Subject: EARLY SPRING ARRIVALS: HUMMERS, SWALLOWS, VULTURES
Date: Feb 8 19:26:11 2000
From: Robert Sundstrom - ixoreus at home.com


Tweets,
One other feature of hummingbird arrival in spring might be mentioned. I
don't have any statistical data to confirm this (and I'm too comfortable to
walk downstairs to the book shelves), but my informal sense based on lots of
early spring birding is that male Rufous Hummingbirds arrive a week or two
ahead of most of the females, so that perhaps the latter are more in
synchronization with some roughly average flower/nectar availability. Does
anyone know what arthropods or other miniscule invertebrates Rufous Hummers
prefer when they are not going after nectar?

Bob Sundstrom

----- Original Message -----
From: Mike Patterson <celata at pacifier.com>
To: WAYNE WEBER <WAYNE_WEBER at bc.sympatico.ca>; tweeters
<tweeters at u.washington.edu>
Cc: Multiple recipients of list OBOL <OBOL at BOBO.NWS.ORST.EDU>
Sent: Saturday, February 05, 2000 4:29 PM
Subject: Re: EARLY SPRING ARRIVALS: HUMMERS, SWALLOWS, VULTURES


> Salmonberry and currant are important early forage crops for
> hummingbirds, but hummingbirds along the Oregon Coast arrive
> well in advance of blooming of either of these species and
> they arrive because of day length not because the flowers
> have bloomed.
>
> The literature is rife with this statement about flowering
> plants as if the birds can somehow sense when the flowers
> are coming into bloom. Flower blooming and hummingbird
> arrival are closely synchronized events, both controlled
> by daylength and they have come to be so timed by natural
> selection. But in the case of hummingbirds, the northward
> movement, latitude by latitude is ahead of most bud burst.
>
> Here's an experiment: Let's inventory flowering plants
> when we hear about the arrival of hummingbirds in our
> area. I predict that latitudinal arrival occurs before
> significant blooming mostly along the coast and western
> interior valleys (this is my hypothesis). Further (second
> hypothesis requiring a different data analysis) longitudinal
> dispersal will be more closely correlated to flower blooms.
>
> And now all us citizen scientists have something to test
> through observation and experiment.
>
> My Theoretical Model: Hummingbirds arrive in our area
> before the food source along routes where the weather
> is, on average, mildest and disperse into less temperate
> areas as the conditions change.
>
> And the beauty is: I could be wrong and if I am we all still
> learn something.
>
>
> WAYNE WEBER wrote:
>
> > The arrival of Rufous Hummers in southwest B.C. seems to be timed
> > to the flowering of Salmonberry (Rubus spectabilis) and Red-flowering
> > Currant (Ribes sanguineum), whose flowers are major food sources for
> > hummers. Salmonberry is noted for its long flowering season, with some
> > plants always in bloom by late March, but most not reaching full bloom
> > till well into April. If most of the Rufous Hummers arrived here in
> > late March, they'd probably starve.
> >
>
>
> --
> Mike Patterson Alas, to wear the mantle of Galileo,
> Astoria, OR it is not enough to be persecuted
> celata at pacifier.com by an unkind establishment,
> you must also be right.
> ---Robert Park
> http://www.pacifier.com/~mpatters/bird/bird.html