Bat Survey Technical Memorandum

LESSER LONG-NOSED BAT SURVEY
OF THE ROSEMONT HOLDINGS AND VICINITY

1. INTRODUCTION

The lesser long-nosed bat (LLNB, Leptonycteris yerbabuenae; Appendix A, Photo 1) is a migratory, endangered species that is known to be present in southern Arizona during the late spring to early fall. The proposed open-pit copper mine at the Rosemont Property (the Property), which encompasses patented and unpatented claims and fee lands within privately owned, USDA Forest Service, and Bureau of Land Management lands on the northeast side of the Santa Rita Mountains (Figure 1 and Appendix A, Photo 2) is within the known geographic and elevational range of this species and provides suitable habitat characteristics for the bats. A detailed study of LLNBs and their use, or potential use, of the Property was undertaken with initial site visits in 2006, ultrasonic acoustic surveys in 2007 and 2008, and wide-ranging surveys for potential roost sites and foraging resources in 2008. This report summarizes the results of these surveys and is presented in six sections:

Section 1 (Introduction) describes the LLNB’s listing status, taxonomic history, habitat requirements, geographic distribution, and relevance of the Property to this species.

Section 2 (Survey Methods) describes the survey methods that were used for acoustic sampling, infrared sampling, and potential roost surveys conducted as part of this effort.

Section 3 (Results) describes the results of the LLNB surveys conducted as part of this effort.

Section 4 (Discussion) provides a discussion of the survey results including an analysis of the acoustic and infrared survey results and roost site survey results.

Section 5 (Summary and Conclusions) summarizes WestLand’s findings and discusses the conclusions that were formed during analysis of the survey results.

Section 6 (References) provides a list of references that were used for this work.

1.1. LESSER LONG-NOSED BAT STATUS

The LLNB was proposed for listing as endangered by the USFWS in 1987 (52 FR 25171) under the name Leptonycteris sanborni. The final ruling was published in 1988 (53 FR 38456), without a designation of critical habitat. This same publication also listed the Mexican long-nosed bat (L. nivalis) as endangered. A recovery plan was prepared for the LLNB (using the name Leptonycteris curasoae yerbabuenae) in the mid-1990s (USFWS 1995) and was approved and finalized in 1997. A recent five-year review of the LLNB (USFWS 2005) concluded that the population of this species is increasing, and that it would be appropriate to revise the listing status from endangered to threatened. However, because this bat has maternal roost colonies in relatively few locations, an impact at any maternity site could have a significant effect on the population.

1.2. TAXONOMIC HISTORY

This species has a complicated taxonomic history. It was originally described as Leptonycteris yerbabuenae by Martinez and Villa (1940), cited by the Integrated Taxonomic Information System (ITIS 2008) as the original publication, but no details of the reference are provided. ITIS also credits Martinez and Villa (1940) for the names Leptonycteris curasoae yerbabuenae and Leptonycteris nivalis yerbabuenae. They apparently recognized the significance of this taxon but could not determine whether it was a distinct species or merely a subspecies of one of the other members of this genus. The taxon was renamed as Sanborn’s long-nosed bat (Leptonycteris sanborni) by Hoffmeister (1957), who apparently ignored the earlier work by Martinez and Villa. Subsequently, other researchers (Arita and Humphrey 1988; Wilkinson and Fleming 1996) determined that this bat should be considered a subspecies of L. curasoae from northern South America, and the name was changed to lesser long-nosed bat (L. c. yerbabuenae). More recently, this bat was re-elevated to full species status as Leptonycteris yerbabuenae (Cole and Wilson 2006), reverting back to the name originally proposed by Martinez and Villa. This change has been accepted by ITIS (2008) and we will follow their standard in this report.

