Clutch and egg size in a Spanish population of Litlle Grebe (Tachybaptus ruficollis)

• Autores: Ricard Gutiérrez Benítez, Jordi Figuerola Borras
• Localización: Butlletí del Grup Català d'Anellament, ISSN 1130-2070, Vol. 12, Nº. 1, 1995, págs. 23-27
• Idioma: inglés
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• Resumen

  • It has been suggested that clutch size in the liftle Grebe could follow a latitudinal cline in Europe. Clutch and egg sizes from cornplete first clutches were studied in the llobregat Delta (NE Spain) between 1992 and 1995. Mean clutch size was 5.7 eggs(s. D. 0.93, n= 76, range 4-7). Mean egg length was 37.4 ± 1.3 mm and mean egg width was 26.150.8 mrn (n=67, range 34.6-40.4 x 23.7-27.6) with a volume of 13.02 ± 7.7 cm3 (n=67). Mean clutch size was significantly greater than that estimated in Austria and ltaly (F2.44= 6.0, p=0.005 one-way ANOVA), being one of the highest reported for Europe. No differences in egg size were found between localities. Differences in clutch size cannot be explained by a latitudinal cline alone, as suspected unti1 now. Additional factors such as habitat quality and wetland characteristics probably play a rnore important role in deterrnining Little Grebe clutch size.