Showing papers by "Ralph Charles Mac Nally published in 1981"

Song energetics of the bladder cicada, Cystosoma saundersii

Abstract: 1.Males of Cystosoma saundersii produced their calling songs while tethered to holders. 2.Oxygen consumption during singing was 0·136 ml min −1 , equivalent to 45·0 mW, an increase of 42·55 mW over the resting metabolic rate. 3.Maximum sound output was 90·6 dB at 20 cm. The whole sound-field was measured and represents a power output of 0·35 mW. The efficiency of sound production is 0·82%. 4.Heat production, estimated from the weight of singing muscle, was 28·7 mW. This leaves 13·5 mW of output unaccounted for. 5.Comparison with other species of insects suggests that none are more than an order of magnitude more efficient than C. saundersii .

Spatial Dynamics and Breeding Ecology in the Cicada Cystosoma saundersii: The Interaction Between Distributions of Resources and Intraspecific Behaviour

Abstract: SUMMARY (1) The population dynamics of adults of Cystosoma saundersii are examined with special emphasis on the spatial dynamics of males and on the mating success associated with contrasting patterns of reproductive behaviour. (2) More males spend longer periods on, and attract more females to, smaller bushes ( 8 m3). (3) The spatial arrays of males are clumped independently of the distributions of the bushes from which they sing. Bushes were given relative weightings based on male preferences for different size classes of bushes. The inclusion of these weighting factors did not affect the above conclusion. (4) Males who share bushes space out so that they are 1-0 to 1.5 m apart. (5) The spatial arrays of males were found to depend, to a certain extent, on the distribution of males on the previous night. (6) Females select males only on the basis of their acoustic displays. The most successful males at obtaining matings were those which appeared to enhance the propagation of their songs by adopting several behavioural strategies. These strategies include the selection of smaller bushes; singing at a height which is maximally efficient for transmitting their song frequency; and by singing in close proximity to other males. Males occurred in pairs, trios and other multiples in bushes more frequently than would be expected in random distributions. Such males attract more females per capita than do isolated males.

On the reproductive energetics of chorusing males: Energy depletion profiles, restoration and growth in two sympatric species of Ranidella (Anura).

Abstract: The reproductive activity of males of two species of Ranidella was recorded for four years Linear densities and vocal activity were monitored, and correlated with rainfall Energy and ash content of somatic tissue were examined during the course of breeding seasons Depletions of energy reserves in somatic tissue, fat-bodies and livers were charted through each breeding season Allometric equations linking these energetic quantities with snout-vent length were used to estimate the growth between breeding seasons of soma, fat-bodies and livers Males invest heavily in current reproduction and relatively little in growth Virtually all of a male's reproductive expenditure is directed to mechanisms of intrasexual competition for matings rather than investment in gonads, gametes or parental behavior