Breeding Grey-headed Lapwings avoid human disturbances during farming by laying eggs early

Abstract

Grey-headed Lapwings Vanellus cinereus nest in rice fields during the farming season, and hence must avoid human disturbance in order to rear their offspring. In this study, we examined the influence of human disturbance on the breeding success of this species. The survey was conducted from 2008 to 2015 in Ogura-ike Polder Reclaimed Land in Kyoto Prefecture. We found a total of 176 nests over eight years. Egg-laying occurred from March to July, but peaked in March and April. Before June, the main breeding habitat was rice fields, after which the birds moved to levees. Hatching success was highest in March and declined thereafter. Although egg-laying on levees increased in June, few nests succeeded in hatching. Hatching failure was caused by human disturbances (plowing and flooding) in rice fields. In the study area, full-scale plowing is during late April and early May. The incubation period of the Grey-headed Lapwing is known to be about a month, hence by laying eggs in March, they have a greater chance of avoiding serious human disturbance than if they nest later. In fact, nearly half of all surviving chicks were from eggs laid in March, thus early eggs contribute significantly to the next-generation. It is suggested that Grey-headed Lapwing are able to breed successfully by avoiding the human disturbances associated with rice farming.