[PCA] 12-Month Finding on Petition To List the Gentry Indigo Bush as Endangered: Not warranted

[Patricia_DeAngelis at fws.gov]

----- Forwarded by Patricia De Angelis/ARL/R9/FWS/DOI on 09/27/2005 02:15
PM -----

From: http://epa.gov/EPA-SPECIES/2005/September/Day-27/

ly to increase in the future
and cause detrimental effects to Gentry indigo bush and its habitat.
Undocumented immigrants may also set fires. Although these fires are
usually accidental (e.g., an escaped campfire), they may be the
ignition source for a future grassland fire in the watershed.
    The border fence in Sycamore Canyon has remained intact since 1998.
Border activity ebbs and flows, and it is difficult to predict where
increased activity will take place. Currently, the level of border
activity is not threatening the continued existence of the plant in
Sycamore Canyon.
Invasive Plants
    The invasive buffelgrass (Pennisetum ciliare) is used throughout
Sonora, Mexico, as a pasture grass, and large natural grassland areas
have been converted to buffelgrass. Buffelgrass lines the major highway
in Sonora to the U.S. border. Noxious weed seeds can be spread by the
wind, on the soles of shoes, and in the tire treads of vehicles.
Riparian areas can also function as dispersal corridors for the
movement of invasive plant species (Stohlgren et al. 1998; Parendes and
Jones 2000). With the increase in border activity, it is probably only
a matter of time before this highly invasive grass species is found in
Sycamore Canyon. The U.S. Department of Agriculture's Agricultural
Research Service has developed and released a cold-tolerant variety of
buffelgrass, ``Frio'', which is intended to be used at higher
elevations and in regions where current buffelgrass cultivars
experience winter damage (Hussey et al. 2005). These cultivars will
increase the potential area of invasion.
    Buffelgrass grows very quickly and out-competes native grass for
water and nutrients. Once stabilized, it rapidly becomes the dominant
plant cover. Should it become the dominant plant species on floodplain
terraces, it could replace Gentry indigo bush along with other native
riparian species in Sycamore Canyon, but it is not known to occur there
at this time. We do not know if buffelgrass is found near the
populations of Gentry indigo bush in Mexico, but it may be a potential
threat to these populations in the future since so much planting of the
grass has taken place in Sonora, Mexico. As of 1997, over one million
ha (2,471,000 ac) of desert and thorn scrub in central Sonora had been
cleared to plant bufflegrass (Van Devender and Felger 1997), but we do
not know how close it is to invading canyons occupied by Gentry indigo
bush.
    Baker (2005) found at least one, and possibly two, species of
Pyracantha in Atascosa and Sycamore canyons. This nonnative, aggressive
species, should it become established and spread in Sycamore Canyon,
could potentially reduce suitable habitat for Gentry indigo bush.
    Many areas of Sonoran desert grasslands in southeast Arizona have
been colonized by Lehman lovegrass (Eragrostis lehmanniana), an
invasive species from South Africa. This grass has become so firmly
established in southern Arizona that there may be no feasible control
for it. Lehman lovegrass produces more fine fuel than native grass
species (Cable 1971; Cox et al. 1984), leading to increased fire
spread. Lehman lovegrass also increases after fire (Ruyle et al. 1988;
Sumrall et al. 1991). Currently, the Bear Valley allotment does not
seem to have continuous patches of Lehman lovegrass, so the effects
from an altered fire regime due to its presence may not pose a threat
to Gentry indigo bush. If the density and distribution of Lehman
lovegrass were to increase on the allotment, then more frequent and
higher intensity fires would be expected. This could potentially result
in increased erosion and precipitation run-off, possibly leading to
more frequent flood events in Sycamore Canyon. More frequent and
greater intensity flooding may not allow for the recolonization of
habitat and reestablishment of sub-populations in Sycamore Canyon
during flood-free intervals, resulting in overall habitat and
population reduction.
    Establishment of these nonnative grasses in Sycamore Canyon or other

