(DRAFT) - Taxonomy
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
TAXONOMY
NAME - VIREO, BELL'S, LEAST
OTHER COMMON NAMES - VIREO, BELL'S, LEAST; VIREO, BELL'S; VIREO, BELL;VIREO, LITTLE; VIREO, LEAST; VIREO, LEAST, CALIFORNIA; GREENLET and LITTLE
ELEMENT CODE -
CATEGORY - Birds
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - AVES,
ORDER AND SUBORDER - PASSERIFORMES,
FAMILY AND SUBFAMILY - VIREONIDAE,
GENUS AND SUBGENUS - VIREO,
SPECIES AND SSP - BELLII, PUSILLUS
SCIENTIFIC NAME - VIREO BELLII PUSILLUS
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Least Bell's Vireo
Vireo bellii pusillus Coues, 1866
KINGDOM: Animal GROUP: Bird
PHYLUM: Chordata CLASS: Aves
ORDER: Passeriformes FAMILY: Vireonidae
The least Bell's vireo (Vireo bellii pusillus) is a small gray
migratory song bird. The crown and back are gray. The wings and tail
are somewhat darker. There is a faint wingbar and the whitish lores
and eye ring form a spectacle. The underside is predominantly buffy
white. The average length is 4 3/4 inches (01). Because of its
relatively secretive behavior, the vireo is more detectable by its
song which has been described as a rapid "cheetle cheetle chee?,
cheetle cheetle chew." The t's indicate a rasping quality to the song.
Three other subspecies of the Bell's vireo are recognized by the
American Ornithologists' Union (1957); Vireo bellii bellii of the
midwestern United States; V. b. medius of Texas; and V. b. arizonae of
the southwestern United States and northern Mexico (02).
In 1844, Audubon first described the species Vireo bellii, Bell's
vireo, from Missouri. Coues, in 1866, described what he considered to
be a new species from southern California, Vireo pusillus, which today
Taxonomy - 1 (DRAFT) - Taxonomy
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
is considered to be a subspecies of Bell's vireo, V. b. pusillus
Coues. Other scientific name synonyms include Vireo bellii albatus
and V. pusillus albatus (03).
The type specimen was taken at Cape Saint Lucas, CA by E. Coues
(12). An excellent photo is available in "Field guide to the birds of
North America" (01) and a description of Vireo bellii may be found in
Bent, 1950 (02).
Least Bell's vireo may also be known by the common names Bell's
vireo, Bell vireo, little vireo, least vireo, California least vireo,
and little greenlet.
Taxonomy - 2 (DRAFT) - Status
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
Federal Migratory
Non-consumptive recreational
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The least Bell's vireo (Vireo bellii pusillus) 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 State of California and in Mexico. Critical Habitat has been
proposed involving 10 areas totaling approximately 43,000 acres
including portion of the following: Prado Basin-Santa Ana River
(Riverside and San Bernardino Cos.), the Santa Ynez River (Santa
Barbara Co.), the Santa Clara River (Ventura and Los Angeles Cos.),
and Sweetwater River, Tijuana River, Coyote Creek, Jamul-Dulzura
Creeks, San Luis Rey River, Santa Margarita River, and San Diego River
(San Diego Co.).
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.
The species is protected by the Migratory Bird Treaty Act
(16 U.S.C. 703-711 et seq.) at the specific level as Vireo bellii,
Bell's vireo (50 CFR 10.13).
RESPONSIBLE FEDERAL AGENCIES:
USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.
BIA -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public lands under their control. Also responsible
for management/recovery on Bureau of Indian Affairs
Status - 1 (DRAFT) - Status
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
lands.
BLM -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public land under their control (43 CFR 4140). Also
responsible for management/recovery on Bureau of Land
Management lands.
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.
USFS -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public lands under their control. Also responsible
for management/recovery on Forest Service lands. The
Forest Service is responsible for integrating
management, protection, and conservation of Federally
listed species into the Forest Planning process
(36 CFR 219.19 and 219.20).
