Content uploaded by Prishnee Bissessur
All content in this area was uploaded by Prishnee Bissessur on Dec 21, 2017
Content may be subject to copyright.
Bulletin Phaethon – Volume 46 (2017)
Bulletin Phaethon, 2017, 46 : 99-100.
Occurrence of the smallest tern of
the world, Saunders’s Tern
at Terre Rouge (Mauritius)
Prishnee Bissessur*, Vashist O. Seegobin*,
Ragilen Mamoodee* & Jean-Michel Probst**
*Tropical Island Biodiversity, Ecology and Conservation
Pole of Research, University of Mauritius
**Association Nature & Patrimoine, île de La Réunion
Résumé : A l’occasion d’une « sortie limicoles », organisée à
Terre Rouge, nous avons eu l’occasion d’observer la plus
petite Sterne du monde, la Sterne de Saunders, Sternula
saundersi, au milieu d’un groupe de Sterne pierregarin,
Sterna hirundo. Cette note retrace les détails de l’observation
et donne les critères de détermination de l’espèce concernée.
Abstract : On the occasion of a "migratory bird watching
session", organised in Terre Rouge, we had the opportunity to
observe the smallest Tern in the world, the Saunders’s Tern,
Sternula saundersi, in the middle of a group of Common
Terns , Sterna hirundo. This note describes in detail the
observation and gives the criteria for determining the species
Mots clés : oiseau migrateur, sterne de Saunders, Maurice
Key words : migratory bird, Saunders’s Tern, Mauritius
The Rivulet Terre Rouge Estuary Bird sanctuary, a
wetland reserve and Ramsar site, is an estuary where
around 20 species of shorebirds and terns migrate
annually and sometimes a few hundreds of individuals
(100-300 birds) can be observed at the same time
(Abhaya & Probst, 1995 ; Probst, 1995a). The site,
described as a humid coastal zone of 26 hectares, is
known to host several migratory bird species mostly
from September to March (Sinclair & Langrand, 2014).
This provides an opportunity to observe and identify
species that regularly migrate to feed themselves and
where rare ones can sometimes be noted (Probst,
1995b). We therefore aimed to observe and record any
new occurrence of shorebirds or terns.
On the 12th December 2017, which was a sunny
day, optimum for bird-watching, a group of four
observers were at the Terre Rouge bird sanctuary from
9:00 to 13:00. Once at the sanctuary, we settled at the
bird hide with binoculars (Nikon, 10 x 42) and cameras
(Figure 1). We noted the common bird species and
estimated the number of individuals of each. In cases of
uncertainty, we used a field guide for bird watchers
(Sinclair & Langrand, 2014) to determine and validate
the species using the criteria for identification such as
the bill size and the primary remiges.
Figure 1 : The Bird Hide at Terre Rouge.
(Photo of Jean-Michel Probst)
Fourteen species were recorded with a total of 108
individuals, among which the whimbrel (Numenius
phaeopus), shanks (e.g. Tringa nebularia), sandpiper
(e.g. Calidris alba), plovers (e.g. Charadrius
leschnaulti, Pluvialis squatarola) and terns (e.g. Sterna
hirundo). We also identified a small non-breeding tern,
Sternula saundersi, commonly known as Saunders’
Tern, (21-23 cm) which is roughly one third smaller
than a Common Tern (31-35 cm) (Figure 2) (Skerrett,
Figure 2 : The Saunders’s Tern (below left) distinguished by
its smaller size compared to the Common Tern (above left).
(Photo of Prishnee Bissessur)
It is so small that it appears almost same size as the
sanderling, C. alba. It could easily be distinguished
from the Common Tern by its size but also by its short
tail. The projected, wing-tips extend well behind
the tail-feathers when the bird is perched with folded
wings (Figure 3). The Saunders’ Tern have a larger
dark primary patch, usually 4-5 dark primaries,
compared to the normal 2-3 dark primaries in Little
Tern (Olsen & Larssen, 1995). The forehead is white
and the crown is black, even under the eyes, which
joins at the nape (Skerrett, 2013).
