Endangered and Threatened Wildlife and Plants; Final Rule to List the Medium Tree-Finch (Camarhynchus pauper, 43853-43864 [2010-18025]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 143 (Tuesday, July 27, 2010)]
[Rules and Regulations]
[Pages 43853-43864]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-18025]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R9-IA-2008-0108]
[90100-1660-1FLA B6]
RIN 1018-AW01


Endangered and Threatened Wildlife and Plants; Final Rule to List 
the Medium Tree-Finch (Camarhynchus pauper) as Endangered Throughout 
Its Range

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine 
endangered status for the medium tree-finch (Camarhynchus pauper) under 
the Endangered Species Act of 1973, as amended (Act). This species is 
native to Floreana Island, one of the Galapagos Islands in Ecuador. 
This rule implements the protections of the Act for this species.

DATE:  This final rule is effective August 26, 2010.

ADDRESSES: The supporting file for this rule is available for public 
inspection, by appointment, during normal business hours, Monday 
through Friday, in Suite 400, 4401 N. Fairfax Drive, Arlington, 
Virginia 22203.

FOR FURTHER INFORMATION CONTACT: Janine Van Norman, Chief, Branch of 
Foreign Species, Endangered Species Program, U.S. Fish and Wildlife 
Service, 4401 N. Fairfax Drive, Room 420, Arlington, VA 22203; 
telephone 703-358-2171; facsimile 703-358-1735. If you use a 
telecommunications device for the deaf (TDD), call the Federal 
Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Background

    In this final rule, we determine endangered status for the medium 
tree-finch (Camarhynchus pauper) under the Act.

Previous Federal Actions

    Section 4(b)(3)(A) of the Act requires us to make a finding (known 
as a ``90-day finding'') on whether a petition to add, remove, or 
reclassify a species from the list of endangered or threatened species 
has presented substantial information indicating that the requested 
action may be warranted. To the maximum extent practicable, the finding 
shall be made within 90 days following receipt of the petition and 
published promptly in the Federal Register. If we find that the 
petition has presented substantial information indicating that the 
requested action may be warranted (a positive finding), section 
4(b)(3)(A) of the Act requires us to commence a status review of the 
species if one has not already been initiated under our internal 
candidate assessment process. In addition, section 4(b)(3)(B) of the 
Act requires us to make a finding within 12 months following receipt of 
the petition on whether the requested action is warranted, not 
warranted, or warranted but precluded by higher-priority listing 
actions (this finding is referred to as the ``12-month finding''). 
Section 4(b)(3)(C) of the Act requires that a finding of warranted but 
precluded for petitioned species should be treated as having been 
resubmitted on the date of the warranted but precluded finding, and is 
therefore subject to a new finding within 1 year and subsequently 
thereafter until we take action on a proposal to list or withdraw our 
original finding. The Service publishes an annual notice of resubmitted 
petition findings (annual notice) for all foreign species for which 
listings were previously found to be warranted but precluded.
    On May 6, 1991, we received a petition (hereafter referred to as 
the 1991 petition) from the International Council for Bird Preservation 
(ICBP), to add 53 species of foreign birds to the list of Threatened 
and Endangered Wildlife

[[Page 43854]]

(50 CFR 17.11(h)), including the medium tree-finch that is the subject 
of this final rule. In response to the 1991 petition, we published a 
positive 90-day finding on December 16, 1991 (56 FR 65207), for all 53 
species, and announced the initiation of a status review. On March 28, 
1994 (59 FR 14496), we published a 12-month finding on the 1991 
petition, along with a proposed rule to list 30 African birds under the 
Act. In that document, we proposed listing 15 of the 53 bird species 
included in the 1991 petition, and announced our finding that listing 
the remaining 38 species from the 1991 petition, including the medium 
tree-finch, was warranted but precluded because of other listing 
activity.
    On May 21, 2004 (69 FR 29354), and April 23, 2007 (72 FR 20184), we 
published in the Federal Register notices announcing our annual 
petition findings for foreign species. In those notices, we made 
warranted but precluded findings for all outstanding foreign species 
from the 1991 petition, including the medium tree-finch which is the 
subject of this final rule.
    Per the Service's listing priority guidelines (September 21, 1983; 
48 FR 43098), our 2007 annual notice of review (ANOR) (April 23, 2007; 
72 FR 20184) identified the listing priority numbers (LPNs) (ranging 
from 1 to 12) for all outstanding foreign species, including the medium 
tree-finch, which was designated with an LPN of 11. The medium tree-
finch does not represent a monotypic genus. As reported in the 2007 
ANOR, the magnitude of threat to the species was moderate as the 
species was common in the forested highlands and its habitat had not 
been highly degraded. The immediacy of threat was nonimminent because 
the species' habitat is protected by the area's national park and World 
Heritage Site status.
    On January 23, 2008, the United States District Court ordered the 
Service to propose listing rules for five foreign bird species, actions 
which had been previously determined to be warranted but precluded: The 
Andean flamingo (Phoenicoparrus andinus), black-breasted puffleg 
(Eriocnemis nigrivestis), Chilean woodstar (Eulidia yarrellii), medium 
tree-finch (Camarhynchus pauper), and the St. Lucia forest thrush 
(Cichlherminia herminieri sanctaeluciae). The court ordered the Service 
to issue proposed listing rules for these species by the end of 2008.
    On July 29, 2008 (73 FR 44062), we published in the Federal 
Register a notice announcing our annual petition findings for foreign 
species. In that notice, we announced that proposing 30 taxa for 
listing under the Act is warranted. In order to comply with the recent 
court-order, the medium tree-finch was included as one of the 30 taxa 
for which listing is warranted.

Summary of Comments and Recommendations

    In the proposed rule published on December 8, 2008 (73 FR 74434), 
we requested that all interested parties submit written comments on the 
proposal by February 6, 2009. We received six comments. We received a 
comment from the Center for Biological Diversity supporting the 
proposed listing. Three comments received were from peer reviewers, and 
two other comments were received from the public that contained no 
substantive information. We did not receive any requests for a public 
hearing.
    During the comment period for the proposed rule, we received three 
comments containing substantive information. No comments in opposition 
of the rule were received. All substantive information provided during 
the comment period has either been incorporated directly into this 
final determination or addressed below.
    New clarifying information, particularly concerning the degree of 
threat by the parasitic fly (Philornis downsi) and confirmation of the 
success of the goat eradication program, was provided by one peer 
reviewer and has been incorporated into this finding.

Peer Review

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from four knowledgeable 
individuals with scientific expertise that included familiarity with 
the medium tree-finch and its habitat, biological needs, and threats. 
We received responses from three of the peer reviewers.
    We reviewed all comments received from the peer reviewers for 
substantive issues and clarifying information regarding the listing of 
the medium tree-finch. The peer reviewers generally concurred with our 
methods and conclusions and provided additional clarifications and 
suggestions to improve the final rule. Peer reviewer comments are 
addressed in the following summary and incorporated into this final 
rule as appropriate.