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:
STATE: California
DESIGNATED STATUS: Endangered
ADMINISTRATIVE AGENCY: California Department of Fish and Game
STATE STATUTE: CA Endangered Species Act; Fish and Game Code
Ch. 1.5, Art. 1, Sec. 2052; Ca. Admin. Code,
Title 14, Sec. 670.5 March 19, 1983.
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
None.
ECONOMIC STATUSES:
The least Bell's vireo is not associated with any known positive
or negative economic values, however, like most birds this species has
non-consumptive recreational value to birding enthusiates.
80/02/06:45 FR 08030/ - Notice of petition acceptance
84/01/20:49 FR 02485/02488 - Petition finding; warranted but precluded
85/05/03:50 FR 18968/18975 - Proposed rule, list; proposed Crit. Hab.
85/06/04:50 FR 23458/23459 - Correction of proposed CH description
85/07/09:50 FR 27992/27993 - Notice of public hearing
85/10/03:50 FR 40424/40425 - Extention of public comment period
86/05/02:51 FR 16474/16482 - Final rule, End.; reopen CH comment per.
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
INLAND AQUATIC
LAND USE -
Residential
Commercial and Services
Industrial
Transportation, communications, and Util
Industrial and Commercial Complexes
Mixed Urban or Built-up Land
Cropland and Pasture
Orchards, Groves, Vineyards, Nurseries,
Shrub and Brush Rangeland
Streams and Canals
Reservoirs
Forested Wetland
Nonforested Wetland
Strip Mines, Quarries, and Gravel Pits
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Riverine, intermittent
Riverine, upper perennial
Riverine, lower perennial
Palustrine SS1
COMMENTS ON HABITAT ASSOCIATIONS -
The least Bell's vireo, Vireo bellii pusillus, inhabits riparian
forests of southern California. Dense low growing thickets of willows
(Salix spp.), mule fat (Baccharis glutinosa), blackberry (Rubus
ursinus), mugwort (Artemisia douglasiana) or other similar species are
an essential part of the habitat. In desert areas mesquite (Prosopis
sp.) thickets are used. An overstory composed of taller willows,
cottonwoods (Populus fremontii), and sycamores (Platanus racemosa) is
also present. In some steeper drainages live oaks (Quercus) form part
of the overstory and vireos sometimes forage in adjacent chaparral.
Elsewhere, vireos forage in adjacent coastal sage scrub; other
adjacent habitats are not used.
The dense riparian thickets occupied by vireos are usually
impenetrable, with ground cover in the shrub layer being nearly 100%.
Shrub densities average 54,400 per acre. Canopy cover is more
variable. Riparian areas which contain least Bell's vireos have
higher shrub and tree cover, and lower amounts of aquatic and
herbaceous cover or open ground. The width of the riparian corridor
at sites occupied by vireos was greater than at unoccupied sites (05).
Although this riparian habitat occurs adjacent to many other
associations, vireos, with very few exceptions, do not utilize
adjoining habitats. Most adjacent sites are highly disturbed and have
been converted to agricultural fields (i.e., row crops of corn, oats,
and vegetables; fruit; or hay and pasture), golf courses, urban
neighborhoods, dairies, airports, or cities. These areas are not used
for foraging or other purposes by vireos, however, disturbance or
alterations in these areas could negatively impact the species or its
habitat. Increases in the density of developments or development
expansion could negatively impact the species' breeding ecology,
increase predation from domestic/feral animals, or increase the
Habitat Associations - 1 likelihood of cowbird parasitism. Pesticide/herbicide applications
could impact the species directly or indirectly through drift or
runoff and by entering the species' food chain (insects).
Since the least Bell's vireo occurs in riparian habitats along
rivers and adjacent to, downstream, or upstream from reservoirs,
disturbance of or management actions in these areas could negatively
impact the habitat. Also some sand mining operations occur adjacent
to the habitat which could negatively impact the species.