[[Page 56431]]

occupied habitat could compromise habitat quality and possibly endanger
the long-term survival of metapopulations because the change in fire
frequency and intensity could increase the frequency and intensity of
flood events, placing sub-populations at increased risk. However, the
threats from invasive species are considered to be only potential at

this time, as there are no populations of the grass species present in
Sycamore Canyon. We do not know if the populations in Mexico or on the
Tohono O'odham Nation are threatened by invasive species.
    In summary, there are ongoing and potential threats to the habitat
of Gentry indigo bush in Sycamore Canyon. Many of the threats
identified have been minimized (e.g., protection from livestock
grazing, reduction in livestock numbers, overall improvement in
watershed health) and while other threats are possible in the future,
there is no evidence that they are currently affecting the population,
and certainly not at a level that threatens the species (e.g., invasive
species, recreation impacts, undocumented immigrant traffic, U.S.
Border Patrol activities, and wildfire). Because they occupy similar
habitat (i.e., canyon bottom), the populations in Mexico may be
affected by the threats discussed in this section; however, due to a
lack of detailed information regarding these sites, there is no direct
evidence of threats to Mexican populations. The status of the
populations in Mexico and on the Tohono O'odham Nation are not known,
but some of the populations have persisted over time.

Factor B: Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes

    There are no known threats to Gentry indigo bush from over-utilization
for commercial, recreational, scientific, or educational purposes.

Factor C: Disease or Predation

Grazing Effects on Plants
    This section discusses the threat from cows directly eating the
plant. Gentry indigo bush plants are palatable, as are most Dalea
species. Gori et al. (1992) concluded, ``Our surveys of Sycamore and
Mendoza Canyons lead us to believe that grazing constitutes a threat to
D. tentaculoides. We observed direct evidence of livestock browsing on,
and even uprooting, the species in lower Sycamore Canyon where trespass
cows from Mexico enter the canyon up to an impassable narrows.''
    As discussed above, Sycamore Canyon is found within the Goodding
RNA and the Pajarita Wilderness within the boundaries of the Coronodo
National Forest, Nogales Ranger District. Livestock grazing is not
permitted within the boundaries of the RNA, but trespass cattle use has
been a sporadic problem (U.S. Department of Agriculture 1998). Trespass
cattle can enter the canyon from the mouth of the canyon at the
northern end, and also from the southern end on U.S.-Mexico border. The
sides of the canyon are generally too steep for livestock. Cattle have
been observed in the northern reaches of the canyon (Brooks 1999), and
Brooks noted heavy cattle use in the southern end of the canyon (i.e.,
below ``the narrows'') most likely attributable to trespass livestock
from Mexico. In 1997, the U.S. Forest Service proposed a set of actions
in Sycamore Canyon to protect the federally threatened Sonora chub
(Gila ditaenia). One of those actions included building a fence at the
northern portion of the canyon to restrict livestock access to the
riparian areas. As long as this fence is maintained and remains
effective, no direct threat of cattle in the upper reaches of Sycamore
Canyon exists.
    In the lower reaches of Sycamore Canyon, trespass cattle from
Mexico may present another problem. Although the U.S.-Mexican border
fence had been in a state of disrepair,in the fall of 1998, 2.4 km (1.5
mi) of fence was repaired and information provided to us during our
status review of the species indicates that the fence is currently
functional in preventing livestock trespass and has not been recently
cut (Parker 2005). Thus, while sporadic grazing was historically
considered a potential threat to Gentry indigo bush, we do not believe
that trespass cattle from Mexico pose a threat at this time in Sycamore
Canyon. This determination is based on the protective status of the
area as an RNA and the measures taken by the U.S. Forest Service to
construct and maintain a fence preventing cattle from entering the
canyon from Mexico.
    We know that livestock grazing occurs on Tohono O'odham Nation in
the general area where the plants were known to be in the southern
Baboquivari Mountains, but have no recent information on plant numbers.
We are currently working with the Nation to gather information on this
population. We anticipate that, if livestock grazing is determined to
be a concern, we can work cooperatively with the Nation to resolve
those issues.
    We do not know if the populations in Mexico are affected by
livestock grazing; nothing was reported on the grazing regime in the
areas surveyed. Van Devender (2005) noted that the populations he found
were in areas not accessible to livestock.
    Gentry indigo bush is palatable to other species beside livestock.
Brooks (1999) provided one observation of a plant being almost totally
eaten by a rabbit. Schmalzel (2005) also noted one Gentry indigo bush
that had evidently been clipped at the base by a valley pocket gopher
(Thomomys bottae), but we do not consider this to be a major threat. We
acknowledge that rabbits, gophers, and other herbivores may eat plants,
but we do not think this constitutes a major threat to the species
because of the size of mature plants and the abundance of other
herbaceous plants in the canyon available for food.
    We know of no diseases threatening this species.

