An Experimental Study of the Costs of Reproduction in the Kittiwake Rissa Tridactyla

Abstract

The cost of reproduction in Kittiwakes Rissa tridactyla were studied from 1990 to 1993 on Hornoy in northern Norway by enlarging and decreasing brood sizes of two chicks to three and one during the first week after hatching. No parents were able to raise the enlarged broods of three to fledging. Most chick mortality occurred in the 19—22 d age group. Chick body mass and fledging success were lower among enlarged broods than among reduced and control broods. Body mass of females, but not males, was lower at the end of the chick—rearing period in enlarged broods. Only those females rearing enlarged broods experienced a higher mortality during the next breeding season. Our results support Lack's hypothesis of clutch size regulation: Kittiwakes laid the maximal number of eggs they were able to raise successfully to fledging. Furthermore, as female Kittiwake mortality increased when clutches were enlarged, females have a trade—off between investment in current reproduction and investment in future reproduction. Because males and females responded differently to brood enlargement, fitness estimates showed that Kittiwakes may have a sex—specific optimal clutch size.

Differential fitness costs of reproduction between the sexes

“…First, although our results are consistent with the idea that reproduction incurs costs, and particularly for women, they do not demonstrate cause and effect, as causal inference is impossible in studies lacking experimental manipulations. Some field experiments with birds are consistent with our findings (37,38); however, they were not able to measure parental survival and cannot rule out the possibility that females were more likely than males to disperse from the study site. Second, the gender differences we found may not be a universal feature of humans, and future research should examine variation among populations.…”

Reproduction and summer mortality of blue mussels Mytilus edulis in the Magdalen Islands, southern Gulf of St. Lawrence

“…The reduction in future reproductive capacity caused by a decrease in survival or growth in exchange for increased current reproductive effort is called 'reproductive cost' (Reznick 1985). Reproductive cost is often measured in terms of lower survival of reproducers (Calow 1973, Tallamy & Denno 1982, Lemckert & Shine 1993, Boyd et al 1995, Jacobsen et al 1995, Luiselli et al 1996 and is called 'survival reproductive cost' (Bell 1980). As indicated by Roff (1992), it is hard to imagine that reproduction does not deplete the resources of an organism, thereby making it more prone to stress-related sources of mortality.…”

Seabird-fishery interactions: quantifying the sensitivity of seabirds to reductions in sandeel abundance, and identification of key areas for sensitive seabirds in the North Sea

“…However, despite predictions of life-history theory, recent studies of black-legged kittiwakes suggest that adult survival rates are reduced when birds have to work hard to provision chicks, either as a result of enlarged brood size or reduced food abundance (Jakobsen et al 1995, Golet et al 1998, Golet & Irons 1999. Changes in numbers of common guillemots attending ledges in Shetland in response to reduced sandeel stock ) despite almost no effect of this on common guillemot breeding success (Table 4), suggest a need to investigate the effects of sandeel abundance on more than just breeding success.…”