Conspecific brood parasitism and nest predation in moorhens

Conspecific brood parasitism was investigated in three species of moorhens on three different continents: common moorhens in the United Kingdom, lesser moorhens in Namibia, and American moorhens in Panama. These are nest data used to summarize population-level rates of conspecific brood parasitism and nest predation. The data reported here were collected using similar field methods, and include nest dates, clutch sizes (number of host eggs), number of parasitic eggs, and nest fates.

Methods
Common moorhens (United Kingdom, 1991-1993)

Data were collected over three field seasons at Peakirk Waterfowl Gardens in Cambridgeshire. Nests were monitored daily, and new eggs were uniquely marked with indelible ink upon discovery. Parasitic eggs were identified through sequence anomalies (when 2 eggs appeared on one day or at least 2 days after the host finished laying. Egg dimensions, color and spot pattern maculation helped distinguishing eggs laid in the same nest on the same day. All complete clutches were photographed and methods for identifying parasitic eggs were verified using DNA fingerprinting. Fates and hatching success of nests were determined from daily nest checks.

Lesser moorhens (Namibia, 1997)

Data were collected in what is now Nyae Nyae Concession Area in Bushmanland, Namibia, about 12 miles south of Tsumkwe. The breeding season began after long-awaited rains filled the salt pans and initiated the brief growing season in these ephemeral wetlands. Lesser moorhens nested within a 6-week period. Nests were monitored daily, and new eggs were uniquely marked with indelible ink upon discovery. Parasitic eggs were identified through sequence anomalies (when 2 eggs appeared on one day or at least 2 days after the host finished laying). In one nest, 2 eggs found buried within the nest upon discovery that did not match the host eggs in dimensions, background color and spot pattern were considered to be parasitic. A sample of complete clutches were photographed. Fates of nests were determined from daily nest checks.

American moorhens (Panama, 1999)

Data were collected on moorhen nests in floating vegetation on the Rio Chagres, close to Gamboa, Panama. Nests were monitored daily, and new eggs were uniquely marked with indelible ink upon discovery. Parasitic eggs were identified through sequence anomalies (when 2 eggs appeared on one day or at least 2 days after the host finished laying). Egg dimensions, color and spot pattern maculation helped distinguishing eggs laid in the same nest on the same day. Complete clutches were photographed. Fates of nests were determined from daily nest checks.