Niedrige Ei- und Körpertemperatur („Hypothermie“) bei brütenden Gelbschnabelsturmtauchern (Calonectris diomedea)
Body and egg temperatures of Cory's Shearwater were recorded in an Aegean colony. Body temperatures of breeding birds were 2 ° C lower than those of non-breeding, resting adults and accounted for 36.7±0.41 ° C in ♂ and 37.6±0.59 ° C in ♀. Incubation temperature, determined telemetrically inside incubated eggs, was 29.6±0.6° C.
Egg Temperature and Embryo Metabolism in Some High-Latitude Procellariiform Birds
The embryos of Procellariiformes develop slowly, reportedly, at least in part, as a result of low incubation temperatures, and some species such as Wilson's and Leach's storm petrels experience long periods of chilling. Incubation temperatures of eggs of Leach's storm petrel (on Kent Island, New Brunswick), Wilson's storm petrel, and the southern giant fulmar (Palmer Station, Antarctica) averaged 35.9, 35.7, and 35.5 C, respectively. These are well within the range of temperatures for other species of birds and indicate that the prolonged incubation periods of petrels are not attributable to low incubation temperatures. We measured the depressing effect of cooling (Q10) on rate of heartbeat of small embryos and rate of oxygen consumption of larger embryos. Values of Q10 increased at lower temperatures but in most cases did not differ from, or in some cases even exceeded, the values for embryos of species that lack cooling tolerance. Large embryos of the giant fulmar, which has slow embryonic development but continuous incubation, did not survive prolonged chilling, indicating that not all slowly developing embryos tolerate protracted cooling, at least in their late stages of development. Rates of oxygen consumption by storm petrel embryos were about two-thirds the level of the similarsized but rapidly growing Japanese quail embryo. Giant fulmar embryos exhibited low rates of oxygen consumption, as do other Procellariiformes, but, surprisingly, so did the rapidly growing skua embryos.
Breeding of the Mallee-fowl, Leipoa ocellata Gould (Megapodiidae)
The beginning and the end of the breeding season of the mallee fowl, Leipou ocellata Gould, are determined by the availability of natural heat for incubation. The breeding is confined to the summer because that is the only time when sufficient heat is available. The clutch size is a function of the length of the period suitable for egg-laying and the interval between successive eggs. The former is determined largely by the amount of winter rainfall and by the composition and location of the mound. The interval between eggs is affected by the amount of food available to the birds. Clutch size, then, is ultimately determined by the food supply of the female. Quantitative data on the size of mallee fowl eggs are presented and seasonal trends in egg size are discussed.