Multiple maternity in black-headed gull Larus ridibundus clutches as revealed by protein fingerprinting

Abstract

Social monogamy with biparental care is the norm in gulls Laridae, but egg colour variation suggests that some nests may contain mixed clutches laid by more than one female. Here we use protein fingerprinting of egg albumen to assess the occurrence of mixed maternity clutches in three colonies of black-headed gulls. Among 160 analysed clutches with 1 egg, 34% contained eggs from more than one female, and 15% of the eggs in clutches 1 came from other females than the major female (laying most eggs in nest). Among clutches with 2Á3 eggs 28% were mixed, and among clutches with 4 or more eggs 89% contained eggs from two or more females. There were significantly fewer eggs from the major female in mixed nests (mean 02.0690.63 SD) than in non-mixed nests (mean 02.8290.43 SD). In nests without evidence of female conflict, hatching success of minority eggs was similar to that of eggs from the major female (12.5 and 8.4%, respectively). In 21% of mixed maternity nests, one or more minority eggs was buried or punctured, and 25% of eggs from major females were also found evicted, suggesting conflict between females and rejection of eggs. Intra-specific nest parasitism seems the most likely cause of mixed clutches, but there are also other possible causes.

Conspecific Brood Parasitism is Biased Towards Relatives in the Common Black-Headed Gull

“…Such estimates, however, may be underestimates as compared with assessments based on biochemical analysis (Grønstøl et al 2006). The frequency of parasitism in this species estimated from protein fingerprinting of egg albumen was in fact much higher as this yielded an average of 34% of clutches parasitized, sampled in three different colonies (Duda et al 2008).…”

“…Nests were monitored every day until the day the eggs hatched or were depredated. The details of the sample storage conditions, electrophoresis and gel reading are given in Duda et al (2008). We regarded an egg as rejected if we found a previously marked egg out of the nest cup within two days after the laying date (Lez v alowá-Piálková & Honza 2008).…”

“…Many aspects of breeding biology in the gull family are described, but CBP has rarely been studied (Moynihan 1955, Pierotti 1980, Nisbet & Drury 1984, Duda et al 2003, Duda et al 2008 Honza 2008). Rejection and acceptance of eggs dumped in Black-headed Gull nests have not been examined in terms of host-parasite relatedness.…”

“…As standard, 2 samples run on other gels were placed on both sides of each gel. The female whose eggs outnumbered the others in this nest was classified as the host (Duda et al 2008). When the number of eggs in a nest from two females was equal we could not assign host or parasite status, but we used those data for estimation of the relationship coefficient between them.…”

High level of extrapair fertilization in individual Tibetan azure‐winged magpies and their adaptive responses

“…The reason is that reduction of paternal care is costly for cuckolded males as their own offspring may starve in a larger, crowded nest (Du et al 2015). In contrast, in the cases of EPM, females often bury or puncture eggs that have been laid by other females, indicating that females are more likely to discriminate between their own eggs and those of others, which is perhaps based on the colour variation of eggs (Duda et al 2010). Therefore, the trade-off of a cuckolded breeder in caring for a mixed brood may also be influenced by whether it can discriminate extrapair young and its own offspring.…”