Common Black-Hawk (Buteogallus anthracinus)   NMPIF level: Biodiversity Conservation Concern, Level 1 (BC1)          NMPIF assessment score: 13 NM stewardship responsibility: Low National PIF status: No special status New Mexico BCRs: 16, 34, 35, (18) Primary breeding habitat(s): Southwest Riparian  Other habitats used: Middle Elevation Riparian   Summary of Concern Common Black-Hawk is an obligate riparian-breeding species associated with mature, streamside gallery forests. The small New Mexico population is highly vulnerable to alterations or further losses of riparian forest habitat along perennial shallow streams.     Associated Species Great Blue Heron, Black-crowned Night-Heron, Gila Woodpecker (BC2), Brown-crested Flycatcher, Lucy’s Warbler (SC1), Summer Tanager (BC2), Hooded Oriole (BC2), Bullock's Oriole (SC2)   Distribution Common Black-Hawk, including several subspecies, is a widely distributed resident across much of central and southern Mexico, Central America, and northern South America. A migratory population breeds from Sinaloa and the northern Mexican states as far north as southwest Utah, northwest Arizona, and central New Mexico (Schnell 1994).   In New Mexico, this species is found along the Gila, San Francisco, and Mimbres Rivers in the southwest quadrant of the state, as well as along the Rio Hondo in the southeast. It occasionally nests along the Rio Grande as far north as Albuquerque, and in the Canadian River and Upper Pecos drainages (Hubbard 1978, Williams 1999, Parmeter et al. 2002).    Ecology and Habitat Requirements In the southwest United States, Common Black-Hawk is an obligate riparian nester. It favors mature gallery forests dominated by Fremont cottonwood or Arizona sycamore, and is usually associated with perennial streams with riffles and shallow (<12 inches) water depth. It may less commonly occur on intermittent streams if pools remain present. Common Black-Hawks prefer groves of larger trees, 75-100 ft. high. They frequently perch on exposed boulders or low branches along streams, and hunt for a variety of prey including fish, snakes, lizards and arthropods (Schnell 1994). Amphibians are a big component of its diet.  Common Black-Hawks arrive in New Mexico by mid-March, and may remain through September. Most nesting activity occurs mid-April to mid-June. Nest sites are generally located in mature, well-developed, relatively isolated gallery forest stands, with nests placed in the crotches of large tree trunks. Of 201 nests observed in Arizona and New Mexico, 79% were located in cottonwoods and 11% in sycamore (Schnell 1994). Normal clutch size is two eggs. Productivity may be directly related to an abundant food supply. Over 16 years at Aravaipa Canyon in Arizona, number of fledglings increased during years of highest fish populations (Schnell 1994).    Conservation Status Species Assessment   DISTRIBUTION  3  THREATS  4  GLOBAL POPULATION SIZE  3  LOCAL POPULATION TREND  2  IMPORTANCE OF NEW MEXICO TO BREEDING  1  COMBINED SCORE  13 Common Black-Hawk is a Biodiversity Conservation Concern, Level 1 species for New Mexico, with a total assessment score of 13. From NMPIF, it receives a high vulnerability score of 4 for threats to breeding in the state. Common Black-Hawk is listed as threatened in the state of New Mexico.    Population Size PIF estimates a species population of 2 million, although this is highly speculative. Less than one percent of the species population occurs in the United States. Schnell (1994) estimated a United States breeding population of 220-250 pairs. Size of the New Mexico population in 1994-1995 was 70-90 pairs (Skaggs 1996) and with recent nesting in eastern New Mexico to the Middle Rio Grande and the Canadian River, the statewide population is likely closer to 100 pairs (New Mexico Department of Game and Fish 2008). Reported densities include 1.3 nests/km2 in west-central Arizona; 0.4 pairs/km along Aravaipa Canyon in Arizona; 0.34 pairs/km along the Rio Bavispe in Sonora; and 0.10 pairs/km along the Rio Yaqui in Sonora (Rodriguez-Estrella and Brown 1990, Schnell 1994).   Population Trend No BBS data are available for this species. It receives a Local Population Trend score of 2 from NMPIF, indicating stable or moderately increasing numbers in the state.    Threats United States populations are thought to be self-sustaining, but are highly precarious due to possible future loss of riparian habitat (Schnell et al. 1988, Schnell 1994). Even moderate degeneration of mature riparian habitat may negatively affect this species, which requires groves of older trees for nesting. Flood-control and water diversion activities may reduce the capacity of gallery forests to be self-sustaining. Any significant modification or decrease in Gila River flows would likely have a large negative impact on the state population. Heavy grazing in shallow river areas may reduce water quality and resource abundance, and interfere with habitat regeneration. This species also has a limited tolerance for humans in breeding areas, where camping or other recreational activities may cause nest abandonment (Schnell 1994).     Management Issues and Recommendations Management for Common Black-Hawk in New Mexico should focus on maintaining the character and quality of streamside riparian habitat.    NMPIF Recommendations Monitor and manage riparian forests along the Gila, Mimbres, and San Francisco rivers. Encourage gallery forest and nest tree regeneration through appropriate water management when and where possible. Manage grazing as needed to encourage success of young cottonwoods. Explore possibilities for limiting human disturbance in key areas during the nesting period, through public lands management and conservation education.  Consider use of small impoundments near nest trees to concentrate resources and thereby increase likelihood of fledging success (Schnell 1994).    Species Conservation Objectives NMPIF Objectives Continue studies to assess status and trends of this species and its habitat. Maintain a minimum population of approximately 100 breeding pairs in the state, while seeking to increase the state population by 25% (Williams 1999). Maintain a stable or increasing nest success rate of at least 78%.    Sources of Information: Hubbard, J. P. 1978. Revised check-list of the birds of New Mexico. N. Mexico Ornithol. Soc. Publ. 6. New Mexico Department of Game and Fish. 2008. Threatened and endangered species of New Mexico: 2008 draft biennial review. Unpublished Report. 143 pp. Parmeter, J., B. Neville, and D. Emkalns. 2002. New Mexico Bird Finding Guide. New Mexico Ornithological Society, Albuquerque, NM. Rodriguez-Estrella, R., and B. T. Brown. 1990. Density and habitat use of raptors along the Rio Bavispe and Rio Yaqui, Sonora, Mexico. J. Raptor Res. 24:47-55. Schnell, J. H. 1994. Common Black-Hawk (Buteogallus anthracinus). In The Birds of North America, No. 122 (A. Poole and F. Gill, Eds.). Philadelphia, PA: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union. Schnell, J. H., R. L. Glinski, and H. Snyder. 1988. Common Black-Hawk. Pp. 65-70 in Southwest Raptor Management Symposium and Workshop (R. L. Glinski et al., eds.). Natl. Wildl. Fed., Washington, D.C. Skaggs, R. W. 1996. The Common Black-Hawk in southwestern New Mexico, 1994-1995 inventories. Report submitted to New Mexico Department of Game and Fish, Santa Fe, NM. 14 pp. Williams, S.O. 1999. Status of State of New Mexico Threatened and Endangered Species. New Mexico Dept. Of Game and Fish, Santa Fe, NM. Unpublished report.