Use F9 to Update TOC

[**Appendix C1 Restore Peregrine Falcons to the Channel
Islands**](#__RefHeading___Toc98576621)

[C1.1 Goals and Nexus to Injury C1-1](#goals-and-nexus-to-injury)

[C1.2 Background C1-1](#background)

[C1.3 Project Description and Methods
C1-2](#project-description-and-methods)

[C1.4 Environmental Benefits and Impacts
C1-3](#environmental-benefits-and-impacts)

[C1.5 Likelihood of Success/Feasibility
C1-5](#likelihood-of-successfeasibility)

[C1.6 Performance Criteria and Monitoring
C1-5](#performance-criteria-and-monitoring)

[C1.7 Evaluation C1-5](#evaluation)

[C1.8 Budget C1-6](#budget)

Appendix C1

Restore Peregrine Falcons to the Channel Islands

### Goals and Nexus to Injury

The goal of this 5-year action is to facilitate recovery of peregrine
falcons to the Channel Islands. Data collected in 1992 in the Southern
California Bight demonstrated severe (\>15 percent) eggshell thinning in
peregrine falcons (Kiff 1994). Peregrine falcons were extirpated from
the Channel Islands by the mid 1950s, largely due to DDT contamination,
which led to eggshell thinning and reproductive failure (Kiff 2000).

### Background

Peregrine falcons once numbered in the hundreds in Southern California
(Walton 1997). Between 20 and 30 pairs are estimated to have nested on
the Channel Islands prior to 1945 (Kiff 1980, Hunt 1994). However, the
historical record of peregrine falcons on the Channel Islands is largely
deficient, and the overall carrying capacity of the territories is
unknown (Kiff 2000, Walton 1999). Peregrine falcons disappeared from the
Channel Islands by 1955, and only two pairs were located in California
in 1970 (Kiff 1980, Herman et al. 1970). In 1973, this species was
listed as endangered under the Endangered Species Act. Contamination by
organochlorines, in particular the pesticide DDT, was a major cause of
the decline of the peregrine falcon on both the Channel Islands and the
mainland (Risebrough and Peakall 1988). DDT is a mixture of several
chemicals that are further metabolized in the environment; DDE is a
component of DDT contamination in the environment that has specifically
been implicated in reproductive failures of many species of birds. A
mean DDE level of 15--20 parts per million (ppm) wet weight in peregrine
eggs is a critical level associated with approximately 17 percent
eggshell thinning and population declines (Peakall et al. 1975, Peakall
and Kiff 1988).

#### Recovery on the Channel Islands

The peregrine falcon has made a dramatic recovery since 1975, in large
part due the restrictions placed on DDTs in 1972 and an active release
program that was initiated soon afterward. Incubation of thin-shelled
eggs removed from wild nests and a captive breeding program provided
source birds for the release program. Between 1978 and 1993, the Santa
Cruz Predatory Bird Research Group released over 719 peregrine falcons
in California (Hunt 1994). On the Channel Islands, 34 birds were hacked
or fostered between 1983 and 1998, including 6 birds on San Miguel
Island and 17 birds on Santa Catalina Island (Linthicum, pers. comm.,
2004). In 1987, the first reestablished pair was documented on San
Miguel Island (Hunt 1994). In 1989, active nests were recorded on
Anacapa and Santa Cruz Islands (Hunt 1994). Between 1992 and 1994, 8 to
10 pairs were noted on the Northern Channel Islands (Hunt 1994). Since
1995, an additional 165 birds have also been released on the proximate
mainland to the Channel Islands at the Vandenberg Air Force Base and the
Santa Ynez area (Linthicum, pers. comm., 2004).

The release program accelerated the recovery of the peregrine falcons in
California and the rest of the United States. The peregrine falcon was
delisted from the List of Threatened and Endangered Species on August
25, 1999 (USFWS 1999). The U.S. Fish and Wildlife Service (USFWS)
recovery goal of five pairs for the Channel Islands was exceeded at the
time of delisting (USFWS 1982). In this ruling, the USFWS acknowledges
that there were areas where impacts from DDT were still occurring, but
those impacts had been reduced to local mortality of eggs and local
territory failures (USFWS 1999).

