Interaction of bodymass, fat, foraging and stopover period in trans-Sahara migrating passerine birds

SummaryThe effect of body mass and fat reserves on the choice of the stopover place and on the stopover period was investigated in 3 species of passerine birds migrating through the Sahara in Egypt. Birds grounded in an oasis with food and water were more than 10% lighter than those from a desert stopover place which offered shade only. Stopover period was in general one day except for the light portion of oasis birds which stopped for up to three weeks during which they regained fat. A calculation of the maximum range which can be covered with the available fat depots revealed that nearly all birds from the desert stopover place should be able to cross the desert whereas about 60% of the oasis birds should not. An intermittant migratory strategy for the desert crossing is proposed with flight during the night and stopover during the day, even without drinking and feeding.

[1]  R. Green,et al.  Foraging behaviour of migrant pied flycatchers, Ficedula hypoleuca, on temporary territories. , 1980 .

[2]  P. Berthold.  Migration: Control and metabolic physiology , 1975 .

[3]  R. Marsh.  Adaptations of the Gray Catbird Dumetella carolinensis to Long-Distance Migration: Flight Muscle Hypertrophy Associated with Elevated Body Mass , 1984, Physiological Zoology.

[4]  G. Zink.  Der Zug europäischer Singvögel. Ein Atlas der Wiederfunde beringter Vögel. 2. Lieferung , 1975 .

[5]  B. Wood.  Weights of Yellow Wagtails wintering in Nigeria , 1978 .

[6]  G. Zink.  Der Zug europäischer Singvögel. Ein Atlas der Wiederfunde beringter Vögel. 1. Lieferung (30 Arten) , 1973 .

[7]  D. Borror.  Analysis of Repeat Records of Banded White‐Throated Sparrows , 1948 .

[8]  R. Meinertzhagen.  Nicoll's Birds of Egypt , 1931 .

[9]  H. Biebach.  Sahara stopover in migratory flycatchers: fat and food affect the time program , 1985, Experientia.

[10]  G. Zink.  Richtungsänderungen auf dem Zuge bei europäischen Singvögeln , 1977 .

[11]  D. Langslow.  Weights of blackcaps on migration , 1976 .

[12]  J. Torre-Bueno.  Evaporative cooling and water balance during flight in birds. , 1978, The Journal of experimental biology.

[13]  E. Odum,et al.  Fat-Free Weights of Birds , 1960 .

[14]  P. Berthold,et al.  Die Federlänge: Ein neues nützliches Flügelmaß , 1979 .

[15]  J. Aschoff,et al.  Der ruheumsatz von Vögeln als Funktion der Tageszeit und der Körpergröße , 2005, Journal für Ornithologie.

[16]  W. Calder.  Size, Function, and Life History , 1988 .

[17]  C. Blem.  3 – The Energetics of Migration , 1980 .

[18]  R. Green,et al.  Food and fattening of migrating Warblers in some French Marshlands , 1983 .

[19]  R. Moreau..  The Palaearctic-African bird migration systems , 1972 .

[20]  F. Bairlein.  Body weights and fat deposition of Palaearctic passerine migrants in the central Sahara , 1985, Oecologia.

[21]  C. Fry.  MIGRATION, MOULT AND WEIGHTS OF BIRDS IN NORTHERN GUINEA SAVANNA IN NIGERIA AND GHANA , 1969 .

[22]  E. Gwinner,et al.  Food availability affects migratory restlessness in caged garden warblers (Sylvia borin) , 2004, Naturwissenschaften.