Habitat Associations - 2 (DRAFT) - Food Habits
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
LIFESTAGE FOOD FOOD PART
General Arthropods
Food Habits - 1 (DRAFT) - Environment Associations
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
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
Environment Associations - 1 (DRAFT) - Life History
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
The least Bell's vireo (Vireo bellii pusillus) is primarily
insectivorous. Adults capture their prey by gleaning insects off
leaves, stems and bark, by hovering and picking items off stationary
objects, and by flycatching (aerial pursuit). The most common
foraging method used is gleaning and most foraging takes place below
12 feet (06). Foraging has not been observed on their wintering
grounds.
HOME RANGE/TERRITORY:
In its breeding range, the least Bell's vireo is territorial;
defending territories appears to be primarily the responsibility of
the male. Territory size has been estimated as between one and four
acres (07). Vireo territories at the Santa Ana River and Prado Basin
have varied between 0.4 and 1.4 acres (08). The type and degree of
territoriality exhibited on their winter range is unknown.
PERIODICITY:
The least Bell's vireo is diurnal.
MIGRATION PATTERNS:
A migratory song bird, this vireo arrives on its breeding grounds
in southern California riparian areas around mid-March to early April,
and departs for wintering grounds by mid- to late September (08).
COVER/SHELTER REQUIREMENTS:
The least Bell's vireo, Vireo bellii pusillus, inhabits riparian
forests of southern California. Dense low growing thickets of willows
(Salix spp.), mule fat (Baccharis glutinosa), blackberry (Rubus
ursinus), mugwort (Artemisia douglasiana) or other similar species are
an essential part of the habitat. In desert areas mesquite (Prosopis
sp.) thickets are used. An overstory composed of taller willows,
cottonwoods (Populus fremontii), and sycamores (Platanus racemosa) is
also present. In some steeper drainages live oaks (Quercus) form part
of the overstory and vireos sometimes forage in adjacent chaparral.
Elsewhere, vireos forage in adjacent coastal sage scrub; other
adjacent habitats are not used.
The dense riparian thickets occupied by vireos are usually
impenetrable, with ground cover in the shrub layer being nearly 100%.
Shrub densities average 54,400 per acre. Canopy cover is more
variable. Riparian areas which contain least Bell's vireos have
higher shrub and tree cover, and lower amounts of aquatic and
herbaceous cover or open ground. The width of the riparian corridor
was also greater than unoccupied sites (05).
Additional habitat requirements are not known.
REPRODUCTIVE SITE REQUIREMENTS:
All breeding behavior takes place within the previously described
riparian habitat. Least Bell's vireos construct hanging cup shaped
nests in forks of branches in shrubs or trees. Nests are neatly woven
out of plant fibers and measure about 2.5 X 3 X 3.5 inches deep
Life History - 1 (DRAFT) - Life History
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
exteriorly and 1.5 X 1.75 X 1.5 inches deep interiorly. The average
nest height is three feet (.99 meters) based upon 256 nests located
along the Santa Margarita River (10).
REPRODUCTIVE CHARACTERISTICS:
Least Bell's vireos breed at one year of age and every year
thereafter. They begin breeding activities upon their arrival in
spring, most breeding is completed by the end of July. The average
clutch size is 3.4 eggs. The eggs are incubated about 14 days (10).
The pair remains together for a given brood. Following fledging or
failure, a female may move to a new mate. Some intra-season movement
of territories has been observed (08). Most pairs raise one brood per
season; however, some can raise two (10).
PARENTAL CARE:
The altricial young remain in the nest for 12 days. Both parents
share in incubation, feeding, and nest guarding. The fledglings
remain in the parental territory. This family unit may remain intact
for 6 to 10 weeks (11). After the family unit breaks up, young are
seen wandering throughout the riparian habitat.
POPULATION BIOLOGY:
All current limiting factors for this species are not known. The
scarcity of suitable habitat is undoubtedly one such factor. The
longevity of this subspecies is not known. Adult and juvenile
mortality rates have been estimated to be 53% and 76% respectively
(10). Sex ratios are variable, usually 1:1 or nearly so. In some
cases there are more males than females (05). Under careful
management the population at the Santa Margarita River increased from
15 territorial males in 1980 to 100 territorial males in 1986 (10).