Eggshells collected in 1992--1993 averaged 19 percent thinner than
pre-1947 museum specimens, and had elevated concentrations of DDE (Hunt
1994, Kiff 1994). Productivity rates are substantially lower when
eggshells range between 17 and 20 percent thinner than normal (Peakall
and Kiff 1988). It has been estimated that 1 ppm of DDE in the diet of
peregrine falcons is sufficient to cause the eggshells to be 16 percent
thinner, and 3 ppm DDE results in eggshells being 10 to 28 percent
thinner (Enderson et al. 1982, Deweese et al. 1986, Hunt 1994).
Peregrine falcons prey almost exclusively on other birds. Data collected
in 1992 indicated that contamination in the food web was still at
sufficient levels to result in substantial eggshell thinning on the
Channel Islands.

In 1998, eggs from eight peregrine falcon territories on the Channel
Islands were sampled to determine eggshell thinning (Walton 1999).
Results indicated average eggshell thinning continued to exceed 17
percent for coastal Channel Islands territories, while most inland
Channel Island territories demonstrated slightly reduced levels of
thinning. These differences are likely a reflection of the higher levels
of DDE in marine-oriented prey (i.e., seabirds) than terrestrial prey
(i.e., land birds) (Walton 1999).

#### Current Status on the Channel Islands

No data are available on peregrine falcon eggshell thinning on the
Channel Islands since 1998. The Natural Resource Trustees for the
Montrose case (Trustees) funded a study in 2004 to determine the
occupancy and reproductive success of peregrine falcons on Santa
Catalina Island, including current levels of eggshell thinning. Although
occupancy was determined for two resident pairs, evidence of egg laying,
incubation, and chick rearing was not observed (PBRG 2004). It is
possible that any early nests failed due to eggshell thinning; however,
this was not determined.

Despite the ongoing presence of DDTs in the marine environment
surrounding the Channel Islands and the potential for eggshell thinning,
it is clear that the number of peregrine falcon pairs is steadily
increasing on the islands. In 2004, approximately 21 peregrine falcon
pairs were occupying breeding territories on six of the eight Channel
Islands (PBRG 2004). The majority of the pairs (18 of 21) occur on the
Northern Channel Islands (San Miguel, Santa Rosa, Santa Cruz, and
Anacapa), while 3 pairs occur on the Southern Channel Islands (2 pairs
were recently confirmed on Santa Catalina Island and 1 on Santa Barbara
Island). Recolonization to the Southern Channel Islands has been slower
than to the Northern Channel Islands. Peregrine falcons have also been
recently observed on San Clemente and San Nicolas Islands; however,
breeding has not been confirmed to date (Walton, pers. comm., 2003,
Smith, pers. comm., 2004).

### Project Description and Methods

The overall goal of this action is to speed the recovery of peregrine
falcons to the Channel Islands. Since the majority of the known occupied
territories in 2004 occurred on the Northern Channel Islands (18 of 21),
this 5-year action would involve active restoration of peregrine falcons
to the Southern Channel Islands through hacking techniques. Hacking is a
process that involves releasing fledgling peregrine falcons from a hack
box and supplementing food for the birds until they develop adequate
hunting skills. Because of the presence of federally endangered and
threatened bird species on both San Clemente and San Nicolas Islands
(that may be preyed upon by the falcons), this project would involve
releasing birds only on Santa Catalina Island. Two hack towers would be
used for the release of 10 birds per year, for a total of 50 birds over
a 5-year period. Peregrine falcons of west coast origin that are either
bred in captivity or removed from urban structures would be released.
All released peregrine falcons would be banded with both USFWS bands and
alphanumeric bands that can be read at a distance. A monitoring
component of the project would also be developed, and additional
documentation pursuant to National Environmental Policy Act
(NEPA)/California Environmental Quality Act (CEQA) would be completed as
needed.

