(DRAFT) - Taxonomy
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
TAXONOMY
NAME - WHITE-EYE, BRIDLED
OTHER COMMON NAMES - WHITE-EYE and BRIDLED; NOSSA
ELEMENT CODE -
CATEGORY - Birds
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - AVES,
ORDER AND SUBORDER - PASSERIFORMES,
FAMILY AND SUBFAMILY - ZOSTEROPIDAE,
GENUS AND SUBGENUS - ZOSTEROPS,
SPECIES AND SSP - CONSPICILLATA, CONSPICILLATA
SCIENTIFIC NAME - ZOSTEROPS CONSPICILLATA CONSPICILLATA
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Bridled White-eye
Zosterops conspicillata conspicillata (Klittlitz, 1832)
KINGDOM: Animal GROUP: Bird
PHYLUM: Chordata CLASS: Aves
ORDER: Passeriformes FAMILY: Zosteropidae
Zosterops c. conspicillata has upper parts light gree becoming
slightly lighter on the rump; orbital ring broad and white; auriculars
grayish green; chin and throat yellowish-white; breast and abdomen
dingy yellow; wing and tail feathers dark brown with greenish-yellow
edges; upper mandible yellow and darker than lower mandible; legs and
feet dark olive-grey; iris light amber (01). According to Baker (01)
adult females have lighter underparts, but this difference is not
discernable in the field (02). Immatures have underparts paler
yellow and upper mandible light yellowish-brown (02,03).
Taxonomic names and synonyms that have been used to describe
Zosterops c. conspicillata are listed below (01).
Dicaeum conspicillatum Klittlitz 1832
Zosterops conspicillata Reichenbach 1852
Zosterops conspicillatum Bonaparte 1856
Taxonomy - 1 (DRAFT) - Taxonomy
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
Zosterops conspicillatus Kuroda 1922
Zosterops conspicillata conspicillata Stresemann 1931
Another name applied to this species is Zosterops conspicillatus
conspicillatus (20).
The indigenous people of Guam, the Chamorros, call this bird the
"Nossa".
There are 34 specimens of Zosterops c. conspicillata in the
American Museum of Natural History, New York (04) and 27 at the U.S.
Museum of Natural History, Washington, D.C.. There may be specimens
in additional museums.
Taxonomy - 2 (DRAFT) - Status
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
Non-consumptive recreational
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The bridled white-eye (Zosterops c. conspicillata) has been
designated as Endangered pursuant to the Endangered Species
Act of 1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884;
16 U.S.C. 1531-1540), as amended. The subspecies has this
status wherever found including the Territory of Guam.
This subspecies is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild
animal (alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation, or foreign law; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
DOD -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public land under their control. Also responsible for
management/recovery on Department of Defense lands.
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.
STATE STATUSES AND LAWS:
TERRITORY: Guam
DESIGNATED STATUS: Endangered
Status - 1 (DRAFT) - Status
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
ADMINISTRATIVE AGENCY: Department of Agriculture, Division of
Aquatic and Wildlife Resources.
STATE STATUTE: Endangered Species Act of Guam 1982; Guam
Public Law 15-36 June, 1979.
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
The species is not listed by CITES, nor by the IUCN Red Book as
of the 1981 publication.
ECONOMIC STATUSES:
This species was a common, endemic insectivore sought by bird
watchers. It was also important as a pollinator and seed dispersal
vectar of native plants.
79/05/18:44 FR 29128/29130 - Notice of review of status.
79/06/13:44 FR 33915/ - Extension of comment period.
83/11/29:48 FR 53729/53733 - Proposed listing as Endangered.
84/08/27:49 FR 33881/33885 - Final listing as Endangered.
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
LAND USE -
Evergreen Forest Land
Mixed Forest Land
COMMENTS ON HABITAT ASSOCIATIONS -
This species may be extinct on Guam. Historically it was
found island-wide. A related subspecies found on Saipan, Tinian, and
Aguigan is the most common bird on those islands and is found in all
habitat types including urban (19).
The bridled white-eye has been found in the past in most
available habitats on Guam including mature, pristine limestone forest
(01), scrubby second growth (09), grasslands and foothills of southern
and central Guam (10), beach strand (11), wetlands of Agana swamp and
mixed woodlands and second growth of the northern plateau (02).
This bird was last found on Guam in mature limestone forest.
