Prior to this inventory, little information existed on the presence, distribution, or relative abundance of high-country breeding birds in Carlsbad Caverns National Park.
Inroduction
Photo © Robert Shantz
Carlsbad Caverns National Park (NP) in southeastern New Mexico, contains high-elevation areas that are rugged, remote, and difficult to access. These areas contain mesic vegetation communities in a generally arid region. Prior to the present study, little information existed on the presence, distribution, or relative abundance of high-country breeding birds in the park. This is in contrast to other areas of Carlsbad Caverns NP (e.g., Rattlesnake Springs), where human visitation is high and a large number of bird species have been recorded. Six study sites in the western half of the park, the least-known portion of the park, were selected for study based primarily on elevation. Elevations in the six study sites ranged from 1,280 to 1,890 meters.
Methods
Study sites were visited twice between May and early July, with at least 7 days between visits to the same site (Table 1). Point-count transects at each site generally followed a ridge top or canyon bottom. Each transect consisted of 14 sampling sites, with 200-250 meters between sites. Each survey began at approximately the same time of day. The researchers recorded bird presence from several categories, including typical detection, flyovers, juveniles, and flushed birds. Birds were recorded in the first 0-3 minute time period (after allowing for a one-minute waiting period so birds could settle down). This was broken down into distance bands of 0-50 m, greater than 50 m, associated flyovers, and individual flyovers. After the 0-3 minute time period, the same information was collected over a 3-5 minute time period. Other information recorded included slope, aspect, dominant landform, vegetation type and height, bird activity, and other wildlife observed.
Table 1. Breeding bird surveys at Carlsbad Caverns NP in 2003. | ||
Study Area | Visit 1 | Visit 2 |
North Slaughter Canyon | May 3 | June 10 |
Rattlesnake Canyon | May 25 | June 30 |
Yucca Mesa | June 2 | June 29 |
Guadalupe Ridge | June 6 | June 24 |
Open Hollow Gulch | June 13 | June 26 |
North Double Canyon | June 20 | July 3 |
Results
A total of 1,524 individuals of 50 species were detected on point counts, and another six species were recorded between survey points or on scouting trips outside of the survey dates. The surveys recorded one new species for the park, the elf owl (Micrathene whitneyi), and provided the second record since 1943 of the Montezuma quail (Cyrtonyx montezumae), a species once thought extirpated. The species detected at point-count stations in the largest numbers were: Northern mockingbird (Mimus polyglottos), blue grosbeak (Guiraca caerulea), Scott’s oriole (Icterus parisorum), gray vireo (Vireo vicinior), cave swallow (Petrochelidon fulva), canyon wren (Catherpes mexianus), Cassin’s kingbird (Tyrannus vociferans), Bewick’s wren (Thryomanes bewickii), rock wren (Salpinctes obsoletus), and ash-throated flycatcher (Myiarchis cinerascens), respectively. Additional details are provided below for each survey area.
North Double Canyon
North Double Canyon (NDC), one of the more isolated areas of the park, had little to no bird work conducted previously. Over the two survey dates, a total of 32 species were found. Gray vireos, a state-level threatened species, comprised a significant proportion of the avifauna of NDC; there was an estimated minimum of 10 pairs along the survey route. At least two pairs of varied buntings (Passerina versicolor), another state-level threatened species, were also found along the survey route.
Yucca Mesa
A total of 33 species were found on the survey at Yucca Mesa, which has an extensive grassland area. Gray vireos were widespread on the mesa, with approximately 10-12 pairs from the trailhead to the end of the survey route. Northern mockingbirds were common, especially on the first survey date.
Open Hollow Gulch
A total of 32 species were found during the survey of this area, where no previous bird work had been done. A male blue-throated hummingbird (Lampornis clemenciae) was recorded in an area just beyond a survey point, making it the third record for the species at the park. A minimum of 6-8 pairs of gray vireos were in the portion of the canyon surveyed. Plumbeous vireos (Vireo plumbeus) were widespread at higher elevations in the canyon, and the northern mockingbird was one of the most common species detected.
North Slaughter Canyon
This survey route passed three of the best-known back-country caves inhabited by cave swallows, so previous information on birds existed for this area. A total of 35 species were found on the survey. The first elf owl recorded for the park was recorded here. A minimum of 6-7 nesting pairs of gray vireos were estimated in the area surveyed. The varied bunting was recorded on both surveys, with only one nesting pair likely. A large number (108) of cave swallows were seen emerging from a cave between survey points.
Guadalupe Ridge
Guadalupe Ridge is largely exposed, and weather conditions (high and cold winds and associated noise) during the first survey affected the number of birds detected on that date (13 species at survey points and 3 between points). With improved weather on the second survey, 21 species were found, including one between survey points. Two white-throated swifts (Aeronautes saxatalis) were found in this area, about 7.2 km from the only known colony in the park. Cave swallows were detected twice, with the nearest known nesting site of the species about 2.8 km away. The northern mockingbird was the most widespread species.
Rattlesnake Canyon
Some previous bird work in Rattlesnake Canyon had been conducted in the winter. A total of 28 species were found during the breeding season survey. The only golden eagle (Aquila chrysaetos) seen during the study was a single adult as a flyover at one of the survey points. The mourning dove (Zenaida macroura) was relatively common during the May survey, but was largely absent by the second survey. The gray vireo was widespread, but found in lower numbers than in other canyons. Three nests were found on the second survey date. A group of five hepatic tanagers (Piranga flava) was found on the first survey date, but fewer individuals were seen on the second date. Varied buntings were seen during both surveys, with 4-5 pairs present.
Discussion
In addition to the project having recorded one new species for the park (the elf owl) and a rare sighting of another (the Montezuma quail), the project also added to the knowledge of nesting species in rarely visited areas of the park. This included information on two state-level threatened species (gray vireo and varied bunting), as well as birds not previously recorded as nesting in the park (gray and plumbeous vireos). The observance of the Montezuma quail leads to questions about whether a viable population exists. There appears to be available habitat for the bird at Yucca Mesa, Guadalupe Ridge, and benches in Open Hollow Gulch and North Double Canyon. Additional work should be conducted on the elf owl to ascertain the status of the species in other areas of the park. The presence of the yellow-billed cuckoo (Coccyzus americanus) in two dry canyons (“atypical” habitat), as well as a nesting record from another canyon, should be examined further; the species may use this type of habitat more than was realized. At least 42 probable nesting territories of the gray vireo were recorded during the project, which covered a relatively small area of the park; this is probably the largest nesting group in New Mexico. Finally, survey findings for the varied bunting suggest additional work; surveys in only a small portion of potential habitat discovered at least eight probable nesting pairs (and two pairs were recorded at the same time in lower Walnut Canyon); this is more than the five or so nesting pairs thought to exist in the state.
Literature Cited
West, S. 2003. Inventory of high elevation breeding birds at Carlsbad Caverns National Park.
Contact
Steve West, Chihuahuan Desert Conservation Alliance, 1105 Ocotillo Canyon, Carlsbad, New Mexico 88220, wthrswift@carlsbadnm.com.
Prepared by Patty Valentine-Darby, Chihuahuan Desert Network I&M Program, 2010.
Last updated: October 1, 2018