Diet and Feeding Ecology of Emperor Penguins
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Metadata record for data from ASAC Project 419 See the link below for public details on this project. From the abstracts of some of the referenced papers: The population size and breeding success of Emperor Penguins (Aptenodytes forsteri) at the Auster and Taylor Glacier colonies were estimated during the 1988 breeding season. At Auster a total of 10963 pairs produced about 6350 fledglings for a breeding success of 58%. At Taylor Glacier about 2900 pairs raised 1774 fledglings for a breeding success of 61%. Fledglings left Taylor Glacier over a period of 33 days at a mean mass of 10.56kg. The accuracy of the tritiated water (HTO) and sodium-22 (22Na) turnover methods as estimators of dietary water and sodium intake was evaluated in emperor penguins fed separate diets of squid and fish. Emperor penguins assimilated 76.2% and 81.8% of available energy in the squid and fish diets, respectively. Both isotopes had equilibrated with body water and exchangeable sodium pools by 2h after intramuscular injection. The tritium method yielded reliable results after blood isotope levels had declined by 35%. On average the tritium method underestimated water intake by 2.9%, with a range of -10.3% to +11.1%. The 22Na method underestimated Na intake on average by 15.9% with the errors among individuals ranging from -37.2% to -1.8%. Discrepancies with 22Na turnover were significantly greater with the squid diet than the fish diet. The results confirm the reliability of the tritium method as an estimator of food consumption by free-living emperor penguins (provided seawater and freshwater ingestion is known) and support the adoption of the 22Na method to derive an approximation of seawater of seawater intake by tritiated emperor penguin chicks and by tritiated adults on foraging trips of short duration. The diet composition of Emperor Penguin Aptenodytes forsteri chicks was examined at Auster and Taylor Glacier colonies, near Australia's Mawson station, Antarctica, between hatching in mid-winter and fledging in mid-summer by 'water-offloading' adults. Chicks at both colonies were fed a similar suite of prey species. Crustaceans occurred in 82% of stomach samples at Auster and 87% of stomachs at Taylor Glacier and were heavily digested; their contribution to food mass could not be quantified. Fish, primarily bentho-pelagic species, accounted for 52% by number and 55% by mass of chick diet at Auster, and squid formed the remainder. At Taylor Glacier the corresponding values were 27% by number and 31% by mass of fish and 73% by number and 69% by mass of squid. of the 33 species or taxa identified, the fish Trematous eulepidotus and the squid Psychroteuthis glacialis and Alluroteuthis antarcticus accounted for 64% and 74% of the diets by mass at Auster and Taylor Glacier, res pectively. The sizes of fish varied temporally but not in a linear manner from winter to summer. Adult penguins captured fish ranging in length from 60 mm (Pleuragramma antarcticum) to 250 mm (T. eulepidotus) and squid (P. glacialis) from 19 to 280 mm in mantle length. The length-frequency distribution of P. glacialis showed seasonal variation, with the size of squid increasing from winter to summer. The energy density of chick diet mix increased significantly prior to 'fledging'.
ASAC项目419数据集元数据记录。可通过下方链接查看该项目的公开详情。 以下源自部分参考文献的论文摘要： 1988年繁殖季，研究人员对奥斯特（Auster）与泰勒冰川（Taylor Glacier）繁殖地的帝企鹅（Aptenodytes forsteri）种群数量及繁殖成功率展开估算。奥斯特繁殖地共有10963对帝企鹅，共产下约6350只雏鸟，繁殖成功率为58%；泰勒冰川繁殖地约2900对帝企鹅抚育出1774只雏鸟，繁殖成功率达61%。泰勒冰川繁殖地的雏鸟在33天内陆续离巢，平均体重为10.56千克。 本研究以分别饲喂鱿鱼与鱼类的帝企鹅为实验对象，评估了氚化水（HTO）与钠-22（²²Na）周转法作为膳食水与钠摄入估算方法的准确性。帝企鹅在鱿鱼与鱼类日粮中分别同化了76.2%与81.8%的可利用能量。两种同位素在肌肉注射后2小时内，即可与体内水体及可交换钠池达到平衡。当血液同位素水平下降35%后，氚标记法可得到可靠结果。平均而言，氚标记法对水摄入量的估算值偏低2.9%，误差区间为-10.3%至+11.1%。钠-22标记法对钠摄入量的平均估算偏差为偏低15.9%，个体误差区间为-37.2%至-1.8%。鱿鱼日粮组的钠-22周转法估算偏差显著高于鱼类日粮组。本研究结果证实，氚标记法可可靠估算野生帝企鹅的食物消耗量（前提已知其海水与淡水摄入量）；同时支持采用钠-22标记法，近似估算经氚标记的帝企鹅雏鸟，以及进行短期觅食之旅的经氚标记成年帝企鹅的海水摄入量。 本研究借助‘控水卸载’的成年帝企鹅，于南极澳大利亚莫森站附近的奥斯特与泰勒冰川繁殖地，针对帝企鹅（Aptenodytes forsteri）雏鸟的日粮组成展开分析，采样时段覆盖从仲冬破壳至仲夏离巢的全周期。两个繁殖地的雏鸟均摄食相似的猎物类群组合。甲壳类动物在奥斯特繁殖地的82%胃容物样本中检出，在泰勒冰川繁殖地的87%胃样本中检出，但因消化程度过高，无法量化其在食物总质量中的占比。奥斯特繁殖地雏鸟日粮中，以深海底栖-远洋洄游物种为主的鱼类按数量占比达52%，按质量占比达55%，剩余部分为鱿鱼。泰勒冰川繁殖地的对应数值为：鱼类按数量占比27%、按质量占比31%，鱿鱼按数量占比73%、按质量占比69%。在已鉴定的33个物种类群中，奥斯特繁殖地日粮按质量计的64%由南极鱼（Trematomus eulepidotus）以及鱿鱼（Psychroteuthis glacialis和Alluroteuthis antarcticus）构成，泰勒冰川繁殖地的对应占比则为74%。鱼类体型随季节变化，但并非呈线性规律变化（从仲冬到仲夏）。成年帝企鹅捕获的鱼类体长范围为60毫米（南极侧带鱼Pleuragramma antarcticum）至250毫米（T. eulepidotus），鱿鱼（P. glacialis）的胴长范围为19至280毫米。冰鱿（Psychroteuthis glacialis）的体长频率分布存在季节差异，鱿鱼体型从仲冬到仲夏逐渐增大。雏鸟日粮混合食物的能量密度在离巢前显著升高。