Factor D: The Inadequacy of Existing Regulatory Mechanisms

    The population in Sycamore Canyon is on the Coronado National
Forest and subject to the general Federal regulations of the National
Forest System. Gentry indigo bush is on the Coronado National Forest's
Sensitive Species List. Populations that may be present on the Tohono
O'odham Nation are not protected by any regulation of which we are
aware. Mexican populations have no protection because they are on
private land and are afforded no protection under Mexican laws. The
Arizona Native Plant Law (State of Arizona) does consider this species
as highly safeguarded, and thus a permit is required from the Arizona
Department of Agriculture to salvage the plant; however, no other
protection is afforded to the species or its habitat.
U.S. Forest Service (Sycamore Canyon, AZ)
    The metapopulation of Gentry indigo bush in Sycamore Canyon is
within the Goodding RNA and the Pajarita Wilderness. There are no other
locations on U.S. Forest Service land. The U.S. Forest Service has
stated that Gentry indigo bush is afforded a high level of protection
because it shares its habitat with critical habitat of the federally
listed Sonora chub. The U.S. Forest Service has done much work to
improve the habitat of Sonora chub, including removal of a road at the
mouth of Sycamore Canyon, protection of riparian areas at the northern
end of Sycamore Canyon, and the expansion of the Goodding RNA. These
actions have contributed to improvement of Sonora chub habitat and are
likely to improve Gentry indigo bush habitat, as discussed above. Many
activities are prohibited within the RNA; livestock grazing,

[[Page 56432]]

timber harvest, and overnight camping are examples. A mining withdrawal
has also been completed for lands within the RNA, for a period of 25
years. In addition to the Sonora chub, the canyon also supports
populations of the federally listed Chiricahua leopard frog (Rana
chiricahuensis) and Mexican spotted owl (Strix occidentalis lucida).
    The surrounding watersheds are also under U.S. Forest Service
management. A multiple-use policy allows for grazing, recreation, and
other activities that may be affecting the habitat of Gentry indigo
bush. These issues were discussed under Factors A and C above.
    In summary, the U.S. Forest Service has completed a number of
conservation actions in Sycamore Canyon that have improved habitat for
Gentry indigo bush. Road closures and the protection of riparian areas
at the canyon mouth have undoubtedly increased the overall health of
the riparian ecosystem in the canyon. We believe that U.S. Forest
Service actions and the amount of protection the canyon receives by
virtue of its wilderness and RNA designation will promote the long-term
conservation of Gentry indigo bush in Sycamore Canyon.
The Tohono O'odham Nation
    The Tohono O'odham Nation has not drafted specific regulations to
address sensitive species on their sovereign lands. We have a Statement
of Relationship with the Nation, and provide technical assistance with
wildlife and plant issues at their request. The Nation is currently
working with us on allowing us access to the Baboquivari Mountains so
that we may assist them in survey and assessment of their Gentry indigo
bush populations.
Mexico
    Three locations of Gentry indigo bush have been documented in
Mexico. We have basic information (e.g., plant community, associated
plant species, elevation, and substrate) and population estimates for
these sites. We are not aware of any protection for these areas, but
Van Devender observed during his 2005 survey work that the sites do not
have obvious direct threats. Furthermore, all of the sites are in remote
locations and in canyons with no livestock access (Van Devender 2005).

