Concept of Endogenous Control of Migration in Warblers

The Autumn Passage of Yellow-Bellied Flycatchers in South Texas

“…Using museum specimens for his analysis, Hussell (1982a) found a difference between adult and immature passage of about 24 days. The similarity of the results from analyzing two very different data sets, together with our finding of highly significant differences between years in distribution vs. no differences in adult median dates of passage, suggest the possibility that autumn migration in this species might be under endogenous control, as has been experimentally determined for several Palearctic sylviid warblers (Berthold 1988). If this is the case, then it is unlikely that population level responses to environmental variability (variance in the opportunity to go south) could be detected in the timing of autumn passage in this species.…”

Value of ringing information for bird conservation in Europe

“…By recording the individual net in which each new bird is trapped and the surrounding habitat along a given transect, a clear picture of species-specific patterns of habitat choice can be obtained, even in situations unfamiliar to a bird (eg a staging area where a nocturnal migrant may have just landed) (Bairlein 1981). The consistency of data relating to the first captures of staging migrants is a clear indication of strong selection mechanisms, allowing migrants to choose sites geared to their characteristic morphology and locomotion (Berthold 1988;Spina et al 1985) (Fig 6). Such preferences indicate the potential vulnerability of the birds to even minor modifications of their selected habitat, offering a further example of how data gathered through ringing can be used to better evaluate the consequences of human activities for birds, in this case through habitat destruction.…”

“…After the first pilot atlas of bird migration was published (Schuz & Weigold 1931), complex migratory strategies, like that of the Blackcap {Sylvia atricapilla), were described through ringing (Berthold 1988, Berthold et al 1990 (Fig 1), as well as those of species wintering in the extreme latitudes of southern Africa (Zink 1973-85, Zink & Bairlein 1995. The movements of waterfowl species have also been investigated using data stored in the EURING (The European Union for Bird Ringing) Data Bank (see below).…”

Genetic differentiation among populations of a migratory songbird: Limnothlypis swainsonii

“…The species' wintering range is split between the Caribbean (primarily Cuba and Jamaica) and mainland Middle America (primarily Mexico and Belize). Experimental studies of long-distance migrant Sylvia warblers (Muscicapidae: Sylviinae) have demonstrated that migratory behaviors such as seasonal fat deposition, timing of migration, and route selection (migratory direction) have a strong genetic basis (Berthold 1988). Experimental crosses between two populations of Blackcaps Sylvia atricapilla differing in migratory behavior showed intermediate migratory restlessness and migratory direction (Berthold 1988, Helbig 1991.…”

“…Experimental studies of long-distance migrant Sylvia warblers (Muscicapidae: Sylviinae) have demonstrated that migratory behaviors such as seasonal fat deposition, timing of migration, and route selection (migratory direction) have a strong genetic basis (Berthold 1988). Experimental crosses between two populations of Blackcaps Sylvia atricapilla differing in migratory behavior showed intermediate migratory restlessness and migratory direction (Berthold 1988, Helbig 1991. Helbig (1991) suggested that these crosses would be selected against because their migrations would end in the Sahara, an unsuitable wintering region.…”