Following the lead of Hal Opperman I have included the abstract and some
notes from an article in the current Auk. I have always understood the
connection between the shape of the bill and the type of food eaten.
Obviously Godwits do not compete with Sanderlings. But combining the
relationship between the shape of the bill and the type of feeding behavior
in an evolutionary perspective adds a new level to the consideration. This
article has more significance for me after watching the great footage of
the Wrybill in New Zealand in Life of Birds last Tuesday.

Evolution of Foraging Strategies in Shorebirds: An Ecomorphological Approach
Andres Barbosa and Eulalia Moreno
Auk Vol. 116 No. 3, July 1999

Abstract
We studied the relationships between bill and hindlimb morphology and
foraging behavior in 17 species of shorebirds within a phylogenetic
framework. The results show that the evolutionary change in bill length is
related to the evolutionary change in foraging strategies from visual
hunting to tactile hunting. We also found evolutionary relationships
between an increase in bill length and both plunging and sweeping foraging
movements, and a decrease in bill length and "routing" behavior. No
relationships were found between hindlimb morphology and movement pattern
(continuous hunting species vs. pause-travel species). Examining the
evolutionary rate of change in bill and hindlimb structures shows that the
family Scolopacidae and the subfamily Recurvirostrinae evolved more rapidly
than the species of Charadriinae. Results from our ecomorphological and
evolutionary analysis support the hypothesis by Zweers and co-workers on
the evolution of feeding mechanisms in shorebirds.

"Our main goal is to demonstrate the coevolution of morphological and
ecological traits, thereby demonstrating the adaptive value of
morphological traits.

The foraging behavior of shorebirds was divided into 7 basic components:
pecking, probing, walking, stopping, routing, sweeping, and plunging.

"Our results show that at least within the species studied, an
ecomorphological pattern relates bill shape and feeding techniques: longer
bills are adaptively coupled to the use of a tactile foraging strategy,
whereas shorter bills are related to a visual strategy."

"Our results show a link between the evolution of a foraging strategy from
pecking to probing and an increase in the number of mechanoreceptors in the
bill tip, which suggests that these specialized structures are an
evolutionary adaptation for tactile foraging."




Jim Rosso
Issaquah, Washington
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