Factor E: Other Natural or Manmade Factors Affecting the Continued
Existence of the Species

    The known extant Gentry indigo bush populations are small,
isolated, and threatened by unpredictable variation in demographic and
environmental characters (i.e. flooding). Genetic factors, such as
reduced genetic variation due to small population size, may also
contribute to this species' overall status. Inbreeding depression and
loss of genetic diversity may occur in small populations of less than a
few hundred individuals; such loss may reduce the fitness of
individuals and the ability of the population to adapt to change
(Frankel and Soule 1981). Both of these genetic considerations result
in an increased likelihood of extirpation (Lande and Barrowclough
1987). Climate change may influence precipitation patterns in ways that
could affect the long-term persistence of the metapopulations.
Flooding
    The past movement of water and sediment in Sycamore Canyon has
affected the plants and their habitat. After the 1993 El Ni[ntilde]o
winter rains, most of the monitoring plot was washed away, and the
then-known overall plant population declined dramatically, with more
than 90 percent of the known individuals washed away or covered with
sediment. Recolonization has slowly occurred; at last count there were
450 to 922 plants recorded in Sycamore Canyon (Darling 2005), fewer
than the estimated 1,400 that were documented in 1992.
    Lefevre, a U.S. Forest Service hydrologist (1999), notes that the
changes observed in Sycamore Canyon after the 1993 flood were, in his
professional opinion, geologic in nature. Large flood events (e.g.,
greater than the 25-year event) and their effects on channel morphology
will likely overshadow any management activity of the U.S. Forest Service.
    In summary, above-average flood events (greater than the 25-year
event) will likely affect the dynamics of the metapopulation in
Sycamore Canyon, but U.S. Forest Service actions are not likely to
influence or minimize the effects from such events. The species does
have the ability to recolonize after flood events, and plants located
out of the floodplain and on associated talus slopes (i.e., the sides
of the canyon) may provide the source for the recolonization of the
plants in stream habitat.
Population Size and Stochastic Events
    Estimated numbers of the metapopulation in Sycamore Canyon have
fluctuated dramatically since the early 1990s. The sub-populations had
seemingly been reduced to very low numbers in 1993, after the canyon
was subjected to a large flood event. Since that time, overall numbers
and patches have been increasing. In 2005, we observed many seedlings
and resprouts, alleviating some of our concern regarding the plant's
seemingly low reproductive output. We still do not know the
environmental factors that allow for successful seed germination, and
do not know how many seedlings will survive. We observed no seedlings
away from patches, although some patches contained only a few larger
plants and were dominated by seedlings.
    This species could potentially be negatively affected by
environmental stochasticity (variations over time in the population's
operational environment) and natural catastrophes (Menges 1991). The
minimum viable metapopulation (MVM) size is an important estimate of
the minimum number of interacting local sub-populations necessary for
the long-term persistence of a metapopulation (Hanski 1999). In
general, 15 `` 20 well-connected patches are required for MVM
(Maschinski, in press). Baker (2005) found 12 patches in Sycamore
Canyon, but that is only an estimate from one of the five known
populations. There were likely more patches than he detected. More
consistent monitoring could help us determine the patch dynamics of
Gentry indigo bush more accurately. A decrease in the overall number
and size of patches, and a lack of recolonization of extirpated
patches, could indicate that the metapopulation is not at equilibrium.
    The most likely adverse scenario in Sycamore Canyon is that of
catastrophic flooding. Increased rainfall combined with an altered
hydrograph in Sycamore Canyon may result in many patches being washed
out. Long-term drought, such as the one the region is experiencing
currently, may affect the species' ability to recolonize vacant
patches. In Sycamore Canyon, the combination of small patch size,
uncertain persistence of the patches, highly variable overall number of
patches, and a highly dynamic and uncertain environment due to flooding
and drought could make this population vulnerable to extirpation,
although it has continued to persist despite such climatic events.
    The species is located in at least five locations, reducing the
risk of stochastic events affecting all of the known populations
simultaneously. The population in Sycamore Canyon, despite a severe
reduction in overall numbers, still persists and is recolonizing the
canyon. Recent observations of seedling recruitment and resprouting
indicate that the metapopulation can recover from