Public Comments

    Comment 1: Three independent specialists agreed that our 
description and analysis of the biology, habitat, population trends 
were accurate and agreed generally with our conclusions. One researcher 
provided recent information on the medium tree finch's nesting success 
between 2004 and 2008; indicating that between 4 and 8 percent of nests 
produced fledglings.
    Our Response: This information has been considered and incorporated 
into the rulemaking as appropriate.
    Comment 2: Three commenters supported the proposed listing.
    Our Response: While general support of a listing is not, in itself, 
a substantive comment that we take into consideration as part of our 
five-factor analysis, we appreciate the support of these commenters. 
Support is important to the conservation of foreign species.
    Comment 3: One commenter suggested that tourist visitation to the 
Scalesia highlands (the preferred habitat of the Medium Tree finch) 
increased more than tenfold since 2004, indicating that there has been 
an increase in the number of bus rides and highland tours.
    Our Response: We acknowledge that tourism may be increasing on 
Floreana Island; however, no supporting information was provided with 
the comment for corroboration. The United Nations Educational, 
Scientific, and Cultural Organization (UNESCO) 2007 report indicated 
that visitation has grown in Galapagos from 40,000 in 1991 to over 
120,000 in 2006 (pp. 9-10). This is discussed in factor B, below.
    Comment 4: One commenter provided additional information on this 
species, specifically three research papers -- two published in 2008 
and the other in 2007-- regarding the avian parasite discussed in 
factor C below.
    Our Response: The Service has reviewed the research, and the 
information has been considered and incorporated into the rulemaking as 
appropriate.

Summary of Changes from Proposed Rule

    A commenter pointed out a typographical mistake, which we have 
corrected. Santa Maroa Island was corrected to Santa Maria Island. We 
also updated the clutch size to clarify that it is generally between 
two and three for this species, rather than between two and four, which 
was the size indicated in the proposed rule. Additionally, the medium 
tree-finch population estimate and trend has been updated in this 
document (see Species Information below).

Species Information

    The medium tree-finch (Camarhynchus pauper) is endemic to Floreana 
Island in the Galapagos Islands, Ecuador (Harris 1982, p. 150; Sibley 
and Monroe 1990, p. 771; BirdLife International (BLI) 2010). This

[[Page 43855]]

species is one of the 14 species of Darwin's finches, collectively 
named in recognition of Charles Darwin's work on the theory of 
evolution (Grant 1986, p. 6). It is approximately 12.5 centimeters (cm) 
(5 inches (in)) in length (Harris 1982, p. 150; BLI 2010). Medium tree-
finches have wings and tails that are short and rounded, and often hold 
their tails slightly cocked in a wren-like manner (Jackson 1985, p. 
188). Males have a black head, neck, and upper breast (Harris 1982, p. 
150; Jackson 1985, p. 188; Fitter et al. 2000, p. 78), and an underside 
that is gray-brown, and white or yellowish in color (BLI 2010). Their 
tail and back are olive green (Fitter et al. 2000, p. 78). Females have 
a head that is more gray-brown (BLI 2010), and a body that is generally 
olive-green above and pale yellowish below (Fitter et al. 2000, p. 78). 
It is similar to the large and small tree-finches of the same genus, 
but differs from the large tree-finch (Camarhynchus psittacula) 
primarily due to its significantly smaller and less parrot-like beak, 
and from the small tree-finch (Camarhynchus parvulus) because of its 
larger beak (Harris 1982, p. 150; BLI 2010). It is also known as the 
Charles tree-finch, the Santa Maria tree-finch, and the Floreana tree-
finch (Sibley and Monroe 1990, p. 771). This is due to the fact that 
the island of Floreana is also referred to as Charles Island or Santa 
Maria Island, the official Spanish name of the island (Harris 1973, p. 
265; Grant 1986, Appendix). The species is locally known as ``Pinzon 
Mediano de arbol'' (Castro and Phillips 1996, p. 130).
    The species was first taxonomically described by Ridgeway in 1890 
(Sibley and Monroe 1990, p. 771). Sulloway (2008a, pers. comm.) 
recently conducted an analysis of the relative numbers of tree-finch 
specimens in the California Academy of Sciences' collections, compared 
with the frequencies found by Dr. Sonia Kleindorfer between 2000 and 
2006. Sulloway found that the population of the medium tree-finch did 
not significantly change for over a century, during which time settlers 
and introduced animals and plants were present on Floreana (2008b, 
pers. comm.). Sulloway's analysis indicates that the medium tree-finch 
is much less common today than it was prior to 1961 (Sulloway 2008a, 
pers. comm.). Specifically, the chance of seeing a medium tree-finch 
today is approximately 25 percent less than it would have been more 
than 50 years ago, as compared to the likelihood of spotting a large or 
small tree-finch (Sulloway 2008a, pers. comm.). As reported by Sulloway 
(2008a, pers. comm.) and O'Connor et al. (2009, p. 862), the population 
density of the medium tree-finch is declining. O'Connor et al found 
(2008a) density of the species decreased from 154 birds/km\2\ (59 
birds/mi\2\) in 2004 to 60 birds/km\2\ (23 birds/mi\2\) in 2008.
    In 1996, Stotz et al. considered the relative abundance of the 
species to be ``common'' (1996, p. 262). BirdLife International 
currently estimates the population to be between 1,000 and 2,499 birds 
(2010, p. 1). In 2006, Fessl et al. reported that there were about 300 
breeding pairs remaining on Floreana (2006a, p. 745). In another study, 
researchers compared bird abundance survey data from 2004 and 2008 in 
order to estimate the population density of the medium tree-finch in 
the highlands of Floreana (O'Connor et al. 2008, 20 pp). Based on the 
results of their study, O'Connor et al. (2008, p. 1) estimate that the 
total medium tree-finch population in 2008 consisted of 860 to 1,220 
individuals (an average of 72 birds/km\2\ (28 birds/mi\2\)) observed in 
their prime habitat. Their study also showed that the population 
density of the species overall decreased from 154 birds/km\2\ (59 
birds/mi\2\) in 2004 to 60 birds/km\2\ (23 birds/mi\2\) in 2008 (pp. 6-
7).

Habitat and Life History

    Floreana, one of the 19 principal islands that make up the 
Galapagos archipelago (McEwen 1988, p. 234), is 173 km\2\ (67 mi\2\) in 
area, and has a maximum elevation of 640 meters (m) (2,100 feet (ft)) 
(Swash and Still 2005, p. 10).
    The medium tree-finch mainly occurs in the moist highland forests 
(i.e., the Scalesia zone, named for the dominant tree species, Scalesia 
spp., found in this zone) (Stewart 2006, p. 193; Kleindorfer 2007, p. 
796), primarily above 300 m (984 ft) (Castro and Phillips 1996, p. 
130). The Scalesia zone begins at an altitude of 180 - 200 m (591 - 656 
ft), and ends at approximately 600 m (1,968 ft) ((Wiggins and Porter 
1971, p. 22; Stephenson 2000, p. 34). On Floreana, the medium tree-
finch's habitat is a lush evergreen cloud forest dominated by Scalesia 
pedunculata (daisy tree), the largest of the 20 species of Scalesia 
found in the Galapagos, (Jackson 1985, p. 95; Fitter et al. 2000, p. 
137). Scalesia form dense stands with S. pedunculata frequently 
reaching 15 m (49 ft) in height, and 20 m (66 ft) or more given good 
environmental conditions (Wiggins and Porter 1971, p. 22; Fitter et al. 
2000, p. 137). A large amount of the Scalesia zone has been destroyed 
on the inhabited islands. The zone is the best area for agriculture 
because the garua (dense sea mist that sometimes blankets the 
highlands) keeps the area well watered during the cool season (Jackson 
1985, p. 61; Fitter et al. 2000, p. 137). Currently, 12 to 17 km\2\ 
(4.6 to 6.6 mi\2\) of Scalesia-dominated forest is believed to remain 
(O'Conner et al. 2008; p. 8).
    On Floreana, other common trees in the Scalesia zone are the 
endemic trees Croton scouleri (Galapagos croton) and Zanthoxylum fagara 
(lime prickly-ash). Dominant plant species include Phoradendron 
henslowii (mistletoe), the shrub Macraea laricifolia, and introduced 
fruit species such as Citrus limetta, Passiflora edulis, and Psidium 
guajava (Christensen and Kleindorfer 2008, p. 5). Beneath the top of 
the canopy, epiphytes (plants that live on another plant without 
causing harm to the host plant) cover trunks, branches, twigs, and even 
leaves of some plant species (Wiggins and Porter 1971, p. 24; Fitter et 
al. 2000, p. 137). Common epiphytes found in the Scalesia zone are 
mosses, liverworts, ferns, Peperomia, bromeliads (such as Tillandsia), 
and orchids (Wiggins and Porter 1971, pp. 22, 24; Jackson 1985, p. 60; 
Fitter et al. 2000, p. 137). Epiphytes are a prominent feature of the 
moist zones of the Galapagos Islands because of the large amount of 
time that clouds and mist cover the upper reaches of the higher islands 
(Fitter et al. 2000, p. 137).
    In 1996, researchers reported that the elevational zone in which 
the medium tree finch is most common is ``Hill Tropical,'' described as 
hills and lower slopes in the altitude range of 500 - 900 m (1,640 - 
2,953 ft) (Stotz et al. 1996, pp. 121, 262). The species reaches its 
minimum elevation in relatively low-relief lowland areas and its 
maximum elevation at 600 m (1,969 ft) (Stotz et al. 1996, p. 262). As a 
result, one can infer from this data that the medium tree-finch is 
predominantly found at the highest end of its elevational distribution, 
between 500 and 600 m (1,640 and 1,969 ft).
    These researchers found that the medium tree-finch forages at more 
than one level within its habitat; specifically, they noted that it can 
be found foraging from the understory (undergrowth) to the canopy 
(Stotz et al. 1996, pp. 120, 262). Camarhynchus species were found to 
spend a little less than 25 percent of their time foraging at the 
ground level, while spending the majority of their time foraging above 
ground (Bowman 1963, p. 132). The medium tree-finch uses its powerful 
tip-biting bill to search under twigs and foliage, probe crevices in 
the bark of trees, and cut into tough woody tissues in search of insect 
larvae (Bowman 1963, pp. 117, 125), which is its primary food source 
(Bowman 1963,

