Confidence of paternity and male parental care: an experimental study in tree swallows

Based on the model of Whittingham et al. (1992, Am. Nat., 139, 1115-1125), it is predicted that males in many monogamous species of birds will not decrease their level of parental care until their confidence of paternity is very low (threshold response). This prediction was tested by holding monogamous male tree swallows, Tachycineta bicolor, in captivity for 1 or 3 days during their mate's fertile (pre-laying, laying) or non-fertile (incubation) periods.