MATE CHANGE BY KENTISH PLOVERS CHARADRIUS-ALEXANDRINUS

The mating system of Kentish Plovers was studied in Hungary in 1988-91 . Pairs renested together after clutch failure on 11 occasions. In add ition, two males and one female changed mates (sequential polygyny and polyandry) between clutches. Biparental care lasted 5.9+/-5.9 (s.d.) d (n = 20) from hatching to desertion, usually by the female. The dura tion of biparental care was not related to the sex of the deserting pa rent, but male-deserted broods hatched earlier than female-deserted on es. In 5 out of 11 cases when pairs renested together, they moved betw een breeding sites (11.8+/-5.8 (s.d.) km), as did all three birds who changed mates (10, 24 and 24 km). These recorded distances suggest tha t the low reported frequency of mate change may be more a reflection o f the high level of breeding dispersal than of the rarity of mate chan ge.