[[Page 56433]]

environmental stochastic events. Given the population's persistence in
Sycamore Canyon, we do not believe that its continued existence is
threatened now or in the foreseeable future.
Genetic Factors
    Harmful genetic effects, such as genetic bottlenecks and founder
effects, are often associated with small plant populations (Hedrick and
Miller 1992). A genetic bottleneck is a significant reduction in the
genetic diversity of a population resulting from a significant
reduction of the number of individuals of a species in a specific place
or time. It is often associated with a stochastic event and can result
in a loss of genetic diversity. The founder effect (Mayr 1963) refers
to the establishment of a new population from only a few colonizing
individuals, which may represent only a small portion of the overall
genetic variation of the original population. Reductions in genetic
diversity from these and other causes can have profound effects on both
short- and long-term population survival, as genetic variation is
related to a population's ability to survive stochastic events
(Huenneke 1991; Rogers and Montalvo 2004; Falk et al. in press). In
Sycamore Canyon, the small number of individuals, small size of the
metapopulation, and the type and severity of environmental factors to
which the metapopulation is exposed could influence the genetic
diversity of the metapopulation.
    The ability of a species to persist over time is related, in part,
to genetic variation in a population, which provides the basis of
adaptation to changing environments. The greater the heterozygosity
(number of different types of alleles) present, the higher the
probability that at least some plants in a population will be able to
adapt to changing circumstances (Huenneke 1991; Reed and Frankham
2003). As populations become depauperate (less variation) in their
genetic make-up, the ability of the populations to adapt to changing
environmental factors, like climate change or changes in the local
environment, may decrease.
    The long-term persistence of a population is also related to the
fitness of the individuals within the population, where fitness is
typically measured in terms of survival and reproduction. Inbreeding
depression is a relative decrease in fitness of offspring resulting
from either selfing (pollination within the same plant as opposed to
between two different plants) or mating between closely-related
individuals compared with outcrossed individuals (Barrett and Kohn
1991). The reduction in fitness is associated with a higher rate of
expression of recessive and often lethal alleles (parts of genes that
control certain characters, i.e., flower color) in a population. This
condition leads to an overall reduction of fitness in a population
until the population cannot produce viable offspring. We do not know if
this is a factor for Gentry indigo bush because we have not identified
the type of breeding system (e.g., obligate outcrosser, selfing, or
combination). Thus, we have no information to indicate that genetic
factors and small population size are a threat to Gentry indigo bush
now or in the foreseeable future. Further, we have no documentation
that this species historically persisted in significantly higher
numbers than it does today, so its rarity is not necessarily an
indication of excessive vulnerability to extinction.
Climate Change
    Mean annual temperatures rose 1.1-1.7 degrees Celsius (C) (2.0-3.1
degrees Fahrenheit (F)) in the American Southwest in the 20th century,
and are predicted to rise 4.5-6.1 degrees C (8.1-11.0 degrees F) in the
21st century. Predictions of changes in precipitation are less certain;
however, some models predict as much as a doubling of annual
precipitation, with the largest increases in winter precipitation
(Southwest Regional Assessment Group 2000). But these predictions
contrast with current trends of a warming North Atlantic and cooling
tropical Pacific, with associated changes from a relatively wet period
to drought, insect outbreaks in Southwestern forests, and increasing
wildfires (Patterson 1997; Betancourt 2004). Some models predict
dramatic changes in Southwestern vegetation communities as a result of
climate change (Thompson et al. 1997). Climate change can occur
abruptly, with associated major changes in the environment (National
Academy of Sciences, Committee on Abrupt Climate Change 2002). Climate
change could affect metapopulations of Gentry indigo bush in
unpredictable ways. For example, changes in precipitation may increase
the frequency and magnitude of flood events, possibly affecting the
distribution and persistence of patches in occupied habitat. Rainfall
patterns may shift towards more summer precipitation and less winter
precipitation. The germination of seeds may be linked to seasonal
rainfall events, and changes in rainfall patterns may affect the
population dynamics of this species. We have no information to indicate
that climate change constitutes a threat to Gentry indigo bush now or
in the foreseeable future.
    In summary, Gentry indigo bush remains a rare, narrowly distributed
endemic plant species throughout its range in southern Arizona and in
Mexico. Extensive survey work in the United States and Mexico has
increased the documentation of populations by one and reconfirmed the
existence of two populations in Mexico. In total, there are
approximately 1,400 individuals, distributed among 5 sites. There are 2
confirmed populations in the United States, containing over 66 percent
of the known individuals. At this time, the majority of Gentry indigo
bush in the United States is located within Sycamore Canyon; we do not
have an accurate assessment of the numbers of Gentry indigo bush on the
Tohono O'odham Nation. We have no information indicating that
populations in Mexico or on the Tohono O'odham Nation are experiencing
any direct threats. The populations, based on observations of the
Sycamore Canyon metapopulation, have the ability to recover from floods
and drought. We have seen seedlings and plants resprout, alleviating
our concern regarding the plant's ability to reproduce and recover from
flood events and sediment deposition. Threats to the Sycamore Canyon
population have been minimized by U.S. Forest Service actions, and
ongoing activities are not immediately threatening the population.

