Breeding Habitat:Wetland-open water
Nest Type:N/A
Migration Status:N/A
Nest Location:N/A
In their United States breeding range, Anhingas are found from the Carolinas to eastern Texas. They are observed in relatively small numbers along BBS routes within this range, becoming most plentiful in southern Florida (Relative Abundance Map). Their relative scarcity on the BBS is not surprising, since this species seldom vocalizes. Most records pertain to sightings of soaring individuals or of birds occupying large wetlands, slow- flowing streams, and similar habitats bordered by woody vegetation. As a result of their low abundances and small sample sizes in most states, the BBS trend estimates should be viewed with some caution.
The 1966-1994 trend estimates are generally non-significant, except for a decline in the Central BBS Region (Trend List). With a non-significant increase in the Eastern BBS Region, the survey-wide trends are stable. There are no consistent geographic patterns to the trends, only scattered increases and declines (Trend Map). During 1966-1979, the trends are non-significant but generally positive. After 1980, Anhingas show significant declines in most areas including Florida, the Eastern and Central BBS regions, and survey-wide. As a result of their low relative abundances along most routes, the survey-wide indices exhibit no temporal patterns (Survey-wide Annual Indices). Indices for the Florida population are variable, but reasonably stable (Florida Annual Indices). Declines in the Mississippi Alluvial Plain (S05) stratum produce similar trends in Louisiana, and are largely responsible for the declines in the Central BBS Region (Mississippi Alluvial Plain Annual Indices).
The overall trends of Anhinga populations are poorly understood. Its breeding distribution has not markedly changed in recent decades, perhaps an indication of fairly stable populations. However, Oberholser (1974) thought this species was declining in Texas, especially in inland counties. Similar declines may have occurred in other states where wetland habitats continue to be drained (Tiner 1984), and may be reflected in the recent trends along BBS routes.
Oberholser, H.C. 1974. The bird life of Texas, Vol. 1. Univ. of
Texas Press, Austin, TX. 530 pp.
Tiner, R.W., Jr. 1984. Wetlands of the United States: current
status and recent trends. National Wetlands Inventory,
Washington, D.C. 59 pp.