(DRAFT) - Taxonomy
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
TAXONOMY
NAME - SHRIKE, LOGGERHEAD, SAN CLEMENTE
OTHER COMMON NAMES - SHRIKE, LOGGERHEAD, SAN CLEMENTE; SHRIKE and LOGGERHEAD
ELEMENT CODE -
CATEGORY - Birds
PHYLUM AND SUBPHYLUM - CHORDATA,
CLASS AND SUBCLASS - AVES,
ORDER AND SUBORDER - PASSERIFORMES,
FAMILY AND SUBFAMILY - LANIIDAE,
GENUS AND SUBGENUS - LANIUS,
SPECIES AND SSP - LUDOVICIANUS, MEARNSI
SCIENTIFIC NAME - LANIUS LUDOVICIANUS MEARNSI
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
San Clemente Loggerhead Shrike
Lanius ludovicianus mearnsi Ridgway, 1903
KINGDOM: Animal GROUP: Bird
PHYLUM: Chordata CLASS: Aves
ORDER: Passeriformes FAMILY: Laniidae
The majority of this discussion has been taken from Miller (03),
the most comprehensive analysis of loggerhead shrike taxonomy to date.
The San Clemente loggerhead shrike (Lanius ludovicianus mearnsi) is a
medium-sized passerine bird with short rounded wings which are
slightly shorter than its tail. It, and the other subspecies of
Lanius ludovicianus have prominently hooded mandibles with tomial
tooth, and plumage coloration of white, gray, black and brown. The
most pronounced features of shrike coloration are: the black mask
which covers the lores and ocular region of the head; the demarcation
between the black flight feathers, white underparts and rump, and gray
back; and the patches of white on the wings and tail.
Miller (03) states that L. l. mearnsi tends to have a shorter
bill and shorter wings than the adjacent mainland subspecies of L. l.
gambeli, grinnelli, and nelsoni. He distinguished specimens of L. l.
mearnsi from L. l. anthonyi, the subspecies on Santa Catalina and
Taxonomy - 1 (DRAFT) - Taxonomy
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
other Channel Islands, by their small bills (males only) and plumage
coloration. L. l. mearnsi has a darker gray back, whiter rump,
generally lighter breast and flanks, and more white (area) on
scapulars. The underparts of L. l. mearnsi are darker than the L. l.
nelsoni and grinelli, but slightly lighter than gambeli.
Debate on the taxonomic status of L. l. mearnsi culminated in the
work of Miller (03) in 1931. The subspecies was described by Ridgway
(08) in 1903, and the type specimen, a female immature in postjuvenal
molt, was deposited in the National Museum (category no. 134781). In
1908, Linton suggested that L. l. mearnsi should be synonymized with
L. l. anthonyi, and it was synonymized with L. l. anthonyi in the
fifteenth supplement to the American Ornithologist's Union (AOU)
Checklist of North America Birds (09). In 1919, Oberholser (10)
revived L. l. mearnsi as a subspecies and it appeared as such in
subsequent AOU checklists (11). Miller (03) mentions discussion on
the validity of L. l. mearnsi but found no compelling reasons to alter
his subspecific categorization of this shrike population.
Taxonomy - 2 (DRAFT) - Status
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
STATUS
Coded Status
E: Federal Endangered
Federal Migratory
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The San Clemente loggerhead shrike (Lanius ludovicianus mearnsi)
has been designated an Endangered species 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.
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
(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.; 50 CFR 10.13).
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:
Status - 1 (DRAFT) - Status
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
STATE: California
DESIGNATED STATUS: Recognized Endangered
ADMINISTRATIVE AGENCY: Department of Fish and Game
STATE STATUTE: California Endangered Species Act of 1970,
Species Preservation Act of 1970, Fish and Game
Code (FGC) Subsection 2000, 2002; FGC Subsection
3005.5, 3504; FGC Section 2225.
The California Environmental Quality Act (PRC 2100 et seq.)
recognizes Federally listed Threatened and Endangered species as among
those species requiring that environmental impact assessments be made
for actions that may detrimentally affect them. See: Guidlines for
Implementation of the California Environmental Quality Act, California
Administrative Code, Chapter 3, Section 15380.
