Eider (Somateria mollissima) Science Article 4
Egg size of Eiders Somateria mollissima was studied in the colony on Vlieland, The Netherlands, during six consecutive years. Mean length and breadth of 2476 eggs was 77.84 and 51.25 mm, respectively. Mean volume measured of 1882 of these eggs was 104.03 cm-3. A large variation in egg size was found, the volume of the smallest egg being only 53 of the largest one. Major factors influencing the size variation appeared to be differences between females and the position of the egg in the laying sequence of the clutch. Differences in egg size between females were not related to their body size. The first egg in a clutch was smaller than the second, but the last egg was the smallest. Also clutch size and age of the female contributed to the variation. Females produced smaller eggs as they grew older. Age affected the last eggs in the clutch more than the first ones. Mean egg size varied only slightly among years, though temperatures in winter and food conditions in spring varied considerably during the study.
Swennen C. & Van Der Meer J., ARDEA 80 (3): 363-373
Eider (Somateria mollissima) - Mwili wa Eider (Somateria mollissima) - ni aina ya ndege wa aina ya Somateria mollissima, ambaye amekuwa akichunguza mayai yake kwa miaka sita mfululizo. Kwa mfano, urefu wa kawaida wa mayai 2476 ulikuwa 77.84 mm na upana wa wastani wa mayai 2476 ulikuwa 51.25 mm. Kiasi cha wastani cha mayai hayo ni 104.03 cm3. Utaratibu wa kuhifadhi mayai ulibadilika kwa kiasi kikubwa, kwa kuwa kiasi cha mayai madogo zaidi kilikuwa na kiasi cha 53 tu cha ile kubwa zaidi. Vitu vikubwa vinavyoathiri tofauti za ukubwa zilionekana kuwa tofauti kati ya wanawake na nafasi ya yai katika mfululizo wa kuweka clutch. Tofauti katika ukubwa wa mayai kati ya wanawake hazikuhusiana na ukubwa wa mwili wao. Yai la kwanza katika kundi lilikuwa dogo kuliko la pili, lakini ya mwisho ilikuwa ndogo zaidi. Pia ukubwa wa kundi na umri wa mwanamke ulichangia tofauti hiyo. Wanawake walitokeza mayai madogo kadiri walivyozeeka. Umri huathiri mayai ya mwisho katika kundi zaidi ya yale ya kwanza. Ukubwa wa mayai ulitofautiana kidogo tu kati ya miaka, ingawa joto wakati wa majira ya baridi kali na hali ya chakula katika majira ya kuchipua ilitofautiana sana wakati wa utafiti. Swenn & Van der Meer, J.