Generalized linear models of the probability of accepting congeneric parasitic eggs in chaffinches and bramblings.

Stepwise backward deletion was used to simplify the global model including all parameters, and significance of parameters was evaluated by the change in deviance between models with and without the parameter in question. ΔTC is the only term included in the minimal adequate model. ΔTB denotes brightness contrast, and was calculated according to [25]. Volume and shape was calculated according to [86] and [87], respectively. Rejection rates were 0.60 (N = 151) for the chaffinch and 0.66 (N = 137) for the brambling. Mean (SD) of ΔTC and ΔTB, respectively, was 0.044 (0.023) and 6.48 (4.20) for the chaffinch and 0.051 (0.031) and 5.52 (4.01) for the brambling.