1.3. HABITAT REQUIREMENTS

The two basic habitat requirements for virtually all species are shelter and food resources and the LLNB is no exception. Potential roost sites must be within reasonable foraging distance from appropriate food resources. These critical resources may limit species distributions spatially and seasonally (Fleming 1982, Ober et al. 2005). Day roost sites are typically natural caves in limestone and basalt and abandoned mines (Appendix A, Photo 3) (Hoffmeister 1986; USFWS 1995). Temporary night roosts may include caves, mines, and abandoned or empty buildings (USFWS 1997). During the spring and early summer, pregnant females congregate in maternity colonies where they give birth and raise their young. At the present time, there are only three known maternity colonies known in southern Arizona (USFWS 2007), as shown on Figure 2.

As a nectar-feeding bat, the LLNB has very specialized dietary requirements and it is able to switch from one food source to another depending on season and availability. In northern Sonora and southern Arizona, it feeds primarily on nectar and pollen from the flowers and on fruit of columnar cactus in the spring and early summer (Wilson 1985). After the maternity season, cactus flowers and fruit are no longer available, and the bats shift their diet to feed primarily on nectar and pollen from flowers of paniculate agaves, especially Palmer’s agave (Appendix A, Photo 4) (Ober and Steidl 2004). This diet change requires a change in distribution, because Palmer’s agave and saguaro are not usually found in the same landscapes (Cockrum and Petryszyn 1991). Palmer’s agave are known from the semidesert grassland (Brown 1994a) through the transition to Madrean evergreen woodland of southern Arizona (Brown 1994b), and their peak blooming period is August and early September (Sidner 2007). Post-maternity dispersal areas and roost sites are thus generally at higher elevations north and east of maternity colony locations (Figures 2 and 3).

1.4. GEOGRAPHIC DISTRIBUTION

In Arizona, New Mexico, and northwestern Mexico this species is migratory. In the early spring, these bats follow a ‘Nectar Corridor’ of flowering columnar cacti north from Mexico. Pregnant females arrive in Arizona in late April and early May and feed on the nectar and pollen of saguaros and other columnar cacti. Maternity colonies are located in natural caves in limestone and basalt and in abandoned mines. Adult males arrive in late July to early August to join the females and young as they disperse from maternity roosts to forage on the nectar and pollen of agave flowers. At this time, the species distribution expands east and north into plant communities at higher elevations than the earlier foraging grounds (Figure 3, Cockrum and Petryszyn 1991). By mid- to late-September, the majority of these bats have left Arizona and returned to Mexico.

1.5. RELEVANCE OF ROSEMONT PROPERTY

The Property is located in the center of the post-maternity dispersal region for the LLNB. The large number of abandoned mine adits and shafts on the Property could provide roosting sites for these bats, and the abundant agaves could provide a foraging resource. For these reasons, a survey of resource use by LLNB on the Property is necessary to prepare an informed evaluation of potential impacts to the bat that could result from development of the proposed open-pit copper mine and related processing facilities.

2. SURVEY METHODS

A variety of methods were used to evaluate the use of the Property and the surrounding vicinity by LLNBs. These methods included active and passive ultrasonic acoustic sampling at flowering agaves, infrared photography and observations at flowering agaves, and surveys of potential roost sites on the Property and several areas in the surrounding region. Bat specialists, Ronnie Sidner, Ph.D. and Debbie Buecher, M.S., conducted these surveys with participation and supervision by WestLand biologists.

2.1. ACOUSTIC SAMPLING

Traditionally, bats are captured in mist nets for identification purposes but nets cover a small area and may require many nights of effort to obtain any particular species. A broader area may be surveyed by using ultrasonic detectors to record the sonar calls of bats. These calls may then be analyzed to look for the calls of LLNBs that might be foraging on Palmer’s agaves.

