Pink Pigeon Columba/Streptopelia
mayeri Ile aux Aigrettes, Mauritius
The Pink Pigeon is one of the rarest - and once one of the most threatened
- birds in the world.
At one time Pink Pigeons were found throughout Mauritius. Subfossil
remains from Mare aux Songes confirm that they once occurred in the lowlands
but by the 19th century Pink Pigeons were confined to the upland forest,
and its distribution had become heavily fragmented by the early 1900’s. The
destruction of native forest on a massive scale, the persecution of pigeons by
people and the introduction of a variety of exotic predators all contributed to
the decline of this large and striking bird. By the 1950’s there were thought
to be only 40 to 60 Pink Pigeons left. By the early 1970s the Pink
Pigeon was confined to the upland forests of the Black River Gorges,
Macchabee and Brise Fer ridges. By the early 1980s this range had declined to a
single population of 20 birds near Bassin Blanc in a grove of introduced
Japanese Red Cedar Cryptomeria japonica called Pigeon Wood. In
1986, only 12 Pigeons could be found in Pigeon Wood and the five nesting
attempts recorded all failed due to predation by Rats. (Adapted from www.mauritian-wildlife.org)
Intensive rearing efforts on Ile aux Aigrettes has been the main reason that
the population of Pink Pigeon now stands at around 360 (Vikash Tatayah,
MWF pers comm, Nov 2005) - of those, there are about 75 on the islet.
Unique to Mauritius
and back from the brink
The Pink Pigeon was
widely distributed throughout Mauritius. Subfossil remains from Mare aux Songes
confirm that they were also found in the lowlands. By the 19th century Pink
Pigeons were confined to the upland forest and its distribution had become
heavily fragmented by the early 1900’s.
Population
decline
The
destruction of native forests on a massive scale, the persecution of pigeons
and the introduction of a staggering list of mammalian predators have all
contributed to the decline of the Pink Pigeon. By the 1950’s there were thought
to be only 40 to 60 Pink Pigeons left. By the late 1960’s the Pink Pigeon was
confined to the upland forests of the Black River Gorges, Macchabée and Brise
Fer ridges. By the mid 1970’s this range had declined to a single population of
20 birds near Bassin Blanc in a grove of introduced Japanese red cedar Cryptomeria
japonica at Plaine Paul (now baptised Pigeon Wood). In 1986, only 12
Pigeons could be found in Pigeon Wood. That year, five nesting attempts were
recorded. All failed due to predation by Ship Rats Rattus rattus. The
outlook for the survival of this species was not very good.
The main reasons for the decline of the Pink Pigeon population have been
habitat loss in favour of economic development and degradation caused by
invasive exotic weed species, primarily Chinese Guava Psidium cattleianum
and the privet Ligustrum robustum var. walkeri. These invade and choke
the forest, thus preventing the regeneration of native plant species.
Pink Pigeons evolved in the absence of mammalian predators, but are now
threatened by Crab-eating Macaques Macaca fascicularus, Feral cats Felis
catus and Mongoose Herpetes javanicus, all efficient bird killers.
The Ship Rat Rattus rattus and the Macaque are both efficient nest
predators eating both pigeon eggs and squabs.
Biology Pink Pigeons are
perfectly adapted for foraging on fruits and leaves at the ends of the long,
thin branches of native trees. Pink Pigeons also forage on the ground where
they turn over leaf litter to pick up leaf fragments, pieces of grit, soil and
fallen seeds. Pink Pigeons are territorial with males holding the territories,
to which females are attracted to. Both males and females build their nests in
the upper canopy of emergent endemic trees. It may take the pair anywhere from
3 to 14 days to build a nest. Pigeons lay one to two eggs per clutch and take
turn incubating and caring for the young. Incubation takes 14 days and the
squabs usually take a further 27 days before they are ready to leave the nest.
The fledglings stay with their parents for several weeks while they learn how
to survive on their own.
Conservation
The releases
of Pink Pigeons back into the wild was planned in the early 1980’s, resulting
in the first trial release of captive-bred birds at the Pamplemousses Botanic
Gardens in 1984. The first release into their native habitat occurred in the
upland forest of Brise Fer in 1988.
We now have 4 upland subpopulations centred around our field stations and
Conservation Management Areas at Brise Fer, Pigeon Wood, Bel Ombre and Combo,
all within the Black River Gorges National Park. In addition, a 5th
subpopulation is doing well on the predator free island Nature Reserve of Ile
aux Aigrettes. In total we have over 320 wild Pink Pigeons at these sites a
dramatic improvement from the 12 birds found in 1986.
In addition to the release of captive bred birds back to the wild, the
management of each subpopulation is very intensive and entails the following
management practices:
Population
monitoring
Nearly every
single Pink Pigeon is ringed with its own metal ID band and unique plastic
colour combination. Each bird can then be identified and followed individually
allowing the health of each subpopulation to be closely followed. All nests are
monitored and the success documented. A large dataset has been collected to
date and is currently being analyzed.
Supplementary feeding
The
degradation of the Pink Pigeon’s natural habitat is so advanced that the birds
are very often not able to find enough food to support themselves. Thus,
supplementary wheat and maize feed is provided at a number of feeding stations
to increase the birds’ chances of survival and improve their general condition.
Consequently, the pigeons are in better health and physical condition, can
avoid predation, and breed more successfully throughout the year (except for a
month or two when they are moulting, thus not laying any eggs).
Predator and disease management
Predators
are recognized as a major limiting factor, and their impacts are limited around
field sites eg poison grids for rats, exclusion from reaching nests in trees by
placing plastic guards and trimming branches etc. In addition, competitors for
supplementary food are excluded through carefully designed feed hoppers.
Some diseases also adversely affect the Pink Pigeon. Most notable are
Trichomoniasis and Avian Pox, both of which have been studied. The former is
thought to have arrived with exotic pigeons and measures to reduce its
transmission are underway.
The Future
The Pink
Pigeon will continue to require supplementary feeding, disease and predator
management. Over the longer term, large restored forest areas will have to be
created. These mainland islands will provide core source areas where the pigeon
population exploits safe nesting areas and is able to spread out into the rest
of the upland forest. For the time being, however, future releases at new field
sites will further increase the wild population and provide a safer and
brighter future for this beautiful endemic pigeon.
CAP SOLEIL - ILE MAURICE - Tour opérateur (License No. 03430) Membre de AIOM (Association of Inbound Operators of Mauritius) Adresse: 5 Impasse des Ibis - Sodnac - Quatre Bornes - Ile Maurice -
Tel: [230] 427 7454 - 55 -
Fax: [230] 427 0444
Email: plamothe@capsoleil.erm.mu OU alamothe@capsoleil.erm.mu