Habitat Associations - 1 (DRAFT) - Food Habits
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORE
LIFESTAGE FOOD FOOD PART
General Evergreen Shrubs-Flowers/Fruit/Seed
General Evergreen Trees-Flowers/Fruit/Seed
General Arthropods
Food Habits - 1 (DRAFT) - Environment Associations
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Coastal Features: Vegetated offshore islands
Environment Associations - 1 (DRAFT) - Life History
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
Based on his 1978-79 study of the bridled white-eye on Guam,
Jenkins (02), concluded that it feeds primarily on insects, apparently
taking little fruit or nectar (02). Mayr (12) noted that other
members of this genus apparently take berries and other small fruit.
In addition, Marshall (03) reported that Z. c. saypani from Saipan
regulary fed on an artificial "nectar-protein" solution, small meal
worms, and various types of fruit (05).
During his study on Guam, Jenkins (02) noted white-eyes in
flocks of three to eight individuals feeding frequently in large
Ficus spp. and Guettarda sp., two of the larger trees found in the
mature limestone forest at Ritidian Point in Northern Guam on
Andersen Air Force Base. Flocks of birds occasionally fly high above
the forest canopy (02) which suggests a widely seperated feeding
circuit as described by Marshall (03) for Z. semperi on Palau.
The non-territorial white-eye is primarily a canopy feeder that
forages "warbler-like" by creeping along branches and ocasionally
leaf sprays searching for insects (02).
HOME RANGE/TERRITORY:
Zosterops c. conspicillata is the only native passerine on Guam
that is non-territorial even when nesting (02). This species feeds in
flocks of 3-20 individuals (13,10,01,09,02), occasionally flying high
above the forest canopy (02), which suggests a widely separated
foraging circuit, as described by Marshall (03) for Z. semperi on
Palau.
PERIODICITY:
Nothing is known about periodicity in this diurnal species.
MIGRATION PATTERNS:
Zosterops c. conspicillata does not migrate.
COVER/SHELTER REQUIREMENTS:
Nothing is known of cover or shelter requirements for the bridled
white-eye on Guam.
REPRODUCTIVE SITE REQUIREMENTS:
Little is known of the reproductive site requirements for
Zosterops c. conspicillata. Nests reported in the literature
were located relatively low in forest areas. One nest was built 2.4
meters up in a Leucaena leucocephala tree and was composed of fine
fibers and rootlets woven into a hanging basket, 4 to 5 centimeters
in diameter by 7 to 8 centimeters deep (02). Hartert (14) found
nests within 1 to 2 meters of the ground in the forks of branches.
REPRODUCTIVE CHARACTERISTICS:
Little is known of the reproductive behavior of the Zosterops c.
conspicillata on Guam. According to Jenkins (02) this species is
non-territorial even when nesting. Marshall (03) suggested that the
white-eye breeds year-round on Guam. Nests are known from February
Life History - 1 (DRAFT) - Life History
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
and March (14); Seale (13) reported nesting from May to July; Division
of Aquatic and Wildlife Resources field notes reported a nest in June;
and Baker reported a bird with enlarged gonads in August. Adults have
been observed feeding fledglings in October (10) and December (15).
One nest (16) contained two light blue-green eggs, and Hartert
(14) stated that nests were found with 2 or 3 egg clutches. No
information is available on incubation, nesting, or fledgling periods
(02).
PARENTAL CARE:
Zosterops c. conspicillata, like all passerines, is highly
altrical (17). It is not known whether both parents participate in
nest building, incubating, brooding or feeding of young. No
information is available on incubation, nesting or fledgling periods.
POPULATION BIOLOGY:
Predation by the introduced, arboreal, nocturnal brown tree
snake, Boiga irregularis, is thought to be responsible for the present
decline of the bridled white-eye on Guam. Other factors presently
or formally limiting the white-eye are unknown. Because the endemic
Zosterops c. conspicillata may presently be extirpated on Guam, it's
recovery potential is low (18).
SPECIES INTERRELATIONSHIPS:
Little is known of the interrelations of the bridled white-eye on
Guam with other species. White-eyes on Guam apparently mob
Micronesian kingfishers, Halcyon c. cinnamomina (03) and Micronesian
Starlings (Aplonis opaca) (02). Marshall (03) observed the
Micronesian kingfisher harassing flocks of bridled white-eyes.
OTHER LIFE HISTORY DESCRIPTORS:
None known.
