Thanks Noah, thanks Mark -- I used binoculars to watch for bees on blooms on silver and red maples four days ago. Not only were there no bees during 30 minutes of observation (sunny, around noon, and not so cold that bees from a hive less than 200 feet from both trees were flying vigorously), but there were no insects of any kind.
Checked again yesterday mid-afternoon. The red maples had several honeybees on them gathering pollen (maybe 25 per tree), as well as a few flies darting around, but the silvers still had nothing. No insects. SOMEHOW they pollinate; in several weeks their seeds will twirl away by the millions.
I'll check again at different times of day (ie. perhaps silver maple nectar and/or pollen is more abundant later in the afternoon?) Perhaps the absence of bees is simply that their populations are still quite low. There aren't nearly as many bees flying now than there will be by late spring. Also, it's likely other plants are providing more copious and easily gather-able resources.
Oh, do the reds provide nectar too? Nibbled on a bud and found a sweet spot, so I'd guess yes, but will keep watching. Apparently bees don't collect pollen and nectar simultaneously.
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Date: 3/25/21 7:35 AM (GMT-05:00)