### Environmental Benefits and Impacts

#### Biological

Benefits

The active restoration of peregrine falcons would speed the recovery of
this species into historically occupied habitat both on the Channel
Islands and mainland. Based on the results of earlier release programs,
this effort would likely result in the establishment of additional
peregrine falcon territories on the Channel Islands (Walton 1997). This
program would result in an influx of birds around the Southern Channel
Islands, thus encouraging recolonization on these islands. Although
peregrine falcons are recolonizing the Southern Channel Islands, as
demonstrated by the recent breeding on Santa Barbara and Santa Catalina
Islands, recolonization has not yet occurred on San Clemente and San
Nicolas Islands. This program would encourage the recolonization of
peregrine falcons into historically occupied habitat on the Channel
Islands. In addition, peregrine falcons that fledge from the Channel
Islands frequently disperse to the mainland (Walton 1999). Therefore,
unoccupied territories on the mainland are also likely to benefit from
the release program.

Raptors, such as the peregrine falcon, are an essential part of healthy,
functioning ecosystems. The peregrine falcon is an apex predator that
fills a particular ecological niche in the Channel Islands ecosystem.
Significant efforts are underway to restore the ecosystems of the
Channel Islands, such as the removal of nonnative species, habitat
restoration, and reintroduction of top predators (e.g., bald eagle).
Although peregrine falcons are once again a top predator on the majority
of the Channel Islands, complete recovery has not yet been achieved.
Additional active restoration would further encourage recovery on the
Channel Islands in an effort to restore a missing component of the
island ecosystem.

Impacts

The peregrine falcon is a highly specialized feeder, concentrating
almost entirely on birds. Kiff (1980) reported that peregrine falcons
prey on at least 22 species of birds on the Channel Islands and the
Coronado Islands. On the Channel Islands, dietary studies of peregrine
falcons in 1992 and 1993 showed that gulls, alcids, and land birds
comprised between 73 and 82 percent of their diet depending on season
(Hunt 1994). Grebes, shorebirds, and phalaropes constituted a smaller,
but substantial part of their diet. Within these groups of birds, the
species that accounted for 5 or more percent of the prey biomass
included the California gull, western gull, Cassin's auklet, Xantus's
murrelet, unidentified grebes, red phalarope, rock dove, mourning dove,
and European starling.

The recovery of the peregrine falcon on the Channel Islands may have a
negative impact on bird populations, particularly for those species that
are in decline or have limited populations. Predators, such as the
peregrine falcon, limit population growth by reducing nest productivity
and increasing adult and juvenile mortality. The Channel Islands are
critical breeding areas for seabirds and support important colonies of
special-status or declining species, such as the state-threatened
Xantus's murrelet, rare ashy storm-petrel, and federally threatened
western snowy plover. Peregrine falcons are known predators of the
Xantus's murrelet and western snowy plover (Hunt 1994, USFWS 2001).
Peregrine falcons have also been documented preying on petrels (Walton
1997, White et al. 2002); therefore, ashy storm-petrels could be
impacted as well. Because many seabirds are under constant threat (e.g.,
from oil spills, human disturbance, El Niño events), they may not be
able to withstand peregrine falcon predation (Paine et al. 1990). In
particular, depressed populations of seabirds may not be able to
effectively absorb the additional predation pressure from increased
peregrine falcons on these islands.

Recolonization of peregrine falcons to the Southern Channel Islands may
also impact the federally endangered San Clemente loggerhead shrike
*(Lanius ludovicianus mearnsi).* This bird subspecies is endemic to the
U.S. Navy--owned San Clemente Island and was listed by the USFWS as
endangered in 1977 due to its localized range, critically low population
numbers, consistently low productivity, and intense predation pressure.
Significant effort has been made to decrease the threat of extinction of
the wild population. Although this population has been recently
increasing, the subspecies remains highly endangered and vulnerable to
predation pressure.

Peregrine falcons do not prey upon California brown pelicans (Walton
1997); therefore, release of additional birds is not expected to
adversely impact this species.

#### Physical

Benefits

This action has no known benefits to the physical environment.

Impacts

This action has no known impacts to the physical environment.

#### Human Use

Benefits

The recovery of the peregrine falcon to the Channel Islands provides
both aesthetic and recreational benefits to visitors of the islands.
Peregrine falcons are known for their spectacular flights with an
average speed of 40--55 kilometers (km)/hour (25--34 miles/hour) with
speeds reaching 112 km/hour (70 miles/hour) (Cade 1982).

