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On 19/10/2018 6:55 AM, Don MacNeill wrote:
> It appears that migration is triggered by things other than the
> abundance of food. I see recommendations that hummingbird feeders be
> kept up until freezing. It also might help to finally fatten up those
> needing it for migration.
> On 10/19/2018 7:28 AM, nancy dowd wrote:
>> I don’t feel that feeders delay HBs and other birds from migrating.
>> Other cues, such as day length and many we don’t fully understand,
>> seem to send the majority on their way at roughly the same time each
>> fall. There are always stragglers like this Hummingbird who is
>> benefitting from Marg’s high-energy feeder at this late date. But I
>> doubt feeders are what postponed its departure in the first place.
* it's a really interesting question how one would study this
much-discussed quandary. With the question of whether populations of
Cardinals and Gray Squirrels are sustained by feeders, you could
temporarily flood some feederless area with feeders, and see if these
areas are colonized and then abandoned when feeding is ended, but with
these autumnal stragglers it's hard to see how you could assess if they
do better or worse in migration (or not-migrating as some of the Orioles
seem to do), than they would have if they hadn't been subsidized -- and
then what the selective impact of these individual better-or-worse
outcomes would be on the overall departure dates of subsequent
generations of the population.
fred.
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Frederick W. Schueler & Aleta Karstad
Fragile Inheritance Natural History
Mudpuppy Night in Oxford Mills - http://pinicola.ca/mudpup1.htm
'Daily' Paintings - http://karstaddailypaintings.blogspot.com/
4 St-Lawrence Street Bishops Mills, RR#2 Oxford Station, Ontario K0G 1T0
on the Smiths Falls Limestone Plain 44.87156° N 75.70095° W
(613)258-3107 <bckcdb at istar.ca> http://pinicola.ca/
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"Feasting on Conolophus to the conclusion of consanguinity"
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