SPECIES INTERRELATIONSHIPS:
The least Bell's vireo is vulnerable to brood parasitism by the
brown-headed cowbird (Molothrus ater). The female cowbird lays her
eggs in the nests of host species. Because the cowbird young is
larger and more aggressive, many host species, including the vireo,
when parasitized raise cowbird young to fledging rather than vireo
young (03,05,06,08,10). Many areas where the vireo exists also have
high cowbird populations. The increase in vireos observed at the
Santa Margarita River is due at least in part to an ongoing cowbird
trapping program (10). Trapping programs have been successful on
other drainages (05).
OTHER LIFE HISTORY DESCRIPTORS:
None.
Life History - 2 (DRAFT) - Management Practices
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling/Restricting Off-Road Vehicles
Beneficial Restricting/regulating human disturbance of populations
Beneficial Developing/maintaining stream structures
Beneficial Developing/maintaining/protecting wetlands
Beneficial Controlling water levels
Beneficial Controlling/Restricting Mining
Beneficial Controlling/Restricting Road Maintainance Actions
Beneficial Maintaining undisturbed/undeveloped areas
Beneficial Land Acquisition
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Controlling/Restricting Pesticide Use
Beneficial Controlling/Restricting Herbicide Use
Beneficial Controlling/Restricting Agricultural Practice
Beneficial Reforestation
Beneficial Maintaining Early Stages of Succession
Beneficial Controlling/Removing Nonnative Vegetation
Beneficial Stocking captive-reared wild-strain animals
Beneficial Controlling/Removing Exotic Vertebrates
Beneficial Controlling/Removing Feral Animals
Beneficial Controlling/Removing Domestic Animals
Adverse Low Gene Pool
Existing Low Gene Pool
Adverse Parasites
Existing Parasites
Adverse Predation
Existing Predation
Adverse Surface Mines
Existing Surface Mines
Adverse Rural Residential/Industrial Areas
Existing Rural Residential/Industrial Areas
Adverse Highway/Railroads
Existing Highway/Railroads
Adverse Soil compaction by heavy equipment in mine areas
Existing Soil compaction by heavy equipment in mine areas
Adverse Draining wetlands, marshes, ponds, lakes
Existing Draining wetlands, marshes, ponds, lakes
Adverse Flooding
Existing Flooding
Adverse Groundwater drawdown
Existing Groundwater drawdown
Adverse Irrigating
Existing Irrigating
Adverse Reservoirs
Existing Reservoirs
Adverse Dredging
Existing Dredging
Adverse Developing/maintaining stream bank vegetation
Existing Developing/maintaining stream bank vegetation
Adverse Shoreline modification/development
Management Practices - 1 (DRAFT) - Management Practices
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
RESULT MANAGEMENT PRACTICE
Existing Shoreline modification/development
Adverse Applying herbicides
Existing Applying herbicides
Adverse Applying pesticides
Existing Applying pesticides
Adverse Exotic/Feral/Introducted Species
Existing Exotic/Feral/Introducted Species
Adverse Grazing
Existing Grazing
Adverse
Existing
COMMENTS ON MANAGEMENT PRACTICES -
The decline of the least Bell's vireo, Vireo bellii pusillus, has
been attributed to a number of factors. This subspecies' former range
has been greatly reduced. Habitat losses have been due to
agricultural developments, livestock grazing, urban expansion, flood
control projects and reservoir and flood control basin developments
(13).
The use of pesticides and herbicides in agriculture, road
maintenance, and flood control projects is also a threat to the vireo.
Shoreline, bank, and channel modification; road construction; and sand
and gravel mining (and the associated heavy equipment) have all
directly destroyed vireo habitat. Wetlands have been filled for many
purposes including urban development, roads, airports, flood control
and the creation of duck ponds (13,14).