[[Page 43856]]

p. 121). The species also feeds, to a lesser extent, on seeds (Bowman 
1963, p. 121), nectar, young buds, and leaves (Castro and Phillips 
1996, p. 130).
    The medium tree-finch prefers to forage and nest in the tree 
Scalesia pedunculata (O'Connor et al. 2009, p. 855). Its clutch size is 
generally between two and three (Fessl et al 2006a, p. 740, Dudaniec et 
al. 2007, pp. 326-327; O'Connor et al. 2009, p. 855). The nests of 
Darwin's finches are similar in construction from one species to 
another: the male builds a dome-shaped nest, made from twigs, grass, 
pieces of bark, lichens, feathers, and other materials, with a small, 
round side entrance (Jackson 1985, p. 191). In a study of the nesting 
success of the small tree-finch in the highlands of Santa Cruz Island 
in the Galapagos, Kleindorfer (2007, p. 796) found that all nests were 
located 6 to 10 m (20 to 33 ft) above the ground, on horizontal 
branches of Scalesia pedunculata, and were positioned by interweaving 
surrounding smaller twigs and leaves.
Range and Distribution
    In 1982, Harris reported that the species was common in the 
highlands on Floreana and uncommon to rare on the coast (p. 150). 
Although the current range of the medium tree-finch is officially 
estimated to be 23 km\2\ (9 mi\2\) (BLI 2010), which encompasses the 
entire highland area of Floreana, the medium tree-finch is restricted 
to fragmented forest patches within the highlands. The actual available 
habitat has been estimated to be approximately 4 to 17 km\2\ (4.5 to 
6.5 mi\2\) (O'Connor et al. (2008, p. 8; O'Connor et al. 2009, p. 856).

Conservation Status

    The medium tree-finch is identified as a critically endangered 
species under Ecuadorian law, Decree No. 3,516-Unified Text of the 
Secondary Legislation of the Ministry of Environment (ECOLEX 2003b). As 
of 2010, this poorly known species is considered ``Critically 
endangered'' by the International Union for Conservation of Nature 
(IUCN). This is because it (1) has a very small range, (2) is 
restricted to a single island, and (3) recent information suggests that 
it is declining rapidly due to the parasite Philornis downsi. (BLI 
2010, p. 1).
    In 1996, in a review of neotropical birds, Stotz et al. described 
the conservation priority for the medium tree-finch as ``high.'' During 
this review, they defined this species as ``threatened,'' which 
generally equated to range or habitat restriction, and already showing 
signs of serious population decline (1996, p. 262).

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533) and its implementing 
regulations at 50 CFR 424, set forth the procedures for adding species 
to the Federal Lists of Endangered and Threatened Wildlife and Plants. 
A species may be determined to be an endangered or threatened species 
due to one or more of the five factors described in section 4(a)(1) of 
the Act. The five listing factors are: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; and (E) other natural or manmade 
factors affecting its continued existence. Below is an analysis of 
these five factors.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of its Habitat or Range

    Floreana has the longest history of human habitation of any of the 
Galapagos Islands (Schofield 1989, p. 229; Fitter et al. 2000, p. 207). 
It was first settled in 1832, 3 years before Darwin's historic visit 
(Jackson 1985, p. 3; Stewart 2006, pp. 55, 68). With human settlement 
came changes to the habitat on Floreana, including clearing of native 
vegetation for agriculture and ranching, as well as the introduction of 
nonnative animals and plants (Grant et al. 2005, p. 501).
    The medium tree-finch prefers to nest and forage in the tree 
Scalesia pedunculata (O'Connor et al. 2009, p. 856). Currently, S. 
pedunculata only occurs in small patches in the highlands of Floreana 
because much of the highlands have been cleared for agriculture, 
destroyed by introduced mammals, and outcompeted by invasive plants 
(O'Connor et al. 2008, p. 2). Although the Galapagos National Park 
covers 97 percent of the land in the Galapagos Islands, a 
disproportionate amount of the limited moist highlands falls in the 
remaining 3 percent (Stewart 2006, p. 105), meaning the majority of the 
medium tree-finch's habitat is unprotected. A large amount of the 
highlands has been cleared or altered for farming. Much of it has been 
further degraded or destroyed by the introduction of animals and plants 
(Stewart 2006, p. 105). Currently, only 12 to 17 km\2\ (4.5 to 6.5 
mi\2\) of habitat for the medium tree-finch remains in the highlands of 
Floreana, and it continues to decline due to the factors described 
below.
Agriculture and Ranching
    Birds, such as the medium tree-finch, are currently facing problems 
in the highlands of inhabited islands like Floreana due to the 
extensive destruction and degradation of habitat as a result of 
agriculture (Castro and Phillips 1996, pp. 22-23; Fitter et al. 2000, 
p. 74; BLI 2010). On Floreana, the highlands (or Scalesia zone) cover 
an area of approximately 21 km\2\ (8 mi\2\) (O'Connor et al. 2008, pp. 
2-3). Within this highland forest, approximately 4 km\2\ (1.5 mi\2\) 
has been cleared for agriculture (O'Connor et al. 2008, p. 8). 
Agriculture is concentrated at higher elevations because of the 
availability of richer soil and greater moisture (Schofield 1989, p. 
233). The Scalesia zone is the richest zone in terms of soil fertility 
and productivity (Jackson 1985, p. 61), and therefore has been 
extensively cleared for agricultural and cattle ranching purposes 
(Grant 1986, p. 30; Harris 1982, p. 37; Jackson 1985, pp. 61, 233). 
Stotz et al. (1996) found that the medium tree-finch forages in 
multiple strata, including the understory (p. 262). When the forest is 
cleared, as is done with agriculture and ranching, the understory layer 
is destroyed which, can have a negative effect on the species (Stotz et 
al. 1996, p. 121).
Introduced Species
    Introduced species are currently considered a major threat to the 
native species of the Galapagos Islands (Causton et al. 2006, p. 121; 
Fitter et al. 2000, p. 218). Since the early 1800s, humans have 
introduced animals and plants to the Galapagos Islands that have 
threatened the native vegetation (Schofield 1989, pp. 227, 233). These 
are further discussed below.