Two commonly accepted acoustic sampling systems were used in these surveys: frequency division ultrasonic bat detectors (Anabat II - Titley Electronics, Ballina, New South Wales, Australia) and time-expansion detectors (Pettersson 240X – Pettersson Elektronik, AB, Uppsala, Sweden). Anabat II ultrasonic bat detectors were cabled to Zero-Crossing Analysis Interface Modules (ZCAIM). This equipment performed frequency division analysis of each call and stored the calls on a compact flash card for later species identification and analysis of activity patterns. Passive sampling was conducted on five nights using Anabat detectors at up to four flowering agaves. To reduce insect noise, the high frequency Anabat microphones were mounted on 6 ft poles, and a highly directional microphone was angled 45^o to a Plexiglass plate that was pointed at the flowering agave stalk (Weller and Zabel 2002) (Appendix A, Photo 5). In this manner, sonar calls emitted by nectar bats at the flowers are reflected into the microphone and recorded for later analysis. These detectors record any ultrasonic sounds within a distance of about 30 to 45 ft for a time period of up to 8 hours. The passive detectors were left in place prior to sunset and were retrieved several hours later, following the active sampling period.

An Anabat II (frequency division) detector collects the original bat call and divides the frequencies produced by the bat by a pre-set number (‘16’ for this project). One advantage of this system is that there is no time lost in downloading bat calls, so this equipment is very useful for comparing activity across both time and space. However, during the process of dividing the original signal, some call parameters are lost. This information includes the true maximum and minimum frequencies used by the bat, plus any harmonics that the animal used.

In contrast, the Pettersson bat detector transforms the ultrasonic bat calls using time-expansion. If a bat echolocates at 80 kHz, the call would be slowed by a factor of 10 and the resulting call is heard at 8 kHz, well within the range of human hearing. However, the process used to ‘time expand’ these bat calls does not alter the original call (i.e. true maximum and minimum frequencies), nor is there a loss of accompanying harmonics (Fenton et al. 2001). The disadvantage of this time-expansion equipment is that during the period required to download each call onto a laptop computer, there is a break in recording calls from bats flying overhead. Therefore, time-expansion equipment is not as useful for continuously monitoring activity patterns of bats, but it is most helpful when attempting to identify particular bat species and/or to distinguish resource use between species.

Because each method has advantages and disadvantages (O’Farrell et al. 1999, Jones et al. 2000, Fenton 2000, Fenton et al. 2001), active sampling was conducted with time-expansion equipment linked to frequency division equipment (Appendix A, Photo 6). During extensive fieldwork conducted throughout southern Arizona, Sidner and Buecher (2006) have developed a technique that coordinates the ultrasonic call from a bat on Anabat II and Pettersson 240X systems. To accomplish this, an Anabat detector is linked to a visual display (Hewlett Packard PDA) to allow observation of bat activity by calls in real time. While watching the PDA display, foraging calls are simultaneously recorded on a Pettersson detector. Unusual calls or calls from an LLNB are saved on both systems logging the time and file name from the Anabat system with the Pettersson call recording. In this way, calls produced by the same animal can be recorded on both systems and analyzed to reveal additional call parameters (Fenton et al. 2001). Because of the amount of equipment needed at each of these sites, it was necessary to find flowering agaves within an easily accessible area (usually within 300 ft of a road), on terrain that could be negotiated safely after dark when packing up the equipment.

During each sampling night, two active detectors and up to four passive detectors were deployed within stands of 1 to 3 flowering agaves. Call data were evaluated to determine if LLNBs were present to infer foraging on the landscape. Echolocation calls recorded on Anabat II bat detectors were analyzed using AnaBat 6.3 and Analook 4.8 - free shareware, DOS compatible software (per. comm. Corben 2002). Bat calls recorded on a Pettersson bat detector were transferred to a laptop in the field and analyzed in the lab using BatSound Pro 3.3 (Pettersson Elektronik real-time spectrogram sound analysis software). The recorded calls were analyzed to identify species, comparing possible LLNB calls to a personal call library to differentiate LLNBs from other species on a landscape. This call library was developed using captured bats for true identification of calls (Sidner and Buecher 2006, Buecher and Sidner 2007).