Water diversion associated with dams has adversely affected this
subspecies' habitat as has groundwater drawdown for agricultural and
urban development (13,14). The California State Endangered Species
Act and Federal provisions for the protection of wetlands have not
been sufficient in preventing the decline in vireo numbers or in the
loss of its habitat.
High predation rates also may have contributed to the species'
decline. Because least Bell's vireos build their nests about one
meter off the ground, and males occasionally sing from the nest, they
may be more easily preyed upon than other avian species. The least
Bell's vireo is vulnerable to brood parasitism by the brown-headed
cowbird. The cowbird has been responsible for reduced nesting success
at most existing locales of the vireo. Some areas which contain
vireos are near urban areas, consequently there may be an increased
predator population in the form of feral house cats (13_.
Least Bell's vireos exhibit strong site tenacity, consequently
local populations may not be mixing reproductively with the vireo
population as a whole and the subspecies may be suffering the effects
of a restricted gene pool (13).
UNAPPROVED PLAN:
U.S. Fish and Wildlife Service. 1986. Least Bell's Vireo Recovery
Plan. Agency Draft. U.S. Fish and Wildl. Serv., Portland, OR.
Management Practices - 2 (DRAFT) - Management Practices
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
173 pp.
The draft recovery plan recommends an increase in the annual
minimum breeding population in California to at least 5,000 pairs,
distributed in 20,000 acres (8,065 ha) within at least 12 or more
secure, protected and managed areas.
Habitat of sufficient size must be secured (through easements,
cooperative agreements and/or acquisition), protected from adverse
development and managed. Techniques to remove the exotic brown-headed
cowbird and exotic plants (e.g., giant reed (Arundo donax), and
tamarisk, (Tamarix ramosissima)) and maintain native vegetation of an
early successional stage are also needed. These methods may be
further refined through additional research. Land rehabilitation
may be needed to restore or create floodplains, stream banks, and
other riparian habitat, or to restore areas overgrown with exotic
plants. Domestic animals, particularly horses and cattle, and feral
house cats may need to be controlled at some locations. Activities
which may adversely impact the vireo and, therefore, may need to be
controlled include sand and gravel mining; the use of pesticides,
herbicides, and the spread of other pollutants; some agricultural
practices (e.g., grazing and land clearing); road maintenance actions
(e.g., rebulldozing roads and herbicide spraying); the use of off-road
vehicles; and stream bank or channel modification. The water table in
reservoirs and in areas subject to agricultural use needs to be
maintained. Captive propagation for reintroduction may be a useful
tool.
Limiting human access to some areas may be needed - accidental
disturbance has disrupted some nesting sites.
Cowbird parasitism and predation must be minimized. A
conservation education program should be developed. Laws and
regulations protecting the vireo and its habitat must be enforced and
their success evaluated. The distribution and status of least Bell's
vireos in Mexico must be determined and the potential contribution to
the recovery of the species must be assessed.
Ongoing recovery actions include cowbird trapping programs on
several drainages and monitoring the status of the species. Efforts
to design Habitat Conservation Plans for key drainages to the species
are also underway.
Management Practices - 3 (DRAFT) - References
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 National Geographic Society. 1983. Field guide to the birds of
North America. Nat. Geog. Soc., Washington, D.C. 464 pp.
02 Bent, A.C. 1950. Life histories of North American wagtails,
shrikes, vireos, and their allies. U.S. Govt. Printing Off.,
Smithsonian Inst., U.S Nat. Mus. Bull. 197.
03 Grinnell, J. and A.H. Miller. 1944. The distribution of the birds
of California. Cooper Ornithol. Club, Berkeley, CA. 617 pp.
04 Smith, F. 1977. A short review of the status o riparian forests
in California. IN: Riparian forests in California: The ecology
and conservation. A. Sands, ed. 121 pp.
05 San Diego Association of Governments (SANDAG) and RECON. 1986.
Draft comprehensive species management plan for the least Bell's
vireo (Vireo bellii pusillus).
