Nannopterum auritum

Urile and Nannopterum were formerly synonymized with Phalacrocorax (e.g., AOU 1983, 1998), but genetic data (Kennedy and Spencer 2014, Kennedy et al. 2019) show deep divergences within Phalacrocorax largely congruent with differences based on osteological data (Worthy 2011) (AOS 2021).

Large breeding range in North America; rapidly increasing populations.

BREEDING: southeastern Bering Sea and southern Alaska; southern British Columbia eastward through Manitoba to coastal Quebec and Newfoundland, south (in isolated colonies) to Baja California, coastal Sonora, central Chihuahua, central Durango, south-central Arizona, southern New Mexico, southern Texas, Gulf Coast, Florida, northern Bahamas, Cuba, Yucatan Peninsula, and Belize (Johnsgard 1993, AOU 1998). Breeding range in North America has expanded in recent years (Johnsgard 1993). Extirpated from Amchitka Island, Alaska, perhaps due to predation by arctic fox (ALOPEX LAGOPUS; Siegel-Causey et al. 1991). Occurs throughout most of the coastal breeding range and beyond when not breeding. NON-BREEDING: Pacific coast from Aleutians and southern Alaska south to Baja California and Nayarit; inland from Washington and Montana south to California and northeastern Colorado, southern Minnesota, and the Great Lakes south to northwestern Mexico, Oklahoma, Texas, and the Gulf states; and along the Atlantic coast, from Lake Ontario and New England south to Florida, Bermuda, the Bahamas, Greater Antilles, Yucatan Peninsula, and northern Belize (AOU 1998).

In 1994, 852 colonies throughout North America (Tyson et al. 1997); number of defined occurrences may be somewhat lower.

PERSECUTION: Has long been hunted for both eggs and meat. Persecuted because thought to compete with fishermen. Hunted illegally; in June of 1998, over 800 birds were shot in eastern Lake Ontario and 20 were shot in 1994 on Four Brothers Island, New York. Also hunted legally; in Quebec, Canada, a government-sponsored control program involves shooting adults, destroying nests, and spraying eggs with an oily substance that asphyxiates the embryos (QBW 1999). U.S. Fish and Wildlife Service permits the lethal take of cormorants, without a permit, on catfish and bait fish farms in 12 southeastern states and Minnesota, where economic impacts have been well-documented and non-lethal control has proven ineffective (USFWS 1999a). PESTICIDES: Contamination by organochlorine pesticides greatly reduced reproductive success during the 1950s and 1960s significantly reducing populations along the Great Lakes and in other areas (Anderson et al. 1969, cited in INRIN 1999; Weseloh et al. 1983, cited in USFWS 1999b). Eggshell thinning due to exposure to DDE, DDT, and PCB's widely reported during this period (INRIN 1999, USFWS 1999a). By the early 1970s, eggshells from the Great Lakes region were nearly 30% thinner than normal (Weseloh and Collier 1999). Contamination caused reproductive failure, and chicks that hatched sometimes had crossed bills, club feet, and eye and skeletal deformities (USFWS 1999a). Deformities resulting from the ingestion of PCBs have been noted in the vicinity of Green Bay, Wisconsin (Ehrlich et al. 1992). Populations increased in New England beginning 1970 after the use of these pesticides was banned; did not increase in other areas until the 1980s (USFWS 1999b). PREDATION: Predation of eggs and young by crows and ravens (CORVUS spp.) and gulls (LARUS spp.; INRIN 1999). Verbeek (1982) reports that crows were responsible for the destruction of 22 percent of eggs (first clutch) in British Columbia. Also, temporary food shortages may be a possible limiting factors. HABITAT: Nesting habitat may become an important limiting factor (USFWS 1999a). See also Spendelow and Patton 1988; Carroll 1988; Johnsgard 1993; Markham, 1978 COSEWIC report; Hyslop and Kennedy 1992; Chapdelaine and Brousseau 1992; Vermeer and Sealy 1984; Lensink 1984; Buckley and Buckley 1984).