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Age‐specific breeding probability in black brant: effects of population density
Author(s) -
Sedinger James S.,
Lindberg Mark S.,
Chelgren Nathan D.
Publication year - 2001
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1046/j.0021-8790.2001.00535.x
Subject(s) - branta , biology , juvenile , biological dispersal , population , anatidae , demography , density dependence , population density , vital rates , ecology , zoology , goose , population growth , sociology
Summary1 We estimated age‐specific probability of breeding for black brant ( Branta bernicla nigricans Lawrence) (hereafter brant) at the Tutakoke River Colony, Alaska, during a series of years in which local breeding density and juvenile mortality both increased. We use these analyses to examine demographic responses to increased population density. 2 Estimates of breeding probability were based on Kendall & Nichols (1995) full‐likelihood modification of Pollock’s (1982) robust design applied to observations of uniquely colour‐banded brant. 3 Breeding probability varied with female age but not across years, indicating lack of response to increased population density. Annual probability of breeding increased from 0·67 ± 0·042 for 2‐year‐old females to 0·90 ± 0·024 for females 5 years old or older. 4 Annual breeding probability of males ≥ 5 years old was 0·78 ± 0·03. Lower breeding probability of males compared to females probably reflects dispersal of males whose mates died. 5 Lower juvenile survival appears to be a general response to increased density in large herbivorous birds and mammals, while changes in adult survival and reproductive investment may be more variable.