Don\u27t count your chicks before they hatch: incubation effort in Leach\u27s storm-petrel (Oceanodroma leucorhoa)

Parents must allocate available energy between the competing demands of self-maintenance and offspring care. Long-lived species such as Leach\u27s storm-petrel (Oceanodroma leucorhoa) may invest preferentially in self-maintenance because any one reproductive event comprises only a small proportion of lifetime reproductive success. During the early incubation period we increased the energetic cost of flight by trimming the outermost 1.5 cm of the primary remiges for one, both, or neither member of breeding pairs. We used egg neglect, length of the incubation period, and chick growth as measures of parental effort and the re-growth rate of an induced outer right rectrix as an index of energy allocated to self-maintenance. Percent neglect determined hatching success (P=0.03) and was higher in the early incubation period (P=0.051). Neglect late in the incubation period was positively correlated with male but not female feather growth rates (P=0.026). Length of the incubation period was positively correlated with percent late neglect (P=0.009) and feather growth rates (P\u3c0.05). We did not observe an effect of treatment on percent neglect, incubation length, chick growth, individual feather growth rate, or mean feather growth rate (P\u3e0.05). Feather growth rate for sham treatment individuals did not differ significantly (P\u3e=0.08) from that of trim treatment individuals