Animals

    When settlers arrived in the Galapagos Islands, they brought with 
them domestic animals, some of which escaped and started feral 
populations (Jackson 1985, p. 233). On Floreana, introduced livestock 
animals include goats (Capra hircus), donkeys (Equus asinus), cattle 
(Bos taurus), and pigs (Sus scrofa domesticus) (Christensen and 
Kleindorfer 2008, pp. 383-391; Jackson 1985, p. 232). These animals 
impact the island by significantly altering the habitat. Goats and 
donkeys damage vegetation by trampling and grazing to the point where 
native plants are not able to regenerate as easily as before. Wild pigs 
dig up and eat plant roots. (Schofield 1989, pp. 229-233;

[[Page 43857]]

Grant et al. 2005, p. 501). This impact, in addition to predation of 
endemic species by introduced cats (Felis catus) and introduced black 
rats (Rattus rattus) (discussed under Factor C), have been linked with 
the extinction of at least four bird species on the island of Floreana: 
the large ground finch (Geospiza magnirostris), the sharp beaked ground 
finch (Geospiza difficilis), the Floreana mockingbird (Nesomimus 
trifasciatus) (Christensen and Kleindorfer 2008, pp. 383-391; Grant et 
al. 2005, p. 501; Harris 1982, pp. 36-37; Sulloway 1982, pp. 68-69, 88-
89), and most recently the warbler finch (Certhidea fusca) (Grant et 
al. 2005, p. 501).
    Introduced animals magnify the detrimental effects of clearing 
large areas of native vegetation on Floreana for agriculture and 
ranching (Grant 1986, p. 30), by further degrading and destroying the 
habitat (Grant et al. 2005, p. 501). The habitat of the medium tree-
finch continues to be altered by herbivore degradation caused by free-
ranging domestic livestock (BLI 2010; Jackson 1985, p. 110; Lawesson 
1986, p. 12). Lawesson (1986) reported that the Scalesia forest on 
Floreana is under the most immediate threat from introduced animals (p. 
13).
    Goats: Of all the introduced animals in the Galapagos Islands, 
goats are the most destructive (Fitter et al. 2000, p. 218; Schofield 
1989, p. 227). Goats were probably introduced to the Galapagos Islands 
in the 19th century by whalers, fisherman, and pirates, who were 
looking for an alternative source of meat (Charles Darwin Research 
Station 2008a; Fitter et al. 2000, p. 218). They were also brought to 
the islands by settlers as livestock (Charles Darwin Research Station 
2008a). Goats are able to adapt to varying conditions extremely well 
and therefore they thrive at all elevations in the Galapagos Islands 
(Schofield 1989, p. 229), from the arid lowlands to the moist highlands 
(Fitter et al. 2000, p. 218). They have a rapid reproductive rate, 
which has allowed their population to flourish at the expense of native 
animals and vegetation (Jackson 1985, pp. 232-233). Goats destroy 
native vegetation by eating plants down to the ground (Smith 2005, p. 
304), converting forests into barren grasslands and causing erosion 
(Charles Darwin Research Station 2008a). Because goats are able to eat 
a variety of vegetation, they have quickly eaten their way across an 
island (Smith 2005, p. 304). A study of goats on Santiago Island in the 
Galapagos showed that at higher elevations, browsing by goats had 
eliminated young trees of the dominant forest overstory species 
consisting of Scalesia pedunculata, Zanthoxylum fagara, and Psidium 
galapageium, in addition to the forest understory (Schofield 1989, p. 
229). On Floreana, Schofield reported that approximately 77 percent of 
the plant species other than cacti were either reduced in number or 
completely eliminated by goats ((1989, p. 229). As discussed in detail 
below, however, eradication programs have significantly reduced the 
goat population on Floreana Island.
    Cattle: Cattle were introduced to Floreana in 1832 (Hoeck 1984, as 
cited in Schofield 1989, p. 231). Initially, cattle were kept at lower 
elevations, but with inadequate moisture available in the lower zones, 
they were allowed to move into the highlands (Kastdalen 1982, p. 9). 
Cattle trample and heavily graze native vegetation (Hamann 1981 and Van 
der Werff 1979, as cited in Schofield 1989, p. 231). When allowed to 
roam freely through highland forests, they essentially destroy the 
understory layer (Stotz et al. 1996, p. 121). On Santa Cruz Island, 
cattle inhibited growth of Scalesia pedunculata (Kastdalen 1982, p. 8). 
Schofield (1989) reports that no organized effort has been made to 
eliminate cattle, but restrictions by the Galapagos National Park 
Service encourage ranchers to fence in herds on Floreana (p. 232). 
However, cattle still stray into native vegetation to graze (Schofield 
1989, pp. 232, 234).
    Donkeys: In 1887, large numbers of donkeys (Equus asinus) were seen 
grazing on hillsides and at the summit on Floreana (Slevin 1959, as 
cited in Schofield 1989, p. 232). By 1932, donkeys had already tramped 
out regular paths through the vegetation on Floreana (Wittmer 1961, as 
cited in Schofield 1989, p. 232). On Santa Cruz, Kastdalen (1982) noted 
that they followed cattle into the humid highlands (p. 9). Studies have 
shown that donkeys on Floreana have depleted some populations of 
Scalesia spp. and Alternanthera nesiotes, another endemic plant 
(Eliasson 1982, p. 10). As discussed in detail below, however, 
eradication programs have significantly reduced the donkey population 
on Floreana Island.
    Pigs: Pigs (Sus scrofa) have lived in the Galapagos Islands for 
over 150 years (Schofield 1989, p. 232). In 1835, Darwin remarked upon 
the many wild pigs he observed in the forests on Floreana (Schofield 
1989, p. 232). Pigs live primarily at higher elevations, where abundant 
forage is available year-round (Schofield 1989, p. 232). Pigs destroy 
native vegetation (Jackson 1985, p. 233) directly by digging up and 
eating plants (Hoeck 1984, as cited in Schofield 1989, p. 232).
    Eradication Programs: Since the Galapagos National Park and the 
Charles Darwin Foundation were established in 1959, efforts to control 
and eradicate introduced animals have been ongoing (Galapagos 
Conservancy n.d.(a)). In 1965, the Charles Darwin Research Station 
began the first eradication program to rid the Galapagos island of 
Santa Fe of goats (Fitter et al. 2000, p. 218). Ten years after the 
program began, the last goat was culled and now, the vegetation on the 
island has recovered and native species are beginning to thrive once 
again (Fitter et al. 2000, p. 218). Over the years, many of these 
control programs have been successful in eradicating introduced animals 
from some of the Galapagos Islands including ridding Santiago Island of 
25,000 feral pigs (Smith 2005, p. 305), removing goats from Espanola, 
Plaza Sur, Santa Fe, Marchena and Rabida Islands (Smith 2005, p. 305), 
and the very successful ``Project Isabela,'' which recently eliminated 
goats from Pinta, donkeys and goats from northern Isabela, and donkeys, 
goats, and pigs from Santiago Island (Galapagos Conservancy n.d.(b)).
    As a result of the success of Project Isabela, the Charles Darwin 
Foundation is planning and implementing several projects in partnership 
with the Galapagos National Park Service, including eradication of 
goats and donkeys from Floreana (Charles Darwin Foundation n.d.(c)). In 
December 2006, the Galapagos National Park started a project with the 
goal of restoring the ecology of Floreana (Galapagos Conservation Trust 
News 2007). The first phase of ``Project Floreana'' was to eradicate 
some of the introduced animals, such as goats and donkeys, in order to 
stop the continuing degradation of the vegetation of the island and 
allow some of the native and endemic plant species to recover 
(Galapagos Conservation Trust News 2007). From the experience gained 
during Project Isabela, the program was able to eradicate 98 percent of 
the donkeys and goats on Floreana in 22 days (Galapagos Conservation 
Trust News 2007). Due to the removal of these invasive species, it is 
expected that within the next few years the benefits to the ecosystem 
on Floreana will be seen (Galapagos Conservation Trust News 2007). This 
will result in an increase in native flora and fauna, and the 
repopulation of native flora and fauna in areas previously destroyed on 
Floreana by herbivore degradation (Galapagos Conservation Trust News 
2007).