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
The San Clemente loggerhead shrike (L. l. mearnsi) is listed as
endangered in the IUCN Red Data Book of 1979.
ECONOMIC STATUSES:
None.
76/06/01:41 FR 22073/22075 - Proposed rule, Endangered
77/08/11:42 FR 40682/ - Final rule, listed as Endangered
82/09/27:47 FR 42387/42388 - Five year review
85/04/05:50 FR 13707/13722 - Revised list of Migratory Birds
87/07/07:52 FR 25523/25528 - Notice of review
Status - 2 HABITAT ASSOCIATIONS
HABITAT - TERRESTRIAL
TERRESTRIAL
COASTAL
LAND USE -
Mixed Urban or Built-up Land
Herbaceous Rangeland
Shrub and Brush Rangeland
Mixed Rangeland
Beaches
Sandy Areas other than Beaches
Transitional Areas
COMMENTS ON HABITAT ASSOCIATIONS -
Lanius ludovicianus mearnsi occurs only on San Clemente Island,
but occupies nearly all of the xeric habitats found on the island.
These habitats are most similar to the coastal sagebrush category of
the chaparral mountain association and annual grassland association.
Because the island has a combination of maritime and desert
associations, the vegetation that the shrikes inhabit are usually
referred to as maritime desert scrub and maritime sage scrub (01).
The canyon bottoms maintain some woodland/shrubland of Prunus, Rhus,
Heteromeles, and Quercus, which most resemble the arid riparian
association. Coastal strand vegetation (01) occurs along the
intertidal zone of the island's coastlines.
Observations indicate that shrikes forage in all vegetations on
the island, but are most clearly associated with maritime desert scrub
vegetation. During the breeding season, activities (including
foraging) are concentrated in maritime desert scrub vegetation near
canyon woodland/shrublands where nesting occurs. Shrikes often forage
near the canyon woodlands during the nonbreeding times of the year,
but establish home ranges in any areas with suitable foraging perches.
Nest shrubs are typically 2 to 4 m in height with nests placed
immediately below the shrub canopy, approximately 2 m off the ground.
The most commonly used species is Rhus integrifolia (lemonade berry),
followed by Prunus lyonii (island cherry), Heteromeles arbutifolia
(toyon), and Quercus tomentella (island oak). Rhus is the most common
of these species on the island, however, even this species is
generally limited to the bottoms of canyons. Nest areas are typically
located in Rhus stands with 3 or more well developed shrubs, and
typically in areas with low topographic heterogeneity (canyon mouths,
bajadas, or shallow canyons). The most frequent features of these
areas are the dense canopy cover of the Rhus shrubs and the high
number of snags associated with the shrub stands.
The dense shrub crowns provide cover for nests and fledge young,
protecting the young until they become adept at predator avoidance.
Snags provide foraging perches, feeding perches, impaling and
butchering sites, and singing perches.
Shrikes typically forage in areas of low shrub vegetation.
Dominant plant species of these areas on the island include: Lycium
spp., Opuntia spp., Atriplex spp., Mirablis spp., Bergerocactus
emorii, Stipa spp., Bromus spp., and Avena spp. (names follow Munz
(02)). Specific plant associations or species do not appear as
critical as forage perch availability in shrike selection of foraging
areas. Shrikes use a number of natural perches but show a preference
for utility lines, particularly where these lines cross desert scrub
vegetation. Large shrubs (both dead and alive), rocks and cacti
are the most common natural perches, although shrikes use Lycium and
Habitat Associations - 1 dead annuals such as Brassica and Stephanomeria as well.
The major human use of San Clemente Island is for research and
development, testing, and evaluation of undersea weapons,
instrumentation, and communications. About 300 civilian and military
personnel commute to the island on a weekly basis. Other activities
include simulated aircraft carrier landing practice, ship to shore
gunnery excercises (concentrated in about 2 square mi. (3 square km)
around China and Pyramid Coves), amphibious exercises, underwater
demolition training and troop maneuvers involving up to 4,000 people.
