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Accession Number 5001877

Title Response of avian communities to forest management on Moosehorn NWR

Project Description Evidence from many recent studies indicate that populations of some neotropical migrant

landbirds are declining (Holmes et al. 1986, Askins and Philbrick 1987, Holmes and Sherry 1988,

Robbins et al. 1989, Askins et al. 1990). Because of the difficulty in studying populations of these

birds on an international scale, the causes of the declines and the geographic area where these

causes affect populations are poorly understood (Holmes et al. 1986, Robbins et al. 1989, Askins

et al. 1990). Several authors have proposed that tropical deforestation has caused declines (Hutto

1988, Robbins et al. 1989, Askins et al. 1990); other evidence supports the alternative hypothesis

that habitat degradation on breeding areas in North America is responsible (Sherry and Holmes

1992, Litwin and Smith 1992, Witham and Hunter 1992). Several populations of species that

migrate to the Neotropics declined in recent decades within North American landscapes where

breeding habitat became fragmented (Robbins 1979, Askins et al. 1990). A major tenet of wildlife

management has been that heterogeneity of habitat benefits wildlife through the edge effect. Many

habitat managers have broken up large homogeneous forests into patches to improve wildlife

habitat for wildlife (Robbinson 1988). During the 1980s this practice was criticized. Several

researchers have stated that small habitat patches are insufficient for large wide-ranging species

(Blake and Karr 1984, Hunter 1987, Whitcomb et al. 1981), and that small habitat patches contain

a disproportionate number of generalist species that compete with habitat specialists (Blake

1983). Nest success of many species suffers in small habitat patches because of parasitism by

brown-headed cowbirds and nest predation along edges (Chasko and Gates 1982, Brittingham

and Temple 1983, Wilcove 1985). Small forest fragments may not provide adequate forest-interior

habitat or special micro habitats such as streams and steep slopes (Bond 1957, Whitcomb et al.

1981, Lynch and Whigham 1984). Research on direct effects of various habitat management

techniques for game species on neotropical migratory birds, however, is sparse (Yahner 1986,

1988, 1991, Therres 1993). Although habitat management for game species may not be a major

environmental threat to neotropical migrant populations, modifications to habitat management for

game species that also benefits neotropical species would be desirable (Therres 1993).

Moosehorn National Wildlife Refuge (MNWR) in eastern Maine was established in 1936 as a

management area for American woodcock (Scolopax minor). The 6,580 ha area is 90% forested

and has had an active program to harvest wood since 1979. During 1978-81, Derleth et al. (1989)

used point counts to determine species richness and relative abundance of birds in conifer,

hardwood, and mixed-wood control (uncut) and treatment (clearcut 0-8 yrs. old) sites on MNWR.

Distributions of species abundance was different between control and treatment plots. Numbers of

species increased in treatment plots with more species gaining rather than losing individuals

(Derleth et al. 1989). Increases in estimated richness and diversity were noted in treated hardwood

and mixed growth stands, but not in conifer stands. Of the 68 species of birds recorded, 17

increased in relative abundance, whereas only 2 species declined after clearcutting began. Stand

treatment was associated with changes in the composition of the bird community. Derleth et al.

(1989) reported that the avian community benefitted and that early-successional species did not

increase at the expense of species requiring undisturbed forest. Creating small openings in

continuous forest had little effect on the avian community. The refuge now contains patches of the

original forest (~5,070 ha), which includes a 2,000 ha permanent wilderness area, and is

interspersed with clearcut blocks and strips <15 years old (~850 ha). We censussed the avian

community to determine if species richness, d

Keywords breeding bird surveys, clearcut, habitat management, neotropical migrants, songbirds,

Principal Daniel G McAuley, USGS Patuxent Wildlife Research Center:; Jerry R

Investigators Longcore, USGS Patuxent Wildlife Research Center:;

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