Geolocators reveal incubation and re-nesting characteristics of Ruddy Turnstones Arenarla Interpres and Eastern Curlews Numenius madagascariensis

We report findings from geolocators on the breeding phenology and incubation of Ruddy Turnstones and Eastern Curlews. Output from 26 geolocators deployed and retrieved from Ruddy Turnstones in SE Australia during 2009–2011 showed that two birds failed to breed but the other 24 made one or two nesting attempts. Eight were apparently successful in hatching their first clutch having incubated for a full term; 16 lost their first clutch and seven of them did not attempt to re-nest; the other nine re-nested, and of those, four succeeded and five failed. The nine birds that re-nested lost their first clutches significantly earlier than the seven that did not attempt to re-nest. This study is the first to report re-nesting in arctic-breeding Ruddy Turnstones. In 2011, half the birds that nested successfully (4/8) did so because they re-nested suggesting that re-nesting might make a significant contribution to overall breeding productivity. For 12 Ruddy Turnstones that completed full-term incubation periods, there was no systematic difference between the sexes in the length of incubation bouts or in the aggregate time spent incubating per day. However, these parameters differed significantly between individual birds and some spent considerably more time incubating than others. Time spent incubating per day averaged 9.9 hours and showed no significant change across the incubation period. The length of incubation bouts showed a significant humped, quadratic relationship with the incubation period, increasing steeply over the first nine days and declining towards the end. Output from three geolocators deployed and retrieved from Eastern Curlews in SE Australia in 2011 showed that all three failed to nest successfully, with one bird possibly making an unsuccessful second nesting attempt. This study demonstrates the value of using geolocators to study the behaviour of arctic-breeding waders.