

, the distance of the nest tree to the

pond

11. Distance

form

, the distance of trees to different

vegetation.

12. N

trunk

, the number of trunk supporting nests

2.3 Nest Characteristics

To determine the characteristics of the nest, 10 (ten)

black cormorant nests were measured. The nest

composition parameters measured including:

- Nest length (cm) is the longest part of the nest

- Nest width (cm) is the widest part of the nest

- Nest depth (cm) is the perpendicular distance from

the inner base

- Nest height (cm) is the distance from the lower

nest to the highest part of the nest.

- Nest edge (cm) is a perpendicular distance from the

nest's mouth to the base of the nest.

2.4 Nest Analysis

All measurement data on variables related to nests

and trees are analyzed using statistical methods

expressed by the average values and standard

deviations.

3 RESULTS AND DISCUSSION

3.1 Nest Tree Characteristics

Tanjung Rejo pond area is a breeding place for water

birds owned by individuals with an area of 4.5 ha.

There are 6 species of water birds inhabit this

location as a place to breed simultaneously. The

water birds found in this location use mangrove

plants that are scattered at the pond location

randomly, according to their body size.

Large-sized water birds will choose locations

difficult to reach by human disturbances in which

located in the middle of the pond position, and

usually not found at the edge of the pond area.

Smaller birds like black cormorant choose to place

nest in random fashion, scattered in all locations

both in the middle and at the edge of the pond area.

The selection of this breeding location by the

water bird found in this breeding location is thought

to be closely related to safety factors to ensure the

success of breeding and survival and the population

of each species, and the strength of the nest tree.

Large-sized water birds need a tree that is

comfortable and strong enough to refute the nest

which will be filled by birdlings and females, while

the smaller cormorants ranging from 58 - 61 cm in

body sizes prefer smaller mangrove trees. The

mangrove trees found in Tanjung Rejo belong to a

small group of secondary mangrove forests.

Black cormorants that breed in Tanjung Rejo

chose to lay their nest only on 4 species of mangrove

trees from 10 species found in this region, namely:

Exocoecaria agallocha, Rhizopora apiculata, R.

mucronata and R. stylosa. This selection is thought

to be closely related to the biological factors i.e. the

size-specific nesting site (Table 1).

The tendency of black cormorantss to choose R.

mucronata is closely related to tree architecture and

nesting habits that are always in groups. Rhizophora

mucronata has many scattered branches and twigs, a

broad canopy and strong branches to support the

nest until reaching 16 nests per stand. (Jumilawaty,

2002).

Nest Characteristics of Little Black Cormorant (Phalacrocorax sulcirostris) at Tanjung Rejo, North Sumatera

141

Table 1. Nest tree characteristics of P. sulcirostris

Tree parameters Mean

tree

(m) 3.5

–

5.5

trunk

(

)

0.0

–

0.5

tree

(cm) 12.5

–

22.5

Distance

edge

(

)

–

Distance

form

(m) 1.0

–

2.5

nest

–

trunk

(cm) 2.5

–

4.5

Distance

(

)

–

175

Distance

out

(cm) 50

–

120

trunk

–

Distance

nest

(

)

–

150

Top (m) 0.5

–

1.2

In comparison to the results of Jumilawaty's

(2002), selection of nests by black cormorants on

Rambut Island, the Jakarta bay is consisted of two

species, namely Excoecaria agalocha and R.

mucronata, displaying a different result to the

recent. The height of the nest tree and placement are

also different where the cormorants on Rambut

Island chose trees with a height (H

tree

): 7 – 10 m and

diameter of trunk placed with nests (D

trunk

): 6 – 8 m,

while in this study, we obtained H

tree

: 3 – 5 m and

trunk

: 2.5 – 4.5 m .

Black cormorants chose specific trees to place

their nests for safety and success breed and to raise

their offsprings. The selection of nest trees by black

cormors is strongly influenced by the availability of

trees or resources in research locations, competition,

body weight and safety factors which are safe from

exposure to wind and human disturbances, tree

structure, density of leaves and wing structures.

Cormorants generally form heterogeneous

colonies with other water birds such as buffalo

egrets, large egrets, and herons, generally inhabited

by 5 – 18 nests. A tree possessing a strong structure

to accommodate large numbers of nests and each

nest is generally inhabited by 3 – 4 birdlings.

Our opinion is in accordance with the results of

Mardiastuti's (1992), through the study of nest trees

selection by water birds in Pulau Rambut which

were greatly influenced by several factors: (1) safety

from the wind, (2) tree structure, (3) foliage density

and (4) wing structure. Furthermore, Rukmi (2002),

stated that in the selection of nest trees; the most

important thing is that the tree structure is

considered quite safe during breeding season to

support the success of breeding.