GPS location data were recorded at each of the sampling locations with handheld Garmin GPS Map 60CSx units using datum WGS 84. Sun and moon rise and set times were determined in advance (using U.S. Naval Observatory data on the internet) to plan for acoustic survey times. Moon cycle and sun and moon rise and set times were confirmed visually and by GPS, respectively, in the field.

2.2 INFRARED SAMPLING

In addition to the ultrasonic acoustic sampling, infrared equipment was used to observe and record bats foraging at the flowering agaves (Appendix A, Photo 7). Night-vision glasses were used to watch the flower panicles for any foraging activity. These devices would work with ambient conditions, but infrared radiation sources aimed at the panicles greatly enhanced visibility. Infrared video cameras were used to record bat foraging activity for visual identification of species. These cameras also relied on the infrared sources for enhanced recording detail. Infrared observations were limited to the sites of active acoustic sampling.

2.3. POTENTIAL ROOST SURVEYS

2.3.1 Impact Area Roost Survey - Surveys of potential roost sites were conducted on or near the proposed impact area within the Property. Initial surveys were conducted in this area in 2006. Surveys in 2008 returned to some of the sites where bats had been seen previously and also included other sites that had not been visited previously. Many of these sites were identified from the USGS topographic maps of this area, but many others were seen from roads or were found while on the way to other sites. Additional geohazard sites mentioned by Cornoyer (2007) within the proposed impact area were also examined for potential bat use. Nearly all of the sites near the impact area were abandoned mine adits or shafts, although one natural limestone cave was located north of Lopez Pass. During these surveys, the bat biologists searched for any live bats roosting in the adit, evidence of guano (Appendix A, Photo 8) or insect parts (Appendix A, Photo 9) on the floor of the adit, and general suitability of the habitat. Nectar-feeding bats produce characteristic yellow splatter guano (Appendix A, Photo 10). In small amounts, the guano of nectar-feeding bats in Arizona cannot be positively distinguished as having been produced by LLNBs or Mexican long-tongued bats (Choeronycteris mexicana). However, large amounts of nectar-feeding guano can indicate a likely presence of LLNB. If live bats were seen, they were captured, if possible, and weighed, measured, photographed for positive identification, and released. Appendix A, Photo 11 shows a lesser long-nosed in hand for identification purposes.

2.3.2 Regional Roost Survey - Similar surveys were conducted on a regional scale, looking at sites in nine different areas, primarily on the north and east sides of the Santa Rita Mountains. Some of these regional sites are actually within the area of patented or other claims owned or controlled by Rosemont Copper, but they are not in or near the anticipated areas of impact. For example, there are several abandoned adits northwest of Gunsight Pass and others near Sycamore Canyon near the south end of the property. The regional sites surveyed were also primarily abandoned mine adits and shafts, but several natural limestone caves were also examined.

3. RESULTS

Acoustic and/or roost site surveys were conducted on a total of 20 different dates between August 4 and November 12, 2008. These dates, survey activities, and general survey locations are summarized in Table 1.

Table 1. Summary of Lesser Long-nosed Bat Survey Activities

3.1. ACOUSTIC AND INFRARED SURVEYS

Ultrasonic acoustic surveys and infrared surveys were conducted on five evenings between August 11 and September 16, 2008. Active sampling was conducted at 10 different locations, and passive samplers were placed at 19 locations. Equipment malfunctions at two passive locations resulted in no data for those points. Two other equipment malfunctions were covered by additional sampling on a different evening (August 30). On the final night of surveys, almost all of the agaves were finished flowering, and only three suitable agaves could be found for the passive detectors. Usable acoustic recordings were successfully collected at 27 agave locations (Figure 4). Locations of all of these sample points are listed in Table 2 and plotted on Figure 4. In addition to the acoustic surveys conducted at the flowering agaves, acoustic and infrared procedures were used for an exit count at an LLNB day roost site within the proposed impact area.

