Parental and chick responses of Laughing Gulls (Leucophaeus atricilla) to increase of flight costs and brood size

Abstract

One main line of thought in life history theory is that investment in offspring must be balanced to minimize negative impacts on adult survival and future breeding. Seabirds have been regarded as fixed investors, although they exhibit a whole gradient of life history traits. We studied the consequences of brood size (one and three chicks) and of increased flight costs to one mate of a pair (3- and 5-cm trimming of the edge of the primary feathers) on parental response and on survival and body condition of chicks of Laughing Gulls (Leucophaeus atricilla). Parent gulls modified their nest attendance when their mate was handicapped, in a pattern dependent on the sex of the latter. Trimming of males affected chicks more severely than that of females. On its part, brood size affected amount of feeding sessions. Both chick body condition and survival were negatively affected by larger broods and by increased flight costs of one of their parents, especially when it was the male. Overall, parental inversion exhibited adjustments depending on the requirements of the brood and the fact that males compensated better the increased flying costs of their mates than vice versa. Despite a certain capacity by the males to compensate for the increased flight costs of the females, compensation was insufficient, and much less so in females, especially in larger broods, affecting chicks’ body condition and survival.