Life History - 2 (DRAFT) - Management Practices
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Suppressing wildfire
Beneficial Land Acquisition
Beneficial Reforestation
Beneficial Stocking captive-reared wild-strain animals
Beneficial Controlling/Removing Exotic Vertebrates
Beneficial Controlling/Removing Feral Animals
Adverse Predation
Existing Predation
Adverse Applying pesticides
Existing Applying pesticides
Adverse Exotic/Feral/Introducted Species
Existing Exotic/Feral/Introducted Species
COMMENTS ON MANAGEMENT PRACTICES -
Predation of eggs, young and adults by the introduced
nocturnal brown tree snake, Boiga irregularis, is thought to be
responsible for the present decline of the Bridled white-eye and
other forest birds of Guam (05).
Recently, introduced diseases were considered as possible causes
for both the range reductions and extinctions noted for most native
forest birds on Guam, but to date, no infectious organisms have been
isolated on Guam that could account for the decline (05). Feral dogs,
cats and rats which are found on Guam are thought to be a major factor
in the decline of the white-eye (05).
There have been major changes in Guam's vegetation before,
during, and after World War II (06). However, substantial native
habitat still remains on Guam and habitat degradation is not thought
to be a major factor at present.
Pesticides may have been a factor for decline in the past,
however, an intensive pesticide survey conducted in 1981 on Guam,
concluded that pesticides were not a significant factor at present
(07).
While agonistic interactions between the bridled white-eye and
black drongo, Dicrurus macrocercus, has been noted (02), Maben (08)
found competition to be an unlikely factor in the white-eye's decline
on Guam.
APPROVED PLAN:
U.S. Fish and Wildlife Service. 1987. Endangered Native Forest Birds
of Guam and Rota of Mariana Islands Recovery Plan. U.S. Fish and
Wildlife Service, Portland, OR. 110 pp.
One of the first bird species to disappear from Guam was the
bridled white-eye. Because hope remains that a few white-eyes may yet
survive, the species is included in the Endangered Native Forest Birds
of Guam and Rota of Mariana Islands Recovery Plan. The recent,
drastic decline of forest bird populations on Guam has been one of
Management Practices - 1 (DRAFT) - Management Practices
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
the most alarming and challenging endangered species problem of
modern times. Current evidence points to an efficient predator of
small birds, the brown tree snake, as the culprit.
The Recovery Plan states among its primary objectives to locate
any white-eyes left in the wild and to ascertain if captive breeding
is possible as a means to prevent extinction. In addition, it is
imperative to develop methods of reducing predation by brown tree
snakes; this action would then allow reintoduction of captive birds
back into their historic range. Down-listing to threatened status
would occur once predation from snakes is under control and white-eyes
again occupy all essential habitat. The recovery plans recommends the
following actions for the Endangered forest birds of the Marianas:
(1) develop cooperative agreements among the USFWS, the Government of
Guam, and the Commonwealth of the Northern Marianas, towards
protection and recovery of forest birds;
(2) conduct annual status surveys of endangered forest birds;
(3) develop a captive breeding program for all species;
(4) reduce avian mortality in the field by monitoring for disease,
preventing diseases and their vectors from becoming established,
monitoring for pesticides, and particularly a program for controlling
predation by snakes, specifically by
(a) research on the biology and ecology of the tree snake,
particularly in its native geographical range,
(b) develop control methods,
(c) implement control measures, and
(d) prevent transport of snakes to Rota;
(5) protect and manage essential habitat;
(6) conduct additional research necessary for refinement recovery
tasks and goals, including rehabilitating regrowth in denuded areas,
controlling alien organisms, identifying habitat requirements of
endangered birds, and developing criteria for delisting these
endangered species;
(7) develop methods for reintroducing endangered birds to essential
habitat and implement where appropriate; and
(8) develop a public awareness program.
Recovery actions ongoing or accomplished for Guam's forest birds
include: (1) legal protection and law enforcement, (2) protection
of essential habitat, including establishment of 6 small natural area
reserves held by the Territory or by the military, and fire control
for all such habitat to prevent further distruction of habitat, (3)
ongoing captive breeding program (this pertains to species other than
the bridled white-eye), (4) a completed public education program
(which should profitably be reinstated), (5) and extensive research on
avian diseases and biology of the brown tree snake. Virtually all of
these activities have been initiated and carried out by the Government
of Guam, in cooperation with the U.S. Fish and Wildlife Service.
Management Practices - 2 (DRAFT) - References
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Baker, R.H. 1951. The avifauna of Micronesia, its origin,
evolution, and distribution. Univ. Kansas Publ., Mus. Nat. Hist.
3:1-359.