3.2. ROSEMONT IMPACT AREA ROOST SURVEYS

A total of 75 sites were visited on or near the anticipated impact area of the Rosemont Project (Figure 7). In this analysis area, the east side of Gunsight Pass and an area north of Lopez Pass were included as potential utility corridors. Of these sites, 21 were visited initially in 2006. Some of these sites were visited again in 2008, in addition to another 28 sites. These sites are listed in Appendix B, with a brief summary of observations. In the interest of public safety, site security, and resource protection, specific locations for these features are not included in this report. Forty-nine of these sites are within the proposed impact area (mine, processing facilities, and waste rock and tailings disposal) and within areas owned as patented claims. Ten other sites are within the proposed impact area, but they are on Coronado National Forest land covered by unpatented mining claims. The remaining 16 sites are on patented claims, possibly within the vicinity of the proposed utility corridor. This group includes the adits southeast of Gunsight Pass and the cave north of Lopez Pass.

A total of 59 sites were examined within the proposed impact area of the project, waste rock and tailings disposal areas, and processing facilities. During these surveys, positive evidence of bat use was found in 9 of these adits, as noted in Appendix B. Bat presence in these adits is indicated by color-coding on Figure 7 and in Appendix B. Evidence of bat presence includes live bats, guano piles, urine stains, or insect parts such as moth wings and beetle elytra. Yellow fecal splatter is positive evidence for the presence of nectar-feeding bats. Three other sites were vertical shafts that could not be evaluated and have unknown potential for bat habitat. One site (probably the Chicago prospect, based on Schrader [1915]) had a small colony of LLNBs using it for a post-maternity dispersal day roost.

Many of the abandoned adits and shafts in this region were actively producing copper over 100 years ago. Schrader and Hill (1914) produced a map showing a number of mines and prospect sites from the Patagonia District on the Mexican border to the Helvetia and Empire Districts near the north end of the Santa Rita Mountains. Schrader (1915) describes many of the mines in the Helvetia and Rosemont areas that are shown on the map. Some of these mines can be related to the adits and shafts currently accessible, but this map is difficult to use because of the original scale (1:125,000) and some discrepancies in topography resulting from mapping techniques. In addition, it is likely that some of the adits and shafts on the Property are more recent than 1914.

Four species of bats were observed in these sites: LLNB (Appendix A, Photo 11), Mexican long-tongued bat (Appendix A, Photo 12), Townsend’s big-eared bat (Plecotus townsendii) (Appendix A, Photo 13), and cave myotis (Myotis velifer) (Appendix A, Photo 14). Both the Mexican long-tongued bat and the Townsend’s big-eared bat are listed as sensitive species by Coronado National Forest.

Twenty-one of the sites in the proposed impact area had no evidence of bat use. Fourteen of these sites were very small or had no features that would provide bat habitat. These sites could be closed or reclaimed with no further evaluation. Seven of the adits were larger (up to 150 ft long) and had features that would appear to provide potential bat habitat. These sites would be suitable for closure, after inspection by a qualified biologist to determine that no bats were present at the time of closure.

Sixteen other sites were examined for bat potential within the patented claim area east of the ridge but outside of the primary impact area. Most of these sites are south and east of Gunsight Pass. Six of these sites have confirmed use by one or more species of bats, and four sites have confirmed use by Mexican long-tongued bats. We did not find LLNBs in any of these sites. The other ten sites have no current evidence of bat use, and some of these sites have already been closed. One of these sites is a natural limestone cave feature that is protected by state and federal cave protection acts.

3.3. REGIONAL ROOST SURVEYS

Similar potential roost site surveys were conducted in public access areas in the region around the Property, primarily on the north and east sides of the Santa Rita Mountains. On 10 days of surveys, we visited a total of 68 sites (Appendix C and Figure 8). Many of these sites were marked on the USGS topographic maps as mine adits, shafts, or test pits, but many other adits were not marked on the maps. Some of the sites were natural caves, most of which are not marked on the maps. Thirteen of these sites were either very small test pits or had been previously closed and had no potential to provide bat roosting sites.

