We investigate parental food provisioning and chick growth to better understand how parental effort and territory structure relate to reproductive success in the American Black Oystercatcher. American Black Oystercatcher chick diet was comprised mainly of limpets. Most prey items were 20 mm or shorter in length. Provisioning rates (kJ h-1) were significantly correlated with mean delivery rates rather than mean prey size, and higher provisioning rates resulted from a greater number of deliveries of small prey items. Provisioning rates were extremely variable among pairs but increased significantly with brood size and brood age. Larger brood sizes occurred more frequently on shallow sloped territories, therefore provisioning rates were significantly higher on shallow sloped than steep sloped territories. Provisioning rates appeared to decrease with increasing intertidal slope, a trend significantly supported by the growth patterns of the slow-growing chick in multi-chick broods. The effect of intertidal slope became more important when chicks were older and demand was higher, with parents occupying shallow territories achieving higher provisioning rates to older chicks relative to parents on steep territories. We discuss the hypothesis that American Black Oystercatcher parents adjust parental effort with respect to territory quality and propose possible parental adjustment mechanisms.
|Publication status||Published - 2002|
- reproductive success