[[Page 43858]]

Plants

    On Floreana, small populations of Scalesia forest still exist in 
the highlands, but these areas are under pressure and competition from 
agriculture and the aggressive Psidium guajava (guava) and Lantana 
camara (Lawesson 1986, p. 13). Introduced plants outcompete native 
vegetation, taking sun, water, and nutrients from native species (Smith 
2005, p. 304). Agriculture is concentrated at higher elevations because 
of the rich soil and moisture available in these areas. As a result, 
escapes by introduced agricultural plants are more frequently found in 
the humid highland forests (Schofield 1989, p. 233). Schofield found 
that accidental escape of introduced plant species, as well as the 
purposeful introduction of these species, has altered the highland 
habitat where tree-finches occur (1989, pp. 233-235). Christensen and 
Kleindorfer found that the medium tree-finch frequently forages on 
introduced fruit species (2008, pp. 383-391). This observation may 
suggest that the species is able to adapt to and potentially benefit 
from this change in its environment (Christensen and Kleindorfer 2008, 
pp. 383-391). These researchers did not observe any species of tree-
finch, including the medium tree-finch, nesting in an introduced plant 
species (Christensen and Kleindorfer 2008, pp. 383-391). However, a 
further study by O'Connor et al. (2008, p. 17) found that the majority 
(99 percent) of nests built by medium tree-finches were constructed in 
native species, Scalesia pedunculata (83 percent), Zanthoxylum fagara 
(14 percent), and Croton scouleri (2 percent), with 1 percent of the 
nests built in the introduced species, guava.
    Guava: The cultivated guava, with its edible fruits, is the most 
widespread introduced plant species in the Galapagos Islands (Schofield 
1989, p. 233). Guava has been characterized as out of control and 
invading vast areas of native vegetation in the humid highlands on 
Floreana (Eckhardt 1972, p. 585; Eliasson 1982, p. 11; Tuoc 1983, p. 
25). It is an aggressive introduced plant that covers 8,000 ha (19,768 
ac) on Floreana (Parque Nacional Galapagos n.d(a)). The dispersal of 
guava is aided by introduced cattle, which eat the fruits and then 
wander from the farm into the National Park and excrete the seeds in 
their dung (De Vries and Black 1983, p. 19; Tuoc 1983, p. 25). In 
addition, as cattle graze, they trample other vegetation, providing the 
open spaces and abundant light needed for the germination of guava 
seeds (Van der Werff 1979, as cited in Schofield 1989, p. 233). Once 
guava becomes established in an open habitat, it grows quickly and 
shades seedlings of native species like Scalesia pedunculata, thus 
preventing their growth (Parque Nacional Galapagos n.d.(a); Perry 1974, 
p. 12).
    One obvious step to take in order to minimize the further spread of 
guava is to fence cattle (De Vries and Black, p. 19; Tuoc 1983, p. 25). 
Although some residents have already done this, herds of free-ranging 
cattle are unable to be restricted in this manner (Schofield 1989, pp. 
233-234). In 1971, a campaign was started to cut down guava trees on 
Santa Cruz Island (Schofield 1989, p. 234). One report indicated that 
over 95,000 guava trees had been eliminated between 1980 and 1981 (Tuoc 
1983, p. 25). Schofield suggested that this program should be expanded 
to other islands with large populations of guava ((1989, p. 234).
    Other Plant Species: Floreana is also impacted by other introduced 
plant species. Lantana camara was introduced as an ornamental on 
Floreana in 1832, and now covers 3,000 ha (7,413 ac) (Parque Nacional 
Galapagos n.d.(a)). A quickly spreading tropical shrub, that displaces 
native vegetation, it is now found on Floreana from the arid region up 
to the Scalesia forest (Hamann 1984, as cited in Schofield 1989, p. 
234). Citrus trees (Citrus spp.) have been reported as ``common'' 
(Eliasson 1982, p. 11) and have invaded the native vegetation at higher 
elevations on Floreana (Eliasson 1982, p. 11; Porter 1973, p. 276). 
Cattle and pigs aide in the further spread of citrus trees (Citrus 
spp.) by feeding on the fruits and dispersing seeds in new locations 
(Wittmer 1961, as cited in Schofield 1989, p. 234).
Summary of Factor A
    The medium tree-finch is found primarily in the moist highland 
forests (i.e., the Scalesia zone) on the island of Floreana. Since the 
island was first settled in 1832, the habitat of the medium tree-finch 
has been cleared for agriculture and ranching, and further degraded by 
introduced animals and plants. Herbivores, such as goats, donkeys, 
cattle, and pigs, destroy the species' habitat by trampling and grazing 
heavily on native vegetation, including Scalesia pedunculata, the tree 
primarily used by the medium tree-finch for nesting and foraging. In 
addition, cattle and pigs help to spread introduced plants, such as 
guava and citrus trees, by feeding on the fruits and depositing the 
seeds into native vegetation. Although an eradication program was 
started in December 2006 to eliminate goats and donkeys from Floreana, 
we are not aware of any current programs to remove cattle and pigs from 
the island. As a result, these species will continue to destroy and 
degrade the habitat of the species. Therefore, we find that the medium 
tree-finch is at significant risk by the habitat destruction of the 
moist highland forests of Floreana, as a result of agriculture and 
introduced species.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    We are not aware of any scientific or commercial information that 
indicates that overutilization of the medium tree-finch for commercial, 
recreational, scientific, or educational purposes poses a threat to 
this species. There is no known use by collectors or hunters of this 
species. A comment received on the proposed rule suggested that tourist 
visitation to the Scalesia highlands (the preferred habitat of the 
Medium Tree finch) increased more than tenfold since 2004. The 
commenter indicated that there has been an increase in the number of 
bus rides and highland tours. However, no corroborating data was 
provided with the comment. A UNESCO 2007 report on the Galapagos 
Islands did indicate that visitation has grown in Galapagos from 40,000 
in 1991 to over 120,000 in 2006 (pp. 9-10). This included all Galapagos 
islands, and the increase mentioned an increase in tourist boats. There 
was no specific mention of Floreana Island. According to this report, 
tourism is being monitored at many levels in Ecuador. The unintended 
negative effects are recognized and are being addressed (UNESCO 2007, 
Annex 3, pp. 1-3). Although tourism may be increasing on Floreana 
Island, a review of the best available information does not indicate 
that tourism is a threat to this species. As a result, we are not 
considering overutilization a contributing factor to the continued 
existence of the medium tree-finch.