Sites visited during these regional surveys are owned or managed by a variety of private owners or government agencies. Fourteen of these sites are located on patented claims held by Rosemont Copper, most of which are on the northwest side of Gunsight Pass (Figure 7). Some of the sites northwest of Gunsight Pass are in an area that could be affected by construction of the water line across Lopez Pass. One site on a patented claim is at the south end of the Property, on the ridge above Sycamore Canyon. Another site is on an unpatented claim held by Rosemont Copper but within Coronado National Forest. Forty-three of the sites are elsewhere on Coronado National Forest lands. The remaining ten sites are on Arizona State Trust lands near the Empire Mountains.

During these regional surveys, evidence of bats was found in 32 different sites. Six species of bats were found and photographed: LLNB, Mexican long-tongued bat, Townsend’s big-eared bat, cave myotis, fringed myotis (Myotis thysanodes) (Appendix A, Photo 15), and big brown bat (Eptesicus fuscus) (Appendix A, Photo 16). Yellow splatter guano, indicating the presence of nectar-feeding bats, was found in nine different sites. Mexican long-tongued bats were identified in eight sites, and LLNBs were identified in only three sites, two of which were connected underground. The high density of yellow splatter in two other sites, clustered in a very small area on Coronado National Forest northeast of the Property, suggests frequent use by large numbers of LLNBs.

4. DISCUSSION

4.1. ANALYSIS OF ACOUSTIC AND INFRARED SURVEYS

As noted previously, both Anabat and Pettersson ultrasonic detectors were used for recording the ultrasonic calls of bats. The different analytical algorithms used by these detectors maximize the amount of information collected. The Pettersson system provides better analytical analysis of individual calls, including representation of harmonic frequencies contained within the calls. This analytical approach may allow better discrimination and assist in identification of species. However, this advantage is offset by a very short data storage time that requires prompt downloading to a computer. No additional calls can be recorded until downloading is complete. The Anabat system does not provide the level of analysis, but it can record for many hours before downloading is necessary. In addition, the Anabat microphone system is more sensitive than the Pettersson, and it can detect bats at somewhat greater distances. For these reasons, the Anabat is the only reasonable device for a passive recording site that can be left unattended for several hours.

Because the LLNB does not always use its ultrasonic calls while foraging, both systems have the potential to provide an underestimation of the occurrence or density of bats. On numerous occasions while using night vision glasses, we were able to watch bats successfully feeding at an agave without emitting any calls. Their eyesight is excellent and allows them to see well enough to find and feed at agave flowers, even on nights with very little moonlight. They will usually give enough calls to confirm that they are in the vicinity, but the frequency of calls cannot be interpreted as an indicator of the intensity of foraging activity. At the passive recording locations, a positive identification of a LLNB call will confirm that these bats were present in the vicinity of the recorder and that they were probably foraging on the agave at that location. However, it provides no information on how many individual bats may have been present or how often they fed at the agave flowers.

The infrared night vision glasses are a useful tool for estimating the intensity of foraging on a flowering agave. However, identification of bats with night vision glasses is very difficult, and positive identification would be unlikely without the acoustic information. Because the LLNB is noticeably larger than the Mexican long-tongued bat, they can be distinguished if seen clearly. They were distinguished by size when they were foraging simultaneously at the same flowering panicle. The infrared video recordings were useful for species identification because they could be replayed at slower speed to allow careful examination. However, the video recording was not adequate for overall foraging intensity because the camera had to be focused on a small portion of the flowering stem.

