Chiroptera Chronicles

We left El Paso on July 9, spending 6 days in the Trans-Pecos of Texas, followed by three weeks in New Mexico. Our first day and night were in the Davis Mountains, where we were unsuccessful in our first three plant genus searches, despite the floral displays being quite good from recent rains. But at a very interesting site called Point of Rocks, about ten miles west of Fort Davis, we found Portulaca pilosa (Pink Purslane). In recent times, the formerly large Portulaca family has been split into four separate entities, three of which are decidedly uncommon. This species was only our second native in the new, narrowly defined Portulacaceae, and so was a very welcome find.   

We spent five days in Big Bend National Park, with the primary target being the Mexican Long-nosed Bat. This nectivorous species is rare in the U.S., only occurring during summer when agaves are flowering. Almost all U.S. records are from the Chisos Mountains, in Big Bend, and the only known roosting site is a remote cave below Emory Peak. Numbers vary markedly from one year to the next, and some years none visit the Chisos Mountains. We spent two evenings at flowering agaves, using both a thermal scope and ultrasonic microphone to try to detect the species, and one night we recorded at some surface water where they have been mist-netted in the past. There was one period of excitement when bats were seen visiting one of the agaves, but their flight was exceptionally agile, almost like a hummingbird, indicating they were Pallid Bats. This species often visits agaves to capture insects feeding at their flowers. Recorded echolocation calls confirmed this identification. Long-nosed Bats are not adept at hovering, and typically brush against the agave flowers as they fly by, then lick the nectar from their pelage. Given our lack of success, we suspect that this was not a good year for the bats in the Chisos Mountains.

Despite our last attempt in late May leading to a flat tire in 107°F weather, we tried again for the rare and local shrub Brongniartia minutifolia after a thunderstorm cooled things down a bit. There was supposed to be a colony around Mile 10 of the River Road (from the east end), and our flat was a bit past Mile 7. This time, as we drove through a wash around Mile 6, I glimpsed a shrub about 25 feet off the road with the right sort of branching pattern, and sure enough, we eventually found perhaps 50 Brongniartia plants in the area! It was a thrill to find our “own” site, but a bit ironic that if I had noticed that first shrub last time, we never would have had a flat! A different genus search was delayed a day because, just as we were about to get out of the truck and start hiking, a mother and cub Black Bear strolled past our front bumper and proceeded up the trail! Another highlight in the Chisos Basin was hearing Eastern Screech-Owl (at the extreme western edge of its range), Western Screech-Owl, and Elf Owl from our campsite.

Departing the Trans-Pecos, we made a long drive to Bottomless Lakes State Park, near Roswell, New Mexico, in the southeast quadrant of the state. This series of nine lakes were formed when the Pecos River carved through the roofs of caves in the limestone bedrock, creating dramatic cenotes (water-filled sinkholes). We were lucky to visit the park during a great display of Kallstroemia grandiflora, with its 3-foot high plants topped with fluorescent orange flowers. Although known as Arizona Poppy, this species is in a different family, with the more familiar creosote bush.

We camped in the park one night, during which our truck security alarm went off twice for no apparent reason. We did not realize it then, but this would be the beginning of a miserable week in which we had multiple nights destroyed by electronic malfunctions, and spent parts of four days in Ford dealerships. Problems included having the horn sound continuously in an unbroken wail for over half an hour, and having the engine refuse to shut off repeatedly, despite turning off the ignition and removing the key!! Replacing a door sensor and reprogramming the Electronic Control Unit may have solved the problems; we’ve now gone two weeks since the last vehicular transgression. But it is curious that the whole fiasco started near Roswell, NM, suggesting a possible extraterrestrial origin …   

We spent three nights in the Manzano Mountains, an hour southeast of Albuquerque, to look for the Manzano Mountain Cottontail, which we failed to find on a previous visit farther north in this mountain range. Rabbits in upland habitats in the arid Southwest are taxonomically controversial, with up to three species being split off from Eastern Cottontail by some authorities. We have previously seen one of these taxa, the Robust Cottontail, in Big Bend. After a lot of daytime scouting for suitable habitat, we spent from sunset to midnight one night driving through the best areas, finding seven of the cottontails, two of which were seen very well! This was an exciting new mammal for us, even though its status as a distinct species is somewhat uncertain.   

Leaving the Manzano Mountains, we spent part of a day hiking on the lovely Sandia Crest, east of Albuquerque, where we saw fine displays of subalpine wildflowers. This long day ended in the Sangre de Cristo Mountains, located north and east of Santa Fe, NM. This range, which we had not explored previously, constitutes the southern terminus of the Rocky Mountains, according to most authorities. We had rather mixed success here, as several of our hikes were cut short by thunderstorms with hail, some painful. Typically at this time of year thunderstorms occur in late afternoon, close to the end of a day of thermal convection. But the nearly daily storms we experienced started much earlier, from late morning to noon. I wonder if they were a northerly extension of the stronger than average monsoonal storm systems that normally dominate summer precipitation in southern Arizona, southern New Mexico, and extreme west Texas. Despite the weather, we did see some really nice wildflower displays, especially in higher-elevation meadows. Not too surprisingly, there was a lot of species overlap with the San Juan Mountains and Crested Butte area in Colorado, which we botanized heavily last year. A Calliope Hummingbird was our first of the year.

