Field energetics of free-living, lactating and non-lactating echidnas (Tachyglossus aculeatus).

We measured daily energy expenditure (DEE) and water turnover rates in lactating and non-lactating short beaked echidnas (Tachyglossus aculeatus) using the doubly labelled water technique during the lactation period in spring. Reproductively inactive echidnas were on average significantly heavier (median: 3354 g; range: 2929-3780 g; N=4) than lactating females (median: 2695 g; range: 2690-2715 g; N=3) during the equivalent time period. The median water flux rate of lactating echidnas (152 ml day(-1); range: 120-198 ml day(-1)) did not differ significantly from that of non-lactating females (170 ml day(-1); range: 128-227 ml day(-1)). The median DEE of echidnas that were lactating was 645 kJ day(-1) (range: 581-850 kJ day(-1)), which was not different from the median DEE of non-reproductive control females (763 kJ day(-1); range: 720-766 kJ day(-1)). Lactating females somehow compensate for the energy costs of milk production, resulting in a daily energy budget that is not different from that of non-reproductive females. At least part of their energy minimising strategy could involve the use of moderate heterothermy, allowing a greater proportion of daily energy expenditure to diverted to milk production.

Resting metabolic rates of Lepilemur ruficaudatus.

Seventeen sportive lemurs (Lepilemur ruficaudatus) were captured in a dry, deciduous forest in western Madagascar, and the resting metabolic rates were measured. According to the data, resting metabolic rates of Lepilemur ruficaudatus are among the lowest of mammalian folivores recorded so far. © 1996 Wiley-Liss, Inc.

Insect secretions determine habitat use patterns by a female lesser mouse lemur (Microcebus murinus).

The lesser mouse lemur (Microcebus murinus) is one of six sympatric nocturnal primates found in the Kirindy forest, west-Madagascar. Each of these species is reported to consume a secretion produced during the austral winter by the Homopteran insect Flatidia coccinea. In July and August 1993 a study was conducted to determine the importance of this food resource in the ecology of female M. murinus. At this study site, animals were distributed only along the forest edge where insect secretions are significantly more abundant than in the forest interior. Abundances of arboreal and nocturnal flying insects do not differ between the forest edge and interior. Experimental resource removal from a 25 × 25 m plot in one female's home range caused a significant shift in the animals' pattern of habitat use while no change occurred in a control plot. Thus, at this study site and time of year, the ranging behavior of a female M. murinus was strongly influenced by the presence of Homopteran secretions. © 1995 Wiley-Liss, Inc.