Finding

    We have carefully assessed the best scientific and commercial
information available regarding past, present, and future threats faced
by the species. We reviewed the petition, available published and
unpublished scientific and commercial information, and information
submitted to us during the public comment periods on our 90-day
finding. This finding reflects and incorporates information we received
during the public comment periods. We also consulted with recognized
plant experts, including those most familiar with this species, and
other Federal resource agencies. On the basis of our review, we find
that the petitioned action of listing the Gentry indigo bush is not
warranted.
    In making this finding, we recognize that one historical population
in the United States has been extirpated and is presumed lost. We also
recognize that populations are still present on the Tohono O'odham
Nation, but that those populations are under the management of a
sovereign nation and subject to their laws. The same is true for
populations in Sonora, Mexico. There are ongoing

[[Page 56434]]

activities and natural events that may be affecting the habitat and
reestablishment of the species. Other threats, like undocumented
immigrant traffic, are larger than one agency's jurisdiction. However,
we believe that existing regulatory mechanisms are sufficient to
protect the species. The overall existing management of the U.S. Forest
Service is protecting much of the habitat in Sycamore Canyon. We also
acknowledge that, due to small population size, demographic or genetic
factors may apply to each of the locations in Arizona and Sonora,
Mexico, but we have no genetic information to determine whether this is
indeed the case.
    We conclude that the Gentry indigo bush does not warrant listing at
this time. In order to make a warranted finding, the species must, at a
minimum, meet the definition of a threatened species. In accordance
with section 3(19) of the Act, a threatened species is one which is
likely to become endangered within the foreseeable future throughout
all or a significant portion of its range. Based on all the information
we have gathered and reviewed, we do not conclude this to be the case
for the following reasons.
    Populations have persisted in all but one of the known locations
over time. A new population was located in Mexico and offers hope that
there may be more populations located with additional surveys. Areas
that were previously overlooked as suitable habitat outside of the
floodplain appear to support Gentry indigo bush. Thus, populations may
not be as vulnerable to extirpation from flood events as previously
thought since the species does have the ability to recolonize after
flood events, and plants located out of the floodplain and on the sides
of the canyon could provide a source for the recolonization of plants
in stream habitat. The largest known population occurs in Sycamore
Canyon within the Goodding RNA, where mining, roads, and grazing are
prohibited and where the U.S. Forest Service has completed a number of
conservation actions that have improved the habitat for Gentry indigo
bush. Additionally, as noted above, the actions of the U.S. Forest
Service and the protection that the canyon receives by virtue of its
wilderness and RNA designations will continue to provide for the long-
term conservation of Gentry indigo bush in Sycamore Canyon. The
metapopulation in Sycamore Canyon has persisted through some dramatic
environmental events, and its numbers have increased; thus, we believe
it will continue to persist into the future. Other factors (e.g.,
