EPOW Ecology Picture of the Week -- Rare Hummingbird With a Twist

Explanation: The two photos above are of the same species of humminbird: the spectacular and rare Velvet-purple Coronet, found only in limited areas of mid-elevation subtropical forest of the western slope of the Andes Mountains in Ecuador and adjoining Columbia.

But what is wrong with the individual on the right? Its bill is ... twisted.

Likely, this is result of a genetic mutation, as no specific injury was apparent.

I watched both individuals feeding from sugar-water supplied from feeders at a local forest lodge near Mindo, Ecuador. The cross-billed individual seemed to have no trouble.

In fact, I speculate that, if somehow the crossed bill provides some unexpected advantage -- such as being able to pry into some flowers for nectar more aptly than can the normal, straight-billed individual -- then perhaps it might incur a slight survival advantage. And perhaps be more apt to pass on its mutation to offspring.

Although this is speculation for this particular instance, in general this is the stuff of evolutionary change and adaptation.

Given a more extreme outcome, perhaps the cross-billed form -- again, only if there was some survival advantage -- could be the vanguard of the development of some future new species. If so, this would be a case of sympatric speciation, that is, the emergence of a new species while still within the geographic range and general habitat of its parent stock.

I wonder, if I could return to this site in future decades, if I would find such a new, cross-billed form flourishing ... although most genetic mutations tend to be maladaptive, and quickly die out.

Only time will tell.

At this angle, the cause of the crossed bill becomes apparent: it is the lower mandible that seems to be skewed to the left and upwards.

But guess what: a number of other bird species also have bills that are naturally crossed or askew! So in some instances, there are natural advantages to this odd asymmetry.

Here's my quiz for the week: what bird species of the world have such asymmetric bills, including crossed bills and bills that curve to the left or the right?

And why?

Give up? Here's the answer.

Crossed bill or not,
this is a truly beautiful bird
of the subtropics!

From this angle, the separation of lower and upper mandibles of the bill seems rather extreme.

Yet, this individual has clearly survived to adult age. Whether it is breeding (and selected by some forgiving or foresightful female) is unknown.

-- Important Update --
18 November 2010
Since the above text was written, new publications have come to light suggesting that there is a disturbing, widespread outbreak of similar beak deformities in many species of birds.
The new observations, reported by Handel et al. (2010) and Van Hemert and Handel (2010) [see references, below], pertain to birds of Alaska and the Pacific Northwest, U.S. According to these studies, some 30 species of birds in this region have been afflicted with beak deformities.  For more information, see their page here sponsored by U.S. Geological Survey's Alaska Science Center, where you can contact them and also report a bird with a deformed beak.
The cause is still uncertain and studies are continuing.
The similar-appearing occurrence in Velvet-purple Coronet in western Ecuador, in this EPOW episode, may be the first reported instance of this affliction in this species or from Ecuador or South America. It may be just an anomalous, unrelated occurrence ... although this is more disturbing than I first thought, and additional observations should be made.

References:
     Handel, C. M., L. M. Pajot, S. M. Matsuoka, C. Van Hemert, J. Terenzi, S. L. Talbot, D. M. Mulcahy, C. U. Meteyer, and K. A. Trust. 2010. Epizootic of beak deformities among wild birds in Alaska: an emerging disease in North America? The Auk 127(4):882-898.
     Van Hemert, C., and C. M. Handel. 2010. Beak deformities in Northwestern Crows: evidence of a multispecies epizootic. The Auk 127(4):746-751.

EPOW - Ecology Picture of the Week