Habitat Associations - 2 (DRAFT) - Food Habits
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
LIFESTAGE FOOD FOOD PART
General Arthropods
General Reptilia
General Aves
General Mammalia
Food Habits - 1 (DRAFT) - Environment Associations
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
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
G Coastal Features: Vegetated offshore islands
G Snags: Unknown
G Availability of fence rows: roadside ditches and grassy
G
Environment Associations - 1 (DRAFT) - Life History
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
LIFE HISTORY
FOOD HABITS:
San Clemente loggerhead shrikes take a broad combination of
arthropods, lizards, rodents and birds. Insects (Orthopterans,
Hymenopterans, and Coleopterans) comprise the highest proportion of
the diet, followed by lizards (Uta stansburiana, side-blotched lizard,
and Xantusia riverensiana, island-night lizard), rodents (Mus
musculus, house mouse, and Peromyscus maniculatus, deer mouse), and
birds (primarily Salpinctes obsoletus, rock wren). Shrikes on the
island are opportunistic foragers with food habits dependent more on
availability than preference. Peaks in prey use typically correspond
with peaks in prey abundance.
Shrikes consume small insects whole, casting the exoskeletons as
regurgitated pellets. Insects larger than 4 cm are typically impaled
and portioned, with wings, elytra and head removed before consumption.
Lizards and rodents are completely consumed, but after they have been
impaled and portioned. Shrikes eat nestling birds whole, but
typically consume only the head and body of adult birds.
No strong preferences for specific food items or food items
essential to the survival of the San Clemente loggerhead shrike have
been observed. Side-blotched lizards are a particularly common prey
item fed to young at fledging and post fledging periods of parental
care, and may constitute a preferred prey item during the breeding
season.
HOME RANGE/TERRITORY:
San Clemente loggerhead shrikes occur in too low a density to
observe territorial behavior. Home ranges, as defined by foraging
behavior, do not appear to overlap during the breeding season, but may
overlap at times when shrikes are not tied to specific breeding
locations. Size of home ranges varies considerably among pairs,
ranging from approximately 40 to 100 ha. Singing, copulation and
other reproductive behaviors typically take place within 500 m of nest
areas. Young typically remain within 50 m of nest areas for two weeks
after fledging, and within 500 m of nest areas during the period of
parental care.
PERIODICITY:
Daily foraging patterns show peaks in the early morning and
afternoon, but there is no strong periodicity to foraging activity.
Shrikes on the island have an extended breeding season, from January
to the end of July. The peaks of nesting activity in 1984 and 1985
occurred in April.
MIGRATION PATTERNS:
Miller (03) considered the San Clemente loggerhead shrike
non-migratory. At present, there is no evidence to suggest otherwise.
COVER/SHELTER REQUIREMENTS:
San Clemente loggerhead shrikes depend on Rhus integrifolia
stands for nesting and cover. While there is great variation in the
age, size and shape of the shrubs used in nesting, all have similar
Life History - 1 (DRAFT) - Life History
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
characteristics of 1) dense crown of individual shrubs, 2) numerous
snag branches, and 3) shrub heights of at least 2 m. Canopy volume of
individual shrub is highly variable, but typically exceeds 8 cubic
meters.
REPRODUCTIVE SITE REQUIREMENTS:
There is relatively little variation in nest placement by San
Clemente loggerhead shrikes. Nests are placed under the shrub crown,
typically less than 1 m below the top of the crown and 30 to 80 cm
from its outside edge. Nest height averages 1.9 m with a range of
1.5 to 2.4 m. Singing perches, impaling posts, food exchange and
copulation sites are highly variable and may be selected, in part, for
their proximity to nest shrubs.
REPRODUCTIVE CHARACTERISTICS:
The breeding season for shrikes on San Clemente Island extends
from mid-January until late July. Shrikes in general, reach sexual
maturity after one year (03) with banded adults living up to 11 years
(04). Nest construction and egg-laying take approximately one week
each. Modal clutch number of shrikes on the island is 5 eggs.
Overall breeding success was 0.86 young per attempt in 1984, and 1.00
in 1985. Modal fledge number is 4, however, the number of young
surviving after fledging is substantially lower. Approximately 10% of
the pairs double-clutched in 1985 (none in 1984), but all pairs that
failed in their first breeding attempt renested during 1984 as well as
1985. Incubation, brooding and other characteristics of parental care
are similar to those described by Miller (03).