02 Jenkins, J.M. 1983. The native forest birds of Guam. Ornith.
Monogr. No. 31. Am. Ornith. Union. Wash., D.C. 61 pp.
03 Marshall, J.T., Jr. 1949. The endemic avifauna of Saipan, Tinian,
Guam and Palau. Condor 51:200-221.
04 Lanyon, W.E. 1985. Per. comm. Am. Mus. of Nat. Hist., New York.
05 Savidge, J.A. In Preparation. The role of disease and predation
in the decline of Guam's avifauna. Ph.D. Thesis, Univ. Illinois,
Champaign-Urbana.
06 Fosberg, F.R. 1960. The vegetation of Micronesia. Bull. Am. Mus.
Nat. Hist. 119(1):1-75.
07 Grue, C.E., C.M. Fecko, and A.J. Krynitsky. In Press. Pesticides
are not responsible for recent declines in native bird populations
on Guam. Micronesica.
08 Maben, Anne F. 1982. The feeding ecology of the black drongo
Dicrurus macrocercus on Guam. MS Thesis. Univ. Calif.,
Long Beach. P. 80-81.
09 Tubb, H.A. 1966. Notes on birds of Guam. Nat. Hist. Bull. Siam.
Soc. 21:135-138.
10 Strophlet, J.J. 1946. Birds of Guam. Auk 53:539-540.
11 King, B. 1962. Guam field notes. Elepaio 23:29-31.
12 Mayr, E. 1945. Birds of Southwest Pacific. The Macmillion Co.,
New York, xix+316 pp., 3pls., 16 figs., 1 map.
13 Seale, A. 1901. Report of a mission to Guam. Occas. Pap. Bernice
P. Bishop Mus. 1:17-128.
14 Hartert, Ernst. 1898. On the Birds of the Marianne Islands.
Novitates Zool. 5(11):51-69.
15 Beck, R.E., Jr. Unbubl. data. Div. of Aquatic and Wildl. Res.,
Dept. of Agric., Guam.
16 Guam Division of Aquatic and Wildlife Resources Field Records.
Dept. of Agric., Guam.
17 Van Tyne, J. and A.J. Berger. 1976. Fundamentals of Ornithology.
John Wily and Sons, New York.
18 U.S. Fish and Wildlife Service. 1985. Unpubl. draft. Recovery
Plan for the Native Forest Birds of Guam and Rota, Mariana Islands.
Technical Review Draft. Guam Aquatic and Wildl. Res., Dept. of
Agriculture, Gov. of Guam, Agana, Guam.
19 Engbring, J., F.L. Ramsey, and V.J. Wildman. 1986. Micronesian
forest bird survey, 1982: Saipan, Tinian, Aguigan, and Rota. U.S.
Fisn and Wildl. Serv. 143 pp.
20 Pratt, Douglas, P. Bruner, and D. Berrett. 1987. The birds of
Hawaii and the tropical Pacific. Princeton Univ. Press 409 pp. +
45 plts.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
References - 1 (DRAFT) - References
Species WHITE-EYE, BRIDLED
Species Id ESIS101031
Date 14 MAR 96
01 Baker, R.H. 1951. The avifauna of Micronesia, its origin,
evolution, and distribution. Univ. Kansas Publ., Mus. Nat.
Hist. 3:1-359.
02 Beck, R.E., Jr. 1984. Survey and inventory of the native land
Birds of Guam. In: Annual Report, FY 1984. Guam Aquatic and
Wildl. Res. Dept. of Agriculture, Gov. of Guam, Agana, Guam.
03 Jenkins, J.M. 1979. Natural history of the Guam rail. Condor.
Monogr. No. 31. Am. Ornitholgists Union., Wash., D.C. 61 pp.
04 Engbring, J. and F.L. Ramsey. 1984. Distribution and abundance of
the forest birds of Guam: Results of a 1981 survey. U.S. Fish and
Wildl. Serv. FWS/OBS-84/20. 54 pp.
05 Aguon, C. 1983. Survey and inventory of native birds on Guam.
In: Guam Div. of Aquatic and Wildl. Res. Annual Report. FY 1984.
Dept. of Agric., Guam.
06 Jenkins, J.M. 1983. The native forest birds of Guam. Ornith.
Monogr. No. 31. Am. Ornith. Union. Wash., D.C. 61 pp.
07 Engbring, J., F.L. Ramsey, and V.J. Wildman. 1986. Micronesian
forest bird survey, 1982: Saipan, Tinian, Aguigan, and Rota. U.S.
Fisn and Wildl. Serv. 143 pp.
References - 2