Correlations between sequential timing decisions do not necessarily indicate strategic behavior: a comment on Bêty et al.
Using correlation analysis, Bêty, Gauthier, and Giroux confirmed that individuals of the migrating snow geese (Chen caerulescens atlantica) arriving earlier on their breeding grounds experienced longer prelaying periods but laid earlier than late-arriving birds. They concluded that these birds strategically adjusted timing to optimize fitness. This test is, however, not sufficient to indicate strategic behavior. We show analytically that, without assuming strategic behavior, arrival date, prelaying period, and laying date are correlated with each other because of their sequential occurrence. We conclude that correlation tests on sequentially occurring variables are not sufficient to detect nonrandom relations.
Schroeder
Julia
J
Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom. julia.schroeder@gmail.com
Mitesser
Oliver
O
Hinsch
Martin
M
D000818:Animals; D001824:Body Constitution / Q000502:physiology; D005260:Female; D005777:Geese / Q000502:physiology*; D009425:Nesting Behavior; D012044:Regression Analysis; D012107:Research Design; D012726:Sexual Behavior, Animal / Q000502:physiology*; D013997:Time Factors