4.2. ANALYSIS OF ROOST SITE SURVEYS

LLNBs are a migratory species and surveys must be conducted at the appropriate season in order to document presence. However, inter-annual variation in both seasonal timing and abundance of flowering agaves means that the “appropriate season” may vary and makes documentation of species presence difficult. Evidence was found to document that LLNBs use the Property to day-roost in adits and to forage on flowering agaves at night. Although mine and cave surveys are an important tool in determining bat-use, nectar bats can occupy a site without leaving large amounts of yellow fecal splatter. Persistence of nectar bat guano is, in part, due to the substrate on which the splatter is deposited. If the floor and walls are dry and dusty, they can greatly absorb liquid splatter. However, if conditions are too wet, the splatter can be diluted and will not persist. Therefore, there is not necessarily a strong relationship between the amount of splatter and number of LLNBs using any particular site. Pyeatt Cave (Fort Huachuca Military Reservation) has a colony of more than 10,000 LLNBs in late summer (Sidner 2007). Given that large number of nectar bats using it each year, there is surprisingly little splatter evident in that cave. Given the transient and elusive nature of this species, it is critical to remember that absence of evidence does not mean evidence of absence.

The survey of potential roost sites covered 143 sites between Temporal Gulch and the north end of the Empire Mountains (Appendices A and B, Figures 7 and 8). Many of these sites were marked as test pits, adits, shafts, or named mines on the topographic maps of this region but many others were not mapped. These other sites were generally located by searching in the proximity of marked sites. The surveyors’ prior knowledge of the area was used to locate the natural limestone caves. We believe that we have examined all potential sites within the proposed Rosemont impact area. However, it is possible that other shafts or adits not shown on the maps were not located or examined, and there is a possibility that these unknown features could provide roosting habitat for the LLNB or other bat species.

During the survey of potential roost sites in the surrounding region, we visited as many adits and shafts as possible, and we believe this survey has covered a reasonable, representative sample of the potential roost sites in this region. However, because of the very large number of abandoned mines in this region, it was not possible to examine all potential sites in the Santa Rita Mountains.

Roost site surveys on the Property and in the surrounding region demonstrate that the LLNB is using relatively few of the potential roost sites. These bats, or definite evidence of their presence, was found in only two adits on the Rosemont Property and in only five adits in the regional area. Therefore, only 7 out of 143 sites (5 percent) had evidence of LLNB. Because of underground connections, these 5 regional adits actually represent only three independent roost sites, which are all within about 500 feet. Collectively, these sites appear to be a previously unknown roost area that is likely to support large numbers of LLNB for periods of time during the post-maternity dispersal period.

The presence of this previously unknown roost area could also explain how bats appear at flowering agaves on the Property so soon after dark, at about the same time they would normally leave their roost. Previously known large colonies at Patagonia Bat Cave and Pyeatt Cave are 20 to 25 miles from the Property and would require flight times of 45 minutes to an hour to reach the Property. From this new roost area, bats could be at any point on the Property within a matter of a few minutes. The closest acoustic detection of LLNB was within about one-quarter mile of this roost area and several other acoustic detections were within one mile.

One difficulty in interpreting our results is that these bats will move around and use a variety of roost sites for brief periods of time. For example, 12 to 15 LLNBs were using a roost site in the proposed impact area on August 4 and 7, 2008, but none were present in this site on September 23, 2008. The previously unknown roost area had 20 to 30 bats as late as October 7, 2008. It is possible that LLNBs are using other sites on the Property and in the surrounding region but were not present on the day of our survey. However, we believe it is unlikely that these other potential sites are heavily used by these bats.

Another shortcoming of this survey is that none of the vertical shafts were entered, and these sites still have unknown potential for bats. The LLNB is known to use vertical mine shafts, if a suitable side tunnel is accessible within a reasonable distance of the surface, probably less than 50 feet (pers comm. Ronnie Sidner, Ph.D.). While the necessary equipment and skills are available, entering these shafts safely would be a very time-consuming activity, and the limited time available was better spent investigating sites that were more readily accessible.

In order to minimize public safety risks, Rosemont Copper has closed selected shafts and adits on their patented claims. As of November 21, 2008, they have closed 33 separate sites, including test pits, adits, and shafts (Figure 9). Seven of these closures were in sites that we had examined in 2006 but many others were in areas that we had not surveyed. Of the sites that we had previously visited, none had any evidence of LLNB use. Mexican long-tongued bats were observed in 2008 within one site that was closed, but this site has other entrances that are still accessible to the bats.