Ornithophily

Word of the day:  Ornithophily — or obligate pollination by birds, and typically by hummingbirds.  Last summer, I wrote about the coevolutionary “perfect fit” of Ruby-throated Hummingbirds and Cardinal flowers.

Ruby-throated Hummingbird sips nectar from Cardinal Flower picking up pollen on its head

As the hummingbird dips its beak into the long flower tube, the top of its head picks up pollen from the flower’s anthers.  The male (anther) parts of the flower are first to project from a new flower.  A day or two later, the anthers fold down and the female (stigma) projects from the flower tube to receive pollen from younger flowers.  In this way, the plant ensures that it gets cross-pollinated.  See Back Yard Biology, Aug 17, 2013/

Plants that depend on birds for pollination typically provide much higher volumes with higher sugar content of the nectar than insect-pollinated flowers. In contrast, insect-pollinated flowers tend to be heavily scented but have meager nectar with low sugar content.  So it’s no wonder so many insects find ways to enjoy the riches of bird-pollinated flowers without performing the vital pollination service.

A clump of Scarlet Beebalm, Monarda didyma

A large clump of Scarlet or Crimson Beebalm in my garden, with its ornithophilous flowers, awaits its pollinators — the Ruby-throated Hummingbirds.

Honeybee obtaining nectar from scarlet beebalm

Honeybees (but there was only one in the garden) land on the lower part of the flower and climb into the long tube to reach the nectaries at the base of the corolla.  Their slender bodies fit perfectly into the floral tube, completely avoiding the anthers and stigma projecting from the flower.

Honeybee obtaining nectar from scarlet beebalm

Side view of the same approach by the honeybee as it walks into the flower tube.  The Y-tipped stigma and lobe-shaped anthers are clearly far away from the dorsal surface of the bee.

Honeybee obtaining nectar from Scarlet Beebalm

This bee had a good long drink of nectar in this flower before moving on.

Bumblebee obtaining nectar from Scarlet Beebalm

Even the bumblebee tried getting some of that rich sucrose each flower in the cluster provides.  However, the bumblebee’s chunkier body didn’t permit it to actually crawl into the flower.  Some Bumblebee species have a long hairy tongue that helps them reach deep into the flower.  I don’t know if this is one of those species.

I think Bumblebees might also have a different strategy to harvest nectar from flowers they are too large to crawl into.  Its body weight is enough to pull the flower down and allow nectar to flow down the floral tube toward the opening where the bee could lap it up.

Bumblebee obtaining nectar from Scarlet Beebalm

Bumblebees might be large enough to contact the anthers and/or stigma as they try to crawl into the flower. At least that’s what it looks like in this photo.  

Clearwing Hummingbird Moth sipping nectar from Scarlet Beebalm (http://www.wqed.org/birdblog/2012/07/07/a-bad-hair-day/)

Another nectar thief, the Clearwing Hummingbird Moth also enjoys the rich nectar of Scarlet Beebalm without coming close to contacting the flower’s reproductive parts.  Photo by Kate St. John.

Ornithophily has its risks.  If birds don’t find the flowers or weather throws off the timing of the arrival of the birds and flower blooms, the plants risk not getting pollinated at all.  But in the case of the beebalm flowers, bumblebees might be able to make up for the lack of bird pollinators by transferring some pollen.  Why else would they call it bee-balm, and not bird-balm?

12 thoughts on “Ornithophily

    • That surprises me, because the typical HB flower is red or yellow, not white or lilac. But obviously they are clever enough to figure out where the best meals are, regardless of color.

      Yes, red flowers are tough to get a sharp photo of — something about the way the camera sensor perceives red, compared to the way the human eye does.

  1. Gorgeous shots, Sue, of the insects (and especially the honeybee). You captured them beautifully as they entered (or tried to enter) the flowers. That’s a tough task for a macro shot and you pulled it off really well.

    • Thanks, Mike. I only had one bee to work with (a common problem this year), but it was a very persistent one, or a very hungry one. In any case, it spent LOTS of time probing and visiting those flowers.

  2. Nice photos! In Costa Rica the bananaquit is a common little bird, but it’s a nectar thief. It’s favorite tactic is to nip flowers at the base and just bypass the whole elaborate pollination infrastructure at the front. So even ornithophiles might have to be ambivalent . . .

    • Interesting! There certainly are a lot of ways to cheat the system. Fortunately, plants have lots of flowers and lots of nectar, so there seems to be enough for all.

  3. I planted Bee Balm to attract hummingbirds and butterflies. I didn’t know it needed them for pollination. It mostly attracts bees and the occasional Clearwing. I’ll have to pay more attention to what those bees are doing.

    • You probably noticed that the beebalm spreads quite nicely (asexually) by sending up stems from an underground rhizome. So, it is not completely reliant on sexual reproduction for propagation. But I know there has been seed dispersal in my garden, because new plants have appeared in scattered locations over the past few years thanks to the birds or the bees.

      • Oh yeah, I noticed. The first year I put in one plant and the next year it had spread 3 feet! I had to move it to a more confining location along the fence – between the day lilies and the Bishop’s weed, where it has to compete for space.

      • Oh, so that’s the trick, put it next to a stronger competitor. It overgrows everything in my yard, so I just pull it out.

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