I'm not an expert in Rubus biology, but I consider it interesting that
hummingbirds are one of their pollinators. On this side of the mountains,
the hummingbirds that come through Pullman on the way uphill in late March
and April seem to rely heavily on fruit tree flowers. We have a big (~35 ft
tall) old cherry tree that is usually a heavy bloomer and a hands-down
favorite with the hummers and insect-pollinators of all types. Neither
Rubus nor apple, plum, or cherry trees are "typical" hummingbird flowers.
Hummer-specialist plants tend to have pink or red tubular flowers with no
landing platform for insects.



Rubus and some of the flowering fruit trees may be pinkish, but are often
white. They are not tubular. I think these early flowering plants are
trading off the danger of early flowering (late frost killing the flower
buds, etc.) for the advantage of having no competition for pollinators. The
pollinators have few choices and must work any flowers they can find. I've
often wondered if these early flowerers can be stingier with the nectar, the
price they have to pay for the pollination service.



Kelly Cassidy

Pullman



From: tweeters-bounces at mailman2.u.washington.edu
[mailto:tweeters-bounces at mailman2.u.washington.edu] On Behalf Of Dennis
Paulson
Sent: Wednesday, February 25, 2009 1:10 PM
To: Tweeters
Subject: [Tweeters] salmonberries and red-flowering currants



Hi, tweets.



I know these aren't birds, but they came up in the discussion of Rufous
Hummingbird arrival times.



I've always found it interesting that these two species of Rubus and Ribes,
respectively, were reddish pink in two genera of plants that feature mostly
white-flowered species. They are also early bloomers. They still attract and
are probably pollinated by bumblebees, like others of their genera, but I
think they evolved the red color to take advantage of the fact that
hummingbirds are much more dependably active during the commonly wet and
chilly spring weather, just as we're having today, than bumblebees are.
Being conspicuous to the hummers, the plants have expanded their options
greatly. They are also both Pacific Northwest plant species, coinciding with
an area in which Rufous is a common (and early) spring migrant and breeder.
But note that neither of them is a classical hummingbird flower, bright red
to red-orange with a long, tubular corolla.



Rufous also breeds well to the east of the range of these two plant species,
and I don't know if there are other plants east of the Cascades that have
taken advantage of spring hummingbird migration. Scarlet gilia serve the
birds well where it occurs, but later in the summer.



Most of the "classical" hummingbird flowers in the PNW bloom in late summer
and early fall and coincide with the southbound migration of Rufous and
Calliope through the mountains. Mother Nature plans well!

-----

Dennis Paulson

1724 NE 98 St.

Seattle, WA 98115

206-528-1382

dennispaulson at comcast.net