Impacts

This action has no known impacts to human uses.

### Likelihood of Success/Feasibility

The methodology proposed for hacking peregrine falcons on Santa Catalina
Island is one that has been successfully employed worldwide to
reestablish peregrine falcons and other species. Hacking of peregrine
falcons in California has been successful and has contributed to the
ongoing recovery of this species on the mainland and in the Northern
Channel Islands. Once birds are released from the hack towers,
operational work beyond monitoring is minimal. The proposed methodology
is technically sound and feasible and the likelihood of increasing the
number of occupied peregrine falcon territories on the Channel Islands
is high. While hacking is a feasible method for increasing the number of
peregrine falcons on the Channel Islands, ongoing contamination of the
food web of the Southern California Bight may impair the ability of
peregrine falcons to successfully reproduce in certain territories.

### Performance Criteria and Monitoring

Specific performance criteria would be developed as part of the
monitoring plan for this action. The plan would outline established
methods for monitoring the distribution, number of pairs, reproductive
success (i.e., productivity), recruitment, foraging behavior, and
dispersal of released peregrine falcons on the Channel Islands.

### Evaluation

The Trustees have evaluated this action against all screening and
evaluation criteria developed to select restoration actions and
concluded that this action is consistent with these selection factors.
Recovery of this species on the Channel Islands is under way, as
documented by the current presence of approximately 21 pairs on six of
the eight Channel Islands. Both the ongoing release program on the
mainland and natural recruitment are responsible for the recolonization
of these islands. Although the historical record is incomplete for the
Channel Islands, between 20 and 30 pairs were estimated prior to 1945
(Kiff 1980, Hunt 1994). In 2004, the current number of pairs occupying
the Channel Islands is within this estimated range and continues to
increase.

The number of pairs on the Channel Islands has been steadily increasing.
In the last 10 years, the number of pairs has doubled from 8 to 10 pairs
in 1994 to 21 pairs in 2004. This increase can be attributed to both
successful production on the islands and hacking efforts on the
mainland. As peregrine falcon numbers continue to increase on the
mainland, natural recruitment to the Channel Islands from the mainland
is likely to increase as well.

Current levels of DDE-associated eggshell thinning are unknown for the
breeding pairs on the Channel Islands. However, because some pairs are
successfully reproducing, contaminant levels are not high enough to
result in widespread failure on the Northern Channel Islands. This may
not be the case with the Southern Channel Islands. The slower rate of
colonization and lack of known successful breeding attempts on the
Southern Channel Islands may indicate that contamination continues to
negatively impact certain pairs. However, for the Channel Islands as a
whole, ongoing impacts due to DDT contamination are being buffered by
the natural recruitment of birds from other areas (Walton 1999).

Peregrine falcons are experiencing an overall expansion on the Channel
Islands despite any ongoing effects from DDE in their diet. The number
of breeding pairs on both the Northern and Southern Channel Islands is
within the estimated range prior to their disappearance from the
islands. Productivity on the islands, recruitment from the mainland, and
ongoing hacking efforts on the mainland continue to result in the
occupation of additional territories on the Channel Islands. Although
additional active restoration may further speed recovery, the Trustees
have determined that additional hacking efforts are not necessary at
this time. However, as part of the Preferred Alternative, the Trustees
will fund several peregrine falcon surveys over the next 5 years that
will provide updated information on the status and distribution of these
birds on the Channel Islands (see Appendix C2). Based on the results of
these surveys, the Trustees may proceed with active restoration
activities on the Channel Islands in Phase 2 of the restoration program.
A subsequent NEPA/CEQA document would be released to the public to
address future restoration projects in Phase 2.

### Budget

The estimated cost of a 5-year active restoration program on Santa
Catalina Island is shown below. This budget does not include all the
associated monitoring and contaminant analysis costs.

-   Labor \$374,000

-   Supplies \$99,000

-   Equipment \$7,000

-   Transportation \$13,000

-   Overhead \$110,000

-   **Total Cost Years 1--5 \$603,000**