SPECIES

Bachman's Warbler Vermivora bachmanii Scientific name definitions

Paul B. Hamel
Version: 1.0 — Published March 4, 2020
Text last updated August 19, 2011

Conservation and Management

Effects of Human Activity

Shooting And Trapping

Shooting and trapping for scientific and millinery purposes were apparently frequent during 1886–1915, when this species was locally numerous.

Pesticides And Other Contaminants/Toxics

Not investigated.

Collisions With Stationary/Moving Structure

27 birds known dead owing to collision with lighthouses (Bassett 1941, Dingle 1953).

Disturbance At Nest

Sensitivity unknown. Stevenson (Stevenson 1938) visited a breeding territory several times but did not remark on this. Wayne (Wayne 1910) was unable to locate females after collecting nests and clutches of eggs, although other early observers (e.g., Widmann 1897) remarked that females sat incubating until observer touched them.

Degradation Of Habitat: Breeding And Wintering

Most probable cause of decline of this species. Direct effects of land clearing and indirect effects of exposure to increased levels of potential predation and nest parasitism, in addition to natural catastrophes and decrease in gross habitat in geologic time, likely reduced species to current status of possibly extinct.

Human/Research Impacts

Not known; probably unimportant. Many specimens were collected, prompting some (L. M. Wright pers. comm.) to suggest that this may have impacted populations. I believe that such impacts were negligible, however, using the following logic (J. V. Remsen pers. comm.). The total number of known specimens is approximately 400. Widmann (Widmann 1907a) and Howell (Howell 1910b) considered the species to be “fairly common” or “moderately common” in areas where they worked in the middle Mississippi alluvial valley. Widmann (Widmann 1897: 305, 309) found “several” [i.e., suppose 3] on approximately 16 ha of a 57-ha tract, suggesting that perhaps 25% of the land provided suitable habitat for a population at a density of 19 pairs/km2. The total land area of Greene Co., AR, and Dunklin Co., MO, where Widmann worked, is approximately 2,907 km2 (Winters and Roberts 1948, Sternitzke 1960). If 25% of that land was potentially suitable habitat, occupied at a density only 10% of that inferred from Widmann, then approximately 1,400 Bachman's Warblers were in the population Widmann studied. Assuming an annual adult mortality of 30% yields an annual loss of approximately 400 adults from those 2 counties—a number equivalent to the total number of specimens collected. Such a brief calculation indicates that scientific collecting probably had little effect on this species, especially when compared to the habitat destruction caused by clearing land for agriculture and other purposes.

Management

Conservation Status

First listed as Endangered by the U.S. Fish and Wildlife Service in 1973 and subsequently by all states in its historical range.

Measures Proposed And Taken

Measures proposed and taken to produce and enhance habitat for this species have been few. One experimental manipulation to produce habitat was conducted in Francis Marion National Forest, SC (Hamel 1986). The manipulation attempted to create numerous small openings in a mature stand of bottomland hardwood forest. The resulting stand had structural characteristics similar to those in historical descriptions of nesting habitat. The species' response could not be determined, for no individual was found in the manipulated stand or elsewhere.

Recommended Citation

Hamel, P. B. (2020). Bachman's Warbler (Vermivora bachmanii), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bacwar.01