By following cyclic and migratory strategies and other opportunistic husbandry practices, the nomads were able to prevent the extinction of their livestock herds and flocks and maintain the bio-diversity of the local breeds (Sidahmed 1996).
Similarly, Ryan, Sales, Tilki and Siara (2009) have underlined the diversity of migratory strategies and social networks of Polish migrants in the UK and how the two influence each other (Ryan et al., 2009).
The observed environmental correlates may at least partially arise from the different environmental niches occupied by birds with different migratory strategies and associated differences in BMR.
Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter.
In the next set of analyses we therefore sought to examine how in this dataset environmental variables and thus environmental niches of birds and their migratory strategy interact with each other, and how this is affected by phylogeny.
We used 15 years of data from a nestbox scheme in the UK to test the assumption of active nest-site choice in three cavity-nesting bird species that differ in breeding and migratory strategy: blue tit (Cyanistes caeruleus), great tit (Parus major) and pied flycatcher (Ficedula hypoleuca).
To do this we fitted linear models in which the environmental variables were individually treated as response variables, and migratory strategy used as a predictor.
And what patterns do we see in genes associated with migration in closely related species that differ in their migratory strategies (Pulido and Berthold 2003; reviewed in Liedvogel et al. 2011)?
To continue producing cashmere of fine quality, the pastoralists need a migratory strategy, quite contrary to the idea of settling down to receive medical aid and livestock husbandry facilities.
If so, the observed differences in brain size between migratory and resident species would not be the consequence, but rather the cause of differences in migratory strategy [18].
