richwhite44
Member
In the past month two wagtail roosts have been located in densely urbanised parts of Singapore. Initial accounts suggest that this behaviour has not been recorded in these locations before, and maybe never before in Singapore.
The main species involved is grey wagtail. Numbers are in the low hundreds. And these roosts are also pulling in small numbers (less than 10 each) of white, yellow and even forest wagtails.
Until last month, none of these four species would have been considered 'easy' to find in Singapore. Yellow wagtail is probably the easiest, and sometimes in flocks in the historic record. A few single grey wagtails are found non-breeding in drainage channels, occasional white wagtails during migration and likewise for forest wagtail.
This raises all sorts of questions. It is possible that these urban locations, overlooked by birders, have held roosts for years unnoticed. But it is also possible that this is a new behaviour.
Then there are question about how far are birds being drawn in to the roost sites? It seems unlikely that all these birds are spending their days unseen somewhere in Singapore, so some are probably coming from Malaysia? But how is a species like forest wagtail being drawn into the assemblage? And why pick these heavily urbanised locations?
Communal roosting in wagtails is well known - but mixed species appears to be unprecedented or at least very rare?
Urban roosting locations are also well known - for example winter pied wagtail roosts in the UK. But this is an common urban species (which does not match the status of any of the species in this case), and second that they may derive some benefit from slightly elevated temperatures in city centres (which hardly seems relevant in the tropics)?
Any input from experience elsewhere would be welcome - for example, how far might wagtails travel to reach a roost? Any experience elsewhere with multi-species wagtail roosts?
The main species involved is grey wagtail. Numbers are in the low hundreds. And these roosts are also pulling in small numbers (less than 10 each) of white, yellow and even forest wagtails.
Until last month, none of these four species would have been considered 'easy' to find in Singapore. Yellow wagtail is probably the easiest, and sometimes in flocks in the historic record. A few single grey wagtails are found non-breeding in drainage channels, occasional white wagtails during migration and likewise for forest wagtail.
This raises all sorts of questions. It is possible that these urban locations, overlooked by birders, have held roosts for years unnoticed. But it is also possible that this is a new behaviour.
Then there are question about how far are birds being drawn in to the roost sites? It seems unlikely that all these birds are spending their days unseen somewhere in Singapore, so some are probably coming from Malaysia? But how is a species like forest wagtail being drawn into the assemblage? And why pick these heavily urbanised locations?
Communal roosting in wagtails is well known - but mixed species appears to be unprecedented or at least very rare?
Urban roosting locations are also well known - for example winter pied wagtail roosts in the UK. But this is an common urban species (which does not match the status of any of the species in this case), and second that they may derive some benefit from slightly elevated temperatures in city centres (which hardly seems relevant in the tropics)?
Any input from experience elsewhere would be welcome - for example, how far might wagtails travel to reach a roost? Any experience elsewhere with multi-species wagtail roosts?