06 Salata, L. 1986. Status of the least Bell's vireo at Camp
Pendleton, California, 1985: Report on research done in 1983.
Prep. for U.S. Marine Corps, Nat. Resour. Office.
07 Greaves, J. 1986. Several telephone conversations during 1986,
regarding research done at the Gibraltar Reservoir, Santa Barbara
County. 73 pp.
08 Hays, L. 1986. The status and management of the least Bell's
vireo within the Prado Basin, California, during 1986. Prep. for
Calif. State Dept. of Transp., San Bernardino, CA.
09 Garrett, K. and J. Dunn. 1981. The birds of southern California
status and distribution. Los Angeles Audubon Soc., Los Angeles,
CA. 408 pp.
10 Salata, L. 1986. Status of the least Bell's vireo at Camp
Pendleton, California in 1985. Prep. for U.S. Marine Corps, Nat.
Resour. Off.
11 Hays, L. 1987. Pers. comm. U.S. Fish and Wildlife Service, 24000
Avila Rd., Laguna Niguel, CA 92656.
12 Coues, E. 1866. Proc. of the Academy of Natural Science,
Philadelphia 18(1):76.
13 U.S. Fish and Wildlife Service. May 2, 1986. Determination of
endangered status for least Bell's vireo. Fed. Reg.
51(85):16474-16482.
14 Kramer, K. 1987. Pers. comm. U.S. Fish & Wildl. Serv., Federal
Bldg., 24000 Avila Rd., Laguna Niguel, CA 92677.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Grinnell, J. and A.H. Miller, 1944. The distribution of the birds
of California. Cooper Ornithol. Club, Berkeley, CA. 617 pp.
02 Roberson, D. 1985. Pers. comm. as cited in U.S. Fish and Wildlife
Service. 1986. Least Bell's Vireo Recovery Plan. USFWS,
Portland, OR.
03 Wier, H. 1986. As cited in: San Diego Association of Governments
(SANDAG) and RECON. 1986. Draft comprehensive species management
plan for the least Bell's vireo (Vireo bellii pusillus).
References - 1 (DRAFT) - References
Species VIREO, BELL'S, LEAST
Species Id ESIS101050
Date 14 MAR 96
04 San Diego Association of Governments (SANDAG) and RECON. 1986.
Draft comprehensive species management plan for the least Bell's
vireo (Vireo bellii pusillus). Available from SANDAG.
05 Jones, B. and J. Newman. 1986. As cited in: San Diego
Association of Governments (SANDAG) and RECON. 1986. Draft
comprehensive species management plan for the least Bell's vireo
(Vireo bellii pusillus).
06 Grifith, J. and J. Griffith. 1986. As cited in: San Diego
Association of Governments (SANDAG) and RECON. 1986. Draft
comprehensive species management plan for the least Bell's vireo
(Vireo bellii pusillus).
07 Salata, L. 1986. Status of the least Bell's vireo at Camp
Pendleton, California, 1985. Prep. for U.S. Marine Corps, Nat.
Resour. Office.
08 Wier, H. and B.L. Jones. 1986. A survey of the birds of riparian
habitats. Anza Borrego Desert State Park, San Diego, County,
California with emphasis on the least Bell's vireo and brown-headed
cowbird. Prep. for SANDAG, CALTRANS, and Ca. Dept. of Parks Rec.,
San Diego.
09 Hays, L. 1986. The status and management of the least Bell's
vireo within the Prado Basin, California, during 1986. Prepared
for the Ca. Dept. of Transp. (CALTRANS).
10 Keeney, T. 1986. As cited in: San Diego Association of
Governments (SANDAG) and RECON. 1986. Draft comprehensive species
management plan for the least Bell's vireo (Vireo bellii pusillus).
11 Franklin, B. 1986. Gibraltar-Mono study of the 1986 breeding
season of the least Bell's vireo. Prep. for Dames and Moore,
Santa Barbara, CA.
References - 2