C. Disease or Predation

Disease
    The discovery of an introduced parasitic fly (Philornis downsi) on 
Floreana Island has raised significant concerns about the impact this 
parasite is having on the medium tree-finch (Fessl et al. 2006b, p. 59; 
Wiedenfeld et al. 2007, p. 17; Dudaniec et al. 2008; O'Connor et al. 
2009, p. 853). This parasite was recently added to the IUCN's Global 
Invasive Species Database (O'Connor et al. pp 864-865). In March 1997, 
Fessl, Couri, and

[[Page 43859]]

Tebbich first observed the presence of P. downsi in the nests of 
Darwin's finches on the Galapagos Islands (Fessl and Tebbich 2002, p. 
445). Since then, researchers have found that P. downsi may cause up to 
100 percent mortality to exposed nestlings (Dudaniec and Kleindorfer 
2006, p. 17). This parasite is believed to be the most significant 
threat to the medium tree-finch (Causton et al., 2006; p. 125; O'Connor 
et al. 2009, p. 853).
    P. downsi was sampled by the entomologists S.B. and J. Peck and 
B.J. Sinclair in 1989, although the fly was not formally identified 
until the collections were examined in detail in 1998 (Fessl et al. 
2001, p. 318; Fessl and Tebbich 2002, p. 445). However, it now appears 
that P. downsi was present in the Galapagos Islands at least 40 years 
ago. It was recently identified from collections made on Santa Cruz 
Island in 1964 (Causton et al. 2006, pp. 134, 143). We are not aware of 
any information indicating when P. downsi may have been introduced to 
the island of Floreana.
    P. downsi is a fly (Muscidae) from a genus of obligate bird 
parasites (Couri 1985, as cited in Fessl and Tebbich 2002, p. 445; 
Fessl et al. 2001, p. 317), and depends on a host for its survival. The 
adult fly is free-living, non-parasitic, and feeds on fruits, flowers, 
and decaying material (Fessl et al. 2001, p. 317; Fessl et al. 2006b, 
p. 56). Larvae of P. downsi belong to the group of external blood 
feeders - first, second, and third instar (developmental stage) larvae 
are haematophages which suck blood from nestlings at night and then 
retreat to the bottom of the nest during the day (Dodge and Aitken 1968 
and Skidmore 1985, as cited in Fessl et al. 2006b, p. 56). Adult flies 
lay eggs inside the nasal cavities of newly hatched nestlings (usually 
one to three days old). These fly eggs then hatch into first instar 
larvae (Fessl et al. 2006a, p. 744; Muth 2007, as cited in Dudaniec at 
al. 2008). As the larvae reach their second instar stage, they exit the 
nasal cavities of nestlings and begin to live as nest-dwelling 
haematophagous larvae (Fessl et al. 2006a, p. 744). Second and third 
instar larvae of P. downsi seem to be exclusively external (Fessl et 
al. 2006b, p. 59), feeding on the blood and tissues of nestlings 
(Dudaniec and Kleindorfer 2006, pp. 15-16). The majority of larvae 
reach their third instar stage at the time of host fledging (Dudaniec 
at al. 2008, p. 5). At this stage, the larvae of P. downsi detach from 
the nestling and form their pupae at the bottom of the nesting 
material, remaining for approximately 2 weeks before emerging as adult 
flies (Dudaniec and Kleindorfer 2006, p. 16; Fessl et al. 2006b, p. 
56).
    P. downsi occurs in finch nests on Floreana (Wiedenfeld et al. 
2007, p. 17), and has been shown to significantly lower fledgling 
success of the finches (Fessl and Tebbich 2002, pp. 448-450). A number 
of studies have associated Philornis spp. parasitism with mortality 
(Fessl and Tebbich 2002, p. 448), and reductions in nestling growth and 
development (Fessl et al. 2006b, p. 58), and a reduction in hemoglobin 
levels (Dudaniec et al. 2006, p. 88). In Causton et al.'s proposed 
ranking system, P. downsi was given the highest invasiveness ranking 
affecting fauna endemic to the Galapagos Islands, because this insect 
seriously impacts species of high conservation value in the Galapagos 
(Causton et al. 2006, pp. 123, 134). The ranking system was based on 
species' trophic functional role, distribution in Galapagos, and 
history of invasiveness in areas other than the Galapagos Islands.
    In 2002, 97 percent of finch nests were infected with the P. downsi 
parasite on Santa Cruz Island, both in the lower arid zone and the 
higher Scalesia zone of the island (Fessl and Tebbich 2002, p. 449). 
Parasitism by P. downsi caused complete brood loss in approximately 19 
percent of the infected finch nests and partial brood loss (defined as 
the loss of one or two nestlings) in an additional 8 percent of the 
finch nests studied (Fessl and Tebbich 2002, p. 448). They also found 
that in parasitized nests, the percentage of successful fledglings 
differed significantly depending upon brood size: Nests with only one 
nestling always failed, nests with two nestlings successfully fledged 
nestlings 50 percent of the time, and nests with three or four 
nestlings successfully fledged nestlings 75-85 percent of the time 
(Fessl and Tebbich 2002, p. 448).
    In 2006, nesting success in the medium tree-finch was examined for 
the first time (Fessl et al. 2006a, p. 746). In an experimental study 
conducted on Santa Cruz Island, researchers found that high mortality 
of nestlings was directly attributable to parasitism by P. downsi, as 
evidenced by a near threefold increase in fledgling success in a 
parasite-reduced group (87 percent) versus a parasite-infested control 
group (34 percent) (pp. 58-59). They also found that within four days, 
mass gain was significantly higher (an almost twofold positive 
difference) in the parasite-reduced group than in the parasite-infested 
control group (Fessl et al. 2006b, p. 58). In studies of other avian 
species, fledgling body mass has been found to be a key factor for 
juvenile survival (Magrath 1991, pp. 343-344; Tinbergen and Boerlijist 
1990, pp. 1123-1124). As a result, Fessl et al. (2006b, p. 59) 
concluded that the results of their study showed that given the 
significant difference in body mass between the two groups, parasitized 
nests will likely provide less recruitment into the breeding 
population. Further, because species with small broods have been found 
to suffer higher parasite loads and higher nestling mortality (Fessl 
and Tebbich 2002, pp. 445, 449-450), infestation of P. downsi on 
species with naturally low clutch sizes, such as the medium tree-finch, 
is of particular concern (Fessl et al. 2006b, p. 59).
    Dudaniec et al. found a significant negative correlation between P. 
downsi parasite intensity and hemoglobin concentrations (2006, pp. 88, 
90, 92). She also found a positive correlation between parasite 
intensity and immature red blood cell counts in small ground finches 
studied on Santa Cruz and Floreana Islands. Small ground finch 
nestlings with higher P. downsi densities suffered from lower 
hemoglobin concentrations and reduced fledging success (Dudaniec et al. 
2006, p. 92). Furthermore, nestlings with lower parasite intensity had 
higher hemoglobin levels and increased fledging success (Dudaniec et 
al. 2006, p. 93). The same researchers also found a negative 
correlation between the number of immature red blood cells and 
hemoglobin levels in nestlings (2006, p. 92). The fitness impacts to 
nestlings of lower hemoglobin levels are significant (Dudaniec et al. 
2006, p. 93). Other researchers found that 6 of 63 monitored nests 
produced fledglings (O'Connor et al. 2008, p. 1). The results of 
another study showed that low hemoglobin levels in nestlings reduce the 
transport of oxygen to tissues (O'Brien et al. 2001, p. 75).
    Thus, fledglings that are anemic (hemoglobin deficient) from 
parasite feeding may have a reduced ability to sustain flight and 
consequently a reduced ability to escape predators and find food 
(O'Brien et al. 2001, p. 75). The high hemoglobin levels found by 
Dudaniec et al. in mature birds, combined with their observation that 
adult finches were never found to be actively parasitized, suggests 
that adult birds are not physiologically affected by P. downsi (2006, 
p. 92). Fessl et al. reported extremely high levels of blood loss in 
nestlings (18 to 55 percent) caused by P. downsi larvae ((2006a, p. 
745). Daily blood loss over 10 percent is likely to have negative 
impacts on nestlings, including health problems and developmental 
deficiencies, while