Bulletin Phaethon – Volume 46 (2017)
Figure 3 : The Saunders’s Tern at Rodrigues.
The projected, wing-tips extend well behind the tail-
feathers when the bird is perched with folded wings
(Photo of Patrick Chefson)
The Saunders’s Tern is the smallest of the
Sternidae. It was previously recorded twice in La
Réunion (Probst, 1995b ; SEOR, 2011) ; once in
Rodrigues (Showler & Cheke, 2002) and twice in
Mauritius (Temple, 1976 ; Safford & Basque, 2007).
This is therefore a third observation for Mauritius,
which was also made at the Terre Rouge wetland after
around ten years.
The Saunders’s Tern usually migrates in groups of
about 10-100 individuals to Madagascar and Seychelles
annually (Skerrett, 2013). However, a single individual
was observed at Terre Rouge (Figure 4) and previous
records mention no more than three individuals
(Skerrett, 2013). Consequently, the occurrence of this
species in Mauritius appears to be occasional as the
island does not fall in its usual migratory route
(Sinclair & Langrand, 2014). This observation
highlights the importance of the Rivulet Terre Rouge
Estuary Bird sanctuary as a resting and feeding ground
for various migratory birds, including certain isolated
or erratic individuals. It also underscores the value of
Terre Rouge for migratory birds coming to the
Mascarenes and supports the need to continue the
ongoing protection and management of this Ramsar
site. For example, installation of a wooden fence and
lath would minimise disturbance of the birds by bird
ABHAYA, K. & PROBST, J.M. 1995. Plaidoyer pour
l’estuaire de Terre Rouge, un lieu d’observation
unique des limicoles et des oiseaux d’eau dans
les Mascareignes (île Maurice). Bulletin
Phaethon, 2 : 107.
OLSEN, K.M. & LARSSEN, H. 1995. Field
identification of Little and Saunders's Tern.
Bull. of the African Bird Club, vol 2 (2) : 81-85.
PROBST J.M. 1995a. Recensement des limicoles et
des oiseaux d’eau à l’île Maurice avec une
mention particulière de deux espèces peu
ordinaires : le chevalier gris Heteroscellus
brevipes et le Bécasseau tacheté Calidris
melanotos. Bulletin Phaethon, 2 : 68-72.
PROBST, J.M. 1995b. Observations de deux sternes
nouvelles à La Réunion : la Sterne de Saunders
Sterna saundersi et la Sterne huppée Sterna
bergii. Bulletin Phaethon, 2 : 75-76.
SAFFORD R. & BASQUE R., 2007. Records of
migrants and amendments to the status of
exotics on Mauritius in 1989-93. Bull. ABC, 14
(1) : 26-35.
SEOR, 2011. Sterne de Saunders Sternula saundersi.
SHOWLER, D.A. & CHEKE, A.S. 2002. Checklist of
the birds of Rodrigues. Pp. 22-24 in Showler,
Dave A. 2002. Bird observations on the Indian
Ocean island of Rodrigues, March-June 1999.
Bull. Of the African Bird Club, 9 : 17-24.
SINCLAIR, J.C. & LANGRAND, O. 2014. Oiseaux
des îles de l’océan indien. Madagascar,
Maurice, Réunion, Rodrigues, Seychelles,
Comores. Delachaux & Niestlé, 1-264.
SKERRETT, A.P. 2013. Saunders’s Tern Sternula
saundersi. Pp. 458-459 in Safford & Hawkins,
2013. The Birds of Africa. Volume 8: The
Malagasy Region: Madagascar, Seychelles,
Comoros, Mascarenes. Christopher Helm,
TEMPLE, S.A. 1976. Observations on seabirds and
shorebirds on Mauritius. Ostrich, 47: 117-125.
Figure 4 : The Saunders’s Tern in the middle of Common Tern group at Terre Rouge
(Photo of Jean-Michel Probst)