vulture ecology, conservation of vulture, migration of vulture
Himalayan vulture migration is restricted probably in Central India. But nowadays Himalayan vulture recorded in Tamil Nadu, Karnataka, Kerala its a actual migration? If its actual migration flock size is more but only one individuals was recorded so far in that region so its a actual migration are unexpected one?
Which age the bird/s is/are? For immature individuals, distant movements are not unusual, and maybe even expected.
Hi
First, I agree with Igor Fefelov- long rage movements of immature vulture, ranging across hundreds of kms and more are common in various species (e.g., Phipps et al 2013 PLoS One ;-) ). These cases can be considered as dispersal movements (or exploratory movements if the same individual return to its original area).
Second, adult vultures also show such long forays (see our 2015 AmNat). In contrast to what was suggested in a previous answer to a relevant question - i suspect that these movement are NOT motivated by resources dynamics (too expensive, too risky, no evidence for enhanced intake, etc). Instead, i think/speculate that these are long forays are motivated by social reasons, perhaps particularly in an attempt to find mates and new colonies. This explanation is likely to be more important in populations that suffer from recent reduction (i.e., almost all vulture populations...), forcing individuals to search in remote areas. Given the recent collapse in vultures populations throughout the Indian sub-continent it might be that these rare observations (or adults?) might reflect a similar behavior.
Finally, migration is usually considered as long range movements (i.e., beyond normal foraging range) with strong synchronization among conspecifics (i.e., many individuals do the same journey more or less at the same time, even if not together), with a circular route and with strong seasonal (or other temporal scales) pattern. if one wants to establish the argument that observations are a result of migration, these are points worth validating. There are some evidence that vulture migrate in flocks, but these might not be the most valualbe criteria for mirgration clssification, especially at low densiteis.
cheers
Orr
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