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COUNTERINTUITIVE PARENTAL INVESTMENT BY FEMALE DABBLING DUCKS IN RESPONSE TO VARIABLE HABITAT QUALITY
Author(s) -
Gunness Michelle A.,
Clark Robert G.,
Weatherhead Patrick J.
Publication year - 2001
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/0012-9658(2001)082[1151:cpibfd]2.0.co;2
Subject(s) - anas , waterfowl , ecology , biology , anatidae , nest (protein structural motif) , reproduction , population , habitat , avian clutch size , abundance (ecology) , wetland , demography , biochemistry , sociology
A central tenet of parental investment theory is that parents should invest more in offspring that are more valuable. Among prairie waterfowl, duckling survival is higher in wetter years. Thus, we tested the prediction that female dabbling ducks should take greater risks protecting their offspring in wetter years. As our measure of risk‐taking, we used the distance at which incubating females flushed from nests when approached by an observer. Data were collected for Mallard ( Anas platyrhynchos ), Blue‐winged Teal ( A. discors ), and Gadwall ( A. strepera ) nesting on the same study area in south‐central Saskatchewan, Canada, over a 14‐yr period during which wetland abundance varied by almost an order of magnitude. Flushing distances of incubating females varied significantly with wetland conditions in all three species, but in a direction opposite to that predicted. Female ducks risked less for their nests in wetter years. These results could not be explained by differences among years in nest initiation dates, renesting potential, clutch size, or age structure of the breeding population. We propose that our counterintuitive results may be a consequence of the way in which wetland abundance affects the cost of reproduction in these ducks. If postbreeding survival of females is higher in wetter years, and increases faster than that of their ducklings as a function of increasing wetland abundance, then the value of the females to themselves (i.e., future reproduction), relative to the value of their current reproductive attempt, could favor reduced parental investment in wetter years.