Extra-pair copulation and sperm competition in the zebra finch

  title={Extra-pair copulation and sperm competition in the zebra finch},
  author={Tim R. Birkhead and Jayne Pellatt and Fiona M. Hunter},
Most birds are monogamous, but recent studies have shown that extra-pair copulations (EPCs) occur frequently1,2 despite a range of paternity guards, including mate-guarding and frequent copulation1. Although EPCs are known to result in extra-pair paternity3–5, there are no previous quantitative estimates of the success of EPCs in fertilizing eggs. We present here estimates of the likelihood of success of extra-pair copulations in a monogamous passerine, the zebra finch Poephila guttata. We show… 

Ejaculate quality and the success of extra-pair copulations in the zebra finch

It is reported that the swimming velocity of sperm of the zebra finch, Taeniopygia guttata, varies predictably within males, and is determined, together with sperm numbers, by the time since last ejaculation.

Sperm competition in the zebra finch, Taeniopygia guttata

Mate Switching and Copulation Behaviour in the Adélie Penguin

A high frequency of copulation may have evolved in pair males to protect paternity against initial males in this species of penguin, and there is no support for last male sperm precedence from either diurnal or seasonal patterns of copulations relative to fertilisation.

Post-copulatory sexual selection and the Zebra Finch

The outcome of sperm competition in the Zebra Finch and other birds is best predicted by the passive sperm loss model, allowing for differences in sperm numbers and quality (fertilising capacity); last male sperm precedence is not a ‘rule’ in birds but is a consequence of the way sperm competition experiments have been conducted.

Frequent copulation as a method of paternity assurance in the northern fulmar

Occurrence of extra-pair copulation in the tree swallow (Tachycineta bicolor)

It is proposed that frequent pair copulations are used by males to ensure their paternity in their mate's offspring, as well as to mark sperm transfer events between birds.

Timing of pair and extra-pair copulations in the northern fulmar

In the Northern Fulmar (Fulmarus glacialis), fertilization is believed to occur within a few days prior to laying, but extra-pair and pair copulations and paternity defense behaviors start to decline around 20 days before egg laying, and by 9 Days prior to egg laying these behaviors are at a minimum.

Sperm competition in the European starling (Sturnus vulgaris): an experimental study of mate switching

This study evaluates sperm competition in the European starling by means of a mate-switching experiment and finds that the success of extra-pair copulations more than 2 d before egg-laying is probably very low.

Pair copulation frequency correlates with female reproductive performance in Tree sparrows Passer montanus

This study examines in a Tree Sparrow population the prediction that high pair-copulation frequencies are associated with better female reproductive performance and suggests that within-pair copulation frequency could be an early expression of the pairs' reproductive ability and might signal their phenotypic quality.

Extra-pair paternity results from female preference for high-quality males in the blue tit

Evidence is presented that such an asymmetry is indeed caused by female behaviour, and that 'attractive' males do not suffer lost paternity, survive better and recruit more young, and the results support the genetic quality hypothesis.



Copulation Behaviour of Birds

The predation and social bond hypotheses were not totally dismissed, but there was no evidence that fertilization ability was limited by copulation frequency (i.e. the fertilization hypothesis), and the sperm competition hypothesis was supported.


The possible advantages to a species of internal rather than external fertilization have frequently been stressed, though one important point appears persistently to have escaped comment. In terms of

Competitive Efficiency of Turkey Sperm

Critical studies by Olsen and Neher (1948) provided direct evidence that fertilization of the hen’s eggs took place in the ovary before ovulation.

Mate guarding in the magpie Pica pica

The effect of ratios and numbers of spermatozoa mixed from two males on proportions of offspring.

It appears that the relationship between sperm ratios and the proportions of offspring sired by two males competing heterospermically is dependent on the ratio of the number of competing spermatozoa but not on total number, season, breed of hen or the interval from insemination to fertilization.

DNA fingerprinting in birds

It is shown here that human minisatellite-derived probes also detect highly variable regions in bird DNAs and it is concluded that house sparrow DNA fingerprints are analagous to those of humans.