[[Page 43860]]

blood loss over 25 percent would become lethal (Kaneko, pers. comm., as 
cited in Gold and Dahlsten 1983, p. 569).
    Another study of tree-finches in the highlands of Floreana showed 
that the medium tree-finch had the highest P. downsi parasite intensity 
(an average of 52 parasites per nest), compared to the small and large 
tree-finches (O'Connor et al. 2009, pp. 853-866). Of 63 active medium 
tree-finch nests, only 16 nests had nestlings that survived to six days 
post-hatching, and only 4 nests produced fledglings (O'Connor et al. 
2009, pp. 853-866). Most nests failed to produce fledglings: 
Approximately 68.8 percent (11 of 16) of medium tree-finch nests 
suffered total brood loss, while 18.8 percent (3 of 16) of nests had 
partial brood loss (O'Connor et al. 2009, pp. 853-866). P. downsi 
larvae or pupae were found in 100 percent (16 of 16) of medium tree-
finch nests, and all nestlings had P. downsi parasites (O'Connor et al. 
2009, pp. 853-866). The majority (54 percent) of nestling mortality in 
medium tree-finches was due to parasitism by P. downsi (O'Connor et al. 
2009, pp. 853-866). All nestlings found dead in nests had large open 
wounds on their bodies and significant loss of blood or body fluids, 
all of which are signs of P. downsi parasitism (O'Connor et al. 2009, 
pp. 853-866). O'Connor et al. discuss the reasons why the P. downsi 
parasite intensity is high in the medium tree-finch (2009, pp. 853-
866). One possible explanation is that the medium tree-finch's 
preferred breeding habitat is next to an agricultural area, where the 
close proximity of the agriculture fields (with citrus trees and other 
fruits) act as a feeding location for the adult flies (O'Connor et al. 
2009, pp. 853-866). In addition, moist highlands favor consistent 
breeding of medium tree-finches, thus providing flies with a dependable 
supply of nestlings for P. downsi larvae to feed upon (O'Connor et al. 
2009, pp. 853-866). Currently, the medium tree-finch has the highest P. 
downsi parasite intensity of any finch species on Floreana, and the 
second highest of any finch species studied on the Galapagos Islands 
(O'Connor et al. 2009, pp. 853-866).
    A study by Wiedenfeld et al. (2007) found that there was a 
significant increase in the number of P. downsi parasites (larvae, 
pupae, or puparia) per nest at higher altitudes (i.e., in the humid 
highlands) (pp. 17-18). According to their study, the distribution of 
P. downsi seems to be related to the amount of humidity and moisture 
available on the islands (Wiedenfeld et al. 2007, p. 18). Although it 
appears that the fly does more poorly in dry conditions (either in the 
lowland, arid zone of islands, or during drought), birds similarly do 
more poorly in these situations (Wiedenfeld et al. 2007, p. 18). In 
addition, during years of abundant rainfall when birds breed more 
successfully, the flies are also likely to be more plentiful and 
therefore, can cause higher mortality (Wiedenfeld et al. 2007, p. 18).
    Researchers believe that finches do not suffer from any type of 
endemic haematophagous ectoparasite (Fessl et al. 2006b, p. 56). 
Therefore, medium tree-finches have not developed an adaptive response 
to this kind of introduced pathogen (Altizer et al. 2003, pp. 593, 
594). Because the medium tree-finch is newly parasitized by P. downsi, 
it may experience significant initial mortality since the host has not 
yet developed a strong behavioral or immunological defense mechanism 
against the parasite (Dudaniec and Kleindorfer 2006, pp. 18-19).
    As many of the above studies show, finches have a slim chance of 
reproducing without avoiding effects of P. downsi mortality (Dudaniec 
and Kleindorfer 2006, p. 18; Wiedenfeld et al. 2007, p. 18). 
Researchers suggest that the decline and possible local extinction of 
one of Darwin's finches, the warbler finch (Certhidea fusca), on 
Floreana by 2004 may have been partially caused by P. downsi although 
there is no conclusive evidence (Grant et al. 2005 p. 502; Fessl et al. 
2006b, p. 59; Dudaniec and Kleindorfer 2006, p. 13).
    Although it is better to eliminate invasive species before they are 
able to genetically adapt to the local environment in which they have 
colonized (Frankham 2005, p. 385), early eradication often does not 
occur. A long-term eradication program in conjunction with continuous 
quarantine and monitoring practices is needed to eradicate P. downsi 
(Dudaniec et al. 2008).
    Programs to eradicate P. downsi from the Galapagos Islands are 
difficult and costly (Fessl et al. 2006b, p. 59). Fessl et al. (2006b, 
pp. 57-59) found that a single insecticide treatment of 1 percent 
pyrethrin solution (done at a nestling age of 4 days) was sufficient to 
reduce the number of parasites per nest to almost zero. This treatment 
offers one short-term solution to locally protect single nests of 
species of high conservation concern (Fessl et al. 2006b, p. 59). 
However, this treatment is not feasible as a long-term solution for 
controlling the fly on the Galapagos Islands.
    The Charles Darwin Foundation (CDF) has begun an effort to develop 
biological control approaches for P. downsi (Charles Darwin Foundation 
n.d.(c)). In 2008, CDF received $58,000 for Phase I of the CDF Priority 
Project ``Control of the parasitic fly P. downsi'' (Charles Darwin 
Foundation 2008b, 2008c). This project studies the biology and life 
history of P. downsi, aiding in the development of effective, long-term 
control methods that will not harm other species (Charles Darwin 
Foundation 2008b). CDF reports that control methods are urgently needed 
to eliminate the threat of extinction among bird species, such as the 
medium tree-finch, affected by this parasite (Charles Darwin Foundation 
2008b). A recent study reported that sterile insect technique (SIT) may 
be effective in controlling this parasite (Dudaniec et al., 2010, p. 
582); however, it has not been fully tested.
Predation
    Floreana has a suite of introduced predators including black rats 
(Rattus rattus) and cats (Felis catus) (O'Connor et al. 2009, pp. 864). 
These predators feed on eggs, nestlings, and even adult birds (Castro 
and Phillips 1996, p. 22), and have seriously depleted native 
populations (Grant et al. 2005, p. 501; Jackson 1985, p. 232).
    Rats: Second only to the parasitic fly (Philornis downsi), black 
rats are one of the worst introduced species to the Galapagos Islands. 
They destroy bird nests and eggs and consume hatchlings (Charles Darwin 
Foundation 2008d; Charles Darwin Research Station 2008b). Rats arrived 
in the Galapagos Islands on ships beginning in the late 1600s, and 
currently are found on all inhabited islands, including Floreana 
(Charles Darwin Research Station 2008b). Because rats can easily climb, 
they have been implicated in the population declines of tree nesting 
birds such as the mangrove finch (Camarhynchus heliobates) (Charles 
Darwin Research Station 2008b). The CDF's long term plan is to 
successfully eradicate introduced rats on all islands, a necessary 
measure in order to restore the Galapagos Islands and its endemic 
species (Charles Darwin Research Station 2008b). One of the next steps 
in accomplishing this goal is to develop the capacity to attempt a rat 
eradication program on large islands such as Floreana (Charles Darwin 
Research Station 2008b).
    Cats: Cats are highly predatory animals, targeting birds and other 
native species (Charles Darwin Foundation 2008b; Charles Darwin 
Research Station 2008c; Smith 2005, p. 304). Cats were introduced to 
the Galapagos Islands by ships and as domestic pets of settlers

