Naturalist Newsletter of October 22, 2007
issued from Yerba Buena Clinic just outside
Pueblo Nuevo Solistahuacan, Chiapas, MÉXICO
about 1740 meters in elevation, ± LAT. 17° 11' 27"N, LONG. -92° 53' 35"W
Down below Inés's house in a wet valley a couple of acres have been cleared for gardening. However, since Inés thought the invaders might succeed in running her off this year, now the whole area is burgeoning with rampant weeds. Inés did halfheartedly sow beans among the weeds but hasn't cared for them, anticipating having to leave anytime. Now the vines are flowering and two bird species are glorifying in gathering nectar from them.
Many White-eared Hummingbirds, whose "ears" are really just white eye-stripes, zip from one clump of flowers to another chattering as they go. Sometimes they spot me and come hovering and buzzing three or four feet before my face a bit tetchy about my presence. Mainly, however, they just rush from bean-flower to bean-flower gathering nectar.
Less common but maybe more interesting are the Cinnamon-bellied Flowerpiercers which, despite being placed in the Emberizinae along with thick-billed sparrrows and brushfinches, are warbler-sized birds looking like slender little American Robins with slate- gray upper parts and dark cinnamon underparts. Like dwarf robins, that is, except for the beak, which is slender, slightly recurved, and with the upper mandible conspicuously hooked at its tip. It's that hooked mandible tip that enables the bird to be a flowerpiercer. You can see a flowerpiercer here.
Instead of approaching flowers from the front the way a decent hummingbird or bee does, Cinnamon-bellied Flowerpiercers go at them from the side. With their hooked beak-tips they puncture and/or rip the blossoms' corollas at the base, down where the nectar resides, enabling the birds to rob the nectar without doing the flowers the favor of pollinating them.
This week in Inés's weedy bean field I've watched the whole process many times but it all happens so quickly that so far I've been unable to see exactly how they do it. The birds approach their flower, do their surgery and withdraw at about the same rate or faster than a hummingbird visits and sups from the front.
While hummingbirds put on a circus flying all over the place, flowerpiercers spend most of their time hidden among the bean vines and weeds, coming into view only when they emerge to pierce a flower. Most of the time you can follow their movements, however, by watching the vegetation shake as the birds hop from stem to stem below.
So, here's a whole species designed to get what it wants without doing the "work" of pollinating the blossoms providing them their sustenance. I suppose the flowers do eventually get pollinated, for hummingbirds do eventually come along, poke in their beaks in the accepted manner, pollinating the flowers even if the flowers already have been robbed dry.
You may recall from back in my Mississippi days my descriptions of how carpenter bees robbed blossoms in a similar manner.
It all just shows what a liberal, experimental, hard- joking streak Mother Nature has, I guess.
Cinnamon-bellied Flowerpiercers occur in highlands from central Mexico south to Nicaragua.