1.

J. Aschoff & H. Pohl . 1970. Der Ruheumsabz von Vogeln als Funktion der Tageszeit und der Körpergrosse. J. Orn. 111: 38–47. Google Scholar

2.

R. V. Baudinette & K. Schmidt-Nielsen . 1974. Energy cost of gliding flight in Herring Gulls. Nature (Lond.) 248: 83–84. Google Scholar

3.

S. Brody 1945. Bioenergetics and growth. Hafner, New York. Google Scholar

4.

D. M. Bryant 1975a. Breeding biology of House Martins Delichon urbica (L) in relation to aerial insect abundance. Ibis 117: 180–216. Google Scholar

5.

D. M. Bryant 1975b. Changes in incubation patch and weight in the nesting House Martin. Ringing & Migration 1: 33–36. Google Scholar

6.

D. M. Bryant 1978. Environmental influences on growth rate and survival of nestling House Martins. Ibis 120: 271–283. Google Scholar

7.

D. M. Bryant 1979. Reproductive costs in the House Martin. J. Anim. Ecol. 48: 655–675. Google Scholar

8.

D. M. Bryant & A. Gardiner . 1979. Energetics of growth in House Martins. J. Zool. Lond. 189: 20 pp. Google Scholar

9.

D. M. Bryant & K. R. Westerterp . (in press). Energetics of foraging and free existence in birds. Int. ornith. Congr. Berlin(1978). Google Scholar

10.

P. R. Evans 1976. Energy balance and optimal foraging strategies in Shorebirds: some implications for their distribution and movements in the non-breeding season. Ardea 64: 117–139. Google Scholar

11.

C.J. Hails 1977. Energetics of free-living House Martins (Delichon urbica) during breeding. Unpublished Ph. D. thesis, University of Stirling. Google Scholar

12.

C. J. Hails 1979. A comparison of flight energetics in hirundines and other birds. Comp. Biochem. Bioch. Physiol. 63A: 581–585. Google Scholar

13.

C. J. Hails & D. M. Bryant . 1979. Reproductive energetics of a free-living bird. J. Anim. Ecol. 48: 471–482. Google Scholar

14.

P. J. Jones & P. Ward . 1977. The level of reserve protein as the proximate factor controlling the timing of breeding and clutch size in the Red-billed Quelea. Ibis 118: 547–574. Google Scholar

15.

S. C. Kendeigh , V. R. Dolnik & V. M. Gavrilov . 1977. Avian Energetics. In J. Pinowski & S. C. Kendeigh . (Eds). Granivorous birds in ecosystems. I.B.P. 12, Cambridge University Press: 127–203. Google Scholar

16.

J. R. Krebs 1978. Optimal foraging: decision rules for predators. In J. R. Krebs & N.B. Davies (Eds) Behavioural ecology: an evolutionary approach. Black-wells, Oxford. Google Scholar

17.

E. A. Lefebvre 1964. The use of D₂O¹⁸ for measuring energy metabolism in Columba livia at rest and in flight. Auk 81: 403–416. Google Scholar

18.

N. Lifson , G. B. Gordon & R. M. McClintock . 1955. Measurements of total carbon dioxide production by means of D₂O¹⁸ J. appl. Physiol. 7: 704–710. Google Scholar

19.

R. A. Norberg 1977. An ecological theory on foraging time and energetics and choice of optimal food searching method. J. Anim. Ecol. 46: 511–530. Google Scholar

20.

C. J. Pennycuick 1972. Soaring behaviour and performance of some East African birds, observed from a motorglider. Ibis 114: 178–218. Google Scholar

21.

L. R. Taylor & J. M. P. Palmer . 1972. Aerial sampling. In H. F. van Emden (Ed.) Aphid Technology, Academic Press, London. Google Scholar

22.

J. M. Utter & E. A. Lefebvre . 1970. Energy expenditure for free-flight by the Purple Martin (Progne subis). Comp. Biochem. Physiol. 35: 713–719. Google Scholar

23.

J. M. Utter & E. A. Lefebvre . 1973. Daily energy expenditure of Purple Martins (Progne subis) during the breeding season: estimates using D₂O¹⁸ and time budget methods. Ecology 54: 597–603. Google Scholar

24.

D. R. Waugh 1979. Predation strategies of aerial feeding birds. Unpublished Ph. D. thesis, University of Stirling. Google Scholar