70 
ALAN LILL 
elegans , and grey moorhen, Gallinula chloropus, 
respectively (Meanly 1969, Ar & Rahn 1985). 
However, M H7G is significantly (30-31%) lower 
than expectedln the Sora rail, Porzana Carolina 
(Drent 1970), and G H2 o is 87% greater than 
would be predicted from egg mass in the Eu¬ 
rasian coot, Fulica atra (Lomholt 1976). In the 
American coot, Fulica americana , P n is not par¬ 
ticularly elevated (2.4 kPa) and Gh^o accords 
with allometric predictions; the egg has a stand¬ 
ard fractional mass loss during incubation, yet 
M h ,o is 17-21% less than would be expected on 
allometric grounds (Drent 1970, Davis et al. 
1984). 
Much more work is required before the inci¬ 
dence of wet-nesting in the Rallidae can be fully 
assessed. Clearly, however, the purple swamp- 
hen and dusky moorhen, despite their nesting 
habits, do not exhibit the wet-nesting syndrome 
typical of some other freshwater birds with sim¬ 
ilar nest placement, such as grebes and loons. 
ACKNOWLEDGEMENTS 
I am grateful to Peter Fell, Peter Domelow, Neil 
Morley, Tym Barlow, La Trobe University and 
the Zoological Board of Victoria for facilitating 
this work in various ways. 
REFERENCES 
Ar, A. & Rahn, H., 1978. Interdependence of gas con¬ 
ductance, incubation length, and weight of the 
avian egg. In Respiratory Function in Birds, 
Adult and Embryonic, J. Piiper, ed., Springer- 
Verlag, Berlin, 227-236. 
Ar, A. & Rahn, H., 1980. Water in the avian egg: over¬ 
all budget of incubation. American Zoologist 
20: 373-384. 
Ar, A, & Rahn, H., 1985. Pores in avian eggshells: gas 
conductance, gas exchange and embryonic 
growth rate. Respiration Physiology 61: 1-20. 
Ar, A., Paganelli. C. V., Reeves. R. B.. Greene, D. 
G. & Rahn, H., 1974. The avian egg: water 
vapor conductance, shell thickness and func¬ 
tional pore area. Condor 16: 153-158. 
Ar. A., Rahn, H. & Paganelli, C. V., 1979. The avian 
egg: mass and strength. Condor 81: 331-337. 
Beruldsen, G., 1980. A Field Guide to Nests and Eggs 
of Australian Birds. Rigby, Adelaide. 
Carey, C, 1979. Increase in conductance to water 
vapor during incubation in eggs of two avian 
species. Journal of Experimental Zoology 209: 
181-186. 
Davis, T. A., Platter-Reiger, M. F. & Ackerman. 
R. A., 1984. Incubation water loss by pied¬ 
billed grebe eggs: adaptation to a hot, wet nest. 
Physiological Zoology 57: 384-391. 
Drent, R., 1970. Functional aspects of incubation in 
the Herring Gull. Behaviour, Supplement 17:1 — 
132. 
Drent, R., 1972. Adaptive aspects of the physiology 
of incubation. Proceedings of the 15th Inter¬ 
national Ornithological Congress, The Ham 
254-280. * ’ 
Falla, R. A., Sibson, R. B. & Turbott, E. G., 1985 
Collins Guide to the Birds of New Zealand. 
Collins, Auckland. 
Garnett, S. T., 1978. The behaviour patterns of the 
dusky moorhen Gallinula tenebrosa Gould 
(Aves: Rallidae). Australian Wildlife Research 
5: 363-384. 
Hoyt, D. F., 1976. The effect of shape on the surface- 
volume relationships of birds 1 eggs. Condor 78- 
343-349. 
Hoyt, D. F., 1979. Practical methods of estimating 
volume and fresh weight of bird eggs Auk %■ 
73-77. 
Lomholt, J. P., 1976. Relationship of weiglit loss to 
ambient humidity of bird eggs during incuba¬ 
tion. Journal of Comparative Physiology % 105- 
189-196. 
Meanly, B., 1969. Natural history of the king rail. 
North American Fauna 67: 1-108. 
National Photographic Index of Australian 
Wildlife, 1985. The Waterbirds of Australia. 
Angus & Robertson, Melbourne. 
O’Grady, G. Y. & Lindsey, T., 1 919 . Australian Birds 
and their Young , Cassell, Stanmore. 
Rahn, H., 1984. Factors controlling the rate of incu¬ 
bation water loss in bird eggs. In Respiration 
and Metabolism of Embryonic Birds , R. S. Sey¬ 
mour, ed.. Plenum Press, New York. 272- 
288. 
Rahn, H. & Ar, A., 1974. The avian egg: incubation 
time and water loss. Condor 76: 147-152. 
Rahn, H., Ackerman, R. A. & Paganelli, C. V.. 
1977. Humidity in the avian nest and egg water 
loss during incubation. Physiological Zoology 
50: 269-283. 
Rahn, H., Paganelli, C. V. & Ar, A., 1987. Pores and 
gas exchange of avian eggs: a review .Journal of 
Experimental Zoology , Supplement 1: 165- 
172. 
Rahn, H., Paganelli, C. V., Nisbet, 1. C. T. & 
Whittow, G. C., 1977. Regulation of incuba¬ 
tion water loss in eggs of seven species of terns. 
Physiological Zoology 49: 245-259. 
Seymour, R. S. & Rahn, H., 1978. Gas conductance 
in the eggshell of the m ound-building brush tur¬ 
key. I n Respiratory Function in Birds, Adult and 
Embryonic , J. Piiper, ed., Springer-Verlag. 
Berlin, 243-246. 
Soper, M. F., 1972. New Zealand Birds. Whitcombe# 
Tombs, Christchurch. 
SOTHERLAND, P. R.. ASHEN, M. D., SHUMAN, R. D. 
&Tracy, C. R., 1984. The water balance of bird 
eggs incubated in water. Physiological Zoolog}' 
57: 338-348. 
Walsberg, G. E., 1 980. The gaseous microclimate of 
the avian nest during incubation. American 
Zoologist 20: 363-372. 
Williams, G. W., 1966. Birds of New Zealand. Reed. 
Wellington. 