PARENTAL CARE:
Observations indicate that the San Clemente loggerhead shrike
follows the pattern of parental care described by Miller (03) for
mainland shrikes. Both adults defend their nest from intruders,
escalating from loud vocalizations to stooping as the intruder nears
the nest. Young have been observed with the adults into the seventh
week after hatching, although they appear to be proficient foragers
by the sixth week. Despite the protection by the adults, predation
currently claims most of the young shortly after they leave the nest.
POPULATION BIOLOGY:
At present, there are no empirical estimates of most of the
population parameters of the San Clemente loggerhead shrike. The
population of shrikes on the island in the early 1900's (05,06,07) had
a wide breeding distribution, and probably occurred in higher
densities. Current factors limiting the abundance and distribution of
shrikes on the island appears to be, 1) predation of breeding adults
and newly fledged young and 2) the paucity of suitable nest shrubs
over the northern half of the island. The predation appears to be a
function of feral cats and native predators, the lack of shrubs is the
result of browsing by feral goats.
SPECIES INTERRELATIONSHIPS:
Feral cat (Felis catus) predation on young and breeding adult
shrikes may have had a direct effect on the number and distribution of
Life History - 2 (DRAFT) - Life History
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
San Clemente loggerhead shrikes. Cats were probably not common on the
island until the 1930's when the establishment of the naval base on
the island increased the human population and subsequently increased
the cat population.
OTHER LIFE HISTORY DESCRIPTORS:
None.
Life History - 3 (DRAFT) - Management Practices
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Suppressing wildfire
Beneficial Prescribed/controlled burning of habitat
Beneficial Land Acquisition
Beneficial Reforestation
Beneficial Controlling/Removing Nonnative Vegetation
Beneficial Controlling/Removing Native Vertebrates
Beneficial Controlling/Removing Exotic Vertebrates
Beneficial Controlling/Removing Feral Animals
Adverse Predation
Existing Predation
Adverse Exotic/Feral/Introducted Species
Existing Exotic/Feral/Introducted Species
Adverse Vegetation Composition Changes
Existing Vegetation Composition Changes
COMMENTS ON MANAGEMENT PRACTICES -
Two factors have been identified that are believed to have been
the primary reasons for the current status of the San Clemente
loggerhead shrike: 1) predation upon young by feral cats (Felis
catus), black rats (Rattus rattus), and native predators, and 2) the
nearly complete removal of suitable nest shrubs in the northern half
of the island and degradation of nest areas in the south by browsing
goats.
Reproduction in 1984 and 1985 was substantially lower as would be
expected from comparisons to mainland populations. The primary reason
appears to be predation upon breeding adults, eggs, young in the nest
and young at the time of fledging. Circumstantial evidence implicates
black rats in predation of shrike eggs. There is strong evidence to
indicate cat predation on nesting females, nestling and fledged
shrikes, and ravens have been observed consuming young.
Goats are able to consume woody shrub species and show a
preference for shrubs when the quality of grasses deteriorates in
summer (and periods of drought) (12). Despite romantic accounts of
goats present on the island dating to the 1600's, circumstantial
evidence now exists which suggests that goats have been on the island
only since the late 1800's or early 1900's. At present, the strongest
line of evidence comes from archeological excavation on the island,
which has failed to recover goat bones from Indian middens dating into
the 1830's. This evidence suggests that the goats are relatively
recent to the island and could do more damage than has already
occurred. Attempts by the Department of the Navy to eradicate the
goats have been hampered by animal protection groups. These groups
succeeded in stopping a goat shooting program and replaced it with
live capture techniques. Because of the intrinsic growth rate in the
goat population, the rugged nature of the island, and the expense and
danger of live capture, the Navy goat removal program is now
equivalent to a sustained yield harvest program (13). The goats occur
in all shrike nesting areas and will continue to degrade these
Management Practices - 1 (DRAFT) - Management Practices
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
habitats until they are removed.
APPROVED PLAN:
U.S. Fish and Wildlife Service. 1984. Recovery Plan for the
Endangered and Threatened Species of the California Channel Islands.
