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¿Son las declinaciones de las aves cantoras insectívoras de Norte América debidas a causas que afectan las áreas de reproducción?
Author(s) -
BöhningGaese Katrin,
Taper Mark L.,
Brown James H.
Publication year - 1993
Publication title -
conservation biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.2
H-Index - 222
eISSN - 1523-1739
pISSN - 0888-8892
DOI - 10.1046/j.1523-1739.1993.07010076.x
Subject(s) - insectivore , predation , nest (protein structural motif) , ecology , geography , population decline , habitat , range (aeronautics) , population , deforestation (computer science) , habitat destruction , biology , demography , biochemistry , materials science , computer science , programming language , composite material , sociology
Previous studies have reported a recent decline in breeding populations of migratory songbirds in eastern and central North America. Several explanations have been suggested: deforestation on the wintering grounds in the tropics and habitat loss, increased predation pressure, and increased cowbirds parasitism on the breeding range. We used these factors to assign 47 species of insectivorous passerines to groups with contrasting vulnerability, and then used the North America Breeding Bird Survey to analyze population trends in these groups on a large continental scale. Variables indexing susceptibility to predation on the breeding ground were most strongly correlated with population trends form 1968 to 1987. During the period from 1978 to 1987, migratory status was also significantly associated with population trends long‐distance migrants to the neotropics exhibited a small, nonsignificant decreasing trend, whereas residents and short‐distance migrants increased strongly. During the same time period, the group of species with low nest location, open nest, and high cowbird parasitism declined significantly. Although it is difficult to separate the effects of multiple factors, our analyses suggest that predation on the breeding ground in North America has played a larger role in the decline of migratory songbirds than deforestation on the wintering grounds in the tropics.