I'll make a preemptive strike before we have another banding /
netting / flagging war .... here is some information from a notable
peer-reviewed journal.
It is not saying that banding doesn't increase mortality by other
means, nor is it generalising to other species. However, it is good
to have some more "cold hard facts" on the issue.
Ringing or colour-banding does not increase predation mortality in
redshanks Tringa totanus
Authors: Cresswell, Will; Lind, Johan; L. Quinn, John; Minderman,
Jeroen; Philip Whitfield, D.
Source: Journal of Avian Biology Volume 38, Number 3, May 2007, pp.
309-316(8)
The use of metal and colour-rings or bands as a means of measuring
survival, movements and behaviour in birds is universal and
fundamental to testing ecological and evolutionary theories. The
practice rests on the largely untested assumption that the rings do
not affect survival. However this assumption may not hold for several
reasons, for example because the `oddity effect' predicts predators
select prey that appear different to their neighbours in order to
avoid the `confusion effect'. We compared the foraging behaviour and
the death rates of redshanks Tringa totanus conspicuously marked with
six colour rings and one metal ring each to unmarked birds in a study
system, where routinely up to 50% of the total population are killed
by avian predators during a winter. If avian predators selectively
target and/or have a higher capture success of ringed birds then we
would predict the proportion of colour-ringed birds in the population
to decline through a winter. The proportion of colour-ringed birds in
the population did not change over the course of three separate
winters, and in one winter the ratio of marked:unmarked birds found
killed by sparrowhawks Accipiter nisus was the same as the ratio of
marked birds alive in the population. In the year with largest sample
size, power was sufficient to detect a greater than 2.2% difference
in predation rate between ringed and unringed groups. The average
kill rate difference between ringed and unringed birds across the
three winters was less than 1% (0.73±2.2%) suggesting that even if
there were differences in predation rate that were not detected
because of low statistical power they were extremely small. There
were no differences in any foraging measures comparing ringed and
unringed birds, suggesting that the rings did not affect the ability
of birds to meet their daily energy budgets. The results showed that
colour-ringed birds were not preferentially targeted or killed by
avian predators, and suggest that the presence of a metal and even
several large colour-rings is unlikely to affect behaviour and
predation mortality even under extreme selection.
Cheers
Russell
Russell Woodford
Birding-Aus List Owner
Geelong Victoria Australia
http://www.birding-aus.org
On 31/05/2007, at 11:56 AM, John Tongue wrote:
As a number have commented, there is some debate about whether
Flame Robins migrate across Bass Strait or not. Some books report
that they do, while others say "there is no firm evidence".
Certainly here in Tassie, they seem to 'disappear' from favoured
summer haunts when the cooler months arrive. However, we have
happened upon large groups of Flame Robins (especially males)
during winter, as well. Perhaps they just move around within
Tassie for the winter (as the Scarlets certainly seem to do), or
perhaps some leave us for warmer climes (though why anyone would
want to leave Tassie, I'm not sure), while others remain behind.
Certainly at least some overwinter in Tasmania. Maybe a worthwhile
banding study for someone??
John Tongue
Ulverstone,
Tasmania
===============================
www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,send the message:
unsubscribe(in the body of the message, with no Subject line)
to:
===============================
--
This email and any attachments may be confidential and if you are not the intended recipient, you must
not disclose or use the information in this email. If received in error, please notify us immediately and
delete the email and all copies. The College does not guarantee that this email is virus or error free. The
attached files are provided, and may only be used, on the basis that the user assumes all responsibility for
any loss, damage or consequence resulting directly from the use of the attached files, whether caused by
the negligence of the sender or not. The content and opinions in this email are not necessarily those of
the College.
==============================www.birding-aus.org
birding-aus.blogspot.com
To unsubscribe from this mailing list,
send the message:
unsubscribe
(in the body of the message, with no Subject line)
to:
=============================
|