U.S. Fish and Wildlife Service, Portland, OR. 165 pp.
Actions recommended for recovery include:
1) Habitat restoration including revegetation to provide additional
habitat and nesting sites (which may require removal of exotic
vegetation, and include both controlled burns in grassland and
chaparral communities and natural fire breaks in maritime desert shrub
communities), erosion control, and removal of feral, exotic and native
animal species, including the kestrel.
2) Implementation of management regimes including establishment of
shrub lands and woodlands.
3) Habitat protection which consists of promulgation and enforcement
of Navy regulations regarding the San Clemente Island cooperative
agreement for management, preventing the introduction of exotic
organisms, and fencing off critical areas (e.g., nesting stumps and
trees); and
4) Determining species requirements, population size and dynamics,
distribution, threats, effects, effects of fire, and competitive
relationship between shrikes and kestels.
Cooperative agreements are being made between the Navy and the
U.S. Fish and Wildlife Service for resource management, also research
and surveys have been conducted.
Management Practices - 2 (DRAFT) - References
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
References
References - 1 (DRAFT) - References
Species SHRIKE, LOGGERHEAD, SAN CLEMENTE
Species Id ESIS101008
Date 14 MAR 96
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Thorne, R.F. 1976. The vascular plant communities of California.
IN: Plant communities of southern California. J. Latting, ed.
Calif. Native Plant Soc. Spec. Publ. No. 2. 32 pp.
02 Munz, R. 1974. A flora of southern California. Univ. of Calif.
Press, Berkeley. 1086 pp.
03 Miller, A.H. 1931. Systematic revision and natural history of the
American shrikes. Univ. Calif. Publ. Zool. 38(2):11-242.
04 Anon. [n.d.] Unpublished data. [Banding records from the Bird
Banding Laboratory.] Office of Migratory Bird Management, U.S.
Fish and Wildlife Service, Laurel, MD.
05 Grinnell, J. 1897. Report on the birds recorded during a visit to
the islands of Santa Barbara, San Nicolas and San Clemente in the
spring of 1897. Pasadena Acad. Sci. Publ. 1:1-26.
06 Linton, C.B. 1908. Notes from San Clemente Island. Condor
10:82-86.
07 Howell, A.B. 1917. Birds of the islands off the coast of southern
California. Pacific Coast Avifauna No. 12. 127 pp.
08 Ridgway, R. 1904. The birds of North and Middle America. Bull.
U.S. Nat. Mus, No. 50, Part III. 801 pp.
09 American Ornithologists Union. 1909. Fifteenth supplement to the
American Ornithologists Union Checklist of North American birds.
Auk 26:294-303.
10 Oberholser, H.C. 1919. Description of a new subspecies of Lanius
ludovicianus. Wilson Bull. 31(3):87-90.
11 American Ornithologists Union. 1957. Checklist of North American
birds. American Ornithologists Union, Baltimore, MD. 691 pp.
12 Coberlitz, B. 1977. Some range relationships of feral goats on
the Santa Catalina Island ecosystem. J. Range Manage. 30:415-419.
13 Caughley, G. 1977. Analysis of vertebrate populations. Wiley &
Sons, New York, NY. 234 pp.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Miller, A.H. 1931. Systematic revision and natural history of the
American shrikes. Univ. Calif. Publ. Zool. 38(2):11-242.
02 Hyde, K.M. 1983. Unpublished report. San Clemente Island
loggerhead shrike/sage sparrow study, 1980-1983. Dept. of the
Navy, Natural Resour. Office, Naval Air Station, North Island.
60 pp.
03 Grinnell, J. 1897. Report on the birds recorded during a visit to
the islands of Santa Barbara, San Nicolas and San Clemente in the
spring of 1897. Pasadena Acad. Sci. Publ. 1:1-26.
04 Howell, A.B. 1917. Birds of the islands off the coast of southern
California. Pacific Coast Avifauna No. 12. 127 pp.
05 Linton, C.B. 1908. Notes from San Clemente Island. Condor
10:82-86.
06 Raven, P.H. 1963. A flora of San Clemente Island, California.
Aliso 5(3):289-347.
References - 2