We spent one day visiting the Glorietta Pass Battlefield, administered by the Pecos National Historical Park. This Civil War battle resulted from a campaign by the Confederacy to secure portions of the southwest for access to natural resources (e.g., mines in Colorado) and commerce (e.g., ports in southern California). While the Confederates gained ground during the battle itself, the Union won a great strategic victory by virtue of a flanking maneuver that led to the discovery and destruction of the entire Confederate supply train. This forced the Confederates to retreat and ended their campaign and quest for westward expansion.  

Our next stop was Storrie Lake State Park, a couple hours east of Santa Fe. I picked this location to try to record Arizona Myotis (Myotis occultus), a small bat. This species, a southwestern split from the widespread and common Little Brown Bat, ranges from southeast Colorado to the vicinity of the California-Arizona boundary. It is not clear how to distinguish it acoustically from Little Brown Bat or Cave Myotis, so to identify it by ultrasonic recording, it must be sought in a portion of its range that does not overlap nor closely approach either of these species. After consulting the literature, and dismissing areas where Arizona Myotis is likely scarce, the prime area seemed to be northeast New Mexico, but not too far northeast, to avoid possible intergradation with Little Brown Bat near the Colorado border. The literature indicated that in this part of its range, it is usually found near significant bodies of water. Studying this region in Google Maps, I decided that Storrie Lake looked like the best bet, with possible foothill roosting areas not too far away, and easy public access and camping.

Although the two acoustically indistinguishable species should not occur at this location, four other “40 kiloHertz” Myotis (with characteristic frequencies from 35 – 45 kHz) could occur in this area, and would have to be ruled out for a positive ID. During a forty-minute period starting an hour and twenty minutes after sunset, I obtained nine decent recordings of 40 kHz Myotis. Southwestern and Long-eared Myotis, both marginal for range, were ruled out based on their higher bandwidth and slope. Dark-nosed Small-footed Myotis have smoothly curved calls that angle sharply to a long, linear tail, whereas the recorded calls were typically kinked, with a minimal tail, and were too low in characteristic frequency for that species. In seven of nine recordings, the calls were generally too low in slope, throughout the call, and often too long in duration, to fall within known variation of the last contender, Hairy-winged Myotis. In contrast, the calls were within the expected ranges for Little Brown Bat, from which Arizona Myotis was split, so I concluded that the recordings were indeed from Arizona Myotis. There are about 47 species of regularly occurring bats in the U.S. and Canada, and with Arizona Myotis finally in the bag, this leaves just three to go: Mexican Long-nosed Bat, mentioned earlier in the post; Seminole Bat; and Southern Yellow Bat.  

From Storrie Lake we headed northwest towards Taos, crossing the Sangre de Cristo Mountains and exploring their northern half. The day we left these mountains, we did a spectacular scenic drive, taking Route 64 west from Taos, then Route 84 south from near Tierra Amarilla. This route passed by the Jemez Soda Dam, a travertine deposit from a spring, through which a river has cut a short tunnel. We finished the day at Bandelier National Monument, west of Santa Fe, where we spent four peaceful nights camping. The ruins of cliff houses and an adjacent valley bottom village were very interesting. One day we hiked to Cañada Bonita Meadow, west of Los Alamos, which has not been grazed since the 1940s. The wildflower display was beautiful, and we enjoyed good views of a Dusky Grouse, a species we’ve seen only a few times. After a very poor start on genus searches, we scored four in a row in this region, two grasses (Piptatheropsis and Pascopyrum), an aster family member (Brickelliastrum), and a carrot family member (Aletes). This brought our totals for our “fall” loop to six successful, five unsuccessful, and one serendipitous.

Leaving Bandelier, we headed west, visiting the beautifully symmetric Valles Caldera, which has high-quality grassland growing in the volcanic soil. While stopped at the small visitor center, I noticed in the distance two Coyotes close together, who seemed rather intently focused on a tall grass area. I could see some movement in the grasses and wondered if they had young there. A bit later, Eileen pointed out that there was quite a bit of dirt flying around, and I imagined pups digging in the soft soil and rolling in the dust. As I watched in binoculars, suddenly a low, dark shape emerged from the dust cloud for a moment, and then disappeared again. It wasn’t a Coyote pup – it was a Badger!!

We spent at least 45 minutes, maybe an hour, watching this closely associating threesome hunting for Gunnison Prairie Dogs. They traveled an estimated 200 yards during this time. A Coyote might lead for a bit, then the Badger might take over, but they never were far apart. Sometimes the Badger would dig and the Coyotes would intently watch the area in case a prairie dog tried to exit from a different tunnel. Coyotes benefit if the prairie dog does come to the surface, as they have a chance to catch it, and the Badger may benefit if the prairie dog is scared back underground by the Coyotes, as it gets another chance to capture it (Minta, 1992). Even though prey items are not directly shared between the species, this type of hunting association likely benefits both species. Such an arrangement is termed “mutualism”, whereas the term “cooperative hunting” is usually reserved for members of a single species that may be genetically related to one another. What an amazing experience!

Our last foray in New Mexico was to Mount Taylor, near Grants, after a long drive through an enormous and intense thunderstorm system. Our hike on the Gooseberry Trail was not as good for flowers as our earlier forays, but we did find the uncommon Crag Lily, Echeandia flavescens, an attractive member of the asparagus family. This was a new genus for us and it was nice to find it serendipitously after missing it in the Davis Mountains earlier in the trip. Next, we head for southeast Arizona, to take advantage of the heavy monsoonal rains this year, and look for a number of new plant genera that depend on these storms.