[[Page 43861]]

(Charles Darwin Research Station 2008c). Both feral and domestic cats 
prey upon and impact the survival of Darwin's finches, and are a threat 
to endemic species on Floreana (Charles Darwin Research Station 2008c). 
In the 19\th\ century, cats may have caused significant declines in the 
populations of large ground finches, sharp-beaked ground finches, and 
mockingbirds, pushing them toward extinction on Floreana (Grant et al. 
2005, p. 501). All three species mostly forage on the ground and are 
approachable (Grant et al. 2005, p. 501). However, the more arboreal 
finches, such as the medium tree-finch, may be less vulnerable to 
predation by cats, unless their nests are constructed unusually low in 
the vegetation (Grant et al. 2005, p. 501). The Galapagos National Park 
Service and the CDF are working to control and eradicate domestic and 
feral cats on all of the islands (Charles Darwin Research Station 
2008c). This plan includes working with communities to gain acceptance 
and compliance with the sterilization or removal of domestic cats, and 
the development of an eradication program to eliminate feral cats from 
natural areas on all populated islands, such as Floreana (Charles 
Darwin Research Station 2008c).
    A study of tree-finches in the highlands of Floreana found that one 
third of medium tree-finch nests experienced nestling predation in both 
2006 and 2008. Egg depredation was observed in 22 percent of the nests 
(but only in 2008) (O'Connor et al. 2009, pp. 853-866). Predators such 
as rats feed on agricultural products being grown in the agricultural 
areas. Because agricultural areas are close to the breeding sites of 
the medium tree-finch, these areas provide a base for the continued 
persistence and movement of introduced predators, mainly rodents, into 
medium tree finch habitat (O'Connor et al. 2009, pp. 853-866).
Summary of Factor C
    As stated above, we believe, based on an abundance of research, 
that Philornis downsi, the introduced parasitic fly, is the most 
significant threat to the survival of the medium tree-finch (Causton et 
al., 2006 as cited in O'Connor et al. 2009, p. 854). The larvae feed on 
finch nestlings, causing mortality, reduced nestling growth, lower 
fledgling success, and a reduction in hemoglobin levels, which all 
combine to severely affect the reproductive success of the species. The 
medium tree-finch has the highest P. downsi parasite intensity of all 
the finch species found on Floreana, and the second highest rate of 
parasitism by P. downsi of any finch species studied in the Galapagos 
Islands. Although a study examining the biology of P. downsi and how to 
control it began in 2008, a long-term (and wide-spread) control method 
for the parasitic fly has not yet been developed. As a result, the 
medium tree-finch and its reproductive success will continue to be 
negatively impacted by P. downsi. Therefore, we find that parasitism by 
P. downsi is a significant threat to the continued existence of the 
medium tree-finch.
    Introduced predators on Floreana, such as black rats and cats, feed 
on eggs and nestlings, causing dramatic reductions in native 
populations. One study found that 33 percent of medium tree-finch nests 
experienced nestling predation; and egg depredation was observed in 22 
percent of the nests. In an effort to help restore endemic species in 
the Galapagos Islands, one goal of CDF is to develop programs to 
eradicate introduced rats and cats on all islands. However, we do not 
have information to indicate that the eradication program has been 
completed on Floreana island. Therefore, we find that predation is a 
threat to the continued existence of the medium tree-finch.

D. Inadequacy of Existing Regulatory Mechanisms

    The medium tree-finch is identified as a critically endangered 
species under Ecuadorian law and Decree No. 3,516-Unified Text of the 
Secondary Legislation of the Ministry of Environment of 2002 (ECOLEX 
2003b). Decree No. 3,516 of 2002 summarizes the legislation governing 
environmental policy in Ecuador and provides that the country's 
biodiversity be protected and used primarily in a sustainable manner 
(ECOLEX 2003b). Appendix 1 of Decree No. 3,516 lists the Ecuadorian 
fauna and flora that are considered threatened or in danger of 
extinction. Species are categorized as critically endangered (En 
peligro critico), endangered (En peligro), or vulnerable. Resolution 
No. 105-Regulatory control of hunting seasons and wildlife species in 
the country, and Agreement No. 143-Standards for the control of hunting 
seasons and licenses for hunting of wildlife, regulate and prohibit 
commercial and sport hunting of all wild bird species except those 
specifically identified by the Ministry of the Environment or otherwise 
permitted (ECOLEX 2000; ECOLEX 2003a). The Ministry of the Environment 
does not permit commercial or sport hunting of the medium tree-finch 
because of its status as a critically endangered species (ECOLEX 
2003b). However, we do not consider hunting (Factor B) to be a risk to 
the medium tree-finch since it is not known to have ever been hunted. 
Although this law does not reduce any threats to the species, hunting 
is not a threat to the species, so it is not applicable.
    The first legislation to specifically protect the Galapagos Islands 
and its wildlife and plants was enacted in 1934 and further 
supplemented in 1936, but effective legislation was not passed until 
1959, when the Ecuadorian government passed new legislation declaring 
the islands a National Park (Fitter et al. 2000, p. 216; Jackson 1985, 
pp. 7, 230; Stewart 2006, p. 164). Ecuador designated 97 percent of the 
Galapagos land area as the National Park, leaving the remaining 3 
percent distributed between the inhabited areas on Santa Cruz, San 
Cristobal, Isabela, and Floreana Islands (Jackson 1985, p. 230; 
Schofield 1989, p. 236). National park protection, however, does not 
mean the area is maintained in a pristine condition. The park land area 
is divided into various zones signifying the level of human use (Parque 
Nacional Galapagos n.d(b)). Although Floreana Island includes a large 
``conservation and restoration'' zone, it also includes a significantly 
sized ``farming'' zone (Parque Nacional Galapagos n.d.(b)), where 
agricultural and grazing activities continue to impact the habitat.
    In March 1998, the National Congress and the Ecuadorian President 
enacted the Law of the Special Regimen for the Conservation and 
Sustainable Development of the Province of the Galapagos, which has 
given the islands some legislative support to establish regulations 
related to the transport of introduced species and implement a 
quarantine and inspection system (Causton et al. 2000, p. 10; Instituto 
Nacional Galapagos n.d.; Smith 2005, p. 304). As a result, in 1999, the 
Inspection and Quarantine System for Galapagos (SICGAL) was implemented 
(Causton et al. 2006, p. 121), with the aim of preventing introduced 
species from reaching the islands (Causton et al. 2000, p. 10; Charles 
Darwin Foundation n.d.(d)). Inspectors are stationed at points of entry 
and exit in the Galapagos Islands and Continental Ecuador, where they 
check freight and luggage for permitted and prohibited items (Charles 
Darwin Foundation n.d.(d)). The goal is to rapidly contain and 
eliminate newly arrived species (detected by SICGAL and early warning 
monitoring programs) that are considered threats for the Galapagos 
Islands (Causton et al. 2006, p. 121). However, a scarcity of 
information on alien insect species currently in the Galapagos Islands 
prevents officials from knowing whether or not a newly detected insect 
is in fact

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a recent introduction (Causton et al. 2006, p. 121). Without the 
necessary information to make this determination, they cannot afford to 
spend the time and resources on a rapid response when the ``new 
introduction'' is actually a species that already occurs elsewhere in 
the Galapagos Islands (Causton et al. 2006, p. 121).
    The April 2007 World Heritage Centre-IUCN monitoring mission report 
assessed the state of conservation in the Galapagos Islands. Based on 
information gathered dur