3.2 Nest Characteristics

The shape of a cormorant nest is very easy to

distinguish from other species characterized by its

dirty appearrance due to feces deposits and shaped

like a concave bowl (Figure 1). The type and size of

the nest is strongly influenced by species, and the

availability of nest material. This is in accordance

with the opinion of Campbell and Lack (1985). The

type and size of nests constructed by bird pairs vary

greatly and are strongly influenced by several

factors, namely; bird species, nest location and

availability of nest material. Generally birds build a

bowl-shaped nest that is open at the top, placed at

large branches.

Figure 1. Nest and eggs of Black cormorant

The cormorant build a regular, solid and coarse –

textured nest characteristics. The base of the nest

consists of long, large-diameter branches that serve

as supporting platform so that the eggs and

offsprings can be safely placed on the tree. While

the top layer consists of fine and small branches,

serve as to maintain humidity of the nest during

incubation and chick development. The further

characteristics of the nest can be seen in Table 2.

The nest microclimate can accelerate the

incubation of eggs and the development of birdlings

by shortening the period of offspring development

hence increasing their survavibility in the wild

(Welty, 1982).

Table 2. Nest characteristics of black cormorant

Parameters

Value

(Mean ± S.D)

Nest depth (cm) 5,38 ± 1,59

Nest width (cm) 39,36± 8,12

Nest len

th (cm) 29,66 ± 2,18

Nest hei

ht (cm) 16,69 ± 3,92

Nest ed

e (cm) 7,03 ± 1,89

Porous structures of nest between branch gaps

allow water to flow and quickly pass through the

nest during rain and enhancing the drying of the

nest. The existence of these gaps can help sanitize

ICNRSD 2018 - International Conference on Natural Resources and Sustainable Development

142

the nest, so that the liquid waste metabolized from

the birdlings may flow out from the nest through the

gaps, and are not pooled on the nest surface.

Concave bowl-shaped nests are thought to be

closely related to protection for altricial type

offspring. Bowl-shaped nests will provide better

protection than flat nests, especially for altricial

birds, characterized by its resistant and sturdy

properties than the possibility of damaged nests from

both inside and outside (Collias and Collias, 1984).

In our study, we obtained different results

regarding the nest length and edges as compared to

our previous study (Jumilawaty, 2002). The nest

length was smaller and the edge was thicker in this

study. Based on observations on 2 nest samples, it

was found that the characteristics of the branches

were divided into 4 straight-branched, straight-

unbranched, branched, falciform-branched and

falciform-unbranched. Nests are generally composed

of dried branches and twigs.

4 CONCLUSIONS

Nest is an important feature in breeding success and

survavibility. Nest tree selection, placement and

structures are supporting factors in specific of

breeding success of black cormorants.

ACKNOWLEDGEMENTS

The authors would like to express the highest

gratitude to Ministry of Research and Higher

Education through their research funding in the

scheme of Fundamental year 2016.

REFERENCES

Ayas, Z. 2008. Nest Site Characteristics And Nest

Densities Of Ardieds (Night Heron: Nycticorax

Nycticorax, Grey Heron: Ardea Cinerea, And Little

Egret: Egretta Garzetta) In The Nall›Han Bird

Sanctuary (SariYar Reservoir, Ankara, Turkey). Turk

J Zool 32 : 167-174.

Campbell, B and E. Lack. 1985. A Dictionary of Birds.

Published Buteo Books-Vermillion.

Collias, N.E. and E.C. Collias. 1984. Nest Building and

Behavior. Princeton University Press.

Jumilawaty E. 2002. Morfometri Dan Kompetisi

Interspesifik Pecuk Hitam (Phalacrocorax

sulcirostris) Dan Pecuk Kecil (Phalacrocorax

niger) Di Koloni Utara Dan Barat Suaka

Margasatwa Pulau Rambut. Tesis. Sekolah

Pascasarjana, Institut Pertanian Bogor.

Mardiastuti, A. 1992. Habitat and Nest-Site Characteristic

of Waterbirds in Pulau Rambut Nature Reserve,

Jakarta Bay, Indonesia. Unpublished PhD

Dissertation. Michigan State University.

Rukmi, DS. 2002. Perilaku dan Kompetisi Interspesifik

Kuntul besar (Egretta alba Linnaeus 1766) dan Cangak

merah (Ardea purpurea Linnaeus 1766) di Suaka

Margasatwa Pulau Rambut Jakarta.

Welty, J.C. 1982. The Life of Birds. Senders College

Publishing, New York.Moore, R., Lopes, J., 1999.

Nest Characteristics of Little Black Cormorant (Phalacrocorax sulcirostris) at Tanjung Rejo, North Sumatera

143