watershed degradation, invasive species, undocumented immigrant and
U.S. Border Patrol activities, recreation, fire, climate change, and
genetic factors associated with small population size) discussed above
have not been documented as more than low magnitude or potential
threats, and therefore it is not reasonably foreseeable that these
factors pose threats over a significant portion of the species' range.
We anticipate that we will have the opportunity to work cooperatively
with the Tohono O'odham Nation, as we have in the past, to census their
populations and address potential concerns, if necessary. We also plan
to emphasize the need for and participation in future monitoring
efforts, surveys, and genetic studies.
    The Service does not believe the Gentry indigo bush is likely to
become a threatened species throughout either all or a significant
portion of its range in the foreseeable future. The only population for
which we have a thorough threats assessment is the one on U.S. Forest
Service land in Sycamore Canyon. While the Sycamore Canyon population
is not entirely devoid of potential threats, we believe that U.S.
Forest Service management (e.g., RNA and Wilderness designations,
exclusion of both domestic and Mexican cattle from the habitat)
sufficiently ameliorates human-influenced threats, while its
persistence over time through droughts and floods, and its discovery
outside the floodplain, render it unlikely to be extirpated from the
canyon as a result of natural factors.
    Threats facing the other populations are less well known. Three
populations are known from Mexico. One population in Mexico has been
present since its original discovery in 1995, another one was relocated
in 2005 after it was initially detected in 2004, and the remaining
population was only detected in 2005. Based on this information, two of
the populations are known to have persisted. In addition, according to
information received during the public comment period, the Mexico
populations are in areas not accessible to cattle. We can verify that
plants still exist on the Tohono O'odham Nation. The fact that the
Mexican and Tohono O'odham Nation populations have persisted under
current management and through various climatic conditions provides
evidence that whatever threats may exist, if any, are not significant.
In summary, we have no evidence to indicate that any portion, let alone
a significant portion, of the species' range is threatened to the
extent that listing under the Act is warranted.
    We will continue to monitor the status of this species and will
accept additional information and comments at any time from all
concerned governmental agencies, the scientific community, industry,
and any other interested party concerning this finding. This
information will help us monitor and encourage beneficial measures for
this species.

References Cited

    A complete list of all references cited herein is available upon
request from the Field Supervisor at the Arizona Ecological Services
Office (see ADDRESSES section).

Author

    The primary author of this document is the Arizona Ecological
Services Office (see ADDRESSES section).

    Authority: The authority for this action is the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).

    Dated: September 14, 2005.
Marshall Jones,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 05-18881 Filed 9-26-05; 8:45 am]
BILLING CODE 4310-55-P

------------------------------------------


http://www.epa.gov/fedrgstr/EPA-SPECIES/index.html
Comments: http://www.epa.gov/fedrgstr/comments.htm
Search: http://epa.gov/fedreg/search.htm
EPA's Federal Register: http://epa.gov/fedreg/